follow up comments

## Problem
Basebackup cache is on the hot path of compute startup and is generated
on every request (may be slow).

- Issue: https://github.com/neondatabase/cloud/issues/29353

## Summary of changes
- Add `BasebackupCache` which stores basebackups on local disk.
- Basebackup prepare requests are triggered by
`XLOG_CHECKPOINT_SHUTDOWN` records in the log.
- Limit the size of the cache by number of entries.
- Add `basebackup_cache_enabled` feature flag to TenantConfig.
- Write tests for the cache

## Not implemented yet
- Limit the size of the cache by total size in bytes

---------

Co-authored-by: Aleksandr Sarantsev <aleksandr@neon.tech>

Cargo.lock

@@ -3898,6 +3898,16 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "nu-ansi-term"
+version = "0.46.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "77a8165726e8236064dbb45459242600304b42a5ea24ee2948e18e023bf7ba84"
+dependencies = [
+ "overload",
+ "winapi",
+]
+
 [[package]]
 name = "num"
 version = "0.4.1"
@@ -4182,6 +4192,12 @@ version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4030760ffd992bef45b0ae3f10ce1aba99e33464c90d14dd7c039884963ddc7a"
 
+[[package]]
+name = "overload"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b15813163c1d831bf4a13c3610c05c0d03b39feb07f7e09fa234dac9b15aaf39"
+
 [[package]]
 name = "p256"
 version = "0.11.1"
@@ -4286,6 +4302,7 @@ dependencies = [
  "enumset",
  "fail",
  "futures",
+ "hashlink",
  "hex",
  "hex-literal",
  "http-utils",
@@ -5238,6 +5255,7 @@ dependencies = [
  "tracing-log",
  "tracing-opentelemetry",
  "tracing-subscriber",
+ "tracing-test",
  "tracing-utils",
  "try-lock",
  "typed-json",
@@ -7688,6 +7706,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e8189decb5ac0fa7bc8b96b7cb9b2701d60d48805aca84a238004d665fcc4008"
 dependencies = [
  "matchers",
+ "nu-ansi-term",
  "once_cell",
  "regex",
  "serde",
@@ -7701,6 +7720,27 @@ dependencies = [
  "tracing-serde",
 ]
 
+[[package]]
+name = "tracing-test"
+version = "0.2.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "557b891436fe0d5e0e363427fc7f217abf9ccd510d5136549847bdcbcd011d68"
+dependencies = [
+ "tracing-core",
+ "tracing-subscriber",
+ "tracing-test-macro",
+]
+
+[[package]]
+name = "tracing-test-macro"
+version = "0.2.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "04659ddb06c87d233c566112c1c9c5b9e98256d9af50ec3bc9c8327f873a7568"
+dependencies = [
+ "quote",
+ "syn 2.0.100",
+]
+
 [[package]]
 name = "tracing-utils"
 version = "0.1.0"
@@ -8553,6 +8593,7 @@ dependencies = [
  "tracing",
  "tracing-core",
  "tracing-log",
+ "tracing-subscriber",
  "url",
  "uuid",
  "zeroize",

compute_tools/src/pg_helpers.rs

@@ -213,8 +213,10 @@ impl Escaping for PgIdent {
 
         // Find the first suitable tag that is not present in the string.
         // Postgres' max role/DB name length is 63 bytes, so even in the
-        // worst case it won't take long.
-        while self.contains(&format!("${tag}$")) || self.contains(&format!("${outer_tag}$")) {
+        // worst case it won't take long. Outer tag is always `tag + "x"`,
+        // so if `tag` is not present in the string, `outer_tag` is not
+        // present in the string either.
+        while self.contains(&tag.to_string()) {
             tag += "x";
             outer_tag = tag.clone() + "x";
         }

compute_tools/tests/pg_helpers_tests.rs

@@ -71,6 +71,14 @@ test.escaping = 'here''s a backslash \\ and a quote '' and a double-quote " hoor
             ("name$$$", ("$x$name$$$$x$", "xx")),
             ("name$$$$", ("$x$name$$$$$x$", "xx")),
             ("name$x$", ("$xx$name$x$$xx$", "xxx")),
+            ("x", ("$xx$x$xx$", "xxx")),
+            ("xx", ("$xxx$xx$xxx$", "xxxx")),
+            ("$x", ("$xx$$x$xx$", "xxx")),
+            ("x$", ("$xx$x$$xx$", "xxx")),
+            ("$x$", ("$xx$$x$$xx$", "xxx")),
+            ("xx$", ("$xxx$xx$$xxx$", "xxxx")),
+            ("$xx", ("$xxx$$xx$xxx$", "xxxx")),
+            ("$xx$", ("$xxx$$xx$$xxx$", "xxxx")),
         ];
 
         for (input, expected) in test_cases {

control_plane/src/pageserver.rs

@@ -546,6 +546,16 @@ impl PageServerNode {
                 .map(serde_json::from_str)
                 .transpose()
                 .context("Falied to parse 'sampling_ratio'")?,
+            relsize_snapshot_cache_capacity: settings
+                .remove("relsize snapshot cache capacity")
+                .map(|x| x.parse::<usize>())
+                .transpose()
+                .context("Falied to parse 'relsize_snapshot_cache_capacity' as integer")?,
+            basebackup_cache_enabled: settings
+                .remove("basebackup_cache_enabled")
+                .map(|x| x.parse::<bool>())
+                .transpose()
+                .context("Failed to parse 'basebackup_cache_enabled' as bool")?,
         };
         if !settings.is_empty() {
             bail!("Unrecognized tenant settings: {settings:?}")

libs/pageserver_api/src/config.rs

@@ -183,6 +183,8 @@ pub struct ConfigToml {
     pub enable_tls_page_service_api: bool,
     pub dev_mode: bool,
     pub timeline_import_config: TimelineImportConfig,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub basebackup_cache_config: Option<BasebackupCacheConfig>,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
@@ -235,7 +237,7 @@ pub enum PageServiceProtocolPipelinedBatchingStrategy {
     ScatteredLsn,
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
 #[serde(tag = "mode", rename_all = "kebab-case")]
 pub enum GetVectoredConcurrentIo {
     /// The read path is fully sequential: layers are visited
@@ -308,6 +310,26 @@ pub struct TimelineImportConfig {
     pub import_job_checkpoint_threshold: NonZeroUsize,
 }
 
+#[derive(Debug, Clone, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
+#[serde(default)]
+pub struct BasebackupCacheConfig {
+    #[serde(with = "humantime_serde")]
+    pub cleanup_period: Duration,
+    // FIXME: Support max_size_bytes.
+    // pub max_size_bytes: usize,
+    pub max_size_entries: i64,
+}
+
+impl Default for BasebackupCacheConfig {
+    fn default() -> Self {
+        Self {
+            cleanup_period: Duration::from_secs(60),
+            // max_size_bytes: 1024 * 1024 * 1024, // 1 GiB
+            max_size_entries: 1000,
+        }
+    }
+}
+
 pub mod statvfs {
     pub mod mock {
         #[derive(Debug, Clone, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
@@ -491,6 +513,14 @@ pub struct TenantConfigToml {
     /// Tenant level performance sampling ratio override. Controls the ratio of get page requests
     /// that will get perf sampling for the tenant.
     pub sampling_ratio: Option<Ratio>,
+
+    /// Capacity of relsize snapshot cache (used by replicas).
+    pub relsize_snapshot_cache_capacity: usize,
+
+    /// Enable preparing basebackup on XLOG_CHECKPOINT_SHUTDOWN and using it in basebackup requests.
+    // FIXME: Remove skip_serializing_if when the feature is stable.
+    #[serde(skip_serializing_if = "std::ops::Not::not")]
+    pub basebackup_cache_enabled: bool,
 }
 
 pub mod defaults {
@@ -664,6 +694,7 @@ impl Default for ConfigToml {
                 import_job_soft_size_limit: NonZeroUsize::new(1024 * 1024 * 1024).unwrap(),
                 import_job_checkpoint_threshold: NonZeroUsize::new(128).unwrap(),
             },
+            basebackup_cache_config: None,
         }
     }
 }
@@ -730,6 +761,7 @@ pub mod tenant_conf_defaults {
     pub const DEFAULT_GC_COMPACTION_VERIFICATION: bool = true;
     pub const DEFAULT_GC_COMPACTION_INITIAL_THRESHOLD_KB: u64 = 5 * 1024 * 1024; // 5GB
     pub const DEFAULT_GC_COMPACTION_RATIO_PERCENT: u64 = 100;
+    pub const DEFAULT_RELSIZE_SNAPSHOT_CACHE_CAPACITY: usize = 1000;
 }
 
 impl Default for TenantConfigToml {
@@ -787,6 +819,8 @@ impl Default for TenantConfigToml {
             gc_compaction_initial_threshold_kb: DEFAULT_GC_COMPACTION_INITIAL_THRESHOLD_KB,
             gc_compaction_ratio_percent: DEFAULT_GC_COMPACTION_RATIO_PERCENT,
             sampling_ratio: None,
+            relsize_snapshot_cache_capacity: DEFAULT_RELSIZE_SNAPSHOT_CACHE_CAPACITY,
+            basebackup_cache_enabled: false,
         }
     }
 }

libs/pageserver_api/src/models.rs

@@ -630,6 +630,10 @@ pub struct TenantConfigPatch {
     pub gc_compaction_ratio_percent: FieldPatch<u64>,
     #[serde(skip_serializing_if = "FieldPatch::is_noop")]
     pub sampling_ratio: FieldPatch<Option<Ratio>>,
+    #[serde(skip_serializing_if = "FieldPatch::is_noop")]
+    pub relsize_snapshot_cache_capacity: FieldPatch<usize>,
+    #[serde(skip_serializing_if = "FieldPatch::is_noop")]
+    pub basebackup_cache_enabled: FieldPatch<bool>,
 }
 
 /// Like [`crate::config::TenantConfigToml`], but preserves the information
@@ -759,6 +763,12 @@ pub struct TenantConfig {
 
     #[serde(skip_serializing_if = "Option::is_none")]
     pub sampling_ratio: Option<Option<Ratio>>,
+
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub relsize_snapshot_cache_capacity: Option<usize>,
+
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub basebackup_cache_enabled: Option<bool>,
 }
 
 impl TenantConfig {
@@ -804,6 +814,8 @@ impl TenantConfig {
             mut gc_compaction_initial_threshold_kb,
             mut gc_compaction_ratio_percent,
             mut sampling_ratio,
+            mut relsize_snapshot_cache_capacity,
+            mut basebackup_cache_enabled,
         } = self;
 
         patch.checkpoint_distance.apply(&mut checkpoint_distance);
@@ -905,6 +917,12 @@ impl TenantConfig {
             .gc_compaction_ratio_percent
             .apply(&mut gc_compaction_ratio_percent);
         patch.sampling_ratio.apply(&mut sampling_ratio);
+        patch
+            .relsize_snapshot_cache_capacity
+            .apply(&mut relsize_snapshot_cache_capacity);
+        patch
+            .basebackup_cache_enabled
+            .apply(&mut basebackup_cache_enabled);
 
         Ok(Self {
             checkpoint_distance,
@@ -944,6 +962,8 @@ impl TenantConfig {
             gc_compaction_initial_threshold_kb,
             gc_compaction_ratio_percent,
             sampling_ratio,
+            relsize_snapshot_cache_capacity,
+            basebackup_cache_enabled,
         })
     }
 
@@ -1052,6 +1072,12 @@ impl TenantConfig {
                 .gc_compaction_ratio_percent
                 .unwrap_or(global_conf.gc_compaction_ratio_percent),
             sampling_ratio: self.sampling_ratio.unwrap_or(global_conf.sampling_ratio),
+            relsize_snapshot_cache_capacity: self
+                .relsize_snapshot_cache_capacity
+                .unwrap_or(global_conf.relsize_snapshot_cache_capacity),
+            basebackup_cache_enabled: self
+                .basebackup_cache_enabled
+                .unwrap_or(global_conf.basebackup_cache_enabled),
         }
     }
 }

libs/proxy/tokio-postgres2/src/error/mod.rs

@@ -86,6 +86,27 @@ pub struct DbError {
 }
 
 impl DbError {
+    pub fn new_test_error(code: SqlState, message: String) -> Self {
+        DbError {
+            severity: "ERROR".to_string(),
+            parsed_severity: Some(Severity::Error),
+            code,
+            message,
+            detail: None,
+            hint: None,
+            position: None,
+            where_: None,
+            schema: None,
+            table: None,
+            column: None,
+            datatype: None,
+            constraint: None,
+            file: None,
+            line: None,
+            routine: None,
+        }
+    }
+
     pub(crate) fn parse(fields: &mut ErrorFields<'_>) -> io::Result<DbError> {
         let mut severity = None;
         let mut parsed_severity = None;

pageserver/Cargo.toml

@@ -30,6 +30,7 @@ crc32c.workspace = true
 either.workspace = true
 fail.workspace = true
 futures.workspace = true
+hashlink.workspace = true
 hex.workspace = true
 humantime.workspace = true
 humantime-serde.workspace = true

pageserver/src/basebackup.rs

@@ -144,7 +144,7 @@ where
         replica,
         ctx,
         io_concurrency: IoConcurrency::spawn_from_conf(
-            timeline.conf,
+            timeline.conf.get_vectored_concurrent_io,
             timeline
                 .gate
                 .enter()
@@ -343,7 +343,7 @@ where
             // Gather non-relational files from object storage pages.
             let slru_partitions = self
                 .timeline
-                .get_slru_keyspace(Version::Lsn(self.lsn), self.ctx)
+                .get_slru_keyspace(Version::at(self.lsn), self.ctx)
                 .await?
                 .partition(
                     self.timeline.get_shard_identity(),
@@ -378,7 +378,7 @@ where
             // Otherwise only include init forks of unlogged relations.
             let rels = self
                 .timeline
-                .list_rels(spcnode, dbnode, Version::Lsn(self.lsn), self.ctx)
+                .list_rels(spcnode, dbnode, Version::at(self.lsn), self.ctx)
                 .await?;
             for &rel in rels.iter() {
                 // Send init fork as main fork to provide well formed empty
@@ -517,7 +517,7 @@ where
     async fn add_rel(&mut self, src: RelTag, dst: RelTag) -> Result<(), BasebackupError> {
         let nblocks = self
             .timeline
-            .get_rel_size(src, Version::Lsn(self.lsn), self.ctx)
+            .get_rel_size(src, Version::at(self.lsn), self.ctx)
             .await?;
 
         // If the relation is empty, create an empty file
@@ -577,7 +577,7 @@ where
         let relmap_img = if has_relmap_file {
             let img = self
                 .timeline
-                .get_relmap_file(spcnode, dbnode, Version::Lsn(self.lsn), self.ctx)
+                .get_relmap_file(spcnode, dbnode, Version::at(self.lsn), self.ctx)
                 .await?;
 
             if img.len()
@@ -631,7 +631,7 @@ where
             if !has_relmap_file
                 && self
                     .timeline
-                    .list_rels(spcnode, dbnode, Version::Lsn(self.lsn), self.ctx)
+                    .list_rels(spcnode, dbnode, Version::at(self.lsn), self.ctx)
                     .await?
                     .is_empty()
             {

pageserver/src/basebackup_cache.rs

@@ -0,0 +1,518 @@
+use std::{collections::HashMap, sync::Arc};
+
+use async_compression::tokio::write::GzipEncoder;
+use camino::{Utf8Path, Utf8PathBuf};
+use metrics::core::{AtomicU64, GenericCounter};
+use pageserver_api::{config::BasebackupCacheConfig, models::TenantState};
+use tokio::{
+    io::{AsyncWriteExt, BufWriter},
+    sync::mpsc::{UnboundedReceiver, UnboundedSender},
+};
+use tokio_util::sync::CancellationToken;
+use utils::{
+    id::{TenantId, TenantTimelineId, TimelineId},
+    lsn::Lsn,
+    shard::TenantShardId,
+};
+
+use crate::{
+    basebackup::send_basebackup_tarball,
+    context::{DownloadBehavior, RequestContext},
+    metrics::{BASEBACKUP_CACHE_ENTRIES, BASEBACKUP_CACHE_PREPARE, BASEBACKUP_CACHE_READ},
+    task_mgr::TaskKind,
+    tenant::{
+        Timeline,
+        mgr::{TenantManager, TenantSlot},
+    },
+};
+
+pub struct BasebackupPrepareRequest {
+    pub tenant_shard_id: TenantShardId,
+    pub timeline_id: TimelineId,
+    pub lsn: Lsn,
+}
+
+pub type BasebackupPrepareSender = UnboundedSender<BasebackupPrepareRequest>;
+pub type BasebackupPrepareReceiver = UnboundedReceiver<BasebackupPrepareRequest>;
+
+type BasebackupRemoveEntrySender = UnboundedSender<Utf8PathBuf>;
+type BasebackupRemoveEntryReceiver = UnboundedReceiver<Utf8PathBuf>;
+
+/// BasebackupCache stores cached basebackup archives for timelines on local disk.
+///
+/// The main purpose of this cache is to speed up the startup process of compute nodes
+/// after scaling to zero.
+/// Thus, the basebackup is stored only for the latest LSN of the timeline and with
+/// fixed set of parameters (gzip=true, full_backup=false, replica=false, prev_lsn=none).
+///
+/// The cache receives prepare requests through the `BasebackupPrepareSender` channel,
+/// generates a basebackup from the timeline in the background, and stores it on disk.
+///
+/// Basebackup requests are pretty rare. We expect ~thousands of entries in the cache
+/// and ~1 RPS for get requests.
+pub struct BasebackupCache {
+    data_dir: Utf8PathBuf,
+    config: BasebackupCacheConfig,
+    tenant_manager: Arc<TenantManager>,
+    remove_entry_sender: BasebackupRemoveEntrySender,
+
+    entries: std::sync::Mutex<HashMap<TenantTimelineId, Lsn>>,
+
+    cancel: CancellationToken,
+
+    read_hit_count: GenericCounter<AtomicU64>,
+    read_miss_count: GenericCounter<AtomicU64>,
+    read_err_count: GenericCounter<AtomicU64>,
+
+    prepare_ok_count: GenericCounter<AtomicU64>,
+    prepare_skip_count: GenericCounter<AtomicU64>,
+    prepare_err_count: GenericCounter<AtomicU64>,
+}
+
+impl BasebackupCache {
+    /// Creates a BasebackupCache and spawns the background task.
+    /// The initialization of the cache is performed in the background and does not
+    /// block the caller. The cache will return `None` for any get requests until
+    /// initialization is complete.
+    pub fn spawn(
+        runtime_handle: &tokio::runtime::Handle,
+        data_dir: Utf8PathBuf,
+        config: Option<BasebackupCacheConfig>,
+        prepare_receiver: BasebackupPrepareReceiver,
+        tenant_manager: Arc<TenantManager>,
+        cancel: CancellationToken,
+    ) -> Arc<Self> {
+        let (remove_entry_sender, remove_entry_receiver) = tokio::sync::mpsc::unbounded_channel();
+
+        let enabled = config.is_some();
+
+        let cache = Arc::new(BasebackupCache {
+            data_dir,
+            config: config.unwrap_or_default(),
+            tenant_manager,
+            remove_entry_sender,
+
+            entries: std::sync::Mutex::new(HashMap::new()),
+
+            cancel,
+
+            read_hit_count: BASEBACKUP_CACHE_READ.with_label_values(&["hit"]),
+            read_miss_count: BASEBACKUP_CACHE_READ.with_label_values(&["miss"]),
+            read_err_count: BASEBACKUP_CACHE_READ.with_label_values(&["error"]),
+
+            prepare_ok_count: BASEBACKUP_CACHE_PREPARE.with_label_values(&["ok"]),
+            prepare_skip_count: BASEBACKUP_CACHE_PREPARE.with_label_values(&["skip"]),
+            prepare_err_count: BASEBACKUP_CACHE_PREPARE.with_label_values(&["error"]),
+        });
+
+        if enabled {
+            runtime_handle.spawn(
+                cache
+                    .clone()
+                    .background(prepare_receiver, remove_entry_receiver),
+            );
+        }
+
+        cache
+    }
+
+    /// Gets a basebackup entry from the cache.
+    /// If the entry is found, opens a file with the basebackup archive and returns it.
+    /// The open file descriptor will prevent the file system from deleting the file
+    /// even if the entry is removed from the cache in the background.
+    pub async fn get(
+        &self,
+        tenant_id: TenantId,
+        timeline_id: TimelineId,
+        lsn: Lsn,
+    ) -> Option<tokio::fs::File> {
+        // Fast path. Check if the entry exists using the in-memory state.
+        let tti = TenantTimelineId::new(tenant_id, timeline_id);
+        if self.entries.lock().unwrap().get(&tti) != Some(&lsn) {
+            self.read_miss_count.inc();
+            return None;
+        }
+
+        let path = self.entry_path(tenant_id, timeline_id, lsn);
+
+        match tokio::fs::File::open(path).await {
+            Ok(file) => {
+                self.read_hit_count.inc();
+                Some(file)
+            }
+            Err(e) => {
+                if e.kind() == std::io::ErrorKind::NotFound {
+                    // We may end up here if the basebackup was concurrently removed by the cleanup task.
+                    self.read_miss_count.inc();
+                } else {
+                    self.read_err_count.inc();
+                    tracing::warn!("Unexpected error opening basebackup cache file: {:?}", e);
+                }
+                None
+            }
+        }
+    }
+
+    // Private methods.
+
+    fn entry_filename(tenant_id: TenantId, timeline_id: TimelineId, lsn: Lsn) -> String {
+        // The default format for LSN is 0/ABCDEF.
+        // The backslash is not filename friendly, so serialize it as plain hex.
+        let lsn = lsn.0;
+        format!("basebackup_{tenant_id}_{timeline_id}_{lsn:016X}.tar.gz")
+    }
+
+    fn entry_path(&self, tenant_id: TenantId, timeline_id: TimelineId, lsn: Lsn) -> Utf8PathBuf {
+        self.data_dir
+            .join(Self::entry_filename(tenant_id, timeline_id, lsn))
+    }
+
+    fn entry_tmp_path(
+        &self,
+        tenant_id: TenantId,
+        timeline_id: TimelineId,
+        lsn: Lsn,
+    ) -> Utf8PathBuf {
+        self.data_dir
+            .join("tmp")
+            .join(Self::entry_filename(tenant_id, timeline_id, lsn))
+    }
+
+    fn parse_entry_filename(filename: &str) -> Option<(TenantId, TimelineId, Lsn)> {
+        let parts: Vec<&str> = filename
+            .strip_prefix("basebackup_")?
+            .strip_suffix(".tar.gz")?
+            .split('_')
+            .collect();
+        if parts.len() != 3 {
+            return None;
+        }
+        let tenant_id = parts[0].parse::<TenantId>().ok()?;
+        let timeline_id = parts[1].parse::<TimelineId>().ok()?;
+        let lsn = Lsn(u64::from_str_radix(parts[2], 16).ok()?);
+
+        Some((tenant_id, timeline_id, lsn))
+    }
+
+    async fn cleanup(&self) -> anyhow::Result<()> {
+        // Cleanup tmp directory.
+        let tmp_dir = self.data_dir.join("tmp");
+        let mut tmp_dir = tokio::fs::read_dir(&tmp_dir).await?;
+        while let Some(dir_entry) = tmp_dir.next_entry().await? {
+            if let Err(e) = tokio::fs::remove_file(dir_entry.path()).await {
+                tracing::warn!("Failed to remove basebackup cache tmp file: {:#}", e);
+            }
+        }
+
+        // Remove outdated entries.
+        let entries_old = self.entries.lock().unwrap().clone();
+        let mut entries_new = HashMap::new();
+        for (tenant_shard_id, tenant_slot) in self.tenant_manager.list() {
+            if !tenant_shard_id.is_shard_zero() {
+                continue;
+            }
+            let TenantSlot::Attached(tenant) = tenant_slot else {
+                continue;
+            };
+            let tenant_id = tenant_shard_id.tenant_id;
+
+            for timeline in tenant.list_timelines() {
+                let tti = TenantTimelineId::new(tenant_id, timeline.timeline_id);
+                if let Some(&entry_lsn) = entries_old.get(&tti) {
+                    if timeline.get_last_record_lsn() <= entry_lsn {
+                        entries_new.insert(tti, entry_lsn);
+                    }
+                }
+            }
+        }
+
+        for (&tti, &lsn) in entries_old.iter() {
+            if !entries_new.contains_key(&tti) {
+                self.remove_entry_sender
+                    .send(self.entry_path(tti.tenant_id, tti.timeline_id, lsn))
+                    .unwrap();
+            }
+        }
+
+        BASEBACKUP_CACHE_ENTRIES.set(entries_new.len() as i64);
+        *self.entries.lock().unwrap() = entries_new;
+
+        Ok(())
+    }
+
+    async fn on_startup(&self) -> anyhow::Result<()> {
+        // Create data_dir and tmp directory if they do not exist.
+        tokio::fs::create_dir_all(&self.data_dir.join("tmp"))
+            .await
+            .map_err(|e| {
+                anyhow::anyhow!(
+                    "Failed to create basebackup cache data_dir {:?}: {:?}",
+                    self.data_dir,
+                    e
+                )
+            })?;
+
+        // Read existing entries from the data_dir and add them to in-memory state.
+        let mut entries = HashMap::new();
+        let mut dir = tokio::fs::read_dir(&self.data_dir).await?;
+        while let Some(dir_entry) = dir.next_entry().await? {
+            let filename = dir_entry.file_name();
+
+            if filename == "tmp" {
+                // Skip the tmp directory.
+                continue;
+            }
+
+            let parsed = Self::parse_entry_filename(filename.to_string_lossy().as_ref());
+            let Some((tenant_id, timeline_id, lsn)) = parsed else {
+                tracing::warn!("Invalid basebackup cache file name: {:?}", filename);
+                continue;
+            };
+
+            let tti = TenantTimelineId::new(tenant_id, timeline_id);
+
+            use std::collections::hash_map::Entry::*;
+
+            match entries.entry(tti) {
+                Occupied(mut entry) => {
+                    let entry_lsn = *entry.get();
+                    // Leave only the latest entry, remove the old one.
+                    if lsn < entry_lsn {
+                        self.remove_entry_sender.send(self.entry_path(
+                            tenant_id,
+                            timeline_id,
+                            lsn,
+                        ))?;
+                    } else if lsn > entry_lsn {
+                        self.remove_entry_sender.send(self.entry_path(
+                            tenant_id,
+                            timeline_id,
+                            entry_lsn,
+                        ))?;
+                        entry.insert(lsn);
+                    } else {
+                        // Two different filenames parsed to the same timline_id and LSN.
+                        // Should never happen.
+                        return Err(anyhow::anyhow!(
+                            "Duplicate basebackup cache entry with the same LSN: {:?}",
+                            filename
+                        ));
+                    }
+                }
+                Vacant(entry) => {
+                    entry.insert(lsn);
+                }
+            }
+        }
+
+        BASEBACKUP_CACHE_ENTRIES.set(entries.len() as i64);
+        *self.entries.lock().unwrap() = entries;
+
+        Ok(())
+    }
+
+    async fn background(
+        self: Arc<Self>,
+        mut prepare_receiver: BasebackupPrepareReceiver,
+        mut remove_entry_receiver: BasebackupRemoveEntryReceiver,
+    ) {
+        // Panic in the background is a safe fallback.
+        // It will drop receivers and the cache will be effectively disabled.
+        self.on_startup()
+            .await
+            .expect("Failed to initialize basebackup cache");
+
+        let mut cleanup_ticker = tokio::time::interval(self.config.cleanup_period);
+        cleanup_ticker.set_missed_tick_behavior(tokio::time::MissedTickBehavior::Skip);
+
+        loop {
+            tokio::select! {
+                Some(req) = prepare_receiver.recv() => {
+                    if let Err(err) = self.prepare_basebackup(
+                        req.tenant_shard_id,
+                        req.timeline_id,
+                        req.lsn,
+                    ).await {
+                        tracing::info!("Failed to prepare basebackup: {:#}", err);
+                        self.prepare_err_count.inc();
+                        continue;
+                    }
+                }
+                Some(req) = remove_entry_receiver.recv() => {
+                    if let Err(e) = tokio::fs::remove_file(req).await {
+                        tracing::warn!("Failed to remove basebackup cache file: {:#}", e);
+                    }
+                }
+                _ = cleanup_ticker.tick() => {
+                    self.cleanup().await.unwrap_or_else(|e| {
+                        tracing::warn!("Failed to clean up basebackup cache: {:#}", e);
+                    });
+                }
+                _ = self.cancel.cancelled() => {
+                    tracing::info!("BasebackupCache background task cancelled");
+                    break;
+                }
+            }
+        }
+    }
+
+    /// Prepare a basebackup for the given timeline.
+    ///
+    /// If the basebackup already exists with a higher LSN or the timeline already
+    /// has a higher last_record_lsn, skip the preparation.
+    ///
+    /// The basebackup is prepared in a temporary directory and then moved to the final
+    /// location to make the operation atomic.
+    async fn prepare_basebackup(
+        &self,
+        tenant_shard_id: TenantShardId,
+        timeline_id: TimelineId,
+        req_lsn: Lsn,
+    ) -> anyhow::Result<()> {
+        tracing::info!(
+            tenant_id = %tenant_shard_id.tenant_id,
+            %timeline_id,
+            %req_lsn,
+            "Preparing basebackup for timeline",
+        );
+
+        let tti = TenantTimelineId::new(tenant_shard_id.tenant_id, timeline_id);
+
+        {
+            let entries = self.entries.lock().unwrap();
+            if let Some(&entry_lsn) = entries.get(&tti) {
+                if entry_lsn >= req_lsn {
+                    tracing::info!(
+                        %timeline_id,
+                        %req_lsn,
+                        %entry_lsn,
+                        "Basebackup entry already exists for timeline with higher LSN, skipping basebackup",
+                    );
+                    self.prepare_skip_count.inc();
+                    return Ok(());
+                }
+            }
+
+            if entries.len() as i64 >= self.config.max_size_entries {
+                tracing::info!(
+                    %timeline_id,
+                    %req_lsn,
+                    "Basebackup cache is full, skipping basebackup",
+                );
+                self.prepare_skip_count.inc();
+                return Ok(());
+            }
+        }
+
+        let tenant = self
+            .tenant_manager
+            .get_attached_tenant_shard(tenant_shard_id)?;
+
+        let tenant_state = tenant.current_state();
+        if tenant_state != TenantState::Active {
+            anyhow::bail!(
+                "Tenant {} is not active, current state: {:?}",
+                tenant_shard_id.tenant_id,
+                tenant_state
+            )
+        }
+
+        let timeline = tenant.get_timeline(timeline_id, true)?;
+
+        let last_record_lsn = timeline.get_last_record_lsn();
+        if last_record_lsn > req_lsn {
+            tracing::info!(
+                %timeline_id,
+                %req_lsn,
+                %last_record_lsn,
+                "Timeline has a higher LSN than the requested one, skipping basebackup",
+            );
+            self.prepare_skip_count.inc();
+            return Ok(());
+        }
+
+        let entry_tmp_path = self.entry_tmp_path(tenant_shard_id.tenant_id, timeline_id, req_lsn);
+
+        let res = self
+            .prepare_basebackup_tmp(&entry_tmp_path, &timeline, req_lsn)
+            .await;
+
+        if let Err(err) = res {
+            tracing::info!("Failed to prepare basebackup tmp file: {:#}", err);
+            // Try to clean up tmp file. If we fail, the background clean up task will take care of it.
+            match tokio::fs::remove_file(&entry_tmp_path).await {
+                Ok(_) => {}
+                Err(e) if e.kind() == std::io::ErrorKind::NotFound => {}
+                Err(e) => {
+                    tracing::info!("Failed to remove basebackup tmp file: {:?}", e);
+                }
+            }
+            return Err(err);
+        }
+
+        // Move the tmp file to the final location atomically.
+        let entry_path = self.entry_path(tenant_shard_id.tenant_id, timeline_id, req_lsn);
+        tokio::fs::rename(&entry_tmp_path, &entry_path).await?;
+
+        let mut entries = self.entries.lock().unwrap();
+        if let Some(old_lsn) = entries.insert(tti, req_lsn) {
+            // Remove the old entry if it exists.
+            self.remove_entry_sender
+                .send(self.entry_path(tenant_shard_id.tenant_id, timeline_id, old_lsn))
+                .unwrap();
+        }
+        BASEBACKUP_CACHE_ENTRIES.set(entries.len() as i64);
+
+        self.prepare_ok_count.inc();
+        Ok(())
+    }
+
+    /// Prepares a basebackup in a temporary file.
+    async fn prepare_basebackup_tmp(
+        &self,
+        emptry_tmp_path: &Utf8Path,
+        timeline: &Arc<Timeline>,
+        req_lsn: Lsn,
+    ) -> anyhow::Result<()> {
+        let ctx = RequestContext::new(TaskKind::BasebackupCache, DownloadBehavior::Download);
+        let ctx = ctx.with_scope_timeline(timeline);
+
+        let file = tokio::fs::File::create(emptry_tmp_path).await?;
+        let mut writer = BufWriter::new(file);
+
+        let mut encoder = GzipEncoder::with_quality(
+            &mut writer,
+            // Level::Best because compression is not on the hot path of basebackup requests.
+            // The decompression is almost not affected by the compression level.
+            async_compression::Level::Best,
+        );
+
+        // We may receive a request before the WAL record is applied to the timeline.
+        // Wait for the requested LSN to be applied.
+        timeline
+            .wait_lsn(
+                req_lsn,
+                crate::tenant::timeline::WaitLsnWaiter::BaseBackupCache,
+                crate::tenant::timeline::WaitLsnTimeout::Default,
+                &ctx,
+            )
+            .await?;
+
+        send_basebackup_tarball(
+            &mut encoder,
+            timeline,
+            Some(req_lsn),
+            None,
+            false,
+            false,
+            &ctx,
+        )
+        .await?;
+
+        encoder.shutdown().await?;
+        writer.flush().await?;
+        writer.into_inner().sync_all().await?;
+
+        Ok(())
+    }
+}

pageserver/src/bin/pageserver.rs

@@ -16,6 +16,7 @@ use http_utils::tls_certs::ReloadingCertificateResolver;
 use metrics::launch_timestamp::{LaunchTimestamp, set_launch_timestamp_metric};
 use metrics::set_build_info_metric;
 use nix::sys::socket::{setsockopt, sockopt};
+use pageserver::basebackup_cache::BasebackupCache;
 use pageserver::config::{PageServerConf, PageserverIdentity, ignored_fields};
 use pageserver::controller_upcall_client::StorageControllerUpcallClient;
 use pageserver::deletion_queue::DeletionQueue;
@@ -541,6 +542,8 @@ fn start_pageserver(
         pageserver::l0_flush::L0FlushGlobalState::new(conf.l0_flush.clone());
 
