pageserver: move EvictionPolicy into models/

This makes the config type more convenient to work with: it
was previously carrying a serde_json::Value to force the
contained types to be opaque, which doesn't make a lot of
sense for an external interface.

Cargo.lock

@@ -3252,6 +3252,7 @@ dependencies = [
  "const_format",
  "enum-map",
  "hex",
+ "humantime-serde",
  "postgres_ffi",
  "rand 0.8.5",
  "serde",

libs/pageserver_api/Cargo.toml

@@ -19,6 +19,7 @@ strum.workspace = true
 strum_macros.workspace = true
 hex.workspace = true
 thiserror.workspace = true
+humantime-serde.workspace = true
 
 workspace_hack.workspace = true
 

libs/pageserver_api/src/models.rs

@@ -4,7 +4,7 @@ use std::{
     collections::HashMap,
     io::Read,
     num::{NonZeroU64, NonZeroUsize},
-    time::SystemTime,
+    time::{Duration, SystemTime},
 };
 
 use byteorder::{BigEndian, ReadBytesExt};
@@ -232,17 +232,37 @@ pub struct TenantConfig {
     pub lagging_wal_timeout: Option<String>,
     pub max_lsn_wal_lag: Option<NonZeroU64>,
     pub trace_read_requests: Option<bool>,
-    // We defer the parsing of the eviction_policy field to the request handler.
-    // Otherwise we'd have to move the types for eviction policy into this package.
-    // We might do that once the eviction feature has stabilizied.
-    // For now, this field is not even documented in the openapi_spec.yml.
-    pub eviction_policy: Option<serde_json::Value>,
+    pub eviction_policy: Option<EvictionPolicy>,
     pub min_resident_size_override: Option<u64>,
     pub evictions_low_residence_duration_metric_threshold: Option<String>,
     pub gc_feedback: Option<bool>,
     pub heatmap_period: Option<String>,
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(tag = "kind")]
+pub enum EvictionPolicy {
+    NoEviction,
+    LayerAccessThreshold(EvictionPolicyLayerAccessThreshold),
+}
+
+impl EvictionPolicy {
+    pub fn discriminant_str(&self) -> &'static str {
+        match self {
+            EvictionPolicy::NoEviction => "NoEviction",
+            EvictionPolicy::LayerAccessThreshold(_) => "LayerAccessThreshold",
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+pub struct EvictionPolicyLayerAccessThreshold {
+    #[serde(with = "humantime_serde")]
+    pub period: Duration,
+    #[serde(with = "humantime_serde")]
+    pub threshold: Duration,
+}
+
 /// A flattened analog of a `pagesever::tenant::LocationMode`, which
 /// lists out all possible states (and the virtual "Detached" state)
 /// in a flat form rather than using rust-style enums.

pageserver/src/tenant/config.rs

@@ -9,7 +9,7 @@
 //! may lead to a data loss.
 //!
 use anyhow::bail;
-use pageserver_api::models;
+use pageserver_api::models::{self, EvictionPolicy};
 use pageserver_api::shard::{ShardCount, ShardIdentity, ShardNumber, ShardStripeSize};
 use serde::de::IntoDeserializer;
 use serde::{Deserialize, Serialize};
@@ -428,30 +428,6 @@ pub struct TenantConfOpt {
     pub heatmap_period: Option<Duration>,
 }
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
-#[serde(tag = "kind")]
-pub enum EvictionPolicy {
-    NoEviction,
-    LayerAccessThreshold(EvictionPolicyLayerAccessThreshold),
-}
-
-impl EvictionPolicy {
-    pub fn discriminant_str(&self) -> &'static str {
-        match self {
-            EvictionPolicy::NoEviction => "NoEviction",
-            EvictionPolicy::LayerAccessThreshold(_) => "LayerAccessThreshold",
-        }
-    }
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
-pub struct EvictionPolicyLayerAccessThreshold {
-    #[serde(with = "humantime_serde")]
-    pub period: Duration,
-    #[serde(with = "humantime_serde")]
-    pub threshold: Duration,
-}
-
 impl TenantConfOpt {
     pub fn merge(&self, global_conf: TenantConf) -> TenantConf {
         TenantConf {

pageserver/src/tenant/timeline.rs

@@ -15,8 +15,8 @@ use fail::fail_point;
 use itertools::Itertools;
 use pageserver_api::{
     models::{
-        DownloadRemoteLayersTaskInfo, DownloadRemoteLayersTaskSpawnRequest, LayerMapInfo,
-        TimelineState,
+        DownloadRemoteLayersTaskInfo, DownloadRemoteLayersTaskSpawnRequest, EvictionPolicy,
+        LayerMapInfo, TimelineState,
     },
     shard::{ShardIdentity, TenantShardId},
 };
@@ -68,7 +68,7 @@ use crate::metrics::{
 use crate::pgdatadir_mapping::LsnForTimestamp;
 use crate::pgdatadir_mapping::{is_inherited_key, is_rel_fsm_block_key, is_rel_vm_block_key};
 use crate::pgdatadir_mapping::{BlockNumber, CalculateLogicalSizeError};
-use crate::tenant::config::{EvictionPolicy, TenantConfOpt};
+use crate::tenant::config::TenantConfOpt;
 use pageserver_api::reltag::RelTag;
 use pageserver_api::shard::ShardIndex;
 

pageserver/src/tenant/timeline/eviction_task.rs

@@ -20,6 +20,7 @@ use std::{
     time::{Duration, SystemTime},
 };
 
+use pageserver_api::models::{EvictionPolicy, EvictionPolicyLayerAccessThreshold};
 use tokio::time::Instant;
 use tokio_util::sync::CancellationToken;
 use tracing::{debug, error, info, info_span, instrument, warn, Instrument};
@@ -29,10 +30,7 @@ use crate::{
     pgdatadir_mapping::CollectKeySpaceError,
     task_mgr::{self, TaskKind, BACKGROUND_RUNTIME},
     tenant::{
-        config::{EvictionPolicy, EvictionPolicyLayerAccessThreshold},
-        tasks::BackgroundLoopKind,
-        timeline::EvictionError,
-        LogicalSizeCalculationCause, Tenant,
+        tasks::BackgroundLoopKind, timeline::EvictionError, LogicalSizeCalculationCause, Tenant,
     },
 };