neon/libs/pageserver_api/src/models.rs

use std::{
    collections::HashMap,
    num::{NonZeroU64, NonZeroUsize},
    time::SystemTime,
};

use byteorder::{BigEndian, ReadBytesExt};
use serde::{Deserialize, Serialize};
use serde_with::{serde_as, DisplayFromStr};
use utils::{
    history_buffer::HistoryBufferWithDropCounter,
    id::{NodeId, TenantId, TimelineId},
    lsn::Lsn,
};

use crate::reltag::RelTag;
use anyhow::bail;
use bytes::{BufMut, Bytes, BytesMut};

/// A state of a tenant in pageserver's memory.
#[derive(Debug, Clone, Copy, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
pub enum TenantState {
    // This tenant is being loaded from local disk
    Loading,
    // This tenant is being downloaded from cloud storage.
    Attaching,
    /// Tenant is fully operational
    Active,
    /// A tenant is recognized by pageserver, but it is being detached or the
    /// system is being shut down.
    Stopping,
    /// A tenant is recognized by the pageserver, but can no longer be used for
    /// any operations, because it failed to be activated.
    Broken,
}

pub mod state {
    pub const LOADING: &str = "loading";
    pub const ATTACHING: &str = "attaching";
    pub const ACTIVE: &str = "active";
    pub const STOPPING: &str = "stopping";
    pub const BROKEN: &str = "broken";
}

impl TenantState {
    pub fn has_in_progress_downloads(&self) -> bool {
        match self {
            Self::Loading => true,
            Self::Attaching => true,
            Self::Active => false,
            Self::Stopping => false,
            Self::Broken => false,
        }
    }

    pub fn as_str(&self) -> &'static str {
        match self {
            TenantState::Loading => state::LOADING,
            TenantState::Attaching => state::ATTACHING,
            TenantState::Active => state::ACTIVE,
            TenantState::Stopping => state::STOPPING,
            TenantState::Broken => state::BROKEN,
        }
    }
}

/// A state of a timeline in pageserver's memory.
#[derive(Debug, Clone, Copy, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
pub enum TimelineState {
    /// The timeline is recognized by the pageserver but is not yet operational.
    /// In particular, the walreceiver connection loop is not running for this timeline.
    /// It will eventually transition to state Active or Broken.
    Loading,
    /// The timeline is fully operational.
    /// It can be queried, and the walreceiver connection loop is running.
    Active,
    /// The timeline was previously Loading or Active but is shutting down.
    /// It cannot transition back into any other state.
    Stopping,
    /// The timeline is broken and not operational (previous states: Loading or Active).
    Broken,
}

#[serde_as]
#[derive(Serialize, Deserialize)]
pub struct TimelineCreateRequest {
    #[serde(default)]
    #[serde_as(as = "Option<DisplayFromStr>")]
    pub new_timeline_id: Option<TimelineId>,
    #[serde(default)]
    #[serde_as(as = "Option<DisplayFromStr>")]
    pub ancestor_timeline_id: Option<TimelineId>,
    #[serde(default)]
    #[serde_as(as = "Option<DisplayFromStr>")]
    pub ancestor_start_lsn: Option<Lsn>,
    pub pg_version: Option<u32>,
}

#[serde_as]
#[derive(Serialize, Deserialize, Default)]
pub struct TenantCreateRequest {
    #[serde(default)]
    #[serde_as(as = "Option<DisplayFromStr>")]
    pub new_tenant_id: Option<TenantId>,
    pub checkpoint_distance: Option<u64>,
    pub checkpoint_timeout: Option<String>,
    pub compaction_target_size: Option<u64>,
    pub compaction_period: Option<String>,
    pub compaction_threshold: Option<usize>,
    pub gc_horizon: Option<u64>,
    pub gc_period: Option<String>,
    pub image_creation_threshold: Option<usize>,
    pub pitr_interval: Option<String>,
    pub walreceiver_connect_timeout: Option<String>,
    pub lagging_wal_timeout: Option<String>,
    pub max_lsn_wal_lag: Option<NonZeroU64>,
    pub trace_read_requests: Option<bool>,
}

#[serde_as]
#[derive(Serialize, Deserialize)]
#[serde(transparent)]
pub struct TenantCreateResponse(#[serde_as(as = "DisplayFromStr")] pub TenantId);

#[derive(Serialize)]
pub struct StatusResponse {
    pub id: NodeId,
}

impl TenantCreateRequest {
    pub fn new(new_tenant_id: Option<TenantId>) -> TenantCreateRequest {
        TenantCreateRequest {
            new_tenant_id,
            ..Default::default()
        }
    }
}