     // Scan the local 'tenants/' directory and start loading the tenants
+    let (basebackup_prepare_sender, basebackup_prepare_receiver) =
+        tokio::sync::mpsc::unbounded_channel();
     let deletion_queue_client = deletion_queue.new_client();
     let background_purges = mgr::BackgroundPurges::default();
     let tenant_manager = BACKGROUND_RUNTIME.block_on(mgr::init_tenant_mgr(
@@ -551,12 +554,22 @@ fn start_pageserver(
             remote_storage: remote_storage.clone(),
             deletion_queue_client,
             l0_flush_global_state,
+            basebackup_prepare_sender,
         },
         order,
         shutdown_pageserver.clone(),
     ))?;
     let tenant_manager = Arc::new(tenant_manager);
 
+    let basebackup_cache = BasebackupCache::spawn(
+        BACKGROUND_RUNTIME.handle(),
+        conf.basebackup_cache_dir(),
+        conf.basebackup_cache_config.clone(),
+        basebackup_prepare_receiver,
+        Arc::clone(&tenant_manager),
+        shutdown_pageserver.child_token(),
+    );
+
     BACKGROUND_RUNTIME.spawn({
         let shutdown_pageserver = shutdown_pageserver.clone();
         let drive_init = async move {
@@ -763,6 +776,7 @@ fn start_pageserver(
         } else {
             None
         },
+        basebackup_cache,
     );
 
     // All started up! Now just sit and wait for shutdown signal.

pageserver/src/config.rs

@@ -232,6 +232,8 @@ pub struct PageServerConf {
     pub dev_mode: bool,
 
     pub timeline_import_config: pageserver_api::config::TimelineImportConfig,
+
+    pub basebackup_cache_config: Option<pageserver_api::config::BasebackupCacheConfig>,
 }
 
 /// Token for authentication to safekeepers
@@ -261,6 +263,10 @@ impl PageServerConf {
         self.workdir.join("metadata.json")
     }
 
+    pub fn basebackup_cache_dir(&self) -> Utf8PathBuf {
+        self.workdir.join("basebackup_cache")
+    }
+
     pub fn deletion_list_path(&self, sequence: u64) -> Utf8PathBuf {
         // Encode a version in the filename, so that if we ever switch away from JSON we can
         // increment this.
@@ -407,6 +413,7 @@ impl PageServerConf {
             enable_tls_page_service_api,
             dev_mode,
             timeline_import_config,
+            basebackup_cache_config,
         } = config_toml;
 
         let mut conf = PageServerConf {
@@ -461,6 +468,7 @@ impl PageServerConf {
             enable_tls_page_service_api,
             dev_mode,
             timeline_import_config,
+            basebackup_cache_config,
 
             // ------------------------------------------------------------
             // fields that require additional validation or custom handling
@@ -544,6 +552,23 @@ impl PageServerConf {
                     ratio.numerator, ratio.denominator
                 )
             );
+
+            let url = Url::parse(&tracing_config.export_config.endpoint)
+                .map_err(anyhow::Error::msg)
+                .with_context(|| {
+                    format!(
+                        "tracing endpoint URL is invalid : {}",
+                        tracing_config.export_config.endpoint
+                    )
+                })?;
+
+            ensure!(
+                url.scheme() == "http" || url.scheme() == "https",
+                format!(
+                    "tracing endpoint URL must start with http:// or https://: {}",
+                    tracing_config.export_config.endpoint
+                )
+            );
         }
 
         IndexEntry::validate_checkpoint_distance(conf.default_tenant_conf.checkpoint_distance)
@@ -660,4 +685,25 @@ mod tests {
         PageServerConf::parse_and_validate(NodeId(0), config_toml, &workdir)
             .expect("parse_and_validate");
     }
+
+    #[test]
+    fn test_config_tracing_endpoint_is_invalid() {
+        let input = r#"
+            control_plane_api = "http://localhost:6666"
+
+            [tracing]
+
+            sampling_ratio = { numerator = 1, denominator = 0 }
+
+            [tracing.export_config]
+            endpoint = "localhost:4317"
+            protocol = "http-binary"
+            timeout = "1ms"
+        "#;
+        let config_toml = toml_edit::de::from_str::<pageserver_api::config::ConfigToml>(input)
+            .expect("config has valid fields");
+        let workdir = Utf8PathBuf::from("/nonexistent");
+        PageServerConf::parse_and_validate(NodeId(0), config_toml, &workdir)
+            .expect_err("parse_and_validate should fail for endpoint without scheme");
+    }
 }

pageserver/src/consumption_metrics/metrics.rs

@@ -18,12 +18,25 @@ use crate::tenant::timeline::logical_size::CurrentLogicalSize;
 // management.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, serde::Serialize, serde::Deserialize)]
 pub(super) enum Name {
-    /// Timeline last_record_lsn, absolute
+    /// Timeline last_record_lsn, absolute.
     #[serde(rename = "written_size")]
     WrittenSize,
     /// Timeline last_record_lsn, incremental
     #[serde(rename = "written_data_bytes_delta")]
     WrittenSizeDelta,
+    /// Written bytes only on this timeline (not including ancestors):
+    /// written_size - ancestor_lsn
+    ///
+    /// On the root branch, this is equivalent to `written_size`.
+    #[serde(rename = "written_size_since_parent")]
+    WrittenSizeSinceParent,
+    /// PITR history size only on this timeline (not including ancestors):
+    /// last_record_lsn - max(pitr_cutoff, ancestor_lsn).
+    ///
+    /// On the root branch, this is its entire PITR history size. Not emitted if GC hasn't computed
+    /// the PITR cutoff yet. 0 if PITR is disabled.
+    #[serde(rename = "pitr_history_size_since_parent")]
+    PitrHistorySizeSinceParent,
     /// Timeline logical size
     #[serde(rename = "timeline_logical_size")]
     LogicalSize,
@@ -157,6 +170,32 @@ impl MetricsKey {
         .incremental_values()
     }
 
+    /// `written_size` - `ancestor_lsn`.
+    const fn written_size_since_parent(
+        tenant_id: TenantId,
+        timeline_id: TimelineId,
+    ) -> AbsoluteValueFactory {
+        MetricsKey {
+            tenant_id,
+            timeline_id: Some(timeline_id),
+            metric: Name::WrittenSizeSinceParent,
+        }
+        .absolute_values()
+    }
+
+    /// `written_size` - max(`pitr_cutoff`, `ancestor_lsn`).
+    const fn pitr_history_size_since_parent(
+        tenant_id: TenantId,
+        timeline_id: TimelineId,
+    ) -> AbsoluteValueFactory {
+        MetricsKey {
+            tenant_id,
+            timeline_id: Some(timeline_id),
+            metric: Name::PitrHistorySizeSinceParent,
+        }
+        .absolute_values()
+    }
+
     /// Exact [`Timeline::get_current_logical_size`].
     ///
     /// [`Timeline::get_current_logical_size`]: crate::tenant::Timeline::get_current_logical_size
@@ -334,7 +373,13 @@ impl TenantSnapshot {
 struct TimelineSnapshot {
     loaded_at: (Lsn, SystemTime),
     last_record_lsn: Lsn,
+    ancestor_lsn: Lsn,
     current_exact_logical_size: Option<u64>,
+    /// Whether PITR is enabled (pitr_interval > 0).
+    pitr_enabled: bool,
+    /// The PITR cutoff LSN. None if not yet initialized. If PITR is disabled, this is approximately
+    /// Some(last_record_lsn), but may lag behind it since it's computed periodically.
+    pitr_cutoff: Option<Lsn>,
 }
 
 impl TimelineSnapshot {
@@ -354,6 +399,9 @@ impl TimelineSnapshot {
         } else {
             let loaded_at = t.loaded_at;
             let last_record_lsn = t.get_last_record_lsn();
+            let ancestor_lsn = t.get_ancestor_lsn();
+            let pitr_enabled = !t.get_pitr_interval().is_zero();
+            let pitr_cutoff = t.gc_info.read().unwrap().cutoffs.time;
 
             let current_exact_logical_size = {
                 let span = tracing::info_span!("collect_metrics_iteration", tenant_id = %t.tenant_shard_id.tenant_id, timeline_id = %t.timeline_id);
@@ -373,7 +421,10 @@ impl TimelineSnapshot {
             Ok(Some(TimelineSnapshot {
                 loaded_at,
                 last_record_lsn,
+                ancestor_lsn,
                 current_exact_logical_size,
+                pitr_enabled,
+                pitr_cutoff,
             }))
         }
     }
@@ -424,6 +475,8 @@ impl TimelineSnapshot {
 
         let up_to = now;
 
+        let written_size_last = written_size_now.value.max(prev.1); // don't regress
+
         if let Some(delta) = written_size_now.value.checked_sub(prev.1) {
             let key_value = written_size_delta_key.from_until(prev.0, up_to, delta);
             // written_size_delta
@@ -441,6 +494,27 @@ impl TimelineSnapshot {
             });
         }
 
+        // Compute the branch-local written size.
+        let written_size_since_parent_key =
+            MetricsKey::written_size_since_parent(tenant_id, timeline_id);
+        metrics.push(
+            written_size_since_parent_key
+                .at(now, written_size_last.saturating_sub(self.ancestor_lsn.0)),
+        );
+
+        // Compute the branch-local PITR history size. Not emitted if GC hasn't yet computed the
+        // PITR cutoff. 0 if PITR is disabled.
+        let pitr_history_size_since_parent_key =
+            MetricsKey::pitr_history_size_since_parent(tenant_id, timeline_id);
+        if !self.pitr_enabled {
+            metrics.push(pitr_history_size_since_parent_key.at(now, 0));
+        } else if let Some(pitr_cutoff) = self.pitr_cutoff {
+            metrics.push(pitr_history_size_since_parent_key.at(
+                now,
+                written_size_last.saturating_sub(pitr_cutoff.max(self.ancestor_lsn).0),
+            ));
+        }
+
         {
             let factory = MetricsKey::timeline_logical_size(tenant_id, timeline_id);
             let current_or_previous = self

pageserver/src/consumption_metrics/metrics/tests.rs

@@ -12,12 +12,17 @@ fn startup_collected_timeline_metrics_before_advancing() {
     let cache = HashMap::new();
 
     let initdb_lsn = Lsn(0x10000);
+    let pitr_cutoff = Lsn(0x11000);
     let disk_consistent_lsn = Lsn(initdb_lsn.0 * 2);
+    let logical_size = 0x42000;
 
     let snap = TimelineSnapshot {
         loaded_at: (disk_consistent_lsn, SystemTime::now()),
         last_record_lsn: disk_consistent_lsn,
-        current_exact_logical_size: Some(0x42000),
+        ancestor_lsn: Lsn(0),
+        current_exact_logical_size: Some(logical_size),
+        pitr_enabled: true,
+        pitr_cutoff: Some(pitr_cutoff),
     };
 
     let now = DateTime::<Utc>::from(SystemTime::now());
@@ -33,7 +38,11 @@ fn startup_collected_timeline_metrics_before_advancing() {
                 0
             ),
             MetricsKey::written_size(tenant_id, timeline_id).at(now, disk_consistent_lsn.0),
-            MetricsKey::timeline_logical_size(tenant_id, timeline_id).at(now, 0x42000)
+            MetricsKey::written_size_since_parent(tenant_id, timeline_id)
+                .at(now, disk_consistent_lsn.0),
+            MetricsKey::pitr_history_size_since_parent(tenant_id, timeline_id)
+                .at(now, disk_consistent_lsn.0 - pitr_cutoff.0),
+            MetricsKey::timeline_logical_size(tenant_id, timeline_id).at(now, logical_size)
         ]
     );
 }
@@ -49,7 +58,9 @@ fn startup_collected_timeline_metrics_second_round() {
     let before = DateTime::<Utc>::from(before);
 
     let initdb_lsn = Lsn(0x10000);
+    let pitr_cutoff = Lsn(0x11000);
     let disk_consistent_lsn = Lsn(initdb_lsn.0 * 2);
+    let logical_size = 0x42000;
 
     let mut metrics = Vec::new();
     let cache = HashMap::from([MetricsKey::written_size(tenant_id, timeline_id)
@@ -59,7 +70,10 @@ fn startup_collected_timeline_metrics_second_round() {
     let snap = TimelineSnapshot {
         loaded_at: (disk_consistent_lsn, init),
         last_record_lsn: disk_consistent_lsn,
-        current_exact_logical_size: Some(0x42000),
+        ancestor_lsn: Lsn(0),
+        current_exact_logical_size: Some(logical_size),
+        pitr_enabled: true,
+        pitr_cutoff: Some(pitr_cutoff),
     };
 
     snap.to_metrics(tenant_id, timeline_id, now, &mut metrics, &cache);
@@ -69,7 +83,11 @@ fn startup_collected_timeline_metrics_second_round() {
         &[
             MetricsKey::written_size_delta(tenant_id, timeline_id).from_until(before, now, 0),
             MetricsKey::written_size(tenant_id, timeline_id).at(now, disk_consistent_lsn.0),
-            MetricsKey::timeline_logical_size(tenant_id, timeline_id).at(now, 0x42000)
+            MetricsKey::written_size_since_parent(tenant_id, timeline_id)
+                .at(now, disk_consistent_lsn.0),
+            MetricsKey::pitr_history_size_since_parent(tenant_id, timeline_id)
+                .at(now, disk_consistent_lsn.0 - pitr_cutoff.0),
+            MetricsKey::timeline_logical_size(tenant_id, timeline_id).at(now, logical_size)
         ]
     );
 }
@@ -86,7 +104,9 @@ fn startup_collected_timeline_metrics_nth_round_at_same_lsn() {
     let before = DateTime::<Utc>::from(before);
 
     let initdb_lsn = Lsn(0x10000);
+    let pitr_cutoff = Lsn(0x11000);
     let disk_consistent_lsn = Lsn(initdb_lsn.0 * 2);
+    let logical_size = 0x42000;
 
     let mut metrics = Vec::new();
     let cache = HashMap::from([
@@ -103,7 +123,10 @@ fn startup_collected_timeline_metrics_nth_round_at_same_lsn() {
     let snap = TimelineSnapshot {
         loaded_at: (disk_consistent_lsn, init),
         last_record_lsn: disk_consistent_lsn,
-        current_exact_logical_size: Some(0x42000),
+        ancestor_lsn: Lsn(0),
+        current_exact_logical_size: Some(logical_size),
+        pitr_enabled: true,
+        pitr_cutoff: Some(pitr_cutoff),
     };
 
     snap.to_metrics(tenant_id, timeline_id, now, &mut metrics, &cache);
@@ -113,16 +136,18 @@ fn startup_collected_timeline_metrics_nth_round_at_same_lsn() {
         &[
             MetricsKey::written_size_delta(tenant_id, timeline_id).from_until(just_before, now, 0),
             MetricsKey::written_size(tenant_id, timeline_id).at(now, disk_consistent_lsn.0),
-            MetricsKey::timeline_logical_size(tenant_id, timeline_id).at(now, 0x42000)
+            MetricsKey::written_size_since_parent(tenant_id, timeline_id)
+                .at(now, disk_consistent_lsn.0),
+            MetricsKey::pitr_history_size_since_parent(tenant_id, timeline_id)
+                .at(now, disk_consistent_lsn.0 - pitr_cutoff.0),
+            MetricsKey::timeline_logical_size(tenant_id, timeline_id).at(now, logical_size)
         ]
     );
 }
 
+/// Tests that written sizes do not regress across restarts.
 #[test]
 fn post_restart_written_sizes_with_rolled_back_last_record_lsn() {
-    // it can happen that we lose the inmemorylayer but have previously sent metrics and we
-    // should never go backwards
-
     let tenant_id = TenantId::generate();
     let timeline_id = TimelineId::generate();
 
@@ -140,7 +165,10 @@ fn post_restart_written_sizes_with_rolled_back_last_record_lsn() {
     let snap = TimelineSnapshot {
         loaded_at: (Lsn(50), at_restart),
         last_record_lsn: Lsn(50),
+        ancestor_lsn: Lsn(0),
         current_exact_logical_size: None,
+        pitr_enabled: true,
+        pitr_cutoff: Some(Lsn(20)),
     };
 
     let mut cache = HashMap::from([
@@ -169,6 +197,8 @@ fn post_restart_written_sizes_with_rolled_back_last_record_lsn() {
                 0
             ),
             MetricsKey::written_size(tenant_id, timeline_id).at(now, 100),
+            MetricsKey::written_size_since_parent(tenant_id, timeline_id).at(now, 100),
+            MetricsKey::pitr_history_size_since_parent(tenant_id, timeline_id).at(now, 80),
         ]
     );
 
@@ -183,6 +213,157 @@ fn post_restart_written_sizes_with_rolled_back_last_record_lsn() {
         &[
             MetricsKey::written_size_delta(tenant_id, timeline_id).from_until(now, later, 0),
             MetricsKey::written_size(tenant_id, timeline_id).at(later, 100),
+            MetricsKey::written_size_since_parent(tenant_id, timeline_id).at(later, 100),
+            MetricsKey::pitr_history_size_since_parent(tenant_id, timeline_id).at(later, 80),
+        ]
+    );
+}
+
+/// Tests that written sizes do not regress across restarts, even on child branches.
+#[test]
+fn post_restart_written_sizes_with_rolled_back_last_record_lsn_and_ancestor_lsn() {
+    let tenant_id = TenantId::generate();
+    let timeline_id = TimelineId::generate();
+
+    let [later, now, at_restart] = time_backwards();
+
+    // FIXME: tests would be so much easier if we did not need to juggle back and forth
+    // SystemTime and DateTime::<Utc> ... Could do the conversion only at upload time?
+    let now = DateTime::<Utc>::from(now);
+    let later = DateTime::<Utc>::from(later);
+    let before_restart = at_restart - std::time::Duration::from_secs(5 * 60);
+    let way_before = before_restart - std::time::Duration::from_secs(10 * 60);
+    let before_restart = DateTime::<Utc>::from(before_restart);
+    let way_before = DateTime::<Utc>::from(way_before);
+
+    let snap = TimelineSnapshot {
+        loaded_at: (Lsn(50), at_restart),
+        last_record_lsn: Lsn(50),
+        ancestor_lsn: Lsn(40),
+        current_exact_logical_size: None,
+        pitr_enabled: true,
+        pitr_cutoff: Some(Lsn(20)),
+    };
+
+    let mut cache = HashMap::from([
+        MetricsKey::written_size(tenant_id, timeline_id)
+            .at(before_restart, 100)
+            .to_kv_pair(),
+        MetricsKey::written_size_delta(tenant_id, timeline_id)
+            .from_until(
+                way_before,
+                before_restart,
+                // not taken into account, but the timestamps are important
+                999_999_999,
+            )
+            .to_kv_pair(),
+    ]);
+
+    let mut metrics = Vec::new();
+    snap.to_metrics(tenant_id, timeline_id, now, &mut metrics, &cache);
+
+    assert_eq!(
+        metrics,
+        &[
+            MetricsKey::written_size_delta(tenant_id, timeline_id).from_until(
+                before_restart,
+                now,
+                0
+            ),
+            MetricsKey::written_size(tenant_id, timeline_id).at(now, 100),
+            MetricsKey::written_size_since_parent(tenant_id, timeline_id).at(now, 60),
+            MetricsKey::pitr_history_size_since_parent(tenant_id, timeline_id).at(now, 60),
+        ]
+    );
+
+    // now if we cache these metrics, and re-run while "still in recovery"
+    cache.extend(metrics.drain(..).map(|x| x.to_kv_pair()));
+
+    // "still in recovery", because our snapshot did not change
+    snap.to_metrics(tenant_id, timeline_id, later, &mut metrics, &cache);
+
+    assert_eq!(
+        metrics,
+        &[
+            MetricsKey::written_size_delta(tenant_id, timeline_id).from_until(now, later, 0),
+            MetricsKey::written_size(tenant_id, timeline_id).at(later, 100),
+            MetricsKey::written_size_since_parent(tenant_id, timeline_id).at(later, 60),
+            MetricsKey::pitr_history_size_since_parent(tenant_id, timeline_id).at(later, 60),
+        ]
+    );
+}
+
+/// Tests that written sizes do not regress across restarts, even on child branches and
+/// with a PITR cutoff after the branch point.
+#[test]
+fn post_restart_written_sizes_with_rolled_back_last_record_lsn_and_ancestor_lsn_and_pitr_cutoff() {
+    let tenant_id = TenantId::generate();
+    let timeline_id = TimelineId::generate();
+
+    let [later, now, at_restart] = time_backwards();
+
+    // FIXME: tests would be so much easier if we did not need to juggle back and forth
+    // SystemTime and DateTime::<Utc> ... Could do the conversion only at upload time?
+    let now = DateTime::<Utc>::from(now);
+    let later = DateTime::<Utc>::from(later);
+    let before_restart = at_restart - std::time::Duration::from_secs(5 * 60);
+    let way_before = before_restart - std::time::Duration::from_secs(10 * 60);
+    let before_restart = DateTime::<Utc>::from(before_restart);
+    let way_before = DateTime::<Utc>::from(way_before);
+
+    let snap = TimelineSnapshot {
+        loaded_at: (Lsn(50), at_restart),
+        last_record_lsn: Lsn(50),
+        ancestor_lsn: Lsn(30),
+        current_exact_logical_size: None,
+        pitr_enabled: true,
+        pitr_cutoff: Some(Lsn(40)),
+    };
+
+    let mut cache = HashMap::from([
+        MetricsKey::written_size(tenant_id, timeline_id)
+            .at(before_restart, 100)
+            .to_kv_pair(),
+        MetricsKey::written_size_delta(tenant_id, timeline_id)
+            .from_until(
+                way_before,
+                before_restart,
+                // not taken into account, but the timestamps are important
+                999_999_999,
+            )
+            .to_kv_pair(),
+    ]);
+
+    let mut metrics = Vec::new();
+    snap.to_metrics(tenant_id, timeline_id, now, &mut metrics, &cache);
+
+    assert_eq!(
+        metrics,
+        &[
+            MetricsKey::written_size_delta(tenant_id, timeline_id).from_until(
+                before_restart,
+                now,
+                0
+            ),
+            MetricsKey::written_size(tenant_id, timeline_id).at(now, 100),
+            MetricsKey::written_size_since_parent(tenant_id, timeline_id).at(now, 70),
+            MetricsKey::pitr_history_size_since_parent(tenant_id, timeline_id).at(now, 60),
+        ]
+    );
+
+    // now if we cache these metrics, and re-run while "still in recovery"
+    cache.extend(metrics.drain(..).map(|x| x.to_kv_pair()));
+
+    // "still in recovery", because our snapshot did not change
+    snap.to_metrics(tenant_id, timeline_id, later, &mut metrics, &cache);
+
+    assert_eq!(
+        metrics,
+        &[
+            MetricsKey::written_size_delta(tenant_id, timeline_id).from_until(now, later, 0),
+            MetricsKey::written_size(tenant_id, timeline_id).at(later, 100),
+            MetricsKey::written_size_since_parent(tenant_id, timeline_id).at(later, 70),
+            MetricsKey::pitr_history_size_since_parent(tenant_id, timeline_id).at(later, 60),
         ]
     );
 }
@@ -201,7 +382,10 @@ fn post_restart_current_exact_logical_size_uses_cached() {
     let snap = TimelineSnapshot {
         loaded_at: (Lsn(50), at_restart),
         last_record_lsn: Lsn(50),
+        ancestor_lsn: Lsn(0),
         current_exact_logical_size: None,
+        pitr_enabled: true,
+        pitr_cutoff: None,
     };
 
     let cache = HashMap::from([MetricsKey::timeline_logical_size(tenant_id, timeline_id)
@@ -286,16 +470,101 @@ fn time_backwards<const N: usize>() -> [std::time::SystemTime; N] {
     times
 }
 
+/// Tests that disabled PITR history does not yield any history size, even when the PITR cutoff
+/// indicates otherwise.
+#[test]
+fn pitr_disabled_yields_no_history_size() {
+    let tenant_id = TenantId::generate();
+    let timeline_id = TimelineId::generate();
+
+    let mut metrics = Vec::new();
+    let cache = HashMap::new();
+
+    let initdb_lsn = Lsn(0x10000);
+    let pitr_cutoff = Lsn(0x11000);
+    let disk_consistent_lsn = Lsn(initdb_lsn.0 * 2);
+
+    let snap = TimelineSnapshot {
+        loaded_at: (disk_consistent_lsn, SystemTime::now()),
+        last_record_lsn: disk_consistent_lsn,
+        ancestor_lsn: Lsn(0),
+        current_exact_logical_size: None,
+        pitr_enabled: false,
+        pitr_cutoff: Some(pitr_cutoff),
+    };
+
+    let now = DateTime::<Utc>::from(SystemTime::now());
+
+    snap.to_metrics(tenant_id, timeline_id, now, &mut metrics, &cache);
+
+    assert_eq!(
+        metrics,
+        &[
+            MetricsKey::written_size_delta(tenant_id, timeline_id).from_until(
+                snap.loaded_at.1.into(),
+                now,
+                0
+            ),
+            MetricsKey::written_size(tenant_id, timeline_id).at(now, disk_consistent_lsn.0),
+            MetricsKey::written_size_since_parent(tenant_id, timeline_id)
+                .at(now, disk_consistent_lsn.0),
+            MetricsKey::pitr_history_size_since_parent(tenant_id, timeline_id).at(now, 0),
+        ]
+    );
+}
+
+/// Tests that uninitialized PITR cutoff does not emit any history size metric at all.
+#[test]
+fn pitr_uninitialized_does_not_emit_history_size() {
+    let tenant_id = TenantId::generate();
+    let timeline_id = TimelineId::generate();
+
+    let mut metrics = Vec::new();
+    let cache = HashMap::new();
+
+    let initdb_lsn = Lsn(0x10000);
+    let disk_consistent_lsn = Lsn(initdb_lsn.0 * 2);
+
+    let snap = TimelineSnapshot {
+        loaded_at: (disk_consistent_lsn, SystemTime::now()),
+        last_record_lsn: disk_consistent_lsn,
+        ancestor_lsn: Lsn(0),
+        current_exact_logical_size: None,
+        pitr_enabled: true,
+        pitr_cutoff: None,
+    };
+
+    let now = DateTime::<Utc>::from(SystemTime::now());
+
+    snap.to_metrics(tenant_id, timeline_id, now, &mut metrics, &cache);
+
+    assert_eq!(
+        metrics,
+        &[
+            MetricsKey::written_size_delta(tenant_id, timeline_id).from_until(
+                snap.loaded_at.1.into(),
+                now,
+                0
+            ),
+            MetricsKey::written_size(tenant_id, timeline_id).at(now, disk_consistent_lsn.0),
+            MetricsKey::written_size_since_parent(tenant_id, timeline_id)
+                .at(now, disk_consistent_lsn.0),
+        ]
+    );
+}
+
 pub(crate) const fn metric_examples_old(
     tenant_id: TenantId,
     timeline_id: TimelineId,
     now: DateTime<Utc>,
     before: DateTime<Utc>,
-) -> [RawMetric; 5] {
+) -> [RawMetric; 7] {
     [
         MetricsKey::written_size(tenant_id, timeline_id).at_old_format(now, 0),
         MetricsKey::written_size_delta(tenant_id, timeline_id)
             .from_until_old_format(before, now, 0),
+        MetricsKey::written_size_since_parent(tenant_id, timeline_id).at_old_format(now, 0),
+        MetricsKey::pitr_history_size_since_parent(tenant_id, timeline_id).at_old_format(now, 0),
         MetricsKey::timeline_logical_size(tenant_id, timeline_id).at_old_format(now, 0),
         MetricsKey::remote_storage_size(tenant_id).at_old_format(now, 0),
         MetricsKey::synthetic_size(tenant_id).at_old_format(now, 1),
@@ -307,10 +576,12 @@ pub(crate) const fn metric_examples(
     timeline_id: TimelineId,
     now: DateTime<Utc>,
     before: DateTime<Utc>,
-) -> [NewRawMetric; 5] {
+) -> [NewRawMetric; 7] {
     [
         MetricsKey::written_size(tenant_id, timeline_id).at(now, 0),
         MetricsKey::written_size_delta(tenant_id, timeline_id).from_until(before, now, 0),
+        MetricsKey::written_size_since_parent(tenant_id, timeline_id).at(now, 0),
+        MetricsKey::pitr_history_size_since_parent(tenant_id, timeline_id).at(now, 0),
         MetricsKey::timeline_logical_size(tenant_id, timeline_id).at(now, 0),
         MetricsKey::remote_storage_size(tenant_id).at(now, 0),
         MetricsKey::synthetic_size(tenant_id).at(now, 1),

pageserver/src/consumption_metrics/upload.rs

@@ -513,6 +513,14 @@ mod tests {
                 line!(),
                 r#"{"type":"incremental","start_time":"2023-09-14T00:00:00.123456789Z","stop_time":"2023-09-15T00:00:00.123456789Z","metric":"written_data_bytes_delta","idempotency_key":"2023-09-15 00:00:00.123456789 UTC-1-0000","value":0,"tenant_id":"00000000000000000000000000000000","timeline_id":"ffffffffffffffffffffffffffffffff"}"#,
             ),
+            (
+                line!(),
+                r#"{"type":"absolute","time":"2023-09-15T00:00:00.123456789Z","metric":"written_size_since_parent","idempotency_key":"2023-09-15 00:00:00.123456789 UTC-1-0000","value":0,"tenant_id":"00000000000000000000000000000000","timeline_id":"ffffffffffffffffffffffffffffffff"}"#,
+            ),
+            (
+                line!(),
+                r#"{"type":"absolute","time":"2023-09-15T00:00:00.123456789Z","metric":"pitr_history_size_since_parent","idempotency_key":"2023-09-15 00:00:00.123456789 UTC-1-0000","value":0,"tenant_id":"00000000000000000000000000000000","timeline_id":"ffffffffffffffffffffffffffffffff"}"#,
+            ),
             (
                 line!(),
                 r#"{"type":"absolute","time":"2023-09-15T00:00:00.123456789Z","metric":"timeline_logical_size","idempotency_key":"2023-09-15 00:00:00.123456789 UTC-1-0000","value":0,"tenant_id":"00000000000000000000000000000000","timeline_id":"ffffffffffffffffffffffffffffffff"}"#,
@@ -560,7 +568,7 @@ mod tests {
         assert_eq!(upgraded_samples, new_samples);
     }
 
-    fn metric_samples_old() -> [RawMetric; 5] {
+    fn metric_samples_old() -> [RawMetric; 7] {
         let tenant_id = TenantId::from_array([0; 16]);
         let timeline_id = TimelineId::from_array([0xff; 16]);
 
@@ -572,7 +580,7 @@ mod tests {
         super::super::metrics::metric_examples_old(tenant_id, timeline_id, now, before)
     }
 
-    fn metric_samples() -> [NewRawMetric; 5] {
+    fn metric_samples() -> [NewRawMetric; 7] {
         let tenant_id = TenantId::from_array([0; 16]);
         let timeline_id = TimelineId::from_array([0xff; 16]);
 

pageserver/src/http/routes.rs

@@ -449,7 +449,7 @@ async fn build_timeline_info_common(
     // Internally we distinguish between the planned GC cutoff (PITR point) and the "applied" GC cutoff (where we
     // actually trimmed data to), which can pass each other when PITR is changed.
     let min_readable_lsn = std::cmp::max(
-        timeline.get_gc_cutoff_lsn(),
+        timeline.get_gc_cutoff_lsn().unwrap_or_default(),
         *timeline.get_applied_gc_cutoff_lsn(),
     );
 
@@ -3199,7 +3199,7 @@ async fn list_aux_files(
             .await?;
 
     let io_concurrency = IoConcurrency::spawn_from_conf(
-        state.conf,
+        state.conf.get_vectored_concurrent_io,
         timeline.gate.enter().map_err(|_| ApiError::Cancelled)?,
     );
 

pageserver/src/lib.rs

@@ -3,6 +3,7 @@
 
 mod auth;
 pub mod basebackup;
+pub mod basebackup_cache;
 pub mod config;
 pub mod consumption_metrics;
 pub mod context;

pageserver/src/metrics.rs

@@ -843,23 +843,50 @@ pub(crate) static COMPRESSION_IMAGE_OUTPUT_BYTES: Lazy<IntCounter> = Lazy::new(|
     .expect("failed to define a metric")
 });
 
-pub(crate) static RELSIZE_CACHE_ENTRIES: Lazy<UIntGauge> = Lazy::new(|| {
+pub(crate) static RELSIZE_LATEST_CACHE_ENTRIES: Lazy<UIntGauge> = Lazy::new(|| {
     register_uint_gauge!(
-        "pageserver_relsize_cache_entries",
-        "Number of entries in the relation size cache",
+        "pageserver_relsize_latest_cache_entries",
+        "Number of entries in the latest relation size cache",
     )
     .expect("failed to define a metric")
 });
 
-pub(crate) static RELSIZE_CACHE_HITS: Lazy<IntCounter> = Lazy::new(|| {
-    register_int_counter!("pageserver_relsize_cache_hits", "Relation size cache hits",)
-        .expect("failed to define a metric")
+pub(crate) static RELSIZE_LATEST_CACHE_HITS: Lazy<IntCounter> = Lazy::new(|| {
+    register_int_counter!(
+        "pageserver_relsize_latest_cache_hits",
+        "Latest relation size cache hits",
+    )
+    .expect("failed to define a metric")
 });
 
-pub(crate) static RELSIZE_CACHE_MISSES: Lazy<IntCounter> = Lazy::new(|| {
+pub(crate) static RELSIZE_LATEST_CACHE_MISSES: Lazy<IntCounter> = Lazy::new(|| {
     register_int_counter!(
-        "pageserver_relsize_cache_misses",
-        "Relation size cache misses",
+        "pageserver_relsize_latest_cache_misses",
+        "Relation size latest cache misses",
+    )
+    .expect("failed to define a metric")
+});
+
+pub(crate) static RELSIZE_SNAPSHOT_CACHE_ENTRIES: Lazy<UIntGauge> = Lazy::new(|| {
+    register_uint_gauge!(
+        "pageserver_relsize_snapshot_cache_entries",
+        "Number of entries in the pitr relation size cache",
+    )
+    .expect("failed to define a metric")
+});
+
+pub(crate) static RELSIZE_SNAPSHOT_CACHE_HITS: Lazy<IntCounter> = Lazy::new(|| {
+    register_int_counter!(
+        "pageserver_relsize_snapshot_cache_hits",
+        "Pitr relation size cache hits",
+    )
+    .expect("failed to define a metric")
+});
+
+pub(crate) static RELSIZE_SNAPSHOT_CACHE_MISSES: Lazy<IntCounter> = Lazy::new(|| {
+    register_int_counter!(
+        "pageserver_relsize_snapshot_cache_misses",
+        "Relation size snapshot cache misses",
     )
     .expect("failed to define a metric")
 });
@@ -1039,6 +1066,15 @@ pub(crate) static TENANT_SYNTHETIC_SIZE_METRIC: Lazy<UIntGaugeVec> = Lazy::new(|
     .expect("Failed to register pageserver_tenant_synthetic_cached_size_bytes metric")
 });
 
+pub(crate) static TENANT_OFFLOADED_TIMELINES: Lazy<UIntGaugeVec> = Lazy::new(|| {
+    register_uint_gauge_vec!(
+        "pageserver_tenant_offloaded_timelines",
+        "Number of offloaded timelines of a tenant",
+        &["tenant_id", "shard_id"]
+    )
+    .expect("Failed to register pageserver_tenant_offloaded_timelines metric")
+});
+
 pub(crate) static EVICTION_ITERATION_DURATION: Lazy<HistogramVec> = Lazy::new(|| {
     register_histogram_vec!(
         "pageserver_eviction_iteration_duration_seconds_global",
@@ -3524,11 +3560,14 @@ impl TimelineMetrics {
 }
 
 pub(crate) fn remove_tenant_metrics(tenant_shard_id: &TenantShardId) {
+    let tid = tenant_shard_id.tenant_id.to_string();
+    let shard_id = tenant_shard_id.shard_slug().to_string();
+
     // Only shard zero deals in synthetic sizes
     if tenant_shard_id.is_shard_zero() {
-        let tid = tenant_shard_id.tenant_id.to_string();
         let _ = TENANT_SYNTHETIC_SIZE_METRIC.remove_label_values(&[&tid]);
     }
+    let _ = TENANT_OFFLOADED_TIMELINES.remove_label_values(&[&tid, &shard_id]);
 
     tenant_throttling::remove_tenant_metrics(tenant_shard_id);
 
@@ -4320,6 +4359,42 @@ pub(crate) fn set_tokio_runtime_setup(setup: &str, num_threads: NonZeroUsize) {
         .set(u64::try_from(num_threads.get()).unwrap());
 }
 
+pub(crate) static BASEBACKUP_CACHE_READ: Lazy<IntCounterVec> = Lazy::new(|| {
+    register_int_counter_vec!(
+        "pageserver_basebackup_cache_read_total",
+        "Number of read accesses to the basebackup cache grouped by hit/miss/error",
+        &["result"]
+    )
+    .expect("failed to define a metric")
+});
+
+pub(crate) static BASEBACKUP_CACHE_PREPARE: Lazy<IntCounterVec> = Lazy::new(|| {
+    register_int_counter_vec!(
+        "pageserver_basebackup_cache_prepare_total",
+        "Number of prepare requests processed by the basebackup cache grouped by ok/skip/error",
+        &["result"]
+    )
+    .expect("failed to define a metric")
+});
+
+pub(crate) static BASEBACKUP_CACHE_ENTRIES: Lazy<IntGauge> = Lazy::new(|| {
+    register_int_gauge!(
+        "pageserver_basebackup_cache_entries_total",
+        "Number of entries in the basebackup cache"
+    )
+    .expect("failed to define a metric")
+});
+
+// FIXME: Support basebackup cache size metrics.
+#[allow(dead_code)]
+pub(crate) static BASEBACKUP_CACHE_SIZE: Lazy<IntGauge> = Lazy::new(|| {
+    register_int_gauge!(
+        "pageserver_basebackup_cache_size_bytes",
+        "Total size of all basebackup cache entries on disk in bytes"
+    )
+    .expect("failed to define a metric")
+});
+
 static PAGESERVER_CONFIG_IGNORED_ITEMS: Lazy<UIntGaugeVec> = Lazy::new(|| {
     register_uint_gauge_vec!(
         "pageserver_config_ignored_items",

pageserver/src/page_service.rs

@@ -9,7 +9,6 @@ use std::sync::Arc;
 use std::time::{Duration, Instant, SystemTime};
 use std::{io, str};
 
-use crate::PERF_TRACE_TARGET;
 use anyhow::{Context, bail};
 use async_compression::tokio::write::GzipEncoder;
 use bytes::Buf;
@@ -18,7 +17,7 @@ use itertools::Itertools;
 use jsonwebtoken::TokenData;
 use once_cell::sync::OnceCell;
 use pageserver_api::config::{
-    PageServicePipeliningConfig, PageServicePipeliningConfigPipelined,
+    GetVectoredConcurrentIo, PageServicePipeliningConfig, PageServicePipeliningConfigPipelined,
     PageServiceProtocolPipelinedBatchingStrategy, PageServiceProtocolPipelinedExecutionStrategy,
 };
 use pageserver_api::key::rel_block_to_key;
@@ -52,8 +51,10 @@ use utils::simple_rcu::RcuReadGuard;
 use utils::sync::gate::{Gate, GateGuard};
 use utils::sync::spsc_fold;
 
+use crate::PERF_TRACE_TARGET;
 use crate::auth::check_permission;
 use crate::basebackup::BasebackupError;
+use crate::basebackup_cache::BasebackupCache;
 use crate::config::PageServerConf;
 use crate::context::{
     DownloadBehavior, PerfInstrumentFutureExt, RequestContext, RequestContextBuilder,
@@ -62,7 +63,7 @@ use crate::metrics::{
     self, COMPUTE_COMMANDS_COUNTERS, ComputeCommandKind, GetPageBatchBreakReason, LIVE_CONNECTIONS,
     SmgrOpTimer, TimelineMetrics,
 };
-use crate::pgdatadir_mapping::Version;
+use crate::pgdatadir_mapping::{LsnRange, Version};
 use crate::span::{
     debug_assert_current_span_has_tenant_and_timeline_id,
     debug_assert_current_span_has_tenant_and_timeline_id_no_shard_id,
@@ -107,6 +108,7 @@ pub fn spawn(
     perf_trace_dispatch: Option<Dispatch>,
     tcp_listener: tokio::net::TcpListener,
     tls_config: Option<Arc<rustls::ServerConfig>>,
+    basebackup_cache: Arc<BasebackupCache>,
 ) -> Listener {
     let cancel = CancellationToken::new();
     let libpq_ctx = RequestContext::todo_child(
@@ -128,6 +130,7 @@ pub fn spawn(
             conf.pg_auth_type,
             tls_config,
             conf.page_service_pipelining.clone(),
+            basebackup_cache,
             libpq_ctx,
             cancel.clone(),
         )
@@ -186,6 +189,7 @@ pub async fn libpq_listener_main(
     auth_type: AuthType,
     tls_config: Option<Arc<rustls::ServerConfig>>,
     pipelining_config: PageServicePipeliningConfig,
+    basebackup_cache: Arc<BasebackupCache>,
     listener_ctx: RequestContext,
     listener_cancel: CancellationToken,
 ) -> Connections {
@@ -229,6 +233,7 @@ pub async fn libpq_listener_main(
                     auth_type,
                     tls_config.clone(),
                     pipelining_config.clone(),
+                    Arc::clone(&basebackup_cache),
                     connection_ctx,
                     connections_cancel.child_token(),
                     gate_guard,
@@ -271,6 +276,7 @@ async fn page_service_conn_main(
     auth_type: AuthType,
     tls_config: Option<Arc<rustls::ServerConfig>>,
     pipelining_config: PageServicePipeliningConfig,
+    basebackup_cache: Arc<BasebackupCache>,
     connection_ctx: RequestContext,
     cancel: CancellationToken,
     gate_guard: GateGuard,
@@ -331,11 +337,12 @@ async fn page_service_conn_main(
     // But it's in a shared crate, so, we store connection_ctx inside PageServerHandler
     // and create the per-query context in process_query ourselves.
     let mut conn_handler = PageServerHandler::new(
-        conf,
         tenant_manager,
         auth,
         pipelining_config,
+        conf.get_vectored_concurrent_io,
         perf_span_fields,
+        basebackup_cache,
         connection_ctx,
         cancel.clone(),
         gate_guard,
@@ -371,7 +378,6 @@ async fn page_service_conn_main(
 }
 
 struct PageServerHandler {
-    conf: &'static PageServerConf,
     auth: Option<Arc<SwappableJwtAuth>>,
     claims: Option<Claims>,
 
@@ -389,6 +395,9 @@ struct PageServerHandler {
     timeline_handles: Option<TimelineHandles>,
 
     pipelining_config: PageServicePipeliningConfig,
+    get_vectored_concurrent_io: GetVectoredConcurrentIo,
+
+    basebackup_cache: Arc<BasebackupCache>,
 
     gate_guard: GateGuard,
 }
@@ -642,7 +651,7 @@ impl std::fmt::Display for BatchedPageStreamError {
 struct BatchedGetPageRequest {
     req: PagestreamGetPageRequest,
     timer: SmgrOpTimer,
-    effective_request_lsn: Lsn,
+    lsn_range: LsnRange,
     ctx: RequestContext,
 }
 
@@ -764,12 +773,12 @@ impl BatchedFeMessage {
                 match batching_strategy {
                     PageServiceProtocolPipelinedBatchingStrategy::UniformLsn => {
                         if let Some(last_in_batch) = accum_pages.last() {
-                            if last_in_batch.effective_request_lsn
-                                != this_pages[0].effective_request_lsn
+                            if last_in_batch.lsn_range.effective_lsn
+                                != this_pages[0].lsn_range.effective_lsn
                             {
                                 trace!(
-                                    accum_lsn = %last_in_batch.effective_request_lsn,
-                                    this_lsn = %this_pages[0].effective_request_lsn,
+                                    accum_lsn = %last_in_batch.lsn_range.effective_lsn,
+                                    this_lsn = %this_pages[0].lsn_range.effective_lsn,
                                     "stopping batching because LSN changed"
                                 );
 
@@ -784,15 +793,15 @@ impl BatchedFeMessage {
                         let same_page_different_lsn = accum_pages.iter().any(|batched| {
                             batched.req.rel == this_pages[0].req.rel
                                 && batched.req.blkno == this_pages[0].req.blkno
-                                && batched.effective_request_lsn
-                                    != this_pages[0].effective_request_lsn
+                                && batched.lsn_range.effective_lsn
+                                    != this_pages[0].lsn_range.effective_lsn
                         });
 
                         if same_page_different_lsn {
                             trace!(
                                 rel=%this_pages[0].req.rel,
                                 blkno=%this_pages[0].req.blkno,
-                                lsn=%this_pages[0].effective_request_lsn,
+                                lsn=%this_pages[0].lsn_range.effective_lsn,
                                 "stopping batching because same page was requested at different LSNs"
                             );
 
@@ -844,17 +853,17 @@ impl BatchedFeMessage {
 impl PageServerHandler {
     #[allow(clippy::too_many_arguments)]
     pub fn new(
-        conf: &'static PageServerConf,
         tenant_manager: Arc<TenantManager>,
         auth: Option<Arc<SwappableJwtAuth>>,
         pipelining_config: PageServicePipeliningConfig,
+        get_vectored_concurrent_io: GetVectoredConcurrentIo,
         perf_span_fields: ConnectionPerfSpanFields,
+        basebackup_cache: Arc<BasebackupCache>,
         connection_ctx: RequestContext,
         cancel: CancellationToken,
         gate_guard: GateGuard,
     ) -> Self {
         PageServerHandler {
-            conf,
             auth,
             claims: None,
             connection_ctx,
@@ -862,6 +871,8 @@ impl PageServerHandler {
             timeline_handles: Some(TimelineHandles::new(tenant_manager)),
             cancel,
             pipelining_config,
+            get_vectored_concurrent_io,
+            basebackup_cache,
             gate_guard,
         }
     }
@@ -1158,7 +1169,7 @@ impl PageServerHandler {
                 .await?;
 
                 // We're holding the Handle
-                let effective_request_lsn = match Self::effective_request_lsn(
+                let effective_lsn = match Self::effective_request_lsn(
                     &shard,
                     shard.get_last_record_lsn(),
                     req.hdr.request_lsn,
@@ -1177,7 +1188,10 @@ impl PageServerHandler {
                     pages: smallvec::smallvec![BatchedGetPageRequest {
                         req,
                         timer,
-                        effective_request_lsn,
+                        lsn_range: LsnRange {
+                            effective_lsn,
+                            request_lsn: req.hdr.request_lsn
+                        },
                         ctx,
                     }],
                     // The executor grabs the batch when it becomes idle.
@@ -1623,7 +1637,7 @@ impl PageServerHandler {
         }
 
         let io_concurrency = IoConcurrency::spawn_from_conf(
-            self.conf,
+            self.get_vectored_concurrent_io,
             match self.gate_guard.try_clone() {
                 Ok(guard) => guard,
                 Err(_) => {
@@ -2127,7 +2141,14 @@ impl PageServerHandler {
         .await?;
 
         let exists = timeline
-            .get_rel_exists(req.rel, Version::Lsn(lsn), ctx)
+            .get_rel_exists(
+                req.rel,
+                Version::LsnRange(LsnRange {
+                    effective_lsn: lsn,
+                    request_lsn: req.hdr.request_lsn,
+                }),
+                ctx,
+            )
             .await?;
 
         Ok(PagestreamBeMessage::Exists(PagestreamExistsResponse {
@@ -2154,7 +2175,14 @@ impl PageServerHandler {
         .await?;
 
         let n_blocks = timeline
-            .get_rel_size(req.rel, Version::Lsn(lsn), ctx)
+            .get_rel_size(
+                req.rel,
+                Version::LsnRange(LsnRange {
+                    effective_lsn: lsn,
+                    request_lsn: req.hdr.request_lsn,
+                }),
+                ctx,
+            )
             .await?;
 
         Ok(PagestreamBeMessage::Nblocks(PagestreamNblocksResponse {
@@ -2181,7 +2209,15 @@ impl PageServerHandler {
         .await?;
 
         let total_blocks = timeline
-            .get_db_size(DEFAULTTABLESPACE_OID, req.dbnode, Version::Lsn(lsn), ctx)
+            .get_db_size(
+                DEFAULTTABLESPACE_OID,
+                req.dbnode,
+                Version::LsnRange(LsnRange {
+                    effective_lsn: lsn,
+                    request_lsn: req.hdr.request_lsn,
+                }),
+                ctx,
+            )
             .await?;
         let db_size = total_blocks as i64 * BLCKSZ as i64;
 
@@ -2214,7 +2250,7 @@ impl PageServerHandler {
                 // Ignore error (trace buffer may be full or tracer may have disconnected).
                 _ = page_trace.try_send(PageTraceEvent {
                     key,
-                    effective_lsn: batch.effective_request_lsn,
+                    effective_lsn: batch.lsn_range.effective_lsn,
                     time,
                 });
             }
@@ -2229,7 +2265,7 @@ impl PageServerHandler {
                     perf_instrument = true;
                 }
 
-                req.effective_request_lsn
+                req.lsn_range.effective_lsn
             })
             .max()
             .expect("batch is never empty");
@@ -2283,7 +2319,7 @@ impl PageServerHandler {
                     (
                         &p.req.rel,
                         &p.req.blkno,
-                        p.effective_request_lsn,
+                        p.lsn_range,
                         p.ctx.attached_child(),
                     )
                 }),
@@ -2468,6 +2504,8 @@ impl PageServerHandler {
             .map_err(QueryError::Disconnected)?;
         self.flush_cancellable(pgb, &self.cancel).await?;
 
+        let mut from_cache = false;
+
         // Send a tarball of the latest layer on the timeline. Compress if not
         // fullbackup. TODO Compress in that case too (tests need to be updated)
         if full_backup {
@@ -2485,7 +2523,33 @@ impl PageServerHandler {
             .map_err(map_basebackup_error)?;
         } else {
             let mut writer = BufWriter::new(pgb.copyout_writer());
-            if gzip {
+
+            let cached = {
+                // Basebackup is cached only for this combination of parameters.
+                if timeline.is_basebackup_cache_enabled()
+                    && gzip
+                    && lsn.is_some()
+                    && prev_lsn.is_none()
+                {
+                    self.basebackup_cache
+                        .get(tenant_id, timeline_id, lsn.unwrap())
+                        .await
+                } else {
+                    None
+                }
+            };
+
+            if let Some(mut cached) = cached {
+                from_cache = true;
+                tokio::io::copy(&mut cached, &mut writer)
+                    .await
+                    .map_err(|e| {
+                        map_basebackup_error(BasebackupError::Client(
+                            e,
+                            "handle_basebackup_request,cached,copy",
+                        ))
+                    })?;
+            } else if gzip {
                 let mut encoder = GzipEncoder::with_quality(
                     &mut writer,
                     // NOTE using fast compression because it's on the critical path
@@ -2544,6 +2608,7 @@ impl PageServerHandler {
         info!(
             lsn_await_millis = lsn_awaited_after.as_millis(),
             basebackup_millis = basebackup_after.as_millis(),
+            %from_cache,
             "basebackup complete"
         );
 

pageserver/src/pgdatadir_mapping.rs

@@ -43,7 +43,9 @@ use crate::aux_file;
 use crate::context::{PerfInstrumentFutureExt, RequestContext, RequestContextBuilder};
 use crate::keyspace::{KeySpace, KeySpaceAccum};
 use crate::metrics::{
-    RELSIZE_CACHE_ENTRIES, RELSIZE_CACHE_HITS, RELSIZE_CACHE_MISSES, RELSIZE_CACHE_MISSES_OLD,
+    RELSIZE_CACHE_MISSES_OLD, RELSIZE_LATEST_CACHE_ENTRIES, RELSIZE_LATEST_CACHE_HITS,
+    RELSIZE_LATEST_CACHE_MISSES, RELSIZE_SNAPSHOT_CACHE_ENTRIES, RELSIZE_SNAPSHOT_CACHE_HITS,
+    RELSIZE_SNAPSHOT_CACHE_MISSES,
 };
 use crate::span::{
     debug_assert_current_span_has_tenant_and_timeline_id,
@@ -90,6 +92,28 @@ pub enum LsnForTimestamp {
     NoData(Lsn),
 }
 
+/// Each request to page server contains LSN range: `not_modified_since..request_lsn`.
+/// See comments libs/pageserver_api/src/models.rs.
+/// Based on this range and `last_record_lsn` PS calculates `effective_lsn`.
+/// But to distinguish requests from primary and replicas we need also to pass `request_lsn`.
+#[derive(Debug, Clone, Copy, Default)]
+pub struct LsnRange {
+    pub effective_lsn: Lsn,
+    pub request_lsn: Lsn,
+}
+
+impl LsnRange {
+    pub fn at(lsn: Lsn) -> LsnRange {
+        LsnRange {
+            effective_lsn: lsn,
+            request_lsn: lsn,
+        }
+    }
+    pub fn is_latest(&self) -> bool {
+        self.request_lsn == Lsn::MAX
+    }
+}
+
 #[derive(Debug, thiserror::Error)]
 pub(crate) enum CalculateLogicalSizeError {
     #[error("cancelled")]
@@ -202,13 +226,13 @@ impl Timeline {
         io_concurrency: IoConcurrency,
     ) -> Result<Bytes, PageReconstructError> {
         match version {
-            Version::Lsn(effective_lsn) => {
+            Version::LsnRange(lsns) => {
                 let pages: smallvec::SmallVec<[_; 1]> = smallvec::smallvec![(tag, blknum)];
                 let res = self
                     .get_rel_page_at_lsn_batched(
-                        pages.iter().map(|(tag, blknum)| {
-                            (tag, blknum, effective_lsn, ctx.attached_child())
-                        }),
+                        pages
+                            .iter()
+                            .map(|(tag, blknum)| (tag, blknum, lsns, ctx.attached_child())),
                         io_concurrency.clone(),
                         ctx,
                     )
@@ -246,7 +270,7 @@ impl Timeline {
     /// The ordering of the returned vec corresponds to the ordering of `pages`.
     pub(crate) async fn get_rel_page_at_lsn_batched(
         &self,
-        pages: impl ExactSizeIterator<Item = (&RelTag, &BlockNumber, Lsn, RequestContext)>,
+        pages: impl ExactSizeIterator<Item = (&RelTag, &BlockNumber, LsnRange, RequestContext)>,
         io_concurrency: IoConcurrency,
         ctx: &RequestContext,
     ) -> Vec<Result<Bytes, PageReconstructError>> {
@@ -265,7 +289,7 @@ impl Timeline {
         let mut req_keyspaces: HashMap<Lsn, KeySpaceRandomAccum> =
             HashMap::with_capacity(pages.len());
 
-        for (response_slot_idx, (tag, blknum, lsn, ctx)) in pages.enumerate() {
+        for (response_slot_idx, (tag, blknum, lsns, ctx)) in pages.enumerate() {
             if tag.relnode == 0 {
                 result_slots[response_slot_idx].write(Err(PageReconstructError::Other(
                     RelationError::InvalidRelnode.into(),
@@ -274,7 +298,7 @@ impl Timeline {
                 slots_filled += 1;
                 continue;
             }
-
+            let lsn = lsns.effective_lsn;
             let nblocks = {
                 let ctx = RequestContextBuilder::from(&ctx)
                     .perf_span(|crnt_perf_span| {
@@ -289,7 +313,7 @@ impl Timeline {
                     .attached_child();
 
                 match self
-                    .get_rel_size(*tag, Version::Lsn(lsn), &ctx)
+                    .get_rel_size(*tag, Version::LsnRange(lsns), &ctx)
                     .maybe_perf_instrument(&ctx, |crnt_perf_span| crnt_perf_span.clone())
                     .await
                 {
@@ -470,7 +494,7 @@ impl Timeline {
             ));
         }
 
-        if let Some(nblocks) = self.get_cached_rel_size(&tag, version.get_lsn()) {
+        if let Some(nblocks) = self.get_cached_rel_size(&tag, version) {
             return Ok(nblocks);
         }
 
@@ -488,7 +512,7 @@ impl Timeline {
         let mut buf = version.get(self, key, ctx).await?;
         let nblocks = buf.get_u32_le();
 
-        self.update_cached_rel_size(tag, version.get_lsn(), nblocks);
+        self.update_cached_rel_size(tag, version, nblocks);
 
         Ok(nblocks)
     }
@@ -510,7 +534,7 @@ impl Timeline {
         }
 
         // first try to lookup relation in cache
-        if let Some(_nblocks) = self.get_cached_rel_size(&tag, version.get_lsn()) {
+        if let Some(_nblocks) = self.get_cached_rel_size(&tag, version) {
             return Ok(true);
         }
         // then check if the database was already initialized.
@@ -586,7 +610,7 @@ impl Timeline {
         // scan directory listing (new), merge with the old results
         let key_range = rel_tag_sparse_key_range(spcnode, dbnode);
         let io_concurrency = IoConcurrency::spawn_from_conf(
-            self.conf,
+            self.conf.get_vectored_concurrent_io,
             self.gate
                 .enter()
                 .map_err(|_| PageReconstructError::Cancelled)?,
@@ -632,7 +656,7 @@ impl Timeline {
     ) -> Result<Bytes, PageReconstructError> {
         assert!(self.tenant_shard_id.is_shard_zero());
         let n_blocks = self
-            .get_slru_segment_size(kind, segno, Version::Lsn(lsn), ctx)
+            .get_slru_segment_size(kind, segno, Version::at(lsn), ctx)
             .await?;
 
         let keyspace = KeySpace::single(
@@ -645,7 +669,7 @@ impl Timeline {
         );
 
         let io_concurrency = IoConcurrency::spawn_from_conf(
-            self.conf,
+            self.conf.get_vectored_concurrent_io,
             self.gate
                 .enter()
                 .map_err(|_| PageReconstructError::Cancelled)?,
@@ -867,11 +891,11 @@ impl Timeline {
         mut f: impl FnMut(TimestampTz) -> ControlFlow<T>,
     ) -> Result<T, PageReconstructError> {
         for segno in self
-            .list_slru_segments(SlruKind::Clog, Version::Lsn(probe_lsn), ctx)
+            .list_slru_segments(SlruKind::Clog, Version::at(probe_lsn), ctx)
             .await?
         {
             let nblocks = self
-                .get_slru_segment_size(SlruKind::Clog, segno, Version::Lsn(probe_lsn), ctx)
+                .get_slru_segment_size(SlruKind::Clog, segno, Version::at(probe_lsn), ctx)
                 .await?;
 
             let keyspace = KeySpace::single(
@@ -885,7 +909,7 @@ impl Timeline {
             );
 
             let io_concurrency = IoConcurrency::spawn_from_conf(
-                self.conf,
+                self.conf.get_vectored_concurrent_io,
                 self.gate
                     .enter()
                     .map_err(|_| PageReconstructError::Cancelled)?,
@@ -1137,7 +1161,7 @@ impl Timeline {
         let mut total_size: u64 = 0;
         for (spcnode, dbnode) in dbdir.dbdirs.keys() {
             for rel in self
-                .list_rels(*spcnode, *dbnode, Version::Lsn(lsn), ctx)
+                .list_rels(*spcnode, *dbnode, Version::at(lsn), ctx)
                 .await?
             {
                 if self.cancel.is_cancelled() {
@@ -1212,7 +1236,7 @@ impl Timeline {
             result.add_key(rel_dir_to_key(spcnode, dbnode));
 
             let mut rels: Vec<RelTag> = self
-                .list_rels(spcnode, dbnode, Version::Lsn(lsn), ctx)
+                .list_rels(spcnode, dbnode, Version::at(lsn), ctx)
                 .await?
                 .into_iter()
                 .collect();
@@ -1329,59 +1353,75 @@ impl Timeline {
         Ok((dense_keyspace, sparse_keyspace))
     }
 
-    /// Get cached size of relation if it not updated after specified LSN
-    pub fn get_cached_rel_size(&self, tag: &RelTag, lsn: Lsn) -> Option<BlockNumber> {
-        let rel_size_cache = self.rel_size_cache.read().unwrap();
-        if let Some((cached_lsn, nblocks)) = rel_size_cache.map.get(tag) {
-            if lsn >= *cached_lsn {
-                RELSIZE_CACHE_HITS.inc();
-                return Some(*nblocks);
+    /// Get cached size of relation. There are two caches: one for primary updates, it captures the latest state of
+    /// of the timeline and snapshot cache, which key includes LSN and so can be used by replicas to get relation size
+    /// at the particular LSN (snapshot).
+    pub fn get_cached_rel_size(&self, tag: &RelTag, version: Version<'_>) -> Option<BlockNumber> {
+        let lsn = version.get_lsn();
+        {
+            let rel_size_cache = self.rel_size_latest_cache.read().unwrap();
+            if let Some((cached_lsn, nblocks)) = rel_size_cache.get(tag) {
+                if lsn >= *cached_lsn {
+                    RELSIZE_LATEST_CACHE_HITS.inc();
+                    return Some(*nblocks);
+                }
+                RELSIZE_CACHE_MISSES_OLD.inc();
             }
-            RELSIZE_CACHE_MISSES_OLD.inc();
         }
-        RELSIZE_CACHE_MISSES.inc();
+        {
+            let mut rel_size_cache = self.rel_size_snapshot_cache.lock().unwrap();
+            if let Some(nblock) = rel_size_cache.get(&(lsn, *tag)) {
+                RELSIZE_SNAPSHOT_CACHE_HITS.inc();
+                return Some(*nblock);
+            }
+        }
+        if version.is_latest() {
+            RELSIZE_LATEST_CACHE_MISSES.inc();
+        } else {
+            RELSIZE_SNAPSHOT_CACHE_MISSES.inc();
+        }
         None
     }
 