#[serde_as]
#[derive(Serialize, Deserialize)]
pub struct TenantConfigRequest {
    #[serde_as(as = "DisplayFromStr")]
    pub tenant_id: TenantId,
    #[serde(default)]
    pub checkpoint_distance: Option<u64>,
    pub checkpoint_timeout: Option<String>,
    pub compaction_target_size: Option<u64>,
    pub compaction_period: Option<String>,
    pub compaction_threshold: Option<usize>,
    pub gc_horizon: Option<u64>,
    pub gc_period: Option<String>,
    pub image_creation_threshold: Option<usize>,
    pub pitr_interval: Option<String>,
    pub walreceiver_connect_timeout: Option<String>,
    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>,
}

impl TenantConfigRequest {
    pub fn new(tenant_id: TenantId) -> TenantConfigRequest {
        TenantConfigRequest {
            tenant_id,
            checkpoint_distance: None,
            checkpoint_timeout: None,
            compaction_target_size: None,
            compaction_period: None,
            compaction_threshold: None,
            gc_horizon: None,
            gc_period: None,
            image_creation_threshold: None,
            pitr_interval: None,
            walreceiver_connect_timeout: None,
            lagging_wal_timeout: None,
            max_lsn_wal_lag: None,
            trace_read_requests: None,
            eviction_policy: None,
        }
    }
}

#[serde_as]
#[derive(Serialize, Deserialize, Clone)]
pub struct TenantInfo {
    #[serde_as(as = "DisplayFromStr")]
    pub id: TenantId,
    pub state: TenantState,
    /// Sum of the size of all layer files.
    /// If a layer is present in both local FS and S3, it counts only once.
    pub current_physical_size: Option<u64>, // physical size is only included in `tenant_status` endpoint
    pub has_in_progress_downloads: Option<bool>,
}

/// This represents the output of the "timeline_detail" and "timeline_list" API calls.
#[serde_as]
#[derive(Debug, Serialize, Deserialize, Clone)]
pub struct TimelineInfo {
    #[serde_as(as = "DisplayFromStr")]
    pub tenant_id: TenantId,
    #[serde_as(as = "DisplayFromStr")]
    pub timeline_id: TimelineId,

    #[serde_as(as = "Option<DisplayFromStr>")]
    pub ancestor_timeline_id: Option<TimelineId>,
    #[serde_as(as = "Option<DisplayFromStr>")]
    pub ancestor_lsn: Option<Lsn>,
    #[serde_as(as = "DisplayFromStr")]
    pub last_record_lsn: Lsn,
    #[serde_as(as = "Option<DisplayFromStr>")]
    pub prev_record_lsn: Option<Lsn>,
    #[serde_as(as = "DisplayFromStr")]
    pub latest_gc_cutoff_lsn: Lsn,
    #[serde_as(as = "DisplayFromStr")]
    pub disk_consistent_lsn: Lsn,
    #[serde_as(as = "DisplayFromStr")]
    pub remote_consistent_lsn: Lsn,
    pub current_logical_size: Option<u64>, // is None when timeline is Unloaded
    /// Sum of the size of all layer files.
    /// If a layer is present in both local FS and S3, it counts only once.
    pub current_physical_size: Option<u64>, // is None when timeline is Unloaded
    pub current_logical_size_non_incremental: Option<u64>,

    pub timeline_dir_layer_file_size_sum: Option<u64>,

    pub wal_source_connstr: Option<String>,
    #[serde_as(as = "Option<DisplayFromStr>")]
    pub last_received_msg_lsn: Option<Lsn>,
    /// the timestamp (in microseconds) of the last received message
    pub last_received_msg_ts: Option<u128>,
    pub pg_version: u32,

    pub state: TimelineState,
}

#[derive(Debug, Clone, Serialize)]
pub struct LayerMapInfo {
    pub in_memory_layers: Vec<InMemoryLayerInfo>,
    pub historic_layers: Vec<HistoricLayerInfo>,
}

#[derive(Debug, Hash, PartialEq, Eq, Clone, Copy, Serialize, Deserialize, enum_map::Enum)]
#[repr(usize)]
pub enum LayerAccessKind {
    GetValueReconstructData,
    Iter,
    KeyIter,
    Dump,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct LayerAccessStatFullDetails {
    pub when_millis_since_epoch: u64,
    pub task_kind: &'static str,
    pub access_kind: LayerAccessKind,
}

/// An event that impacts the layer's residence status.
#[serde_as]
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct LayerResidenceEvent {
    /// The time when the event occurred.
    /// NB: this timestamp is captured while the residence status changes.
    /// So, it might be behind/ahead of the actual residence change by a short amount of time.
    ///
    #[serde(rename = "timestamp_millis_since_epoch")]
    #[serde_as(as = "serde_with::TimestampMilliSeconds")]
    pub timestamp: SystemTime,
    /// The new residence status of the layer.
    pub status: LayerResidenceStatus,
    /// The reason why we had to record this event.
    pub reason: LayerResidenceEventReason,
}