     /// Update cached relation size if there is no more recent update
-    pub fn update_cached_rel_size(&self, tag: RelTag, lsn: Lsn, nblocks: BlockNumber) {
-        let mut rel_size_cache = self.rel_size_cache.write().unwrap();
-
-        if lsn < rel_size_cache.complete_as_of {
-            // Do not cache old values. It's safe to cache the size on read, as long as
-            // the read was at an LSN since we started the WAL ingestion. Reasoning: we
-            // never evict values from the cache, so if the relation size changed after
-            // 'lsn', the new value is already in the cache.
-            return;
-        }
-
-        match rel_size_cache.map.entry(tag) {
-            hash_map::Entry::Occupied(mut entry) => {
-                let cached_lsn = entry.get_mut();
-                if lsn >= cached_lsn.0 {
-                    *cached_lsn = (lsn, nblocks);
+    pub fn update_cached_rel_size(&self, tag: RelTag, version: Version<'_>, nblocks: BlockNumber) {
+        let lsn = version.get_lsn();
+        if version.is_latest() {
+            let mut rel_size_cache = self.rel_size_latest_cache.write().unwrap();
+            match rel_size_cache.entry(tag) {
+                hash_map::Entry::Occupied(mut entry) => {
+                    let cached_lsn = entry.get_mut();
+                    if lsn >= cached_lsn.0 {
+                        *cached_lsn = (lsn, nblocks);
+                    }
+                }
+                hash_map::Entry::Vacant(entry) => {
+                    entry.insert((lsn, nblocks));
+                    RELSIZE_LATEST_CACHE_ENTRIES.inc();
                 }
             }
-            hash_map::Entry::Vacant(entry) => {
-                entry.insert((lsn, nblocks));
-                RELSIZE_CACHE_ENTRIES.inc();
+        } else {
+            let mut rel_size_cache = self.rel_size_snapshot_cache.lock().unwrap();
+            if rel_size_cache.capacity() != 0 {
+                rel_size_cache.insert((lsn, tag), nblocks);
+                RELSIZE_SNAPSHOT_CACHE_ENTRIES.set(rel_size_cache.len() as u64);
             }
         }
     }
 
     /// Store cached relation size
     pub fn set_cached_rel_size(&self, tag: RelTag, lsn: Lsn, nblocks: BlockNumber) {
-        let mut rel_size_cache = self.rel_size_cache.write().unwrap();
-        if rel_size_cache.map.insert(tag, (lsn, nblocks)).is_none() {
-            RELSIZE_CACHE_ENTRIES.inc();
+        let mut rel_size_cache = self.rel_size_latest_cache.write().unwrap();
+        if rel_size_cache.insert(tag, (lsn, nblocks)).is_none() {
+            RELSIZE_LATEST_CACHE_ENTRIES.inc();
         }
     }
 
     /// Remove cached relation size
     pub fn remove_cached_rel_size(&self, tag: &RelTag) {
-        let mut rel_size_cache = self.rel_size_cache.write().unwrap();
-        if rel_size_cache.map.remove(tag).is_some() {
-            RELSIZE_CACHE_ENTRIES.dec();
+        let mut rel_size_cache = self.rel_size_latest_cache.write().unwrap();
+        if rel_size_cache.remove(tag).is_some() {
+            RELSIZE_LATEST_CACHE_ENTRIES.dec();
         }
     }
 }
@@ -1585,7 +1625,10 @@ impl DatadirModification<'_> {
         //       check the cache too. This is because eagerly checking the cache results in
         //       less work overall and 10% better performance. It's more work on cache miss
         //       but cache miss is rare.
-        if let Some(nblocks) = self.tline.get_cached_rel_size(&rel, self.get_lsn()) {
+        if let Some(nblocks) = self
+            .tline
+            .get_cached_rel_size(&rel, Version::Modified(self))
+        {
             Ok(nblocks)
         } else if !self
             .tline
@@ -2667,7 +2710,7 @@ pub struct DatadirModificationStats {
 /// timeline to not miss the latest updates.
 #[derive(Clone, Copy)]
 pub enum Version<'a> {
-    Lsn(Lsn),
+    LsnRange(LsnRange),
     Modified(&'a DatadirModification<'a>),
 }
 
@@ -2679,7 +2722,7 @@ impl Version<'_> {
         ctx: &RequestContext,
     ) -> Result<Bytes, PageReconstructError> {
         match self {
-            Version::Lsn(lsn) => timeline.get(key, *lsn, ctx).await,
+            Version::LsnRange(lsns) => timeline.get(key, lsns.effective_lsn, ctx).await,
             Version::Modified(modification) => modification.get(key, ctx).await,
         }
     }
@@ -2701,12 +2744,26 @@ impl Version<'_> {
         }
     }
 
-    fn get_lsn(&self) -> Lsn {
+    pub fn is_latest(&self) -> bool {
         match self {
-            Version::Lsn(lsn) => *lsn,
+            Version::LsnRange(lsns) => lsns.is_latest(),
+            Version::Modified(_) => true,
+        }
+    }
+
+    pub fn get_lsn(&self) -> Lsn {
+        match self {
+            Version::LsnRange(lsns) => lsns.effective_lsn,
             Version::Modified(modification) => modification.lsn,
         }
     }
+
+    pub fn at(lsn: Lsn) -> Self {
+        Version::LsnRange(LsnRange {
+            effective_lsn: lsn,
+            request_lsn: lsn,
+        })
+    }
 }
 
 //--- Metadata structs stored in key-value pairs in the repository.

pageserver/src/task_mgr.rs

@@ -380,6 +380,10 @@ pub enum TaskKind {
     DetachAncestor,
 
     ImportPgdata,
+
+    /// Background task of [`crate::basebackup_cache::BasebackupCache`].
+    /// Prepares basebackups and clears outdated entries.
+    BasebackupCache,
 }
 
 #[derive(Default)]

pageserver/src/tenant.rs

@@ -78,6 +78,7 @@ use self::timeline::uninit::{TimelineCreateGuard, TimelineExclusionError, Uninit
 use self::timeline::{
     EvictionTaskTenantState, GcCutoffs, TimelineDeleteProgress, TimelineResources, WaitLsnError,
 };
+use crate::basebackup_cache::BasebackupPrepareSender;
 use crate::config::PageServerConf;
 use crate::context;
 use crate::context::RequestContextBuilder;
@@ -86,8 +87,8 @@ use crate::deletion_queue::{DeletionQueueClient, DeletionQueueError};
 use crate::l0_flush::L0FlushGlobalState;
 use crate::metrics::{
     BROKEN_TENANTS_SET, CIRCUIT_BREAKERS_BROKEN, CIRCUIT_BREAKERS_UNBROKEN, CONCURRENT_INITDBS,
-    INITDB_RUN_TIME, INITDB_SEMAPHORE_ACQUISITION_TIME, TENANT, TENANT_STATE_METRIC,
-    TENANT_SYNTHETIC_SIZE_METRIC, remove_tenant_metrics,
+    INITDB_RUN_TIME, INITDB_SEMAPHORE_ACQUISITION_TIME, TENANT, TENANT_OFFLOADED_TIMELINES,
+    TENANT_STATE_METRIC, TENANT_SYNTHETIC_SIZE_METRIC, remove_tenant_metrics,
 };
 use crate::task_mgr::TaskKind;
 use crate::tenant::config::LocationMode;
@@ -157,6 +158,7 @@ pub struct TenantSharedResources {
     pub remote_storage: GenericRemoteStorage,
     pub deletion_queue_client: DeletionQueueClient,
     pub l0_flush_global_state: L0FlushGlobalState,
+    pub basebackup_prepare_sender: BasebackupPrepareSender,
 }
 
 /// A [`TenantShard`] is really an _attached_ tenant.  The configuration
@@ -317,12 +319,15 @@ pub struct TenantShard {
     gc_cs: tokio::sync::Mutex<()>,
     walredo_mgr: Option<Arc<WalRedoManager>>,
 
-    // provides access to timeline data sitting in the remote storage
+    /// Provides access to timeline data sitting in the remote storage.
     pub(crate) remote_storage: GenericRemoteStorage,
 
-    // Access to global deletion queue for when this tenant wants to schedule a deletion
+    /// Access to global deletion queue for when this tenant wants to schedule a deletion.
     deletion_queue_client: DeletionQueueClient,
 
+    /// A channel to send async requests to prepare a basebackup for the basebackup cache.
+    basebackup_prepare_sender: BasebackupPrepareSender,
+
     /// Cached logical sizes updated updated on each [`TenantShard::gather_size_inputs`].
     cached_logical_sizes: tokio::sync::Mutex<HashMap<(TimelineId, Lsn), u64>>,
     cached_synthetic_tenant_size: Arc<AtomicU64>,
@@ -1286,6 +1291,7 @@ impl TenantShard {
             remote_storage,
             deletion_queue_client,
             l0_flush_global_state,
+            basebackup_prepare_sender,
         } = resources;
 
         let attach_mode = attached_conf.location.attach_mode;
@@ -1301,6 +1307,7 @@ impl TenantShard {
             remote_storage.clone(),
             deletion_queue_client,
             l0_flush_global_state,
+            basebackup_prepare_sender,
         ));
 
         // The attach task will carry a GateGuard, so that shutdown() reliably waits for it to drop out if
@@ -3348,6 +3355,13 @@ impl TenantShard {
                 activated_timelines += 1;
             }
 
+            let tid = self.tenant_shard_id.tenant_id.to_string();
+            let shard_id = self.tenant_shard_id.shard_slug().to_string();
+            let offloaded_timeline_count = timelines_offloaded_accessor.len();
+            TENANT_OFFLOADED_TIMELINES
+                .with_label_values(&[&tid, &shard_id])
+                .set(offloaded_timeline_count as u64);
+
             self.state.send_modify(move |current_state| {
                 assert!(
                     matches!(current_state, TenantState::Activating(_)),
@@ -4232,6 +4246,7 @@ impl TenantShard {
         remote_storage: GenericRemoteStorage,
         deletion_queue_client: DeletionQueueClient,
         l0_flush_global_state: L0FlushGlobalState,
+        basebackup_prepare_sender: BasebackupPrepareSender,
     ) -> TenantShard {
         assert!(!attached_conf.location.generation.is_none());
 
@@ -4335,6 +4350,7 @@ impl TenantShard {
             ongoing_timeline_detach: std::sync::Mutex::default(),
             gc_block: Default::default(),
             l0_flush_global_state,
+            basebackup_prepare_sender,
         }
     }
 
@@ -4587,7 +4603,7 @@ impl TenantShard {
 
             target.cutoffs = GcCutoffs {
                 space: space_cutoff,
-                time: Lsn::INVALID,
+                time: None,
             };
         }
     }
@@ -4671,7 +4687,7 @@ impl TenantShard {
                 if let Some(ancestor_id) = timeline.get_ancestor_timeline_id() {
                     if let Some(ancestor_gc_cutoffs) = gc_cutoffs.get(&ancestor_id) {
                         target.within_ancestor_pitr =
-                            timeline.get_ancestor_lsn() >= ancestor_gc_cutoffs.time;
+                            Some(timeline.get_ancestor_lsn()) >= ancestor_gc_cutoffs.time;
                     }
                 }
 
@@ -4684,13 +4700,15 @@ impl TenantShard {
                     } else {
                         0
                     });
-                timeline.metrics.pitr_history_size.set(
-                    timeline
-                        .get_last_record_lsn()
-                        .checked_sub(target.cutoffs.time)
-                        .unwrap_or(Lsn(0))
-                        .0,
-                );
+                if let Some(time_cutoff) = target.cutoffs.time {
+                    timeline.metrics.pitr_history_size.set(
+                        timeline
+                            .get_last_record_lsn()
+                            .checked_sub(time_cutoff)
+                            .unwrap_or_default()
+                            .0,
+                    );
+                }
 
                 // Apply the cutoffs we found to the Timeline's GcInfo.  Why might we _not_ have cutoffs for a timeline?
                 // - this timeline was created while we were finding cutoffs
@@ -4699,8 +4717,8 @@ impl TenantShard {
                     let original_cutoffs = target.cutoffs.clone();
                     // GC cutoffs should never go back
                     target.cutoffs = GcCutoffs {
-                        space: Lsn(cutoffs.space.0.max(original_cutoffs.space.0)),
-                        time: Lsn(cutoffs.time.0.max(original_cutoffs.time.0)),
+                        space: cutoffs.space.max(original_cutoffs.space),
+                        time: cutoffs.time.max(original_cutoffs.time),
                     }
                 }
             }
@@ -5252,6 +5270,7 @@ impl TenantShard {
             pagestream_throttle_metrics: self.pagestream_throttle_metrics.clone(),
             l0_compaction_trigger: self.l0_compaction_trigger.clone(),
             l0_flush_global_state: self.l0_flush_global_state.clone(),
+            basebackup_prepare_sender: self.basebackup_prepare_sender.clone(),
         }
     }
 
@@ -5560,6 +5579,14 @@ impl TenantShard {
             }
         }
 
+        // Update metrics
+        let tid = self.tenant_shard_id.to_string();
+        let shard_id = self.tenant_shard_id.shard_slug().to_string();
+        let set_key = &[tid.as_str(), shard_id.as_str()][..];
+        TENANT_OFFLOADED_TIMELINES
+            .with_label_values(set_key)
+            .set(manifest.offloaded_timelines.len() as u64);
+
         // Upload the manifest. Remote storage does no retries internally, so retry here.
         match backoff::retry(
             || async {
@@ -5826,6 +5853,8 @@ pub(crate) mod harness {
         ) -> anyhow::Result<Arc<TenantShard>> {
             let walredo_mgr = Arc::new(WalRedoManager::from(TestRedoManager));
 
+            let (basebackup_requst_sender, _) = tokio::sync::mpsc::unbounded_channel();
+
             let tenant = Arc::new(TenantShard::new(
                 TenantState::Attaching,
                 self.conf,
@@ -5843,6 +5872,7 @@ pub(crate) mod harness {
                 self.deletion_queue.new_client(),
                 // TODO: ideally we should run all unit tests with both configs
                 L0FlushGlobalState::new(L0FlushConfig::default()),
+                basebackup_requst_sender,
             ));
 
             let preload = tenant
@@ -8596,8 +8626,10 @@ mod tests {
         lsn: Lsn,
         ctx: &RequestContext,
     ) -> Result<Option<Bytes>, GetVectoredError> {
-        let io_concurrency =
-            IoConcurrency::spawn_from_conf(tline.conf, tline.gate.enter().unwrap());
+        let io_concurrency = IoConcurrency::spawn_from_conf(
+            tline.conf.get_vectored_concurrent_io,
+            tline.gate.enter().unwrap(),
+        );
         let mut reconstruct_state = ValuesReconstructState::new(io_concurrency);
         let query = VersionedKeySpaceQuery::uniform(KeySpace::single(key..key.next()), lsn);
         let mut res = tline
@@ -8935,7 +8967,7 @@ mod tests {
                 .await;
             // Update GC info
             let mut guard = tline.gc_info.write().unwrap();
-            guard.cutoffs.time = Lsn(0x30);
+            guard.cutoffs.time = Some(Lsn(0x30));
             guard.cutoffs.space = Lsn(0x30);
         }
 
@@ -9043,7 +9075,7 @@ mod tests {
                 .await;
             // Update GC info
             let mut guard = tline.gc_info.write().unwrap();
-            guard.cutoffs.time = Lsn(0x40);
+            guard.cutoffs.time = Some(Lsn(0x40));
             guard.cutoffs.space = Lsn(0x40);
         }
         tline
@@ -9461,7 +9493,7 @@ mod tests {
             *guard = GcInfo {
                 retain_lsns: vec![],
                 cutoffs: GcCutoffs {
-                    time: Lsn(0x30),
+                    time: Some(Lsn(0x30)),
                     space: Lsn(0x30),
                 },
                 leases: Default::default(),
@@ -9545,7 +9577,7 @@ mod tests {
                 .await;
             // Update GC info
             let mut guard = tline.gc_info.write().unwrap();
-            guard.cutoffs.time = Lsn(0x40);
+            guard.cutoffs.time = Some(Lsn(0x40));
             guard.cutoffs.space = Lsn(0x40);
         }
         tline
@@ -10016,7 +10048,7 @@ mod tests {
                     (Lsn(0x20), tline.timeline_id, MaybeOffloaded::No),
                 ],
                 cutoffs: GcCutoffs {
-                    time: Lsn(0x30),
+                    time: Some(Lsn(0x30)),
                     space: Lsn(0x30),
                 },
                 leases: Default::default(),
@@ -10079,7 +10111,7 @@ mod tests {
         let verify_result = || async {
             let gc_horizon = {
                 let gc_info = tline.gc_info.read().unwrap();
-                gc_info.cutoffs.time
+                gc_info.cutoffs.time.unwrap_or_default()
             };
             for idx in 0..10 {
                 assert_eq!(
@@ -10157,7 +10189,7 @@ mod tests {
                 .await;
             // Update GC info
             let mut guard = tline.gc_info.write().unwrap();
-            guard.cutoffs.time = Lsn(0x38);
+            guard.cutoffs.time = Some(Lsn(0x38));
             guard.cutoffs.space = Lsn(0x38);
         }
         tline
@@ -10265,7 +10297,7 @@ mod tests {
                     (Lsn(0x20), tline.timeline_id, MaybeOffloaded::No),
                 ],
                 cutoffs: GcCutoffs {
-                    time: Lsn(0x30),
+                    time: Some(Lsn(0x30)),
                     space: Lsn(0x30),
                 },
                 leases: Default::default(),
@@ -10328,7 +10360,7 @@ mod tests {
         let verify_result = || async {
             let gc_horizon = {
                 let gc_info = tline.gc_info.read().unwrap();
-                gc_info.cutoffs.time
+                gc_info.cutoffs.time.unwrap_or_default()
             };
             for idx in 0..10 {
                 assert_eq!(
@@ -10514,7 +10546,7 @@ mod tests {
             *guard = GcInfo {
                 retain_lsns: vec![(Lsn(0x18), branch_tline.timeline_id, MaybeOffloaded::No)],
                 cutoffs: GcCutoffs {
-                    time: Lsn(0x10),
+                    time: Some(Lsn(0x10)),
                     space: Lsn(0x10),
                 },
                 leases: Default::default(),
@@ -10534,7 +10566,7 @@ mod tests {
             *guard = GcInfo {
                 retain_lsns: vec![(Lsn(0x40), branch_tline.timeline_id, MaybeOffloaded::No)],
                 cutoffs: GcCutoffs {
-                    time: Lsn(0x50),
+                    time: Some(Lsn(0x50)),
                     space: Lsn(0x50),
                 },
                 leases: Default::default(),
@@ -11255,7 +11287,7 @@ mod tests {
             *guard = GcInfo {
                 retain_lsns: vec![(Lsn(0x20), tline.timeline_id, MaybeOffloaded::No)],
                 cutoffs: GcCutoffs {
-                    time: Lsn(0x30),
+                    time: Some(Lsn(0x30)),
                     space: Lsn(0x30),
                 },
                 leases: Default::default(),
@@ -11644,7 +11676,7 @@ mod tests {
                     (Lsn(0x20), tline.timeline_id, MaybeOffloaded::No),
                 ],
                 cutoffs: GcCutoffs {
-                    time: Lsn(0x30),
+                    time: Some(Lsn(0x30)),
                     space: Lsn(0x30),
                 },
                 leases: Default::default(),
@@ -11707,7 +11739,7 @@ mod tests {
         let verify_result = || async {
             let gc_horizon = {
                 let gc_info = tline.gc_info.read().unwrap();
-                gc_info.cutoffs.time
+                gc_info.cutoffs.time.unwrap_or_default()
             };
             for idx in 0..10 {
                 assert_eq!(
@@ -11896,7 +11928,7 @@ mod tests {
                     (Lsn(0x20), tline.timeline_id, MaybeOffloaded::No),
                 ],
                 cutoffs: GcCutoffs {
-                    time: Lsn(0x30),
+                    time: Some(Lsn(0x30)),
                     space: Lsn(0x30),
                 },
                 leases: Default::default(),
@@ -11959,7 +11991,7 @@ mod tests {
         let verify_result = || async {
             let gc_horizon = {
                 let gc_info = tline.gc_info.read().unwrap();
-                gc_info.cutoffs.time
+                gc_info.cutoffs.time.unwrap_or_default()
             };
             for idx in 0..10 {
                 assert_eq!(
@@ -12222,7 +12254,7 @@ mod tests {
             *guard = GcInfo {
                 retain_lsns: vec![],
                 cutoffs: GcCutoffs {
-                    time: Lsn(0x30),
+                    time: Some(Lsn(0x30)),
                     space: Lsn(0x30),
                 },
                 leases: Default::default(),

pageserver/src/tenant/size.rs

@@ -235,7 +235,7 @@ pub(super) async fn gather_inputs(
         // than our internal space cutoff.  This means that if someone drops a database and waits for their
         // PITR interval, they will see synthetic size decrease, even if we are still storing data inside
         // the space cutoff.
-        let mut next_pitr_cutoff = gc_info.cutoffs.time;
+        let mut next_pitr_cutoff = gc_info.cutoffs.time.unwrap_or_default(); // TODO: handle None
 
         // If the caller provided a shorter retention period, use that instead of the GC cutoff.
         let retention_param_cutoff = if let Some(max_retention_period) = max_retention_period {

pageserver/src/tenant/storage_layer.rs

@@ -31,6 +31,7 @@ pub use inmemory_layer::InMemoryLayer;
 pub(crate) use layer::{EvictionError, Layer, ResidentLayer};
 pub use layer_desc::{PersistentLayerDesc, PersistentLayerKey};
 pub use layer_name::{DeltaLayerName, ImageLayerName, LayerName};
+use pageserver_api::config::GetVectoredConcurrentIo;
 use pageserver_api::key::Key;
 use pageserver_api::keyspace::{KeySpace, KeySpaceRandomAccum};
 use pageserver_api::record::NeonWalRecord;
@@ -43,7 +44,6 @@ use self::inmemory_layer::InMemoryLayerFileId;
 use super::PageReconstructError;
 use super::layer_map::InMemoryLayerDesc;
 use super::timeline::{GetVectoredError, ReadPath};
-use crate::config::PageServerConf;
 use crate::context::{
     AccessStatsBehavior, PerfInstrumentFutureExt, RequestContext, RequestContextBuilder,
 };
@@ -318,11 +318,10 @@ impl IoConcurrency {
     }
 
     pub(crate) fn spawn_from_conf(
-        conf: &'static PageServerConf,
+        conf: GetVectoredConcurrentIo,
         gate_guard: GateGuard,
     ) -> IoConcurrency {
-        use pageserver_api::config::GetVectoredConcurrentIo;
-        let selected = match conf.get_vectored_concurrent_io {
+        let selected = match conf {
             GetVectoredConcurrentIo::Sequential => SelectedIoConcurrency::Sequential,
             GetVectoredConcurrentIo::SidecarTask => SelectedIoConcurrency::SidecarTask(gate_guard),
         };

pageserver/src/tenant/storage_layer/inmemory_layer.rs

@@ -63,7 +63,28 @@ pub struct InMemoryLayer {
 
     opened_at: Instant,
 
-    /// The above fields never change, except for `end_lsn`, which is only set once.
+    /// All versions of all pages in the layer are kept here. Indexed
+    /// by block number and LSN. The [`IndexEntry`] is an offset into the
+    /// ephemeral file where the page version is stored.
+    ///
+    /// We use a separate lock for the index to reduce the critical section
+    /// during which reads cannot be planned.
+    ///
+    /// If you need access to both the index and the underlying file at the same time,
+    /// respect the following locking order to avoid deadlocks:
+    /// 1. [`InMemoryLayer::inner`]
+    /// 2. [`InMemoryLayer::index`]
+    ///
+    /// Note that the file backing [`InMemoryLayer::inner`] is append-only,
+    /// so it is not necessary to hold simultaneous locks on index.
+    /// This avoids holding index locks across IO, and is crucial for avoiding read tail latency.
+    /// In particular:
+    /// 1. It is safe to read and release [`InMemoryLayer::index`] before locking and reading from [`InMemoryLayer::inner`].
+    /// 2. It is safe to write and release [`InMemoryLayer::inner`] before locking and updating [`InMemoryLayer::index`].
+    index: RwLock<BTreeMap<CompactKey, VecMap<Lsn, IndexEntry>>>,
+
+    /// The above fields never change, except for `end_lsn`, which is only set once,
+    /// and `index` (see rationale there).
     /// All other changing parts are in `inner`, and protected by a mutex.
     inner: RwLock<InMemoryLayerInner>,
 
@@ -81,11 +102,6 @@ impl std::fmt::Debug for InMemoryLayer {
 }
 
 pub struct InMemoryLayerInner {
-    /// All versions of all pages in the layer are kept here. Indexed
-    /// by block number and LSN. The [`IndexEntry`] is an offset into the
-    /// ephemeral file where the page version is stored.
-    index: BTreeMap<CompactKey, VecMap<Lsn, IndexEntry>>,
-
     /// The values are stored in a serialized format in this file.
     /// Each serialized Value is preceded by a 'u32' length field.
     /// PerSeg::page_versions map stores offsets into this file.
@@ -105,7 +121,7 @@ const MAX_SUPPORTED_BLOB_LEN_BITS: usize = {
     trailing_ones
 };
 
-/// See [`InMemoryLayerInner::index`].
+/// See [`InMemoryLayer::index`].
 ///
 /// For memory efficiency, the data is packed into a u64.
 ///
@@ -425,7 +441,7 @@ impl InMemoryLayer {
             .page_content_kind(PageContentKind::InMemoryLayer)
             .attached_child();
 
-        let inner = self.inner.read().await;
+        let index = self.index.read().await;
 
         struct ValueRead {
             entry_lsn: Lsn,
@@ -435,10 +451,7 @@ impl InMemoryLayer {
         let mut ios: HashMap<(Key, Lsn), OnDiskValueIo> = Default::default();
 
         for range in keyspace.ranges.iter() {
-            for (key, vec_map) in inner
-                .index
-                .range(range.start.to_compact()..range.end.to_compact())
-            {
+            for (key, vec_map) in index.range(range.start.to_compact()..range.end.to_compact()) {
                 let key = Key::from_compact(*key);
                 let slice = vec_map.slice_range(lsn_range.clone());
 
@@ -466,7 +479,7 @@ impl InMemoryLayer {
                 }
             }
         }
-        drop(inner); // release the lock before we spawn the IO; if it's serial-mode IO we will deadlock on the read().await below
+        drop(index); // release the lock before we spawn the IO; if it's serial-mode IO we will deadlock on the read().await below
         let read_from = Arc::clone(self);
         let read_ctx = ctx.attached_child();
         reconstruct_state
@@ -573,8 +586,8 @@ impl InMemoryLayer {
             start_lsn,
             end_lsn: OnceLock::new(),
             opened_at: Instant::now(),
+            index: RwLock::new(BTreeMap::new()),
             inner: RwLock::new(InMemoryLayerInner {
-                index: BTreeMap::new(),
                 file,
                 resource_units: GlobalResourceUnits::new(),
             }),
@@ -592,31 +605,39 @@ impl InMemoryLayer {
         serialized_batch: SerializedValueBatch,
         ctx: &RequestContext,
     ) -> anyhow::Result<()> {
-        let mut inner = self.inner.write().await;
-        self.assert_writable();
+        let (base_offset, metadata) = {
+            let mut inner = self.inner.write().await;
+            self.assert_writable();
 
-        let base_offset = inner.file.len();
+            let base_offset = inner.file.len();
 
-        let SerializedValueBatch {
-            raw,
-            metadata,
-            max_lsn: _,
-            len: _,
-        } = serialized_batch;
+            let SerializedValueBatch {
+                raw,
+                metadata,
+                max_lsn: _,
+                len: _,
+            } = serialized_batch;
 
-        // Write the batch to the file
-        inner.file.write_raw(&raw, ctx).await?;
-        let new_size = inner.file.len();
+            // Write the batch to the file
+            inner.file.write_raw(&raw, ctx).await?;
+            let new_size = inner.file.len();
 
-        let expected_new_len = base_offset
-            .checked_add(raw.len().into_u64())
-            // write_raw would error if we were to overflow u64.
-            // also IndexEntry and higher levels in
-            //the code don't allow the file to grow that large
-            .unwrap();
-        assert_eq!(new_size, expected_new_len);
+            let expected_new_len = base_offset
+                .checked_add(raw.len().into_u64())
+                // write_raw would error if we were to overflow u64.
+                // also IndexEntry and higher levels in
+                //the code don't allow the file to grow that large
+                .unwrap();
+            assert_eq!(new_size, expected_new_len);
+
+            inner.resource_units.maybe_publish_size(new_size);
+
+            (base_offset, metadata)
+        };
 
         // Update the index with the new entries
+        let mut index = self.index.write().await;
+
         for meta in metadata {
             let SerializedValueMeta {
                 key,
@@ -639,7 +660,7 @@ impl InMemoryLayer {
                 will_init,
             })?;
 
-            let vec_map = inner.index.entry(key).or_default();
+            let vec_map = index.entry(key).or_default();
             let old = vec_map.append_or_update_last(lsn, index_entry).unwrap().0;
             if old.is_some() {
                 // This should not break anything, but is unexpected: ingestion code aims to filter out
@@ -658,8 +679,6 @@ impl InMemoryLayer {
             );
         }
 
-        inner.resource_units.maybe_publish_size(new_size);
-
         Ok(())
     }
 
@@ -680,6 +699,18 @@ impl InMemoryLayer {
 
     /// Records the end_lsn for non-dropped layers.
     /// `end_lsn` is exclusive
+    ///
+    /// A note on locking:
+    /// The current API of [`InMemoryLayer`] does not ensure that there's no ongoing
+    /// writes while freezing the layer. This is enforced at a higher level via
+    /// [`crate::tenant::Timeline::write_lock`]. Freeze might be called via two code paths:
+    /// 1. Via the active [`crate::tenant::timeline::TimelineWriter`]. This holds the
+    ///    Timeline::write_lock for its lifetime. The rolling is handled in
+    ///    [`crate::tenant::timeline::TimelineWriter::put_batch`]. It's a &mut self function
+    ///    so can't be called from different threads.
+    /// 2. In the background via [`crate::tenant::Timeline::maybe_freeze_ephemeral_layer`].
+    ///    This only proceeds if try_lock on Timeline::write_lock succeeds (i.e. there's no active writer),
+    ///    hence there can be no concurrent writes
     pub async fn freeze(&self, end_lsn: Lsn) {
         assert!(
             self.start_lsn < end_lsn,
@@ -700,8 +731,8 @@ impl InMemoryLayer {
 
         #[cfg(debug_assertions)]
         {
-            let inner = self.inner.write().await;
-            for vec_map in inner.index.values() {
+            let index = self.index.read().await;
+            for vec_map in index.values() {
                 for (lsn, _) in vec_map.as_slice() {
                     assert!(*lsn < end_lsn);
                 }
@@ -724,14 +755,11 @@ impl InMemoryLayer {
     ) -> Result<Option<(PersistentLayerDesc, Utf8PathBuf)>> {
         // Grab the lock in read-mode. We hold it over the I/O, but because this
         // layer is not writeable anymore, no one should be trying to acquire the
-        // write lock on it, so we shouldn't block anyone. There's one exception
-        // though: another thread might have grabbed a reference to this layer
-        // in `get_layer_for_write' just before the checkpointer called
-        // `freeze`, and then `write_to_disk` on it. When the thread gets the
-        // lock, it will see that it's not writeable anymore and retry, but it
-        // would have to wait until we release it. That race condition is very
-        // rare though, so we just accept the potential latency hit for now.
+        // write lock on it, so we shouldn't block anyone. See the comment on
+        // [`InMemoryLayer::freeze`] to understand how locking between the append path
+        // and layer flushing works.
         let inner = self.inner.read().await;
+        let index = self.index.read().await;
 
         use l0_flush::Inner;
         let _concurrency_permit = match l0_flush_global_state {
@@ -743,13 +771,9 @@ impl InMemoryLayer {
         let key_count = if let Some(key_range) = key_range {
             let key_range = key_range.start.to_compact()..key_range.end.to_compact();
 
-            inner
-                .index
-                .iter()
-                .filter(|(k, _)| key_range.contains(k))
-                .count()
+            index.iter().filter(|(k, _)| key_range.contains(k)).count()
         } else {
-            inner.index.len()
+            index.len()
         };
         if key_count == 0 {
             return Ok(None);
@@ -772,7 +796,7 @@ impl InMemoryLayer {
                 let file_contents = inner.file.load_to_io_buf(ctx).await?;
                 let file_contents = file_contents.freeze();
 
-                for (key, vec_map) in inner.index.iter() {
+                for (key, vec_map) in index.iter() {
                     // Write all page versions
                     for (lsn, entry) in vec_map
                         .as_slice()

pageserver/src/tenant/timeline.rs

@@ -14,6 +14,7 @@ pub mod span;
 pub mod uninit;
 mod walreceiver;
 
+use hashlink::LruCache;
 use std::array;
 use std::cmp::{max, min};
 use std::collections::btree_map::Entry;
@@ -23,8 +24,6 @@ use std::sync::atomic::{AtomicBool, AtomicU64, Ordering as AtomicOrdering};
 use std::sync::{Arc, Mutex, OnceLock, RwLock, Weak};
 use std::time::{Duration, Instant, SystemTime};
 
-use crate::PERF_TRACE_TARGET;
-use crate::walredo::RedoAttemptType;
 use anyhow::{Context, Result, anyhow, bail, ensure};
 use arc_swap::{ArcSwap, ArcSwapOption};
 use bytes::Bytes;
@@ -93,10 +92,12 @@ use super::storage_layer::{LayerFringe, LayerVisibilityHint, ReadableLayer};
 use super::tasks::log_compaction_error;
 use super::upload_queue::NotInitialized;
 use super::{
-    AttachedTenantConf, GcError, HeatMapTimeline, MaybeOffloaded,
+    AttachedTenantConf, BasebackupPrepareSender, GcError, HeatMapTimeline, MaybeOffloaded,
     debug_assert_current_span_has_tenant_and_timeline_id,
 };
+use crate::PERF_TRACE_TARGET;
 use crate::aux_file::AuxFileSizeEstimator;
+use crate::basebackup_cache::BasebackupPrepareRequest;
 use crate::config::PageServerConf;
 use crate::context::{
     DownloadBehavior, PerfInstrumentFutureExt, RequestContext, RequestContextBuilder,
@@ -130,6 +131,7 @@ use crate::tenant::tasks::BackgroundLoopKind;
 use crate::tenant::timeline::logical_size::CurrentLogicalSize;
 use crate::virtual_file::{MaybeFatalIo, VirtualFile};
 use crate::walingest::WalLagCooldown;
+use crate::walredo::RedoAttemptType;
 use crate::{ZERO_PAGE, task_mgr, walredo};
 
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
@@ -195,16 +197,7 @@ pub struct TimelineResources {
     pub pagestream_throttle_metrics: Arc<crate::metrics::tenant_throttling::Pagestream>,
     pub l0_compaction_trigger: Arc<Notify>,
     pub l0_flush_global_state: l0_flush::L0FlushGlobalState,
-}
-
-/// The relation size cache caches relation sizes at the end of the timeline. It speeds up WAL
-/// ingestion considerably, because WAL ingestion needs to check on most records if the record
-/// implicitly extends the relation.  At startup, `complete_as_of` is initialized to the current end
-/// of the timeline (disk_consistent_lsn).  It's used on reads of relation sizes to check if the
-/// value can be used to also update the cache, see [`Timeline::update_cached_rel_size`].
-pub(crate) struct RelSizeCache {
-    pub(crate) complete_as_of: Lsn,
-    pub(crate) map: HashMap<RelTag, (Lsn, BlockNumber)>,
+    pub basebackup_prepare_sender: BasebackupPrepareSender,
 }
 
 pub struct Timeline {
@@ -365,7 +358,8 @@ pub struct Timeline {
     pub walreceiver: Mutex<Option<WalReceiver>>,
 
     /// Relation size cache
-    pub(crate) rel_size_cache: RwLock<RelSizeCache>,
+    pub(crate) rel_size_latest_cache: RwLock<HashMap<RelTag, (Lsn, BlockNumber)>>,
+    pub(crate) rel_size_snapshot_cache: Mutex<LruCache<(Lsn, RelTag), BlockNumber>>,
 
     download_all_remote_layers_task_info: RwLock<Option<DownloadRemoteLayersTaskInfo>>,
 
@@ -447,6 +441,9 @@ pub struct Timeline {
     pub(crate) rel_size_v2_status: ArcSwapOption<RelSizeMigration>,
 
     wait_lsn_log_slow: tokio::sync::Semaphore,
+
+    /// A channel to send async requests to prepare a basebackup for the basebackup cache.
+    basebackup_prepare_sender: BasebackupPrepareSender,
 }
 
 pub(crate) enum PreviousHeatmap {
@@ -537,29 +534,24 @@ impl GcInfo {
 /// The `GcInfo` component describing which Lsns need to be retained.  Functionally, this
 /// is a single number (the oldest LSN which we must retain), but it internally distinguishes
 /// between time-based and space-based retention for observability and consumption metrics purposes.
-#[derive(Debug, Clone)]
+#[derive(Clone, Debug, Default)]
 pub(crate) struct GcCutoffs {
     /// Calculated from the [`pageserver_api::models::TenantConfig::gc_horizon`], this LSN indicates how much
     /// history we must keep to retain a specified number of bytes of WAL.
     pub(crate) space: Lsn,
 
-    /// Calculated from [`pageserver_api::models::TenantConfig::pitr_interval`], this LSN indicates how much
-    /// history we must keep to enable reading back at least the PITR interval duration.
-    pub(crate) time: Lsn,
-}
-
-impl Default for GcCutoffs {
-    fn default() -> Self {
-        Self {
-            space: Lsn::INVALID,
-            time: Lsn::INVALID,
-        }
-    }
+    /// Calculated from [`pageserver_api::models::TenantConfig::pitr_interval`], this LSN indicates
+    /// how much history we must keep to enable reading back at least the PITR interval duration.
+    ///
+    /// None indicates that the PITR cutoff has not been computed. A PITR interval of 0 will yield
+    /// Some(last_record_lsn).
+    pub(crate) time: Option<Lsn>,
 }
 
 impl GcCutoffs {
     fn select_min(&self) -> Lsn {
-        std::cmp::min(self.space, self.time)
+        // NB: if we haven't computed the PITR cutoff yet, we can't GC anything.
+        self.space.min(self.time.unwrap_or_default())
     }
 }
 
@@ -1041,6 +1033,7 @@ pub(crate) enum WaitLsnWaiter<'a> {
     Tenant,
     PageService,
     HttpEndpoint,
+    BaseBackupCache,
 }
 
 /// Argument to [`Timeline::shutdown`].
@@ -1096,11 +1089,14 @@ impl Timeline {
     /// Get the bytes written since the PITR cutoff on this branch, and
     /// whether this branch's ancestor_lsn is within its parent's PITR.
     pub(crate) fn get_pitr_history_stats(&self) -> (u64, bool) {
+        // TODO: for backwards compatibility, we return the full history back to 0 when the PITR
+        // cutoff has not yet been initialized. This should return None instead, but this is exposed
+        // in external HTTP APIs and callers may not handle a null value.
         let gc_info = self.gc_info.read().unwrap();
         let history = self
             .get_last_record_lsn()
-            .checked_sub(gc_info.cutoffs.time)
-            .unwrap_or(Lsn(0))
+            .checked_sub(gc_info.cutoffs.time.unwrap_or_default())
+            .unwrap_or_default()
             .0;
         (history, gc_info.within_ancestor_pitr)
     }
@@ -1110,9 +1106,10 @@ impl Timeline {
         self.applied_gc_cutoff_lsn.read()
     }
 
-    /// Read timeline's planned GC cutoff: this is the logical end of history that users
-    /// are allowed to read (based on configured PITR), even if physically we have more history.
-    pub(crate) fn get_gc_cutoff_lsn(&self) -> Lsn {
+    /// Read timeline's planned GC cutoff: this is the logical end of history that users are allowed
+    /// to read (based on configured PITR), even if physically we have more history. Returns None
+    /// if the PITR cutoff has not yet been initialized.
+    pub(crate) fn get_gc_cutoff_lsn(&self) -> Option<Lsn> {
         self.gc_info.read().unwrap().cutoffs.time
     }
 
@@ -1563,7 +1560,8 @@ impl Timeline {
                         }
                         WaitLsnWaiter::Tenant
                         | WaitLsnWaiter::PageService
-                        | WaitLsnWaiter::HttpEndpoint => unreachable!(
+                        | WaitLsnWaiter::HttpEndpoint
+                        | WaitLsnWaiter::BaseBackupCache => unreachable!(
                             "tenant or page_service context are not expected to have task kind {:?}",
                             ctx.task_kind()
                         ),
@@ -2468,6 +2466,41 @@ impl Timeline {
             false
         }
     }
+
+    pub(crate) fn is_basebackup_cache_enabled(&self) -> bool {
+        let tenant_conf = self.tenant_conf.load();
+        tenant_conf
+            .tenant_conf
+            .basebackup_cache_enabled
+            .unwrap_or(self.conf.default_tenant_conf.basebackup_cache_enabled)
+    }
+
+    /// Prepare basebackup for the given LSN and store it in the basebackup cache.
+    /// The method is asynchronous and returns immediately.
+    /// The actual basebackup preparation is performed in the background
+    /// by the basebackup cache on a best-effort basis.
+    pub(crate) fn prepare_basebackup(&self, lsn: Lsn) {
+        if !self.is_basebackup_cache_enabled() {
+            return;
+        }
+        if !self.tenant_shard_id.is_shard_zero() {
+            // In theory we should never get here, but just in case check it.
+            // Preparing basebackup doesn't make sense for shards other than shard zero.
+            return;
+        }
+
+        let res = self
+            .basebackup_prepare_sender
+            .send(BasebackupPrepareRequest {
+                tenant_shard_id: self.tenant_shard_id,
+                timeline_id: self.timeline_id,
+                lsn,
+            });
+        if let Err(e) = res {
+            // May happen during shutdown, it's not critical.
+            info!("Failed to send shutdown checkpoint: {e:#}");
+        }
+    }
 }
 
 /// Number of times we will compute partition within a checkpoint distance.
@@ -2545,6 +2578,13 @@ impl Timeline {
             .unwrap_or(self.conf.default_tenant_conf.checkpoint_timeout)
     }
 
+    pub(crate) fn get_pitr_interval(&self) -> Duration {
+        let tenant_conf = &self.tenant_conf.load().tenant_conf;
+        tenant_conf
+            .pitr_interval
+            .unwrap_or(self.conf.default_tenant_conf.pitr_interval)
+    }
+
     fn get_compaction_period(&self) -> Duration {
         let tenant_conf = self.tenant_conf.load().tenant_conf.clone();
         tenant_conf
@@ -2820,6 +2860,13 @@ impl Timeline {
 
             self.remote_client.update_config(&new_conf.location);
 
+            let mut rel_size_cache = self.rel_size_snapshot_cache.lock().unwrap();
+            if let Some(new_capacity) = new_conf.tenant_conf.relsize_snapshot_cache_capacity {
+                if new_capacity != rel_size_cache.capacity() {
+                    rel_size_cache.set_capacity(new_capacity);
+                }
+            }
+
             self.metrics
                 .evictions_with_low_residence_duration
                 .write()
@@ -2878,6 +2925,14 @@ impl Timeline {
             ancestor_gc_info.insert_child(timeline_id, metadata.ancestor_lsn(), is_offloaded);
         }
 
+        let relsize_snapshot_cache_capacity = {
+            let loaded_tenant_conf = tenant_conf.load();
+            loaded_tenant_conf
+                .tenant_conf
+                .relsize_snapshot_cache_capacity
+                .unwrap_or(conf.default_tenant_conf.relsize_snapshot_cache_capacity)
+        };
+
         Arc::new_cyclic(|myself| {
             let metrics = Arc::new(TimelineMetrics::new(
                 &tenant_shard_id,
@@ -2969,10 +3024,8 @@ impl Timeline {
                 last_image_layer_creation_check_instant: Mutex::new(None),
 
                 last_received_wal: Mutex::new(None),
-                rel_size_cache: RwLock::new(RelSizeCache {
-                    complete_as_of: disk_consistent_lsn,
-                    map: HashMap::new(),
-                }),
+                rel_size_latest_cache: RwLock::new(HashMap::new()),
+                rel_size_snapshot_cache: Mutex::new(LruCache::new(relsize_snapshot_cache_capacity)),
 
                 download_all_remote_layers_task_info: RwLock::new(None),
 
@@ -3017,6 +3070,8 @@ impl Timeline {
                 rel_size_v2_status: ArcSwapOption::from_pointee(rel_size_v2_status),
 
                 wait_lsn_log_slow: tokio::sync::Semaphore::new(1),
+
+                basebackup_prepare_sender: resources.basebackup_prepare_sender,
             };
 
             result.repartition_threshold =
@@ -3530,7 +3585,7 @@ impl Timeline {
                 };
 
                 let io_concurrency = IoConcurrency::spawn_from_conf(
-                    self_ref.conf,
+                    self_ref.conf.get_vectored_concurrent_io,
                     self_ref
                         .gate
                         .enter()
@@ -5559,7 +5614,7 @@ impl Timeline {
             });
 
             let io_concurrency = IoConcurrency::spawn_from_conf(
-                self.conf,
+                self.conf.get_vectored_concurrent_io,
                 self.gate
                     .enter()
                     .map_err(|_| CreateImageLayersError::Cancelled)?,
@@ -6230,14 +6285,12 @@ impl Timeline {
 
         pausable_failpoint!("Timeline::find_gc_cutoffs-pausable");
 
-        if cfg!(test) {
+        if cfg!(test) && pitr == Duration::ZERO {
             // Unit tests which specify zero PITR interval expect to avoid doing any I/O for timestamp lookup
-            if pitr == Duration::ZERO {
-                return Ok(GcCutoffs {
-                    time: self.get_last_record_lsn(),
-                    space: space_cutoff,
-                });
-            }
+            return Ok(GcCutoffs {
+                time: Some(self.get_last_record_lsn()),
+                space: space_cutoff,
+            });
         }
 
         // Calculate a time-based limit on how much to retain:
@@ -6251,14 +6304,14 @@ impl Timeline {
                 // PITR is not set. Retain the size-based limit, or the default time retention,
                 // whichever requires less data.
                 GcCutoffs {
-                    time: self.get_last_record_lsn(),
+                    time: Some(self.get_last_record_lsn()),
                     space: std::cmp::max(time_cutoff, space_cutoff),
                 }
             }
             (Duration::ZERO, None) => {
                 // PITR is not set, and time lookup failed
                 GcCutoffs {
-                    time: self.get_last_record_lsn(),
+                    time: Some(self.get_last_record_lsn()),
                     space: space_cutoff,
                 }
             }
@@ -6266,7 +6319,7 @@ impl Timeline {
                 // PITR interval is set & we didn't look up a timestamp successfully.  Conservatively assume PITR
                 // cannot advance beyond what was already GC'd, and respect space-based retention
                 GcCutoffs {
-                    time: *self.get_applied_gc_cutoff_lsn(),
+                    time: Some(*self.get_applied_gc_cutoff_lsn()),
                     space: space_cutoff,
                 }
             }
@@ -6274,7 +6327,7 @@ impl Timeline {
                 // PITR interval is set and we looked up timestamp successfully.  Ignore
                 // size based retention and make time cutoff authoritative
                 GcCutoffs {
-                    time: time_cutoff,
+                    time: Some(time_cutoff),
                     space: time_cutoff,
                 }
             }
@@ -6327,7 +6380,7 @@ impl Timeline {
             )
         };
 
-        let mut new_gc_cutoff = Lsn::min(space_cutoff, time_cutoff);
+        let mut new_gc_cutoff = space_cutoff.min(time_cutoff.unwrap_or_default());
         let standby_horizon = self.standby_horizon.load();
         // Hold GC for the standby, but as a safety guard do it only within some
         // reasonable lag.
@@ -6376,7 +6429,7 @@ impl Timeline {
     async fn gc_timeline(
         &self,
         space_cutoff: Lsn,
-        time_cutoff: Lsn,
+        time_cutoff: Option<Lsn>, // None if uninitialized
         retain_lsns: Vec<Lsn>,
         max_lsn_with_valid_lease: Option<Lsn>,
         new_gc_cutoff: Lsn,
@@ -6395,6 +6448,12 @@ impl Timeline {
             return Ok(result);
         }
 
+        let Some(time_cutoff) = time_cutoff else {
+            // The GC cutoff should have been computed by now, but let's be defensive.
+            info!("Nothing to GC: time_cutoff not yet computed");
+            return Ok(result);
+        };
+
         // We need to ensure that no one tries to read page versions or create
         // branches at a point before latest_gc_cutoff_lsn. See branch_timeline()
         // for details. This will block until the old value is no longer in use.

pageserver/src/tenant/timeline/compaction.rs

@@ -1526,7 +1526,7 @@ impl Timeline {
         info!(
             "starting shard ancestor compaction, rewriting {} layers and dropping {} layers, \
                 checked {layers_checked}/{layers_total} layers \
-                (latest_gc_cutoff={} pitr_cutoff={})",
+                (latest_gc_cutoff={} pitr_cutoff={:?})",
             layers_to_rewrite.len(),
             drop_layers.len(),
             *latest_gc_cutoff,

pageserver/src/tenant/timeline/detach_ancestor.rs

@@ -188,7 +188,7 @@ pub(crate) async fn generate_tombstone_image_layer(
         "removing non-inherited keys by writing an image layer with tombstones at the detach LSN"
     );
     let io_concurrency = IoConcurrency::spawn_from_conf(
-        detached.conf,
+        detached.conf.get_vectored_concurrent_io,
         detached.gate.enter().map_err(|_| Error::ShuttingDown)?,
     );
     let mut reconstruct_state = ValuesReconstructState::new(io_concurrency);

pageserver/src/walingest.rs

@@ -1316,6 +1316,12 @@ impl WalIngest {
             }
         });
 
+        if modification.tline.is_basebackup_cache_enabled()
+            && info == pg_constants::XLOG_CHECKPOINT_SHUTDOWN
+        {
+            modification.tline.prepare_basebackup(lsn);
+        }
+
         Ok(())
     }
 
@@ -1684,31 +1690,31 @@ mod tests {
         // The relation was created at LSN 2, not visible at LSN 1 yet.
         assert_eq!(
             tline
-                .get_rel_exists(TESTREL_A, Version::Lsn(Lsn(0x10)), &ctx)
+                .get_rel_exists(TESTREL_A, Version::at(Lsn(0x10)), &ctx)
                 .await?,
             false
         );
         assert!(
             tline
-                .get_rel_size(TESTREL_A, Version::Lsn(Lsn(0x10)), &ctx)
+                .get_rel_size(TESTREL_A, Version::at(Lsn(0x10)), &ctx)
                 .await
                 .is_err()
         );
         assert_eq!(
             tline
-                .get_rel_exists(TESTREL_A, Version::Lsn(Lsn(0x20)), &ctx)
+                .get_rel_exists(TESTREL_A, Version::at(Lsn(0x20)), &ctx)
                 .await?,
             true
         );
         assert_eq!(
             tline
-                .get_rel_size(TESTREL_A, Version::Lsn(Lsn(0x20)), &ctx)
+                .get_rel_size(TESTREL_A, Version::at(Lsn(0x20)), &ctx)
                 .await?,
             1
         );
         assert_eq!(
             tline
-                .get_rel_size(TESTREL_A, Version::Lsn(Lsn(0x50)), &ctx)
+                .get_rel_size(TESTREL_A, Version::at(Lsn(0x50)), &ctx)
                 .await?,
             3
         );
@@ -1719,7 +1725,7 @@ mod tests {
                 .get_rel_page_at_lsn(
                     TESTREL_A,
                     0,
-                    Version::Lsn(Lsn(0x20)),
+                    Version::at(Lsn(0x20)),
                     &ctx,
                     io_concurrency.clone()
                 )
@@ -1733,7 +1739,7 @@ mod tests {
                 .get_rel_page_at_lsn(
                     TESTREL_A,
                     0,
-                    Version::Lsn(Lsn(0x30)),
+                    Version::at(Lsn(0x30)),
                     &ctx,
                     io_concurrency.clone()
                 )
@@ -1747,7 +1753,7 @@ mod tests {
                 .get_rel_page_at_lsn(
                     TESTREL_A,
                     0,
-                    Version::Lsn(Lsn(0x40)),
+                    Version::at(Lsn(0x40)),
                     &ctx,
                     io_concurrency.clone()
                 )
@@ -1760,7 +1766,7 @@ mod tests {
                 .get_rel_page_at_lsn(
                     TESTREL_A,
                     1,
-                    Version::Lsn(Lsn(0x40)),
+                    Version::at(Lsn(0x40)),
                     &ctx,
                     io_concurrency.clone()
                 )
@@ -1774,7 +1780,7 @@ mod tests {
                 .get_rel_page_at_lsn(
                     TESTREL_A,
                     0,
-                    Version::Lsn(Lsn(0x50)),
+                    Version::at(Lsn(0x50)),
                     &ctx,
                     io_concurrency.clone()
                 )
@@ -1787,7 +1793,7 @@ mod tests {
                 .get_rel_page_at_lsn(
                     TESTREL_A,
                     1,
-                    Version::Lsn(Lsn(0x50)),
+                    Version::at(Lsn(0x50)),
                     &ctx,
                     io_concurrency.clone()
                 )
@@ -1800,7 +1806,7 @@ mod tests {
                 .get_rel_page_at_lsn(
                     TESTREL_A,
                     2,
-                    Version::Lsn(Lsn(0x50)),
+                    Version::at(Lsn(0x50)),
                     &ctx,
                     io_concurrency.clone()
                 )
@@ -1820,7 +1826,7 @@ mod tests {
         // Check reported size and contents after truncation
         assert_eq!(
             tline
-                .get_rel_size(TESTREL_A, Version::Lsn(Lsn(0x60)), &ctx)
+                .get_rel_size(TESTREL_A, Version::at(Lsn(0x60)), &ctx)
                 .await?,
             2
         );
@@ -1829,7 +1835,7 @@ mod tests {
                 .get_rel_page_at_lsn(
                     TESTREL_A,
                     0,
-                    Version::Lsn(Lsn(0x60)),
+                    Version::at(Lsn(0x60)),
                     &ctx,
                     io_concurrency.clone()
                 )
@@ -1842,7 +1848,7 @@ mod tests {
                 .get_rel_page_at_lsn(
                     TESTREL_A,
                     1,
-                    Version::Lsn(Lsn(0x60)),
+                    Version::at(Lsn(0x60)),
                     &ctx,
                     io_concurrency.clone()
                 )
@@ -1854,7 +1860,7 @@ mod tests {
         // should still see the truncated block with older LSN
         assert_eq!(
             tline
-                .get_rel_size(TESTREL_A, Version::Lsn(Lsn(0x50)), &ctx)
+                .get_rel_size(TESTREL_A, Version::at(Lsn(0x50)), &ctx)
                 .await?,
             3
         );
@@ -1863,7 +1869,7 @@ mod tests {
                 .get_rel_page_at_lsn(
                     TESTREL_A,
                     2,
-                    Version::Lsn(Lsn(0x50)),
+                    Version::at(Lsn(0x50)),
                     &ctx,
                     io_concurrency.clone()
                 )
@@ -1880,7 +1886,7 @@ mod tests {
         m.commit(&ctx).await?;
         assert_eq!(
             tline
-                .get_rel_size(TESTREL_A, Version::Lsn(Lsn(0x68)), &ctx)
+                .get_rel_size(TESTREL_A, Version::at(Lsn(0x68)), &ctx)
                 .await?,
             0
         );
@@ -1893,7 +1899,7 @@ mod tests {
         m.commit(&ctx).await?;
         assert_eq!(
             tline
-                .get_rel_size(TESTREL_A, Version::Lsn(Lsn(0x70)), &ctx)
+                .get_rel_size(TESTREL_A, Version::at(Lsn(0x70)), &ctx)
                 .await?,
             2
         );
@@ -1902,7 +1908,7 @@ mod tests {
                 .get_rel_page_at_lsn(
                     TESTREL_A,
                     0,
-                    Version::Lsn(Lsn(0x70)),
+                    Version::at(Lsn(0x70)),
                     &ctx,
                     io_concurrency.clone()
                 )
@@ -1915,7 +1921,7 @@ mod tests {
                 .get_rel_page_at_lsn(
                     TESTREL_A,
                     1,
-                    Version::Lsn(Lsn(0x70)),
+                    Version::at(Lsn(0x70)),
                     &ctx,
                     io_concurrency.clone()
                 )
@@ -1932,7 +1938,7 @@ mod tests {
         m.commit(&ctx).await?;
         assert_eq!(
             tline
-                .get_rel_size(TESTREL_A, Version::Lsn(Lsn(0x80)), &ctx)
+                .get_rel_size(TESTREL_A, Version::at(Lsn(0x80)), &ctx)
                 .await?,
             1501
         );
@@ -1942,7 +1948,7 @@ mod tests {
                     .get_rel_page_at_lsn(
                         TESTREL_A,
                         blk,
-                        Version::Lsn(Lsn(0x80)),
+                        Version::at(Lsn(0x80)),
                         &ctx,
                         io_concurrency.clone()
                     )
@@ -1956,7 +1962,7 @@ mod tests {
                 .get_rel_page_at_lsn(
                     TESTREL_A,
                     1500,
-                    Version::Lsn(Lsn(0x80)),
+                    Version::at(Lsn(0x80)),
                     &ctx,
                     io_concurrency.clone()
                 )
@@ -1990,13 +1996,13 @@ mod tests {
         // Check that rel exists and size is correct
         assert_eq!(
             tline
-                .get_rel_exists(TESTREL_A, Version::Lsn(Lsn(0x20)), &ctx)
+                .get_rel_exists(TESTREL_A, Version::at(Lsn(0x20)), &ctx)
                 .await?,
             true
         );
         assert_eq!(
             tline
-                .get_rel_size(TESTREL_A, Version::Lsn(Lsn(0x20)), &ctx)
+                .get_rel_size(TESTREL_A, Version::at(Lsn(0x20)), &ctx)
                 .await?,
             1
         );
@@ -2011,7 +2017,7 @@ mod tests {
         // Check that rel is not visible anymore
         assert_eq!(
             tline
-                .get_rel_exists(TESTREL_A, Version::Lsn(Lsn(0x30)), &ctx)
+                .get_rel_exists(TESTREL_A, Version::at(Lsn(0x30)), &ctx)
                 .await?,
             false
         );
@@ -2029,13 +2035,13 @@ mod tests {
         // Check that rel exists and size is correct
         assert_eq!(
             tline
-                .get_rel_exists(TESTREL_A, Version::Lsn(Lsn(0x40)), &ctx)
+                .get_rel_exists(TESTREL_A, Version::at(Lsn(0x40)), &ctx)
                 .await?,
             true
         );
         assert_eq!(
             tline
-                .get_rel_size(TESTREL_A, Version::Lsn(Lsn(0x40)), &ctx)
+                .get_rel_size(TESTREL_A, Version::at(Lsn(0x40)), &ctx)
                 .await?,
             1
         );
@@ -2077,26 +2083,26 @@ mod tests {
         // The relation was created at LSN 20, not visible at LSN 1 yet.
         assert_eq!(
             tline
-                .get_rel_exists(TESTREL_A, Version::Lsn(Lsn(0x10)), &ctx)
+                .get_rel_exists(TESTREL_A, Version::at(Lsn(0x10)), &ctx)
                 .await?,
             false
         );
         assert!(
             tline
-                .get_rel_size(TESTREL_A, Version::Lsn(Lsn(0x10)), &ctx)
+                .get_rel_size(TESTREL_A, Version::at(Lsn(0x10)), &ctx)
                 .await
                 .is_err()
         );
 
         assert_eq!(
             tline
-                .get_rel_exists(TESTREL_A, Version::Lsn(Lsn(0x20)), &ctx)
+                .get_rel_exists(TESTREL_A, Version::at(Lsn(0x20)), &ctx)
                 .await?,
             true
         );
         assert_eq!(
             tline
-                .get_rel_size(TESTREL_A, Version::Lsn(Lsn(0x20)), &ctx)
+                .get_rel_size(TESTREL_A, Version::at(Lsn(0x20)), &ctx)
                 .await?,
             relsize
         );
@@ -2110,7 +2116,7 @@ mod tests {
                     .get_rel_page_at_lsn(
                         TESTREL_A,
                         blkno,
-                        Version::Lsn(lsn),
+                        Version::at(lsn),
                         &ctx,
                         io_concurrency.clone()
                     )
@@ -2131,7 +2137,7 @@ mod tests {
         // Check reported size and contents after truncation
         assert_eq!(
             tline
-                .get_rel_size(TESTREL_A, Version::Lsn(Lsn(0x60)), &ctx)
+                .get_rel_size(TESTREL_A, Version::at(Lsn(0x60)), &ctx)
                 .await?,
             1
         );
@@ -2144,7 +2150,7 @@ mod tests {
                     .get_rel_page_at_lsn(
                         TESTREL_A,
                         blkno,
-                        Version::Lsn(Lsn(0x60)),
+                        Version::at(Lsn(0x60)),
                         &ctx,
                         io_concurrency.clone()
                     )
@@ -2157,7 +2163,7 @@ mod tests {
         // should still see all blocks with older LSN
         assert_eq!(
             tline
-                .get_rel_size(TESTREL_A, Version::Lsn(Lsn(0x50)), &ctx)
+                .get_rel_size(TESTREL_A, Version::at(Lsn(0x50)), &ctx)
                 .await?,
             relsize
         );
@@ -2169,7 +2175,7 @@ mod tests {
                     .get_rel_page_at_lsn(
                         TESTREL_A,
                         blkno,
-                        Version::Lsn(Lsn(0x50)),
+                        Version::at(Lsn(0x50)),
                         &ctx,
                         io_concurrency.clone()
                     )
@@ -2193,13 +2199,13 @@ mod tests {
 
         assert_eq!(
             tline
-                .get_rel_exists(TESTREL_A, Version::Lsn(Lsn(0x80)), &ctx)
+                .get_rel_exists(TESTREL_A, Version::at(Lsn(0x80)), &ctx)
                 .await?,
             true
         );
         assert_eq!(
             tline
-                .get_rel_size(TESTREL_A, Version::Lsn(Lsn(0x80)), &ctx)
+                .get_rel_size(TESTREL_A, Version::at(Lsn(0x80)), &ctx)
                 .await?,
             relsize
         );
@@ -2212,7 +2218,7 @@ mod tests {
                     .get_rel_page_at_lsn(
                         TESTREL_A,
                         blkno,
-                        Version::Lsn(Lsn(0x80)),
+                        Version::at(Lsn(0x80)),
                         &ctx,
                         io_concurrency.clone()
                     )
@@ -2250,7 +2256,7 @@ mod tests {
 
         assert_eq!(
             tline
-                .get_rel_size(TESTREL_A, Version::Lsn(Lsn(lsn)), &ctx)
+                .get_rel_size(TESTREL_A, Version::at(Lsn(lsn)), &ctx)
                 .await?,
             RELSEG_SIZE + 1
         );
@@ -2264,7 +2270,7 @@ mod tests {
         m.commit(&ctx).await?;
         assert_eq!(
             tline
-                .get_rel_size(TESTREL_A, Version::Lsn(Lsn(lsn)), &ctx)
+                .get_rel_size(TESTREL_A, Version::at(Lsn(lsn)), &ctx)
                 .await?,
             RELSEG_SIZE
         );
@@ -2279,7 +2285,7 @@ mod tests {
         m.commit(&ctx).await?;
         assert_eq!(
             tline
-                .get_rel_size(TESTREL_A, Version::Lsn(Lsn(lsn)), &ctx)
+                .get_rel_size(TESTREL_A, Version::at(Lsn(lsn)), &ctx)
                 .await?,
             RELSEG_SIZE - 1
         );
@@ -2297,7 +2303,7 @@ mod tests {
             m.commit(&ctx).await?;
             assert_eq!(
                 tline
-                    .get_rel_size(TESTREL_A, Version::Lsn(Lsn(lsn)), &ctx)
+                    .get_rel_size(TESTREL_A, Version::at(Lsn(lsn)), &ctx)
                     .await?,
                 size as BlockNumber
             );

poetry.lock

@@ -3170,19 +3170,24 @@ pbr = "*"
 
 [[package]]
 name = "setuptools"
-version = "70.0.0"
+version = "78.1.1"
 description = "Easily download, build, install, upgrade, and uninstall Python packages"
 optional = false
-python-versions = ">=3.8"
+python-versions = ">=3.9"
 groups = ["main"]
 files = [
-    {file = "setuptools-70.0.0-py3-none-any.whl", hash = "sha256:54faa7f2e8d2d11bcd2c07bed282eef1046b5c080d1c32add737d7b5817b1ad4"},
-    {file = "setuptools-70.0.0.tar.gz", hash = "sha256:f211a66637b8fa059bb28183da127d4e86396c991a942b028c6650d4319c3fd0"},
+    {file = "setuptools-78.1.1-py3-none-any.whl", hash = "sha256:c3a9c4211ff4c309edb8b8c4f1cbfa7ae324c4ba9f91ff254e3d305b9fd54561"},
+    {file = "setuptools-78.1.1.tar.gz", hash = "sha256:fcc17fd9cd898242f6b4adfaca46137a9edef687f43e6f78469692a5e70d851d"},
 ]
 
 [package.extras]
-docs = ["furo", "jaraco.packaging (>=9.3)", "jaraco.tidelift (>=1.4)", "pygments-github-lexers (==0.0.5)", "pyproject-hooks (!=1.1)", "rst.linker (>=1.9)", "sphinx (>=3.5)", "sphinx-favicon", "sphinx-inline-tabs", "sphinx-lint", "sphinx-notfound-page (>=1,<2)", "sphinx-reredirects", "sphinxcontrib-towncrier"]
-testing = ["build[virtualenv] (>=1.0.3)", "filelock (>=3.4.0)", "importlib-metadata", "ini2toml[lite] (>=0.14)", "jaraco.develop (>=7.21) ; python_version >= \"3.9\" and sys_platform != \"cygwin\"", "jaraco.envs (>=2.2)", "jaraco.path (>=3.2.0)", "mypy (==1.9)", "packaging (>=23.2)", "pip (>=19.1)", "pyproject-hooks (!=1.1)", "pytest (>=6,!=8.1.1)", "pytest-checkdocs (>=2.4)", "pytest-cov ; platform_python_implementation != \"PyPy\"", "pytest-enabler (>=2.2)", "pytest-home (>=0.5)", "pytest-mypy", "pytest-perf ; sys_platform != \"cygwin\"", "pytest-ruff (>=0.2.1) ; sys_platform != \"cygwin\"", "pytest-subprocess", "pytest-timeout", "pytest-xdist (>=3)", "tomli", "tomli-w (>=1.0.0)", "virtualenv (>=13.0.0)", "wheel"]
+check = ["pytest-checkdocs (>=2.4)", "pytest-ruff (>=0.2.1) ; sys_platform != \"cygwin\"", "ruff (>=0.8.0) ; sys_platform != \"cygwin\""]
+core = ["importlib_metadata (>=6) ; python_version < \"3.10\"", "jaraco.functools (>=4)", "jaraco.text (>=3.7)", "more_itertools", "more_itertools (>=8.8)", "packaging (>=24.2)", "platformdirs (>=4.2.2)", "tomli (>=2.0.1) ; python_version < \"3.11\"", "wheel (>=0.43.0)"]
+cover = ["pytest-cov"]
+doc = ["furo", "jaraco.packaging (>=9.3)", "jaraco.tidelift (>=1.4)", "pygments-github-lexers (==0.0.5)", "pyproject-hooks (!=1.1)", "rst.linker (>=1.9)", "sphinx (>=3.5)", "sphinx-favicon", "sphinx-inline-tabs", "sphinx-lint", "sphinx-notfound-page (>=1,<2)", "sphinx-reredirects", "sphinxcontrib-towncrier", "towncrier (<24.7)"]
+enabler = ["pytest-enabler (>=2.2)"]
+test = ["build[virtualenv] (>=1.0.3)", "filelock (>=3.4.0)", "ini2toml[lite] (>=0.14)", "jaraco.develop (>=7.21) ; python_version >= \"3.9\" and sys_platform != \"cygwin\"", "jaraco.envs (>=2.2)", "jaraco.path (>=3.7.2)", "jaraco.test (>=5.5)", "packaging (>=24.2)", "pip (>=19.1)", "pyproject-hooks (!=1.1)", "pytest (>=6,!=8.1.*)", "pytest-home (>=0.5)", "pytest-perf ; sys_platform != \"cygwin\"", "pytest-subprocess", "pytest-timeout", "pytest-xdist (>=3)", "tomli-w (>=1.0.0)", "virtualenv (>=13.0.0)", "wheel (>=0.44.0)"]
+type = ["importlib_metadata (>=7.0.2) ; python_version < \"3.10\"", "jaraco.develop (>=7.21) ; sys_platform != \"cygwin\"", "mypy (==1.14.*)", "pytest-mypy"]
 
 [[package]]
 name = "six"

proxy/Cargo.toml

@@ -127,3 +127,4 @@ rstest.workspace = true
 walkdir.workspace = true
 rand_distr = "0.4"
 tokio-postgres.workspace = true
+tracing-test = "0.2"

proxy/src/auth/backend/mod.rs

@@ -80,10 +80,22 @@ impl std::fmt::Display for Backend<'_, ()> {
                     .field(&endpoint.url())
                     .finish(),
                 #[cfg(any(test, feature = "testing"))]
-                ControlPlaneClient::PostgresMock(endpoint) => fmt
-                    .debug_tuple("ControlPlane::PostgresMock")
-                    .field(&endpoint.url())
-                    .finish(),
+                ControlPlaneClient::PostgresMock(endpoint) => {
+                    let url = endpoint.url();
+                    match url::Url::parse(url) {
+                        Ok(mut url) => {
+                            let _ = url.set_password(Some("_redacted_"));
+                            let url = url.as_str();
+                            fmt.debug_tuple("ControlPlane::PostgresMock")
+                                .field(&url)
+                                .finish()
+                        }
+                        Err(_) => fmt
+                            .debug_tuple("ControlPlane::PostgresMock")
+                            .field(&url)
+                            .finish(),
+                    }
+                }
                 #[cfg(test)]
                 ControlPlaneClient::Test(_) => fmt.debug_tuple("ControlPlane::Test").finish(),
             },

proxy/src/binary/pg_sni_router.rs

@@ -383,19 +383,12 @@ async fn handle_client(
     info!("performing the proxy pass...");
 
     let res = match client {
-        Connection::Raw(mut c) => {
-            copy_bidirectional_client_compute(&mut tls_stream, &mut c, |_, _| {}).await
-        }
-        Connection::Tls(mut c) => {
-            copy_bidirectional_client_compute(&mut tls_stream, &mut c, |_, _| {}).await
-        }
+        Connection::Raw(mut c) => copy_bidirectional_client_compute(&mut tls_stream, &mut c).await,
+        Connection::Tls(mut c) => copy_bidirectional_client_compute(&mut tls_stream, &mut c).await,
     };
 
     match res {
-        Ok(()) => Ok(()),
-        Err(ErrorSource::Timeout(_)) => Err(anyhow!(
-            "timed out while gracefully shutting down the connection"
-        )),
+        Ok(_) => Ok(()),
         Err(ErrorSource::Client(err)) => Err(err).context("client"),
         Err(ErrorSource::Compute(err)) => Err(err).context("compute"),
     }

proxy/src/binary/proxy.rs

@@ -1,9 +1,13 @@
+#[cfg(any(test, feature = "testing"))]
+use std::env;
 use std::net::SocketAddr;
 use std::path::PathBuf;
 use std::pin::pin;
 use std::sync::Arc;
 use std::time::Duration;
 
+#[cfg(any(test, feature = "testing"))]
+use anyhow::Context;
 use anyhow::{bail, ensure};
 use arc_swap::ArcSwapOption;
 use futures::future::Either;
@@ -35,6 +39,8 @@ use crate::scram::threadpool::ThreadPool;
 use crate::serverless::GlobalConnPoolOptions;
 use crate::serverless::cancel_set::CancelSet;
 use crate::tls::client_config::compute_client_config_with_root_certs;
+#[cfg(any(test, feature = "testing"))]
+use crate::url::ApiUrl;
 use crate::{auth, control_plane, http, serverless, usage_metrics};
 
 project_git_version!(GIT_VERSION);
@@ -777,7 +783,13 @@ fn build_auth_backend(
 
         #[cfg(any(test, feature = "testing"))]
         AuthBackendType::Postgres => {
-            let url = args.auth_endpoint.parse()?;
+            let mut url: ApiUrl = args.auth_endpoint.parse()?;
+            if url.password().is_none() {
+                let password = env::var("PGPASSWORD")
+                    .with_context(|| "auth-endpoint does not contain a password and environment variable `PGPASSWORD` is not set")?;
+                url.set_password(Some(&password))
+                    .expect("Failed to set password");
+            }
             let api = control_plane::client::mock::MockControlPlane::new(
                 url,
                 !args.is_private_access_proxy,

proxy/src/console_redirect_proxy.rs

@@ -129,12 +129,6 @@ pub async fn task_main(
                     let _disconnect = ctx.log_connect();
                     match p.proxy_pass(&config.connect_to_compute).await {
                         Ok(()) => {}
-                        Err(ErrorSource::Timeout(_)) => {
-                            info!(
-                                ?session_id,
-                                "per-client task timed out while gracefully shutting down the connection"
-                            );
-                        }
                         Err(ErrorSource::Client(e)) => {
                             error!(
                                 ?session_id,

proxy/src/logging.rs

@@ -1,13 +1,11 @@
-use std::cell::{Cell, RefCell};
+use std::cell::RefCell;
 use std::collections::HashMap;
-use std::hash::BuildHasher;
+use std::sync::Arc;
 use std::sync::atomic::{AtomicU32, Ordering};
-use std::{array, env, fmt, io};
+use std::{env, io};
 
 use chrono::{DateTime, Utc};
-use indexmap::IndexSet;
 use opentelemetry::trace::TraceContextExt;
-use scopeguard::defer;
 use serde::ser::{SerializeMap, Serializer};
 use tracing::subscriber::Interest;
 use tracing::{Event, Metadata, Span, Subscriber, callsite, span};
@@ -19,7 +17,6 @@ use tracing_subscriber::fmt::{FormatEvent, FormatFields};
 use tracing_subscriber::layer::{Context, Layer};
 use tracing_subscriber::prelude::*;
 use tracing_subscriber::registry::{LookupSpan, SpanRef};
-use try_lock::TryLock;
 
 /// Initialize logging and OpenTelemetry tracing and exporter.
 ///
@@ -55,7 +52,7 @@ pub async fn init() -> anyhow::Result<LoggingGuard> {
             StderrWriter {
                 stderr: std::io::stderr(),
             },
-            ["request_id", "session_id", "conn_id"],
+            &["request_id", "session_id", "conn_id"],
         ))
     } else {
         None
@@ -183,50 +180,65 @@ impl Clock for RealClock {
 /// Name of the field used by tracing crate to store the event message.
 const MESSAGE_FIELD: &str = "message";
 
+/// Tracing used to enforce that spans/events have no more than 32 fields.
+/// It seems this is no longer the case, but it's still documented in some places.
+/// Generally, we shouldn't expect more than 32 fields anyway, so we can try and
+/// rely on it for some (minor) performance gains.
+const MAX_TRACING_FIELDS: usize = 32;
+
 thread_local! {
-    /// Protects against deadlocks and double panics during log writing.
-    /// The current panic handler will use tracing to log panic information.
-    static REENTRANCY_GUARD: Cell<bool> = const { Cell::new(false) };
     /// Thread-local instance with per-thread buffer for log writing.
-    static EVENT_FORMATTER: RefCell<EventFormatter> = RefCell::new(EventFormatter::new());
+    static EVENT_FORMATTER: RefCell<EventFormatter> = const { RefCell::new(EventFormatter::new()) };
     /// Cached OS thread ID.
     static THREAD_ID: u64 = gettid::gettid();
 }
 
+/// Map for values fixed at callsite registration.
+// We use papaya here because registration rarely happens post-startup.
+// papaya is good for read-heavy workloads.
+//
+// We use rustc_hash here because callsite::Identifier will always be an integer with low-bit entropy,
+// since it's always a pointer to static mutable data. rustc_hash was designed for low-bit entropy.
+type CallsiteMap<T> =
+    papaya::HashMap<callsite::Identifier, T, std::hash::BuildHasherDefault<rustc_hash::FxHasher>>;
+
 /// Implements tracing layer to handle events specific to logging.
-struct JsonLoggingLayer<C: Clock, W: MakeWriter, const F: usize> {
+struct JsonLoggingLayer<C: Clock, W: MakeWriter> {
     clock: C,
-    skipped_field_indices: papaya::HashMap<callsite::Identifier, SkippedFieldIndices>,
-    callsite_ids: papaya::HashMap<callsite::Identifier, CallsiteId>,
     writer: W,
-    // We use a const generic and arrays to bypass one heap allocation.
-    extract_fields: IndexSet<&'static str>,
-    _marker: std::marker::PhantomData<[&'static str; F]>,
+
+    /// tracks which fields of each **event** are duplicates
+    skipped_field_indices: CallsiteMap<SkippedFieldIndices>,
+
+    span_info: CallsiteMap<CallsiteSpanInfo>,
+
+    /// Fields we want to keep track of in a separate json object.
+    extract_fields: &'static [&'static str],
 }
 
-impl<C: Clock, W: MakeWriter, const F: usize> JsonLoggingLayer<C, W, F> {
-    fn new(clock: C, writer: W, extract_fields: [&'static str; F]) -> Self {
+impl<C: Clock, W: MakeWriter> JsonLoggingLayer<C, W> {
+    fn new(clock: C, writer: W, extract_fields: &'static [&'static str]) -> Self {
         JsonLoggingLayer {
             clock,
-            skipped_field_indices: papaya::HashMap::default(),
-            callsite_ids: papaya::HashMap::default(),
+            skipped_field_indices: CallsiteMap::default(),
+            span_info: CallsiteMap::default(),
             writer,
-            extract_fields: IndexSet::from_iter(extract_fields),
-            _marker: std::marker::PhantomData,
+            extract_fields,
         }
     }
 
     #[inline]
-    fn callsite_id(&self, cs: callsite::Identifier) -> CallsiteId {
-        *self
-            .callsite_ids
+    fn span_info(&self, metadata: &'static Metadata<'static>) -> CallsiteSpanInfo {
+        self.span_info
             .pin()
-            .get_or_insert_with(cs, CallsiteId::next)
+            .get_or_insert_with(metadata.callsite(), || {
+                CallsiteSpanInfo::new(metadata, self.extract_fields)
+            })
+            .clone()
     }
 }
 
-impl<S, C: Clock + 'static, W: MakeWriter + 'static, const F: usize> Layer<S>
-    for JsonLoggingLayer<C, W, F>
+impl<S, C: Clock + 'static, W: MakeWriter + 'static> Layer<S> for JsonLoggingLayer<C, W>
 where
     S: Subscriber + for<'a> LookupSpan<'a>,
 {
@@ -237,35 +249,25 @@ where
         //       early, before OTel machinery, and add as event extension.
         let now = self.clock.now();
 
-        let res: io::Result<()> = REENTRANCY_GUARD.with(move |entered| {
-            if entered.get() {
-                let mut formatter = EventFormatter::new();
-                formatter.format::<S, F>(
-                    now,
-                    event,
-                    &ctx,
-                    &self.skipped_field_indices,
-                    &self.callsite_ids,
-                    &self.extract_fields,
-                )?;
-                self.writer.make_writer().write_all(formatter.buffer())
-            } else {
-                entered.set(true);
-                defer!(entered.set(false););
+        let res: io::Result<()> = EVENT_FORMATTER.with(|f| {
+            let mut borrow = f.try_borrow_mut();
+            let formatter = match borrow.as_deref_mut() {
+                Ok(formatter) => formatter,
+                // If the thread local formatter is borrowed,
+                // then we likely hit an edge case were we panicked during formatting.
+                // We allow the logging to proceed with an uncached formatter.
+                Err(_) => &mut EventFormatter::new(),
+            };
 
-                EVENT_FORMATTER.with_borrow_mut(move |formatter| {
-                    formatter.reset();
-                    formatter.format::<S, F>(
-                        now,
-                        event,
-                        &ctx,
-                        &self.skipped_field_indices,
-                        &self.callsite_ids,
-                        &self.extract_fields,
-                    )?;
-                    self.writer.make_writer().write_all(formatter.buffer())
-                })
-            }
+            formatter.reset();
+            formatter.format(
+                now,
+                event,
+                &ctx,
+                &self.skipped_field_indices,
+                self.extract_fields,
+            )?;
+            self.writer.make_writer().write_all(formatter.buffer())
         });
 
         // In case logging fails we generate a simpler JSON object.
@@ -287,50 +289,48 @@ where
     /// Registers a SpanFields instance as span extension.
     fn on_new_span(&self, attrs: &span::Attributes<'_>, id: &span::Id, ctx: Context<'_, S>) {
         let span = ctx.span(id).expect("span must exist");
-        let fields = SpanFields::default();
-        fields.record_fields(attrs);
 
-        // This could deadlock when there's a panic somewhere in the tracing
-        // event handling and a read or write guard is still held. This includes
-        // the OTel subscriber.
-        let mut exts = span.extensions_mut();
+        let mut fields = SpanFields::new(self.span_info(span.metadata()));
+        attrs.record(&mut fields);
 
-        exts.insert(fields);
+        // This is a new span: the extensions should not be locked
+        // unless some layer spawned a thread to process this span.
+        // I don't think any layers do that.
+        span.extensions_mut().insert(fields);
     }
 
     fn on_record(&self, id: &span::Id, values: &span::Record<'_>, ctx: Context<'_, S>) {
         let span = ctx.span(id).expect("span must exist");
-        let ext = span.extensions();
-        if let Some(data) = ext.get::<SpanFields>() {
-            data.record_fields(values);
+
+        // assumption: `on_record` is rarely called.
+        // assumption: a span being updated by one thread,
+        //             and formatted by another thread is even rarer.
+        let mut ext = span.extensions_mut();
+        if let Some(fields) = ext.get_mut::<SpanFields>() {
+            values.record(fields);
         }
     }
 
-    /// Called (lazily) whenever a new log call is executed. We quickly check
-    /// for duplicate field names and record duplicates as skippable. Last one
-    /// wins.
+    /// Called (lazily) roughly once per event/span instance. We quickly check
+    /// for duplicate field names and record duplicates as skippable. Last field wins.
     fn register_callsite(&self, metadata: &'static Metadata<'static>) -> Interest {
+        debug_assert!(
+            metadata.fields().len() <= MAX_TRACING_FIELDS,
+            "callsite {metadata:?} has too many fields."
+        );
+
         if !metadata.is_event() {
-            self.callsite_id(metadata.callsite());
+            // register the span info.
+            self.span_info(metadata);
             // Must not be never because we wouldn't get trace and span data.
             return Interest::always();
         }
 
         let mut field_indices = SkippedFieldIndices::default();
-        let mut seen_fields = HashMap::<&'static str, usize>::new();
+        let mut seen_fields = HashMap::new();
         for field in metadata.fields() {
-            use std::collections::hash_map::Entry;
-            match seen_fields.entry(field.name()) {
-                Entry::Vacant(entry) => {
-                    // field not seen yet
-                    entry.insert(field.index());
-                }
-                Entry::Occupied(mut entry) => {
-                    // replace currently stored index
-                    let old_index = entry.insert(field.index());
-                    // ... and append it to list of skippable indices
-                    field_indices.push(old_index);
-                }
+            if let Some(old_index) = seen_fields.insert(field.name(), field.index()) {
+                field_indices.set(old_index);
             }
         }
 
@@ -344,110 +344,113 @@ where
     }
 }
 
-#[derive(Copy, Clone, Debug, Default)]
-#[repr(transparent)]
-struct CallsiteId(u32);
+/// Any span info that is fixed to a particular callsite. Not variable between span instances.
+#[derive(Clone)]
+struct CallsiteSpanInfo {
+    /// index of each field to extract. usize::MAX if not found.
+    extract: Arc<[usize]>,
 
-impl CallsiteId {
-    #[inline]
-    fn next() -> Self {
-        // Start at 1 to reserve 0 for default.
-        static COUNTER: AtomicU32 = AtomicU32::new(1);
-        CallsiteId(COUNTER.fetch_add(1, Ordering::Relaxed))
-    }
+    /// tracks the fixed "callsite ID" for each span.
+    /// note: this is not stable between runs.
+    normalized_name: Arc<str>,
 }
 
-impl fmt::Display for CallsiteId {
-    #[inline]
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        self.0.fmt(f)
+impl CallsiteSpanInfo {
+    fn new(metadata: &'static Metadata<'static>, extract_fields: &[&'static str]) -> Self {
+        // Start at 1 to reserve 0 for default.
+        static COUNTER: AtomicU32 = AtomicU32::new(1);
+
+        let names: Vec<&'static str> = metadata.fields().iter().map(|f| f.name()).collect();
+
+        // get all the indices of span fields we want to focus
+        let extract = extract_fields
+            .iter()
+            // use rposition, since we want last match wins.
+            .map(|f1| names.iter().rposition(|f2| f1 == f2).unwrap_or(usize::MAX))
+            .collect();
+
+        // normalized_name is unique for each callsite, but it is not
+        // unified across separate proxy instances.
+        // todo: can we do better here?
+        let cid = COUNTER.fetch_add(1, Ordering::Relaxed);
+        let normalized_name = format!("{}#{cid}", metadata.name()).into();
+
+        Self {
+            extract,
+            normalized_name,
+        }
     }
 }
 
 /// Stores span field values recorded during the spans lifetime.
-#[derive(Default)]
 struct SpanFields {
-    // TODO: Switch to custom enum with lasso::Spur for Strings?
-    fields: papaya::HashMap<&'static str, serde_json::Value>,
+    values: [serde_json::Value; MAX_TRACING_FIELDS],
+
+    /// cached span info so we can avoid extra hashmap lookups in the hot path.
+    span_info: CallsiteSpanInfo,
 }
 
 impl SpanFields {
-    #[inline]
-    fn record_fields<R: tracing_subscriber::field::RecordFields>(&self, fields: R) {
-        fields.record(&mut SpanFieldsRecorder {
-            fields: self.fields.pin(),
-        });
+    fn new(span_info: CallsiteSpanInfo) -> Self {
+        Self {
+            span_info,
+            values: [const { serde_json::Value::Null }; MAX_TRACING_FIELDS],
+        }
     }
 }
 
-/// Implements a tracing field visitor to convert and store values.
-struct SpanFieldsRecorder<'m, S, G> {
-    fields: papaya::HashMapRef<'m, &'static str, serde_json::Value, S, G>,
-}
-
-impl<S: BuildHasher, G: papaya::Guard> tracing::field::Visit for SpanFieldsRecorder<'_, S, G> {
+impl tracing::field::Visit for SpanFields {
     #[inline]
     fn record_f64(&mut self, field: &tracing::field::Field, value: f64) {
-        self.fields
-            .insert(field.name(), serde_json::Value::from(value));
+        self.values[field.index()] = serde_json::Value::from(value);
     }
 
     #[inline]
     fn record_i64(&mut self, field: &tracing::field::Field, value: i64) {
-        self.fields
-            .insert(field.name(), serde_json::Value::from(value));
+        self.values[field.index()] = serde_json::Value::from(value);
     }
 
     #[inline]
     fn record_u64(&mut self, field: &tracing::field::Field, value: u64) {
-        self.fields
-            .insert(field.name(), serde_json::Value::from(value));
+        self.values[field.index()] = serde_json::Value::from(value);
     }
 
     #[inline]
     fn record_i128(&mut self, field: &tracing::field::Field, value: i128) {
         if let Ok(value) = i64::try_from(value) {
-            self.fields
-                .insert(field.name(), serde_json::Value::from(value));
+            self.values[field.index()] = serde_json::Value::from(value);
         } else {
-            self.fields
-                .insert(field.name(), serde_json::Value::from(format!("{value}")));
+            self.values[field.index()] = serde_json::Value::from(format!("{value}"));
         }
     }
 
     #[inline]
     fn record_u128(&mut self, field: &tracing::field::Field, value: u128) {
         if let Ok(value) = u64::try_from(value) {
-            self.fields
-                .insert(field.name(), serde_json::Value::from(value));
+            self.values[field.index()] = serde_json::Value::from(value);
         } else {
-            self.fields
-                .insert(field.name(), serde_json::Value::from(format!("{value}")));
+            self.values[field.index()] = serde_json::Value::from(format!("{value}"));
         }
     }
 
     #[inline]
     fn record_bool(&mut self, field: &tracing::field::Field, value: bool) {
-        self.fields
-            .insert(field.name(), serde_json::Value::from(value));
+        self.values[field.index()] = serde_json::Value::from(value);
     }
 
     #[inline]
     fn record_bytes(&mut self, field: &tracing::field::Field, value: &[u8]) {
-        self.fields
-            .insert(field.name(), serde_json::Value::from(value));
+        self.values[field.index()] = serde_json::Value::from(value);
     }
 
     #[inline]
     fn record_str(&mut self, field: &tracing::field::Field, value: &str) {
-        self.fields
-            .insert(field.name(), serde_json::Value::from(value));
+        self.values[field.index()] = serde_json::Value::from(value);
     }
 
     #[inline]
     fn record_debug(&mut self, field: &tracing::field::Field, value: &dyn std::fmt::Debug) {
-        self.fields
-            .insert(field.name(), serde_json::Value::from(format!("{value:?}")));
+        self.values[field.index()] = serde_json::Value::from(format!("{value:?}"));
     }
 
     #[inline]
@@ -456,38 +459,33 @@ impl<S: BuildHasher, G: papaya::Guard> tracing::field::Visit for SpanFieldsRecor
         field: &tracing::field::Field,
         value: &(dyn std::error::Error + 'static),
     ) {
-        self.fields
-            .insert(field.name(), serde_json::Value::from(format!("{value}")));
+        self.values[field.index()] = serde_json::Value::from(format!("{value}"));
     }
 }
 
 /// List of field indices skipped during logging. Can list duplicate fields or
 /// metafields not meant to be logged.
-#[derive(Clone, Default)]
+#[derive(Copy, Clone, Default)]
 struct SkippedFieldIndices {
-    bits: u64,
+    // 32-bits is large enough for `MAX_TRACING_FIELDS`
+    bits: u32,
 }
 
 impl SkippedFieldIndices {
     #[inline]
-    fn is_empty(&self) -> bool {
+    fn is_empty(self) -> bool {
         self.bits == 0
     }
 
     #[inline]
-    fn push(&mut self, index: usize) {
-        self.bits |= 1u64
-            .checked_shl(index as u32)
-            .expect("field index too large");
+    fn set(&mut self, index: usize) {
+        debug_assert!(index <= 32, "index out of bounds of 32-bit set");
+        self.bits |= 1 << index;
     }
 
     #[inline]
-    fn contains(&self, index: usize) -> bool {
-        self.bits
-            & 1u64
-                .checked_shl(index as u32)
-                .expect("field index too large")
-            != 0
+    fn contains(self, index: usize) -> bool {
+        self.bits & (1 << index) != 0
     }
 }
 
@@ -499,7 +497,7 @@ struct EventFormatter {
 
 impl EventFormatter {
     #[inline]
-    fn new() -> Self {
+    const fn new() -> Self {
         EventFormatter {
             logline_buffer: Vec::new(),
         }
@@ -515,14 +513,13 @@ impl EventFormatter {
         self.logline_buffer.clear();
     }
 
-    fn format<S, const F: usize>(
+    fn format<S>(
         &mut self,
         now: DateTime<Utc>,
         event: &Event<'_>,
         ctx: &Context<'_, S>,
-        skipped_field_indices: &papaya::HashMap<callsite::Identifier, SkippedFieldIndices>,
-        callsite_ids: &papaya::HashMap<callsite::Identifier, CallsiteId>,
-        extract_fields: &IndexSet<&'static str>,
+        skipped_field_indices: &CallsiteMap<SkippedFieldIndices>,
+        extract_fields: &'static [&'static str],
     ) -> io::Result<()>
     where
         S: Subscriber + for<'a> LookupSpan<'a>,
@@ -533,8 +530,11 @@ impl EventFormatter {
         let normalized_meta = event.normalized_metadata();
         let meta = normalized_meta.as_ref().unwrap_or_else(|| event.metadata());
 
-        let skipped_field_indices = skipped_field_indices.pin();
-        let skipped_field_indices = skipped_field_indices.get(&meta.callsite());
+        let skipped_field_indices = skipped_field_indices
+            .pin()
+            .get(&meta.callsite())
+            .copied()
+            .unwrap_or_default();
 
         let mut serialize = || {
             let mut serializer = serde_json::Serializer::new(&mut self.logline_buffer);
@@ -565,9 +565,11 @@ impl EventFormatter {
             }
 
             let spans = SerializableSpans {
-                ctx,
-                callsite_ids,
-                extract: ExtractedSpanFields::<'_, F>::new(extract_fields),
+                // collect all spans from parent to root.
+                spans: ctx
+                    .event_span(event)
+                    .map_or(vec![], |parent| parent.scope().collect()),
+                extracted: ExtractedSpanFields::new(extract_fields),
             };
             serializer.serialize_entry("spans", &spans)?;
 
@@ -620,9 +622,9 @@ impl EventFormatter {
                 }
             }
 
-            if spans.extract.has_values() {
+            if spans.extracted.has_values() {
                 // TODO: add fields from event, too?
-                serializer.serialize_entry("extract", &spans.extract)?;
+                serializer.serialize_entry("extract", &spans.extracted)?;
             }
 
             serializer.end()
@@ -635,15 +637,15 @@ impl EventFormatter {
 }
 
 /// Extracts the message field that's mixed will other fields.
-struct MessageFieldExtractor<'a, S: serde::ser::SerializeMap> {
+struct MessageFieldExtractor<S: serde::ser::SerializeMap> {
     serializer: S,
-    skipped_field_indices: Option<&'a SkippedFieldIndices>,
+    skipped_field_indices: SkippedFieldIndices,
     state: Option<Result<(), S::Error>>,
 }
 
-impl<'a, S: serde::ser::SerializeMap> MessageFieldExtractor<'a, S> {
+impl<S: serde::ser::SerializeMap> MessageFieldExtractor<S> {
     #[inline]
-    fn new(serializer: S, skipped_field_indices: Option<&'a SkippedFieldIndices>) -> Self {
+    fn new(serializer: S, skipped_field_indices: SkippedFieldIndices) -> Self {
         Self {
             serializer,
             skipped_field_indices,
@@ -665,13 +667,11 @@ impl<'a, S: serde::ser::SerializeMap> MessageFieldExtractor<'a, S> {
     fn accept_field(&self, field: &tracing::field::Field) -> bool {
         self.state.is_none()
             && field.name() == MESSAGE_FIELD
-            && !self
-                .skipped_field_indices
-                .is_some_and(|i| i.contains(field.index()))
+            && !self.skipped_field_indices.contains(field.index())
     }
 }
 
-impl<S: serde::ser::SerializeMap> tracing::field::Visit for MessageFieldExtractor<'_, S> {
+impl<S: serde::ser::SerializeMap> tracing::field::Visit for MessageFieldExtractor<S> {
     #[inline]
     fn record_f64(&mut self, field: &tracing::field::Field, value: f64) {
         if self.accept_field(field) {
@@ -751,14 +751,14 @@ impl<S: serde::ser::SerializeMap> tracing::field::Visit for MessageFieldExtracto
 /// can be skipped.
 // This is entirely optional and only cosmetic, though maybe helps a
 // bit during log parsing in dashboards when there's no field with empty object.
-struct FieldsPresent<'a>(pub bool, Option<&'a SkippedFieldIndices>);
+struct FieldsPresent(pub bool, SkippedFieldIndices);
 
 // Even though some methods have an overhead (error, bytes) it is assumed the
 // compiler won't include this since we ignore the value entirely.
-impl tracing::field::Visit for FieldsPresent<'_> {
+impl tracing::field::Visit for FieldsPresent {
     #[inline]
     fn record_debug(&mut self, field: &tracing::field::Field, _: &dyn std::fmt::Debug) {
-        if !self.1.is_some_and(|i| i.contains(field.index()))
+        if !self.1.contains(field.index())
             && field.name() != MESSAGE_FIELD
             && !field.name().starts_with("log.")
         {
@@ -768,10 +768,7 @@ impl tracing::field::Visit for FieldsPresent<'_> {
 }
 
 /// Serializes the fields directly supplied with a log event.
-struct SerializableEventFields<'a, 'event>(
-    &'a tracing::Event<'event>,
-    Option<&'a SkippedFieldIndices>,
-);
+struct SerializableEventFields<'a, 'event>(&'a tracing::Event<'event>, SkippedFieldIndices);
 
 impl serde::ser::Serialize for SerializableEventFields<'_, '_> {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -788,15 +785,15 @@ impl serde::ser::Serialize for SerializableEventFields<'_, '_> {
 }
 
 /// A tracing field visitor that skips the message field.
-struct MessageFieldSkipper<'a, S: serde::ser::SerializeMap> {
+struct MessageFieldSkipper<S: serde::ser::SerializeMap> {
     serializer: S,
-    skipped_field_indices: Option<&'a SkippedFieldIndices>,
+    skipped_field_indices: SkippedFieldIndices,
     state: Result<(), S::Error>,
 }
 
-impl<'a, S: serde::ser::SerializeMap> MessageFieldSkipper<'a, S> {
+impl<S: serde::ser::SerializeMap> MessageFieldSkipper<S> {
     #[inline]
-    fn new(serializer: S, skipped_field_indices: Option<&'a SkippedFieldIndices>) -> Self {
+    fn new(serializer: S, skipped_field_indices: SkippedFieldIndices) -> Self {
         Self {
             serializer,
             skipped_field_indices,
@@ -809,9 +806,7 @@ impl<'a, S: serde::ser::SerializeMap> MessageFieldSkipper<'a, S> {
         self.state.is_ok()
             && field.name() != MESSAGE_FIELD
             && !field.name().starts_with("log.")
-            && !self
-                .skipped_field_indices
-                .is_some_and(|i| i.contains(field.index()))
+            && !self.skipped_field_indices.contains(field.index())
     }
 
     #[inline]
@@ -821,7 +816,7 @@ impl<'a, S: serde::ser::SerializeMap> MessageFieldSkipper<'a, S> {
     }
 }
 
-impl<S: serde::ser::SerializeMap> tracing::field::Visit for MessageFieldSkipper<'_, S> {
+impl<S: serde::ser::SerializeMap> tracing::field::Visit for MessageFieldSkipper<S> {
     #[inline]
     fn record_f64(&mut self, field: &tracing::field::Field, value: f64) {
         if self.accept_field(field) {
@@ -905,18 +900,17 @@ impl<S: serde::ser::SerializeMap> tracing::field::Visit for MessageFieldSkipper<
 /// with the span names as keys. To prevent collision we append a numberic value
 /// to the name. Also, collects any span fields we're interested in. Last one
 /// wins.
-struct SerializableSpans<'a, 'ctx, Span, const F: usize>
+struct SerializableSpans<'ctx, S>
 where
-    Span: Subscriber + for<'lookup> LookupSpan<'lookup>,
+    S: for<'lookup> LookupSpan<'lookup>,
 {
-    ctx: &'a Context<'ctx, Span>,
-    callsite_ids: &'a papaya::HashMap<callsite::Identifier, CallsiteId>,
-    extract: ExtractedSpanFields<'a, F>,
+    spans: Vec<SpanRef<'ctx, S>>,
+    extracted: ExtractedSpanFields,
 }
 
-impl<Span, const F: usize> serde::ser::Serialize for SerializableSpans<'_, '_, Span, F>
+impl<S> serde::ser::Serialize for SerializableSpans<'_, S>
 where
-    Span: Subscriber + for<'lookup> LookupSpan<'lookup>,
+    S: for<'lookup> LookupSpan<'lookup>,
 {
     fn serialize<Ser>(&self, serializer: Ser) -> Result<Ser::Ok, Ser::Error>
     where
@@ -924,25 +918,22 @@ where
     {
         let mut serializer = serializer.serialize_map(None)?;
 
-        if let Some(leaf_span) = self.ctx.lookup_current() {
-            for span in leaf_span.scope().from_root() {
-                // Append a numeric callsite ID to the span name to keep the name unique
-                // in the JSON object.
-                let cid = self
-                    .callsite_ids
-                    .pin()
-                    .get(&span.metadata().callsite())
-                    .copied()
-                    .unwrap_or_default();
+        for span in self.spans.iter().rev() {
+            let ext = span.extensions();
 
-                // Loki turns the # into an underscore during field name concatenation.
-                serializer.serialize_key(&format_args!("{}#{}", span.metadata().name(), &cid))?;
+            // all spans should have this extension.
+            let Some(fields) = ext.get() else { continue };
 
-                serializer.serialize_value(&SerializableSpanFields {
-                    span: &span,
-                    extract: &self.extract,
-                })?;
-            }
+            self.extracted.layer_span(fields);
+
+            let SpanFields { values, span_info } = fields;
+            serializer.serialize_entry(
+                &*span_info.normalized_name,
+                &SerializableSpanFields {
+                    fields: span.metadata().fields(),
+                    values,
+                },
+            )?;
         }
 
         serializer.end()
@@ -950,80 +941,77 @@ where
 }
 
 /// Serializes the span fields as object.
-struct SerializableSpanFields<'a, 'span, Span, const F: usize>
-where
-    Span: for<'lookup> LookupSpan<'lookup>,
-{
-    span: &'a SpanRef<'span, Span>,
-    extract: &'a ExtractedSpanFields<'a, F>,
+struct SerializableSpanFields<'span> {
+    fields: &'span tracing::field::FieldSet,
+    values: &'span [serde_json::Value; MAX_TRACING_FIELDS],
 }
 
-impl<Span, const F: usize> serde::ser::Serialize for SerializableSpanFields<'_, '_, Span, F>
-where
-    Span: for<'lookup> LookupSpan<'lookup>,
-{
+impl serde::ser::Serialize for SerializableSpanFields<'_> {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
         S: serde::ser::Serializer,
     {
         let mut serializer = serializer.serialize_map(None)?;
 
-        let ext = self.span.extensions();
-        if let Some(data) = ext.get::<SpanFields>() {
-            for (name, value) in &data.fields.pin() {
-                serializer.serialize_entry(name, value)?;
-                // TODO: replace clone with reference, if possible.
-                self.extract.set(name, value.clone());
+        for (field, value) in std::iter::zip(self.fields, self.values) {
+            if value.is_null() {
+                continue;
             }
+            serializer.serialize_entry(field.name(), value)?;
         }
 
         serializer.end()
     }
 }
 
-struct ExtractedSpanFields<'a, const F: usize> {
-    names: &'a IndexSet<&'static str>,
-    // TODO: replace TryLock with something local thread and interior mutability.
-    //       serde API doesn't let us use `mut`.
-    values: TryLock<([Option<serde_json::Value>; F], bool)>,
+struct ExtractedSpanFields {
+    names: &'static [&'static str],
+    values: RefCell<Vec<serde_json::Value>>,
 }
 
-impl<'a, const F: usize> ExtractedSpanFields<'a, F> {
-    fn new(names: &'a IndexSet<&'static str>) -> Self {
+impl ExtractedSpanFields {
+    fn new(names: &'static [&'static str]) -> Self {
         ExtractedSpanFields {
             names,
-            values: TryLock::new((array::from_fn(|_| Option::default()), false)),
+            values: RefCell::new(vec![serde_json::Value::Null; names.len()]),
         }
     }
 
-    #[inline]
-    fn set(&self, name: &'static str, value: serde_json::Value) {
-        if let Some((index, _)) = self.names.get_full(name) {
-            let mut fields = self.values.try_lock().expect("thread-local use");
-            fields.0[index] = Some(value);
-            fields.1 = true;
+    fn layer_span(&self, fields: &SpanFields) {
+        let mut v = self.values.borrow_mut();
+        let SpanFields { values, span_info } = fields;
+
+        // extract the fields
+        for (i, &j) in span_info.extract.iter().enumerate() {
+            let Some(value) = values.get(j) else { continue };
+
+            if !value.is_null() {
+                // TODO: replace clone with reference, if possible.
+                v[i] = value.clone();
+            }
         }
     }
 
     #[inline]
     fn has_values(&self) -> bool {
-        self.values.try_lock().expect("thread-local use").1
+        self.values.borrow().iter().any(|v| !v.is_null())
     }
 }
 
-impl<const F: usize> serde::ser::Serialize for ExtractedSpanFields<'_, F> {
+impl serde::ser::Serialize for ExtractedSpanFields {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
         S: serde::ser::Serializer,
     {
         let mut serializer = serializer.serialize_map(None)?;
 
-        let values = self.values.try_lock().expect("thread-local use");
-        for (i, value) in values.0.iter().enumerate() {
-            if let Some(value) = value {
-                let key = self.names[i];
-                serializer.serialize_entry(key, value)?;
+        let values = self.values.borrow();
+        for (key, value) in std::iter::zip(self.names, &*values) {
+            if value.is_null() {
+                continue;
             }
+
+            serializer.serialize_entry(key, value)?;
         }
 
         serializer.end()
@@ -1032,7 +1020,6 @@ impl<const F: usize> serde::ser::Serialize for ExtractedSpanFields<'_, F> {
 
 #[cfg(test)]
 mod tests {
-    use std::marker::PhantomData;
     use std::sync::{Arc, Mutex, MutexGuard};
 
     use assert_json_diff::assert_json_eq;
@@ -1081,10 +1068,9 @@ mod tests {
         let log_layer = JsonLoggingLayer {
             clock: clock.clone(),
             skipped_field_indices: papaya::HashMap::default(),
-            callsite_ids: papaya::HashMap::default(),
+            span_info: papaya::HashMap::default(),
             writer: buffer.clone(),
-            extract_fields: IndexSet::from_iter(["x"]),
-            _marker: PhantomData::<[&'static str; 1]>,
+            extract_fields: &["x"],
         };
 
         let registry = tracing_subscriber::Registry::default().with(log_layer);

proxy/src/metrics.rs

@@ -200,10 +200,8 @@ pub enum HttpDirection {
 #[derive(FixedCardinalityLabel, Copy, Clone)]
 #[label(singleton = "direction")]
 pub enum Direction {
-    #[label(rename = "tx")]
-    ComputeToClient,
-    #[label(rename = "rx")]
-    ClientToCompute,
+    Tx,
+    Rx,
 }
 
 #[derive(FixedCardinalityLabel, Clone, Copy, Debug)]

proxy/src/proxy/copy_bidirectional.rs

@@ -1,394 +1,313 @@
 use std::future::poll_fn;
 use std::io;
-use std::ops::Range;
 use std::pin::Pin;
 use std::task::{Context, Poll, ready};
-use std::time::Duration;
 
 use tokio::io::{AsyncRead, AsyncWrite, ReadBuf};
 use tracing::info;
 
-use crate::metrics::Direction;
+#[derive(Debug)]
+enum TransferState {
+    Running(CopyBuffer),
+    ShuttingDown(u64),
+    Done(u64),
+}
 
-const DISCONNECT_TIMEOUT: Duration = Duration::from_secs(10);
+#[derive(Debug)]
+pub(crate) enum ErrorDirection {
+    Read(io::Error),
+    Write(io::Error),
+}
 
-/// Mark a value as being unlikely.
-#[cold]
-#[inline(always)]
-fn cold<I>(i: I) -> I {
-    i
+impl ErrorSource {
+    fn from_client(err: ErrorDirection) -> ErrorSource {
+        match err {
+            ErrorDirection::Read(client) => Self::Client(client),
+            ErrorDirection::Write(compute) => Self::Compute(compute),
+        }
+    }
+    fn from_compute(err: ErrorDirection) -> ErrorSource {
+        match err {
+            ErrorDirection::Write(client) => Self::Client(client),
+            ErrorDirection::Read(compute) => Self::Compute(compute),
+        }
+    }
 }
 
 #[derive(Debug)]
 pub enum ErrorSource {
     Client(io::Error),
     Compute(io::Error),
-    Timeout(tokio::time::error::Elapsed),
 }
 
-impl ErrorSource {
-    fn read(dir: Direction, err: io::Error) -> Self {
-        match dir {
-            Direction::ComputeToClient => ErrorSource::Compute(err),
-            Direction::ClientToCompute => ErrorSource::Client(err),
-        }
-    }
-
-    fn write(dir: Direction, err: io::Error) -> Self {
-        match dir {
-            Direction::ComputeToClient => ErrorSource::Client(err),
-            Direction::ClientToCompute => ErrorSource::Compute(err),
+fn transfer_one_direction<A, B>(
+    cx: &mut Context<'_>,
+    state: &mut TransferState,
+    r: &mut A,
+    w: &mut B,
+) -> Poll<Result<u64, ErrorDirection>>
+where
+    A: AsyncRead + AsyncWrite + Unpin + ?Sized,
+    B: AsyncRead + AsyncWrite + Unpin + ?Sized,
+{
+    let mut r = Pin::new(r);
+    let mut w = Pin::new(w);
+    loop {
+        match state {
+            TransferState::Running(buf) => {
+                let count = ready!(buf.poll_copy(cx, r.as_mut(), w.as_mut()))?;
+                *state = TransferState::ShuttingDown(count);
+            }
+            TransferState::ShuttingDown(count) => {
+                ready!(w.as_mut().poll_shutdown(cx)).map_err(ErrorDirection::Write)?;
+                *state = TransferState::Done(*count);
+            }
+            TransferState::Done(count) => return Poll::Ready(Ok(*count)),
         }
     }
 }
 
+#[tracing::instrument(skip_all)]
 pub async fn copy_bidirectional_client_compute<Client, Compute>(
     client: &mut Client,
     compute: &mut Compute,
-    mut f: impl for<'a> FnMut(Direction, &'a [u8]),
-) -> Result<(), ErrorSource>
+) -> Result<(u64, u64), ErrorSource>
 where
     Client: AsyncRead + AsyncWrite + Unpin + ?Sized,
     Compute: AsyncRead + AsyncWrite + Unpin + ?Sized,
 {
-    let f = &mut f;
-    let mut client_to_compute = CopyBuffer::new(Direction::ClientToCompute);
-    let mut compute_to_client = CopyBuffer::new(Direction::ComputeToClient);
+    let mut client_to_compute = TransferState::Running(CopyBuffer::new());
+    let mut compute_to_client = TransferState::Running(CopyBuffer::new());
 
-    let mut client = Pin::new(client);
-    let mut compute = Pin::new(compute);
+    poll_fn(|cx| {
+        let mut client_to_compute_result =
+            transfer_one_direction(cx, &mut client_to_compute, client, compute)
+                .map_err(ErrorSource::from_client)?;
+        let mut compute_to_client_result =
+            transfer_one_direction(cx, &mut compute_to_client, compute, client)
+                .map_err(ErrorSource::from_compute)?;
 
-    // Initial copy hot path
-    let close_dir = poll_fn(|cx| -> Poll<Result<_, ErrorSource>> {
-        let copy1 = client_to_compute.poll_copy(cx, f, client.as_mut(), compute.as_mut())?;
-        let copy2 = compute_to_client.poll_copy(cx, f, compute.as_mut(), client.as_mut())?;
+        // TODO: 1 info log, with a enum label for close direction.
 
-        match (copy1, copy2) {
-            (Poll::Pending, Poll::Pending) => Poll::Pending,
-            (Poll::Ready(()), _) => Poll::Ready(Ok(client_to_compute.dir)),
-            (_, Poll::Ready(())) => Poll::Ready(Ok(compute_to_client.dir)),
+        // Early termination checks from compute to client.
+        if let TransferState::Done(_) = compute_to_client {
+            if let TransferState::Running(buf) = &client_to_compute {
+                info!("Compute is done, terminate client");
+                // Initiate shutdown
+                client_to_compute = TransferState::ShuttingDown(buf.amt);
+                client_to_compute_result =
+                    transfer_one_direction(cx, &mut client_to_compute, client, compute)
+                        .map_err(ErrorSource::from_client)?;
+            }
         }
+
+        // Early termination checks from client to compute.
+        if let TransferState::Done(_) = client_to_compute {
+            if let TransferState::Running(buf) = &compute_to_client {
+                info!("Client is done, terminate compute");
+                // Initiate shutdown
+                compute_to_client = TransferState::ShuttingDown(buf.amt);
+                compute_to_client_result =
+                    transfer_one_direction(cx, &mut compute_to_client, compute, client)
+                        .map_err(ErrorSource::from_compute)?;
+            }
+        }
+
+        // It is not a problem if ready! returns early ... (comment remains the same)
+        let client_to_compute = ready!(client_to_compute_result);
+        let compute_to_client = ready!(compute_to_client_result);
+
+        Poll::Ready(Ok((client_to_compute, compute_to_client)))
     })
-    .await?;
-
-    // initiate shutdown.
-    match close_dir {
-        Direction::ClientToCompute => {
-            info!("Client is done, terminate compute");
-
-            // we will never write anymore data to the client.
-            compute_to_client.filled = 0..0;
-
-            // make sure to shutdown the client conn.
-            compute_to_client.need_flush = true;
-        }
-        Direction::ComputeToClient => {
-            info!("Compute is done, terminate client");
-
-            // we will never write anymore data to the compute.
-            client_to_compute.filled = 0..0;
-
-            // make sure to shutdown the compute conn.
-            client_to_compute.need_flush = true;
-        }
-    }
-
-    // Finish sending the rest of the data to client/compute before shutting it down.
-    //
-    // Edge case:
-    // * peer has filled the TCP buffers and is blocking on a `write()`,
-    // * proxy has filled the TCP buffers and is waiting on a `write()`.
-    // Since no side is reading from the buffers, no progress will be made.
-    let shutdown = poll_fn(|cx| {
-        let res1 = client_to_compute.poll_empty(cx, compute.as_mut())?;
-        let res2 = compute_to_client.poll_empty(cx, client.as_mut())?;
-
-        if res1.is_ready() && res2.is_ready() {
-            Poll::Ready(Ok(()))
-        } else {
-            Poll::Pending
-        }
-    });
-
-    // We assume most peers will have enough buffer space so this issue doesn't arise, but we apply
-    // a timeout just in case.
-    //
-    // We could also update `poll_empty` to try and read the data, but I think this is not an edge case
-    // worth overcomplicating.
-    let res = tokio::time::timeout(DISCONNECT_TIMEOUT, shutdown).await;
-
-    match res {
-        Ok(res) => res,
-        Err(timeout) => Err(ErrorSource::Timeout(timeout)),
-    }
+    .await
 }
 
-const DEFAULT_BUF_SIZE: usize = 1024;
+#[derive(Debug)]
 pub(super) struct CopyBuffer {
-    dir: Direction,
+    read_done: bool,
     need_flush: bool,
-    filled: Range<usize>,
-    buf: [u8; DEFAULT_BUF_SIZE],
+    pos: usize,
+    cap: usize,
+    amt: u64,
+    buf: Box<[u8]>,
 }
+const DEFAULT_BUF_SIZE: usize = 1024;
 
 impl CopyBuffer {
-    pub(super) const fn new(dir: Direction) -> Self {
+    pub(super) fn new() -> Self {
         Self {
-            dir,
+            read_done: false,
             need_flush: false,
-            filled: 0..0,
-            buf: [0; DEFAULT_BUF_SIZE],
+            pos: 0,
+            cap: 0,
+            amt: 0,
+            buf: vec![0; DEFAULT_BUF_SIZE].into_boxed_slice(),
         }
     }
 
-    /// Returns Ready(Ok(())) when no more writes could progress, and the buffer has space to read.
-    #[inline(always)]
-    fn poll_write_loop<W>(
+    fn poll_fill_buf<R>(
         &mut self,
         cx: &mut Context<'_>,
-        mut writer: Pin<&mut W>,
-    ) -> Poll<Result<(), ErrorSource>>
-    where
-        W: AsyncWrite + ?Sized,
-    {
-        debug_assert!(!self.filled.is_empty());
-
-        loop {
-            let filled_buf = &self.buf[self.filled.clone()];
-            match writer.as_mut().poll_write(cx, filled_buf) {
-                Poll::Ready(Err(err)) => {
-                    return Poll::Ready(Err(ErrorSource::write(self.dir, cold(err))));
-                }
-                Poll::Ready(Ok(0)) => {
-                    let err =
-                        io::Error::new(io::ErrorKind::WriteZero, "write zero byte into writer");
-                    return Poll::Ready(Err(ErrorSource::write(self.dir, cold(err))));
-                }
-                Poll::Ready(Ok(i)) => {
-                    // update the write head.
-                    self.filled.start += i;
-                    self.need_flush = true;
-
-                    // we wrote some data, but the filled buffer might not be fully empty yet.
-                    if !self.filled.is_empty() {
-                        continue;
-                    }
-
-                    // the buffer is definitely empty. reset positions.
-                    self.filled = 0..0;
-                    break;
-                }
-                // While we couldn't write, we might be able to read.
-                Poll::Pending if self.filled.end < self.buf.len() => break,
-                // We couldn't write, and have no space to read. Just exit.
-                Poll::Pending => return Poll::Pending,
-            }
-        }
-
-        Poll::Ready(Ok(()))
-    }
-
-    /// Returns Ready(Ok((true))) when read returns EOF.
-    /// Returns Ready(Ok((false))) when read returns data.
-    #[inline(always)]
-    fn poll_read_once<R>(
-        &mut self,
-        cx: &mut Context<'_>,
-        f: &mut impl for<'a> FnMut(Direction, &'a [u8]),
         reader: Pin<&mut R>,
-    ) -> Poll<Result<bool, ErrorSource>>
+    ) -> Poll<io::Result<()>>
     where
         R: AsyncRead + ?Sized,
     {
-        debug_assert!(self.filled.end < self.buf.len());
-        let mut buf = ReadBuf::new(&mut self.buf[self.filled.end..]);
+        let me = &mut *self;
+        let mut buf = ReadBuf::new(&mut me.buf);
+        buf.set_filled(me.cap);
 
-        match reader.poll_read(cx, &mut buf) {
-            Poll::Ready(Ok(())) => {
-                let filled = buf.filled();
-                // no more data to read, switch to shutdown mode.
-                if filled.is_empty() {
-                    self.need_flush = true;
-                    return Poll::Ready(Ok(true));
-                }
-
-                // run our inspection callback.
-                f(self.dir, filled);
-
-                // update the read head.
-                self.filled.end += filled.len();
-
-                // read more data
-                Poll::Ready(Ok(false))
-            }
-            // cannot continue on error.
-            Poll::Ready(Err(e)) => Poll::Ready(Err(ErrorSource::read(self.dir, cold(e)))),
-            // No more data to read, and no more data to write.
-            Poll::Pending => Poll::Pending,
+        let res = reader.poll_read(cx, &mut buf);
+        if let Poll::Ready(Ok(())) = res {
+            let filled_len = buf.filled().len();
+            me.read_done = me.cap == filled_len;
+            me.cap = filled_len;
         }
+        res
     }
 
-    /// Returns Ready(Ok(())) when read returns EOF.
-    fn poll_copy<R, W>(
+    fn poll_write_buf<R, W>(
         &mut self,
         cx: &mut Context<'_>,
-        f: &mut impl for<'a> FnMut(Direction, &'a [u8]),
         mut reader: Pin<&mut R>,
         mut writer: Pin<&mut W>,
-    ) -> Poll<Result<(), ErrorSource>>
+    ) -> Poll<Result<usize, ErrorDirection>>
     where
         R: AsyncRead + ?Sized,
         W: AsyncWrite + ?Sized,
     {
-        // this register eliminates a branch in the hot loop.
-        let mut empty = self.filled.is_empty();
-
-        // write then read hot loop
-        loop {
-            if !empty {
-                ready!(self.poll_write_loop(cx, writer.as_mut())?);
-            }
-
-            // If empty is true, there is guaranteed space to read.
-            // If empty is false, and the write loop returned ready, then we know there's space for more reads.
-            match self.poll_read_once(cx, f, reader.as_mut())? {
-                // EOF
-                Poll::Ready(true) => return Poll::Ready(Ok(())),
-                // Needs write.
-                Poll::Ready(false) => empty = false,
-                // Cannot read. The peer might not send us anything until
-                // they receive data from us, so let's switch to flushing.
-                Poll::Pending => break,
+        let me = &mut *self;
+        match writer.as_mut().poll_write(cx, &me.buf[me.pos..me.cap]) {
+            Poll::Pending => {
+                // Top up the buffer towards full if we can read a bit more
+                // data - this should improve the chances of a large write
+                if !me.read_done && me.cap < me.buf.len() {
+                    ready!(me.poll_fill_buf(cx, reader.as_mut())).map_err(ErrorDirection::Read)?;
+                }
+                Poll::Pending
             }
+            res @ Poll::Ready(_) => res.map_err(ErrorDirection::Write),
         }
-
-        if self.need_flush {
-            let flush = writer.as_mut().poll_flush(cx);
-            ready!(flush.map_err(|e| ErrorSource::write(self.dir, e))?);
-            self.need_flush = false;
-        }
-
-        // there might be more data still to read.
-        Poll::Pending
     }
 
-    /// Returns Ready(Ok(())) when the conn is fully shutdown.
-    pub(super) fn poll_empty<W>(
+    pub(super) fn poll_copy<R, W>(
         &mut self,
         cx: &mut Context<'_>,
+        mut reader: Pin<&mut R>,
         mut writer: Pin<&mut W>,
-    ) -> Poll<Result<(), ErrorSource>>
+    ) -> Poll<Result<u64, ErrorDirection>>
     where
+        R: AsyncRead + ?Sized,
         W: AsyncWrite + ?Sized,
     {
-        if !self.filled.is_empty() {
-            ready!(self.poll_write_loop(cx, writer.as_mut())?);
+        loop {
+            // If there is some space left in our buffer, then we try to read some
+            // data to continue, thus maximizing the chances of a large write.
+            if self.cap < self.buf.len() && !self.read_done {
+                match self.poll_fill_buf(cx, reader.as_mut()) {
+                    Poll::Ready(Ok(())) => (),
+                    Poll::Ready(Err(err)) => return Poll::Ready(Err(ErrorDirection::Read(err))),
+                    Poll::Pending => {
+                        // Ignore pending reads when our buffer is not empty, because
+                        // we can try to write data immediately.
+                        if self.pos == self.cap {
+                            // Try flushing when the reader has no progress to avoid deadlock
+                            // when the reader depends on buffered writer.
+                            if self.need_flush {
+                                ready!(writer.as_mut().poll_flush(cx))
+                                    .map_err(ErrorDirection::Write)?;
+                                self.need_flush = false;
+                            }
 
-            if !self.filled.is_empty() {
-                // still some data to write
-                return Poll::Pending;
+                            return Poll::Pending;
+                        }
+                    }
+                }
+            }
+
+            // If our buffer has some data, let's write it out!
+            while self.pos < self.cap {
+                let i = ready!(self.poll_write_buf(cx, reader.as_mut(), writer.as_mut()))?;
+                if i == 0 {
+                    return Poll::Ready(Err(ErrorDirection::Write(io::Error::new(
+                        io::ErrorKind::WriteZero,
+                        "write zero byte into writer",
+                    ))));
+                }
+                self.pos += i;
+                self.amt += i as u64;
+                self.need_flush = true;
+            }
+
+            // If pos larger than cap, this loop will never stop.
+            // In particular, user's wrong poll_write implementation returning
+            // incorrect written length may lead to thread blocking.
+            debug_assert!(
+                self.pos <= self.cap,
+                "writer returned length larger than input slice"
+            );
+
+            // All data has been written, the buffer can be considered empty again
+            self.pos = 0;
+            self.cap = 0;
+
+            // If we've written all the data and we've seen EOF, flush out the
+            // data and finish the transfer.
+            if self.read_done {
+                ready!(writer.as_mut().poll_flush(cx)).map_err(ErrorDirection::Write)?;
+                return Poll::Ready(Ok(self.amt));
             }
         }
-
-        if self.need_flush {
-            let res = writer.poll_shutdown(cx);
-            ready!(res.map_err(|e| ErrorSource::write(self.dir, e))?);
-            self.need_flush = false;
-        }
-
-        // no data to read, no data to write.
-        Poll::Ready(Ok(()))
     }
 }
 
 #[cfg(test)]
 mod tests {
-    use tokio::io::{AsyncReadExt, AsyncWriteExt};
+    use tokio::io::AsyncWriteExt;
 
     use super::*;
 
     #[tokio::test]
     async fn test_client_to_compute() {
-        let (mut client, mut client_proxy) = tokio::io::duplex(32); // Create a mock duplex stream
-        let (mut proxy_compute, mut compute) = tokio::io::duplex(16); // Create a mock duplex stream
+        let (mut client_client, mut client_proxy) = tokio::io::duplex(8); // Create a mock duplex stream
+        let (mut compute_proxy, mut compute_client) = tokio::io::duplex(32); // Create a mock duplex stream
 
-        client.write_all(b"Neon Serverless Postgres").await.unwrap();
-        compute.write_all(b"is amazing").await.unwrap();
+        // Simulate 'a' finishing while there's still data for 'b'
+        client_client.write_all(b"hello").await.unwrap();
+        client_client.shutdown().await.unwrap();
+        compute_client.write_all(b"Neon").await.unwrap();
+        compute_client.shutdown().await.unwrap();
 
-        client.shutdown().await.unwrap();
-
-        let copy = tokio::spawn(async move {
-            copy_bidirectional_client_compute(&mut client_proxy, &mut proxy_compute, |_, _| {})
-                .await
-                .unwrap();
-        });
+        let result = copy_bidirectional_client_compute(&mut client_proxy, &mut compute_proxy)
+            .await
+            .unwrap();
 
         // Assert correct transferred amounts
-        let mut client_recv = String::new();
-        let mut compute_recv = String::new();
-
-        client.read_to_string(&mut client_recv).await.unwrap();
-        compute.read_to_string(&mut compute_recv).await.unwrap();
-
-        assert_eq!(compute_recv, "Neon Serverless Postgres");
-        assert_eq!(client_recv, "is amazing");
-
-        copy.await.unwrap();
+        let (client_to_compute_count, compute_to_client_count) = result;
+        assert_eq!(client_to_compute_count, 5); // 'hello' was transferred
+        assert_eq!(compute_to_client_count, 4); // response only partially transferred or not at all
     }
 
     #[tokio::test]
     async fn test_compute_to_client() {
-        let (mut client, mut client_proxy) = tokio::io::duplex(32); // Create a mock duplex stream
-        let (mut proxy_compute, mut compute) = tokio::io::duplex(16); // Create a mock duplex stream
+        let (mut client_client, mut client_proxy) = tokio::io::duplex(32); // Create a mock duplex stream
+        let (mut compute_proxy, mut compute_client) = tokio::io::duplex(8); // Create a mock duplex stream
 
-        client.write_all(b"Neon Serverless Postgres").await.unwrap();
-        compute.write_all(b"is amazing").await.unwrap();
+        // Simulate 'a' finishing while there's still data for 'b'
+        compute_client.write_all(b"hello").await.unwrap();
+        compute_client.shutdown().await.unwrap();
+        client_client
+            .write_all(b"Neon Serverless Postgres")
+            .await
+            .unwrap();
 
-        compute.shutdown().await.unwrap();
-
-        let copy = tokio::spawn(async move {
-            copy_bidirectional_client_compute(&mut client_proxy, &mut proxy_compute, |_, _| {})
-                .await
-                .unwrap();
-        });
+        let result = copy_bidirectional_client_compute(&mut client_proxy, &mut compute_proxy)
+            .await
+            .unwrap();
 
         // Assert correct transferred amounts
-        let mut client_recv = String::new();
-        let mut compute_recv = String::new();
-
-        client.read_to_string(&mut client_recv).await.unwrap();
-        compute.read_to_string(&mut compute_recv).await.unwrap();
-
-        assert_eq!(compute_recv, "Neon Serverless ");
-        assert_eq!(client_recv, "is amazing");
-
-        copy.await.unwrap();
-    }
-
-    #[tokio::test(start_paused = true)]
-    async fn test_timeout() {
-        let (mut client, mut client_proxy) = tokio::io::duplex(32); // Create a mock duplex stream
-        let (mut proxy_compute, mut compute) = tokio::io::duplex(16); // Create a mock duplex stream
-
-        // Try to send 24 bytes to compute, but compute only has space for 16 bytes.
-        // Writes will not succeed.
-        client.write_all(b"Neon Serverless Postgres").await.unwrap();
-        client.shutdown().await.unwrap();
-
-        let copy = tokio::spawn(async move {
-            copy_bidirectional_client_compute(&mut client_proxy, &mut proxy_compute, |_, _| {})
-                .await
-                .unwrap_err()
-        });
-
-        tokio::time::advance(DISCONNECT_TIMEOUT).await;
-
-        let res = copy.await.unwrap();
-        assert!(matches!(res, ErrorSource::Timeout(_)));
-
-        // Assert correct transferred amounts
-        let mut compute_recv = String::new();
-        compute.read_to_string(&mut compute_recv).await.unwrap();
-        assert_eq!(compute_recv, "Neon Serverless ");
+        let (client_to_compute_count, compute_to_client_count) = result;
+        assert_eq!(compute_to_client_count, 5); // 'hello' was transferred
+        assert!(client_to_compute_count <= 8); // response only partially transferred or not at all
     }
 }

proxy/src/proxy/mod.rs

@@ -167,12 +167,6 @@ pub async fn task_main(
                     let _disconnect = ctx.log_connect();
                     match p.proxy_pass(&config.connect_to_compute).await {
                         Ok(()) => {}
-                        Err(ErrorSource::Timeout(_)) => {
-                            info!(
-                                ?session_id,
-                                "per-client task timed out while gracefully shutting down the connection"
-                            );
-                        }
                         Err(ErrorSource::Client(e)) => {
                             warn!(
                                 ?session_id,

proxy/src/proxy/passthrough.rs

@@ -1,6 +1,7 @@
 use smol_str::SmolStr;
 use tokio::io::{AsyncRead, AsyncWrite};
 use tracing::debug;
+use utils::measured_stream::MeasuredStream;
 
 use super::copy_bidirectional::ErrorSource;
 use crate::cancellation;
@@ -8,15 +9,14 @@ use crate::compute::PostgresConnection;
 use crate::config::ComputeConfig;
 use crate::control_plane::messages::MetricsAuxInfo;
 use crate::metrics::{Direction, Metrics, NumClientConnectionsGuard, NumConnectionRequestsGuard};
-use crate::proxy::copy_bidirectional_client_compute;
 use crate::stream::Stream;
 use crate::usage_metrics::{Ids, MetricCounterRecorder, USAGE_METRICS};
 
 /// Forward bytes in both directions (client <-> compute).
-#[tracing::instrument(level = "debug", skip_all)]
+#[tracing::instrument(skip_all)]
 pub(crate) async fn proxy_pass(
-    mut client: Stream<impl AsyncRead + AsyncWrite + Unpin>,
-    mut compute: impl AsyncRead + AsyncWrite + Unpin,
+    client: impl AsyncRead + AsyncWrite + Unpin,
+    compute: impl AsyncRead + AsyncWrite + Unpin,
     aux: MetricsAuxInfo,
     private_link_id: Option<SmolStr>,
 ) -> Result<(), ErrorSource> {
@@ -28,30 +28,37 @@ pub(crate) async fn proxy_pass(
     });
 
     let metrics = &Metrics::get().proxy.io_bytes;
-    let m_sent = metrics.with_labels(Direction::ComputeToClient);
-    let m_recv = metrics.with_labels(Direction::ClientToCompute);
+    let m_sent = metrics.with_labels(Direction::Tx);
+    let mut client = MeasuredStream::new(
+        client,
+        |_| {},
+        |cnt| {
+            // Number of bytes we sent to the client (outbound).
+            metrics.get_metric(m_sent).inc_by(cnt as u64);
+            usage_tx.record_egress(cnt as u64);
+        },
+    );
 
-    let inspect = |direction, bytes: &[u8]| match direction {
-        Direction::ComputeToClient => {
-            metrics.get_metric(m_sent).inc_by(bytes.len() as u64);
-            usage_tx.record_egress(bytes.len() as u64);
-        }
-        Direction::ClientToCompute => {
-            metrics.get_metric(m_recv).inc_by(bytes.len() as u64);
-            usage_tx.record_ingress(bytes.len() as u64);
-        }
-    };
+    let m_recv = metrics.with_labels(Direction::Rx);
+    let mut compute = MeasuredStream::new(
+        compute,
+        |_| {},
+        |cnt| {
+            // Number of bytes the client sent to the compute node (inbound).
+            metrics.get_metric(m_recv).inc_by(cnt as u64);
+            usage_tx.record_ingress(cnt as u64);
+        },
+    );
 
     // Starting from here we only proxy the client's traffic.
     debug!("performing the proxy pass...");
+    let _ = crate::proxy::copy_bidirectional::copy_bidirectional_client_compute(
+        &mut client,
+        &mut compute,
+    )
+    .await?;
 
-    // reduce branching internal to the hot path.
-    match &mut client {
-        Stream::Raw { raw } => copy_bidirectional_client_compute(raw, &mut compute, inspect).await,
-        Stream::Tls { tls, .. } => {
-            copy_bidirectional_client_compute(&mut *tls, &mut compute, inspect).await
-        }
-    }
+    Ok(())
 }
 
 pub(crate) struct ProxyPassthrough<S> {

proxy/src/proxy/retry.rs

@@ -48,7 +48,7 @@ impl ShouldRetryWakeCompute for postgres_client::error::DbError {
         use postgres_client::error::SqlState;
         // Here are errors that happens after the user successfully authenticated to the database.
         // TODO: there are pgbouncer errors that should be retried, but they are not listed here.
-        !matches!(
+        let non_retriable_pg_errors = matches!(
             self.code(),
             &SqlState::TOO_MANY_CONNECTIONS
                 | &SqlState::OUT_OF_MEMORY
@@ -56,8 +56,20 @@ impl ShouldRetryWakeCompute for postgres_client::error::DbError {
                 | &SqlState::T_R_SERIALIZATION_FAILURE
                 | &SqlState::INVALID_CATALOG_NAME
                 | &SqlState::INVALID_SCHEMA_NAME
-                | &SqlState::INVALID_PARAMETER_VALUE
-        )
+                | &SqlState::INVALID_PARAMETER_VALUE,
+        );
+        if non_retriable_pg_errors {
+            return false;
+        }
+        // PGBouncer errors that should not trigger a wake_compute retry.
+        if self.code() == &SqlState::PROTOCOL_VIOLATION {
+            // Source for the error message:
+            // https://github.com/pgbouncer/pgbouncer/blob/f15997fe3effe3a94ba8bcc1ea562e6117d1a131/src/client.c#L1070
+            return !self
+                .message()
+                .contains("no more connections allowed (max_client_conn)");
+        }
+        true
     }
 }
 
@@ -110,3 +122,55 @@ pub(crate) fn retry_after(num_retries: u32, config: RetryConfig) -> time::Durati
         .base_delay
         .mul_f64(config.backoff_factor.powi((num_retries as i32) - 1))
 }
+
+#[cfg(test)]
+mod tests {
+    use super::ShouldRetryWakeCompute;
+    use postgres_client::error::{DbError, SqlState};
+
+    #[test]
+    fn should_retry_wake_compute_for_db_error() {
+        // These SQLStates should NOT trigger a wake_compute retry.
+        let non_retry_states = [
+            SqlState::TOO_MANY_CONNECTIONS,
+            SqlState::OUT_OF_MEMORY,
+            SqlState::SYNTAX_ERROR,
+            SqlState::T_R_SERIALIZATION_FAILURE,
+            SqlState::INVALID_CATALOG_NAME,
+            SqlState::INVALID_SCHEMA_NAME,
+            SqlState::INVALID_PARAMETER_VALUE,
+        ];
+        for state in non_retry_states {
+            let err = DbError::new_test_error(state.clone(), "oops".to_string());
+            assert!(
+                !err.should_retry_wake_compute(),
+                "State {state:?} unexpectedly retried"
+            );
+        }
+
+        // Errors coming from pgbouncer should not trigger a wake_compute retry
+        let non_retry_pgbouncer_errors = ["no more connections allowed (max_client_conn)"];
+        for error in non_retry_pgbouncer_errors {
+            let err = DbError::new_test_error(SqlState::PROTOCOL_VIOLATION, error.to_string());
+            assert!(
+                !err.should_retry_wake_compute(),
+                "PGBouncer error {error:?} unexpectedly retried"
+            );
+        }
+
+        // These SQLStates should trigger a wake_compute retry.
+        let retry_states = [
+            SqlState::CONNECTION_FAILURE,
+            SqlState::CONNECTION_EXCEPTION,
+            SqlState::CONNECTION_DOES_NOT_EXIST,
+            SqlState::SQLCLIENT_UNABLE_TO_ESTABLISH_SQLCONNECTION,
+        ];
+        for state in retry_states {
+            let err = DbError::new_test_error(state.clone(), "oops".to_string());
+            assert!(
+                err.should_retry_wake_compute(),
+                "State {state:?} unexpectedly skipped retry"
+            );
+        }
+    }
+}

proxy/src/proxy/tests/mod.rs

@@ -15,6 +15,7 @@ use rstest::rstest;
 use rustls::crypto::ring;
 use rustls::pki_types;
 use tokio::io::DuplexStream;
+use tracing_test::traced_test;
 
 use super::connect_compute::ConnectMechanism;
 use super::retry::CouldRetry;
@@ -381,8 +382,14 @@ enum ConnectAction {
     WakeFail,
     WakeRetry,
     Connect,
+    // connect_once -> Err, could_retry = true, should_retry_wake_compute = true
     Retry,
+    // connect_once -> Err, could_retry = true, should_retry_wake_compute = false
+    RetryNoWake,
+    // connect_once -> Err, could_retry = false, should_retry_wake_compute = true
     Fail,
+    // connect_once -> Err, could_retry = false, should_retry_wake_compute = false
+    FailNoWake,
 }
 
 #[derive(Clone)]
@@ -424,6 +431,7 @@ struct TestConnection;
 #[derive(Debug)]
 struct TestConnectError {
     retryable: bool,
+    wakeable: bool,
     kind: crate::error::ErrorKind,
 }
 
@@ -448,7 +456,7 @@ impl CouldRetry for TestConnectError {
 }
 impl ShouldRetryWakeCompute for TestConnectError {
     fn should_retry_wake_compute(&self) -> bool {
-        true
+        self.wakeable
     }
 }
 
@@ -471,10 +479,22 @@ impl ConnectMechanism for TestConnectMechanism {
             ConnectAction::Connect => Ok(TestConnection),
             ConnectAction::Retry => Err(TestConnectError {
                 retryable: true,
+                wakeable: true,
+                kind: ErrorKind::Compute,
+            }),
+            ConnectAction::RetryNoWake => Err(TestConnectError {
+                retryable: true,
+                wakeable: false,
                 kind: ErrorKind::Compute,
             }),
             ConnectAction::Fail => Err(TestConnectError {
                 retryable: false,
+                wakeable: true,
+                kind: ErrorKind::Compute,
+            }),
+            ConnectAction::FailNoWake => Err(TestConnectError {
+                retryable: false,
+                wakeable: false,
                 kind: ErrorKind::Compute,
             }),
             x => panic!("expecting action {x:?}, connect is called instead"),
@@ -709,3 +729,92 @@ async fn wake_non_retry() {
         .unwrap_err();
     mechanism.verify();
 }
+
+#[tokio::test]
+#[traced_test]
+async fn fail_but_wake_invalidates_cache() {
+    let ctx = RequestContext::test();
+    let mech = TestConnectMechanism::new(vec![
+        ConnectAction::Wake,
+        ConnectAction::Fail,
+        ConnectAction::Wake,
+        ConnectAction::Connect,
+    ]);
+    let user = helper_create_connect_info(&mech);
+    let cfg = config();
+
+    connect_to_compute(&ctx, &mech, &user, cfg.retry, &cfg)
+        .await
+        .unwrap();
+
+    assert!(logs_contain(
+        "invalidating stalled compute node info cache entry"
+    ));
+}
+
+#[tokio::test]
+#[traced_test]
+async fn fail_no_wake_skips_cache_invalidation() {
+    let ctx = RequestContext::test();
+    let mech = TestConnectMechanism::new(vec![
+        ConnectAction::Wake,
+        ConnectAction::FailNoWake,
+        ConnectAction::Connect,
+    ]);
+    let user = helper_create_connect_info(&mech);
+    let cfg = config();
+
+    connect_to_compute(&ctx, &mech, &user, cfg.retry, &cfg)
+        .await
+        .unwrap();
+
+    assert!(!logs_contain(
+        "invalidating stalled compute node info cache entry"
+    ));
+}
+
+#[tokio::test]
+#[traced_test]
+async fn retry_but_wake_invalidates_cache() {
+    let _ = env_logger::try_init();
+    use ConnectAction::*;
+
+    let ctx = RequestContext::test();
+    // Wake → Retry (retryable + wakeable) → Wake → Connect
+    let mechanism = TestConnectMechanism::new(vec![Wake, Retry, Wake, Connect]);
+    let user_info = helper_create_connect_info(&mechanism);
+    let cfg = config();
+
+    connect_to_compute(&ctx, &mechanism, &user_info, cfg.retry, &cfg)
+        .await
+        .unwrap();
+    mechanism.verify();
+
+    // Because Retry has wakeable=true, we should see invalidate_cache
+    assert!(logs_contain(
+        "invalidating stalled compute node info cache entry"
+    ));
+}
+
+#[tokio::test]
+#[traced_test]
+async fn retry_no_wake_skips_invalidation() {
+    let _ = env_logger::try_init();
+    use ConnectAction::*;
+
+    let ctx = RequestContext::test();
+    // Wake → RetryNoWake (retryable + NOT wakeable)
+    let mechanism = TestConnectMechanism::new(vec![Wake, RetryNoWake]);
+    let user_info = helper_create_connect_info(&mechanism);
+    let cfg = config();
+
+    connect_to_compute(&ctx, &mechanism, &user_info, cfg.retry, &cfg)
+        .await
+        .unwrap_err();
+    mechanism.verify();
+
+    // Because RetryNoWake has wakeable=false, we must NOT see invalidate_cache
+    assert!(!logs_contain(
+        "invalidating stalled compute node info cache entry"
+    ));
+}

proxy/src/scram/pbkdf2.rs

@@ -13,22 +13,19 @@ pub(crate) struct Pbkdf2 {
 // inspired from <https://github.com/neondatabase/rust-postgres/blob/20031d7a9ee1addeae6e0968e3899ae6bf01cee2/postgres-protocol/src/authentication/sasl.rs#L36-L61>
 impl Pbkdf2 {
     pub(crate) fn start(str: &[u8], salt: &[u8], iterations: u32) -> Self {
-        let hmac =
+        // key the HMAC and derive the first block in-place
+        let mut hmac =
             Hmac::<Sha256>::new_from_slice(str).expect("HMAC is able to accept all key sizes");
-
-        let prev = hmac
-            .clone()
-            .chain_update(salt)
-            .chain_update(1u32.to_be_bytes())
-            .finalize()
-            .into_bytes();
+        hmac.update(salt);
+        hmac.update(&1u32.to_be_bytes());
+        let init_block = hmac.finalize_reset().into_bytes();
 
         Self {
             hmac,
-            // one consumed for the hash above
+            // one iteration spent above
             iterations: iterations - 1,
-            hi: prev,
-            prev,
+            hi: init_block,
+            prev: init_block,
         }
     }
 
@@ -44,14 +41,17 @@ impl Pbkdf2 {
             iterations,
         } = self;
 
-        // only do 4096 iterations per turn before sharing the thread for fairness
+        // only do up to 4096 iterations per turn for fairness
         let n = (*iterations).clamp(0, 4096);
         for _ in 0..n {
-            *prev = hmac.clone().chain_update(*prev).finalize().into_bytes();
+            hmac.update(prev);
+            let block = hmac.finalize_reset().into_bytes();
 
-            for (hi, prev) in hi.iter_mut().zip(*prev) {
-                *hi ^= prev;
+            for (hi_byte, &b) in hi.iter_mut().zip(block.iter()) {
+                *hi_byte ^= b;
             }
+
+            *prev = block;
         }
 
         *iterations -= n;

proxy/src/serverless/websocket.rs

@@ -2,7 +2,7 @@ use std::pin::Pin;
 use std::sync::Arc;
 use std::task::{Context, Poll, ready};
 
-use anyhow::{Context as _, anyhow};
+use anyhow::Context as _;
 use bytes::{Buf, BufMut, Bytes, BytesMut};
 use framed_websockets::{Frame, OpCode, WebSocketServer};
 use futures::{Sink, Stream};
@@ -169,9 +169,6 @@ pub(crate) async fn serve_websocket(
             ctx.log_connect();
             match p.proxy_pass(&config.connect_to_compute).await {
                 Ok(()) => Ok(()),
-                Err(ErrorSource::Timeout(_)) => Err(anyhow!(
-                    "timed out while gracefully shutting down the connection"
-                )),
                 Err(ErrorSource::Client(err)) => Err(err).context("client"),
                 Err(ErrorSource::Compute(err)) => Err(err).context("compute"),
             }

proxy/src/url.rs

@@ -43,6 +43,12 @@ impl std::ops::Deref for ApiUrl {
     }
 }
 
+impl std::ops::DerefMut for ApiUrl {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
 impl std::fmt::Display for ApiUrl {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         self.0.fmt(f)

test_runner/fixtures/metrics.py

@@ -184,6 +184,7 @@ PAGESERVER_PER_TENANT_METRICS: tuple[str, ...] = (
     "pageserver_evictions_with_low_residence_duration_total",
     "pageserver_aux_file_estimated_size",
     "pageserver_valid_lsn_lease_count",
+    "pageserver_tenant_offloaded_timelines",
     counter("pageserver_tenant_throttling_count_accounted_start"),
     counter("pageserver_tenant_throttling_count_accounted_finish"),
     counter("pageserver_tenant_throttling_wait_usecs_sum"),

test_runner/regress/test_attach_tenant_config.py

@@ -187,6 +187,7 @@ def test_fully_custom_config(positive_env: NeonEnv):
             "args": {"format": "bincode", "compression": {"zstd": {"level": 1}}},
         },
         "rel_size_v2_enabled": True,
+        "relsize_snapshot_cache_capacity": 10000,
         "gc_compaction_enabled": True,
         "gc_compaction_verification": False,
         "gc_compaction_initial_threshold_kb": 1024000,

test_runner/regress/test_basebackup.py

@@ -0,0 +1,77 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from fixtures.utils import wait_until
+
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnvBuilder
+
+
+def test_basebackup_cache(neon_env_builder: NeonEnvBuilder):
+    """
+    Simple test for basebackup cache.
+    1. Check that we always hit the cache after compute restart.
+    2. Check that we eventually delete old basebackup files, but not the latest one.
+    3. Check that we delete basebackup file for timeline with active compute.
+    """
+
+    neon_env_builder.pageserver_config_override = """
+        tenant_config = { basebackup_cache_enabled = true }
+        basebackup_cache_config = { cleanup_period = '1s' }
+    """
+
+    env = neon_env_builder.init_start()
+    ep = env.endpoints.create("main")
+    ps = env.pageserver
+    ps_http = ps.http_client()
+
+    # 1. Check that we always hit the cache after compute restart.
+    for i in range(3):
+        ep.start()
+        ep.stop()
+
+        def check_metrics(i=i):
+            metrics = ps_http.get_metrics()
+            # Never miss.
+            # The first time compute_ctl sends `get_basebackup` with lsn=None, we do not cache such requests.
+            # All other requests should be a hit
+            assert (
+                metrics.query_one(
+                    "pageserver_basebackup_cache_read_total", {"result": "miss"}
+                ).value
+                == 0
+            )
+            # All but the first requests are hits.
+            assert (
+                metrics.query_one("pageserver_basebackup_cache_read_total", {"result": "hit"}).value
+                == i
+            )
+            # Every compute shut down should trigger a prepare reuest.
+            assert (
+                metrics.query_one(
+                    "pageserver_basebackup_cache_prepare_total", {"result": "ok"}
+                ).value
+                == i + 1
+            )
+
+        wait_until(check_metrics)
+
+    # 2. Check that we eventually delete old basebackup files, but not the latest one.
+    def check_bb_file_count():
+        bb_files = list(ps.workdir.joinpath("basebackup_cache").iterdir())
+        # tmp dir + 1 basebackup file.
+        assert len(bb_files) == 2
+
+    wait_until(check_bb_file_count)
+
+    # 3. Check that we delete basebackup file for timeline with active compute.
+    ep.start()
+    ep.safe_psql("create table t1 as select generate_series(1, 10) as n")
+
+    def check_bb_dir_empty():
+        bb_files = list(ps.workdir.joinpath("basebackup_cache").iterdir())
+        # only tmp dir.
+        assert len(bb_files) == 1
+
+    wait_until(check_bb_dir_empty)

test_runner/regress/test_compute_catalog.py

@@ -19,6 +19,16 @@ TEST_ROLE_NAMES = [
     {"name": "role$"},
     {"name": "role$$"},
     {"name": "role$x$"},
+    {"name": "x"},
+    {"name": "xx"},
+    {"name": "$x"},
+    {"name": "x$"},
+    {"name": "$x$"},
+    {"name": "xx$"},
+    {"name": "$xx"},
+    {"name": "$xx$"},
+    # 63 bytes is the limit for role/DB names in Postgres
+    {"name": "x" * 63},
 ]
 
 TEST_DB_NAMES = [
@@ -74,6 +84,43 @@ TEST_DB_NAMES = [
         "name": "db name$x$",
         "owner": "role$x$",
     },
+    {
+        "name": "x",
+        "owner": "x",
+    },
+    {
+        "name": "xx",
+        "owner": "xx",
+    },
+    {
+        "name": "$x",
+        "owner": "$x",
+    },
+    {
+        "name": "x$",
+        "owner": "x$",
+    },
+    {
+        "name": "$x$",
+        "owner": "$x$",
+    },
+    {
+        "name": "xx$",
+        "owner": "xx$",
+    },
+    {
+        "name": "$xx",
+        "owner": "$xx",
+    },
+    {
+        "name": "$xx$",
+        "owner": "$xx$",
+    },
+    # 63 bytes is the limit for role/DB names in Postgres
+    {
+        "name": "x" * 63,
+        "owner": "x" * 63,
+    },
 ]
 
 
@@ -146,6 +193,10 @@ def test_compute_create_drop_dbs_and_roles(neon_simple_env: NeonEnv):
     """
     Test that compute_ctl can create and work with databases and roles
     with special characters (whitespaces, %, tabs, etc.) in the name.
+    Also use `drop_subscriptions_before_start: true`. We do not actually
+    have any subscriptions in this test, so it should be no-op, but it
+    i) simulates the case when we create a second dev branch together with
+    a new project creation, and ii) just generally stresses more code paths.
     """
     env = neon_simple_env
 
@@ -159,6 +210,7 @@ def test_compute_create_drop_dbs_and_roles(neon_simple_env: NeonEnv):
         **{
             "spec": {
                 "skip_pg_catalog_updates": False,
+                "drop_subscriptions_before_start": True,
                 "cluster": {
                     "roles": TEST_ROLE_NAMES,
                     "databases": TEST_DB_NAMES,
@@ -202,6 +254,7 @@ def test_compute_create_drop_dbs_and_roles(neon_simple_env: NeonEnv):
         **{
             "spec": {
                 "skip_pg_catalog_updates": False,
+                "drop_subscriptions_before_start": True,
                 "cluster": {
                     "roles": [],
                     "databases": [],

test_runner/regress/test_pageserver_metric_collection.py

@@ -508,6 +508,9 @@ PER_METRIC_VERIFIERS = {
     "remote_storage_size": CannotVerifyAnything,
     "written_size": WrittenDataVerifier,
     "written_data_bytes_delta": WrittenDataDeltaVerifier,
+    "written_size_since_parent": WrittenDataVerifier,  # same as written_size on root
+    "pitr_cutoff": CannotVerifyAnything,
+    "pitr_history_size_since_parent": WrittenDataVerifier,  # same as written_size on root w/o GC
     "timeline_logical_size": CannotVerifyAnything,
     "synthetic_storage_size": SyntheticSizeVerifier,
 }

test_runner/regress/test_replica_start.py

@@ -27,8 +27,9 @@ from contextlib import closing
 
 import psycopg2
 import pytest
+from fixtures.common_types import Lsn
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import NeonEnv, wait_for_last_flush_lsn, wait_replica_caughtup
+from fixtures.neon_fixtures import NeonEnv, PgBin, wait_for_last_flush_lsn, wait_replica_caughtup
 from fixtures.pg_version import PgVersion
 from fixtures.utils import query_scalar, skip_on_postgres, wait_until
 
@@ -695,3 +696,110 @@ def test_replica_start_with_too_many_unused_xids(neon_simple_env: NeonEnv):
     with secondary.cursor() as secondary_cur:
         secondary_cur.execute("select count(*) from t")
         assert secondary_cur.fetchone() == (n_restarts,)
+
+
+def test_ephemeral_endpoints_vacuum(neon_simple_env: NeonEnv, pg_bin: PgBin):
+    env = neon_simple_env
+    endpoint = env.endpoints.create_start("main")
+
+    sql = """
+CREATE TABLE CHAR_TBL(f1 char(4));
+CREATE TABLE FLOAT8_TBL(f1 float8);
+CREATE TABLE INT2_TBL(f1 int2);
+CREATE TABLE INT4_TBL(f1 int4);
+CREATE TABLE INT8_TBL(q1 int8, q2 int8);
+CREATE TABLE POINT_TBL(f1 point);
+CREATE TABLE TEXT_TBL (f1 text);
+CREATE TABLE VARCHAR_TBL(f1 varchar(4));
+CREATE TABLE onek (unique1		int4);
+CREATE TABLE onek2 AS SELECT * FROM onek;
+CREATE TABLE tenk1 (unique1		int4);
+CREATE TABLE tenk2 AS SELECT * FROM tenk1;
+CREATE TABLE person (name text, age int4,location point);
+CREATE TABLE emp (salary int4, manager name) INHERITS (person);
+CREATE TABLE student (gpa float8) INHERITS (person);
+CREATE TABLE stud_emp (	percent 	int4) INHERITS (emp, student);
+CREATE TABLE road (name		text,thepath 	path);
+CREATE TABLE ihighway () INHERITS (road);
+CREATE TABLE shighway(surface		text) INHERITS (road);
+CREATE TABLE BOOLTBL3 (d text, b bool, o int);
+CREATE TABLE booltbl4(isfalse bool, istrue bool, isnul bool);
+DROP TABLE BOOLTBL3;
+DROP TABLE BOOLTBL4;
+CREATE TABLE ceil_floor_round (a numeric);
+DROP TABLE ceil_floor_round;
+CREATE TABLE width_bucket_test (operand_num numeric, operand_f8 float8);
+DROP TABLE width_bucket_test;
+CREATE TABLE num_input_test (n1 numeric);
+CREATE TABLE num_variance (a numeric);
+INSERT INTO num_variance VALUES (0);
+CREATE TABLE snapshot_test (nr	integer, snap	txid_snapshot);
+CREATE TABLE guid1(guid_field UUID, text_field TEXT DEFAULT(now()));
+CREATE TABLE guid2(guid_field UUID, text_field TEXT DEFAULT(now()));
+CREATE INDEX guid1_btree ON guid1 USING BTREE (guid_field);
+CREATE INDEX guid1_hash  ON guid1 USING HASH  (guid_field);
+TRUNCATE guid1;
+DROP TABLE guid1;
+DROP TABLE guid2 CASCADE;
+CREATE TABLE numrange_test (nr NUMRANGE);
+CREATE INDEX numrange_test_btree on numrange_test(nr);
+CREATE TABLE numrange_test2(nr numrange);
+CREATE INDEX numrange_test2_hash_idx on numrange_test2 using hash (nr);
+INSERT INTO numrange_test2 VALUES('[, 5)');
+CREATE TABLE textrange_test (tr text);
+CREATE INDEX textrange_test_btree on textrange_test(tr);
+CREATE TABLE test_range_gist(ir int4range);
+CREATE INDEX test_range_gist_idx on test_range_gist using gist (ir);
+DROP INDEX test_range_gist_idx;
+CREATE INDEX test_range_gist_idx on test_range_gist using gist (ir);
+CREATE TABLE test_range_spgist(ir int4range);
+CREATE INDEX test_range_spgist_idx on test_range_spgist using spgist (ir);
+DROP INDEX test_range_spgist_idx;
+CREATE INDEX test_range_spgist_idx on test_range_spgist using spgist (ir);
+CREATE TABLE test_range_elem(i int4);
+CREATE INDEX test_range_elem_idx on test_range_elem (i);
+CREATE INDEX ON test_range_elem using spgist(int4range(i,i+10));
+DROP TABLE test_range_elem;
+CREATE TABLE test_range_excl(room int4range, speaker int4range, during tsrange, exclude using gist (room with =, during with &&), exclude using gist (speaker with =, during with &&));
+CREATE TABLE f_test(f text, i int);
+CREATE TABLE i8r_array (f1 int, f2 text);
+CREATE TYPE arrayrange as range (subtype=int4[]);
+CREATE TYPE two_ints as (a int, b int);
+DROP TYPE two_ints cascade;
+CREATE TABLE text_support_test (t text);
+CREATE TABLE TEMP_FLOAT (f1 FLOAT8);
+CREATE TABLE TEMP_INT4 (f1 INT4);
+CREATE TABLE TEMP_INT2 (f1 INT2);
+CREATE TABLE TEMP_GROUP (f1 INT4, f2 INT4, f3 FLOAT8);
+CREATE TABLE POLYGON_TBL(f1 polygon);
+CREATE TABLE quad_poly_tbl (id int, p polygon);
+INSERT INTO quad_poly_tbl SELECT (x - 1) * 100 + y, polygon(circle(point(x * 10, y * 10), 1 + (x + y) % 10)) FROM generate_series(1, 200) x, generate_series(1, 100) y;
+CREATE TABLE quad_poly_tbl_ord_seq2 AS SELECT 1 FROM quad_poly_tbl;
+CREATE TABLE quad_poly_tbl_ord_idx2 AS SELECT 1 FROM quad_poly_tbl;
+"""
+
+    with endpoint.cursor() as cur:
+        lsn = Lsn(query_scalar(cur, "SELECT pg_current_wal_flush_lsn()"))
+        env.endpoints.create_start(branch_name="main", lsn=lsn)
+        log.info(f"lsn: {lsn}")
+
+        for line in sql.split("\n"):
+            if len(line.strip()) == 0 or line.startswith("--"):
+                continue
+            cur.execute(line)
+
+        lsn = Lsn(query_scalar(cur, "SELECT pg_current_wal_flush_lsn()"))
+        env.endpoints.create_start(branch_name="main", lsn=lsn)
+        log.info(f"lsn: {lsn}")
+
+        cur.execute("VACUUM FULL pg_class;")
+
+    for ep in env.endpoints.endpoints:
+        log.info(f"{ep.endpoint_id} / {ep.pg_port}")
+        pg_dump_command = ["pg_dumpall", "-f", f"/tmp/dump-{ep.endpoint_id}.sql"]
+        env_vars = {
+            "PGPORT": str(ep.pg_port),
+            "PGUSER": endpoint.default_options["user"],
+            "PGHOST": endpoint.default_options["host"],
+        }
+        pg_bin.run_capture(pg_dump_command, env=env_vars)

test_runner/regress/test_timeline_archive.py

@@ -193,6 +193,11 @@ def test_timeline_offloading(neon_env_builder: NeonEnvBuilder, manual_offload: b
         "test_ancestor_branch_archive_branch1", tenant_id, "test_ancestor_branch_archive_parent"
     )
 
+    offloaded_count = ps_http.get_metric_value(
+        "pageserver_tenant_offloaded_timelines", {"tenant_id": f"{tenant_id}"}
+    )
+    assert offloaded_count == 0
+
     ps_http.timeline_archival_config(
         tenant_id,
         leaf_timeline_id,
@@ -244,6 +249,11 @@ def test_timeline_offloading(neon_env_builder: NeonEnvBuilder, manual_offload: b
     wait_until(leaf_offloaded)
     wait_until(parent_offloaded)
 
+    offloaded_count = ps_http.get_metric_value(
+        "pageserver_tenant_offloaded_timelines", {"tenant_id": f"{tenant_id}"}
+    )
+    assert offloaded_count == 2
+
     # Offloaded child timelines should still prevent deletion
     with pytest.raises(
         PageserverApiException,

workspace_hack/Cargo.toml

@@ -107,6 +107,7 @@ tower = { version = "0.4", default-features = false, features = ["balance", "buf
 tracing = { version = "0.1", features = ["log"] }
 tracing-core = { version = "0.1" }
 tracing-log = { version = "0.2" }
+tracing-subscriber = { version = "0.3", features = ["env-filter", "json"] }
 url = { version = "2", features = ["serde"] }
 uuid = { version = "1", features = ["serde", "v4", "v7"] }
 zeroize = { version = "1", features = ["derive", "serde"] }