/// The reason for recording a given [`ResidenceEvent`].
#[derive(Debug, Clone, Copy, Serialize, Deserialize)]
pub enum LayerResidenceEventReason {
    /// The layer map is being populated, e.g. during timeline load or attach.
    /// This includes [`RemoteLayer`] objects created in [`reconcile_with_remote`].
    /// We need to record such events because there is no persistent storage for the events.
    LayerLoad,
    /// We just created the layer (e.g., freeze_and_flush or compaction).
    /// Such layers are always [`LayerResidenceStatus::Resident`].
    LayerCreate,
    /// We on-demand downloaded or evicted the given layer.
    ResidenceChange,
}

/// The residence status of the layer, after the given [`LayerResidenceEvent`].
#[derive(Debug, Clone, Copy, Serialize, Deserialize)]
pub enum LayerResidenceStatus {
    /// Residence status for a layer file that exists locally.
    /// It may also exist on the remote, we don't care here.
    Resident,
    /// Residence status for a layer file that only exists on the remote.
    Evicted,
}

impl LayerResidenceEvent {
    pub fn new(status: LayerResidenceStatus, reason: LayerResidenceEventReason) -> Self {
        Self {
            status,
            reason,
            timestamp: SystemTime::now(),
        }
    }
}

#[derive(Debug, Clone, Serialize)]
pub struct LayerAccessStats {
    pub access_count_by_access_kind: HashMap<LayerAccessKind, u64>,
    pub task_kind_access_flag: Vec<&'static str>,
    pub first: Option<LayerAccessStatFullDetails>,
    pub accesses_history: HistoryBufferWithDropCounter<LayerAccessStatFullDetails, 16>,
    pub residence_events_history: HistoryBufferWithDropCounter<LayerResidenceEvent, 16>,
}

#[serde_as]
#[derive(Debug, Clone, Serialize)]
#[serde(tag = "kind")]
pub enum InMemoryLayerInfo {
    Open {
        #[serde_as(as = "DisplayFromStr")]
        lsn_start: Lsn,
    },
    Frozen {
        #[serde_as(as = "DisplayFromStr")]
        lsn_start: Lsn,
        #[serde_as(as = "DisplayFromStr")]
        lsn_end: Lsn,
    },
}

#[serde_as]
#[derive(Debug, Clone, Serialize)]
#[serde(tag = "kind")]
pub enum HistoricLayerInfo {
    Delta {
        layer_file_name: String,
        layer_file_size: Option<u64>,

        #[serde_as(as = "DisplayFromStr")]
        lsn_start: Lsn,
        #[serde_as(as = "DisplayFromStr")]
        lsn_end: Lsn,
        remote: bool,
        access_stats: LayerAccessStats,
    },
    Image {
        layer_file_name: String,
        layer_file_size: Option<u64>,

        #[serde_as(as = "DisplayFromStr")]
        lsn_start: Lsn,
        remote: bool,
        access_stats: LayerAccessStats,
    },
}

#[derive(Debug, Serialize, Deserialize)]
pub struct DownloadRemoteLayersTaskSpawnRequest {
    pub max_concurrent_downloads: NonZeroUsize,
}

#[derive(Debug, Serialize, Deserialize, Clone)]
pub struct DownloadRemoteLayersTaskInfo {
    pub task_id: String,
    pub state: DownloadRemoteLayersTaskState,
    pub total_layer_count: u64,         // stable once `completed`
    pub successful_download_count: u64, // stable once `completed`
    pub failed_download_count: u64,     // stable once `completed`
}

#[derive(Debug, Serialize, Deserialize, Clone)]
pub enum DownloadRemoteLayersTaskState {
    Running,
    Completed,
    ShutDown,
}

pub type ConfigureFailpointsRequest = Vec<FailpointConfig>;

/// Information for configuring a single fail point
#[derive(Debug, Serialize, Deserialize)]
pub struct FailpointConfig {
    /// Name of the fail point
    pub name: String,
    /// List of actions to take, using the format described in `fail::cfg`
    ///
    /// We also support `actions = "exit"` to cause the fail point to immediately exit.
    pub actions: String,
}

#[derive(Debug, Serialize, Deserialize)]
pub struct TimelineGcRequest {
    pub gc_horizon: Option<u64>,
}

// Wrapped in libpq CopyData
#[derive(PartialEq, Eq, Debug)]
pub enum PagestreamFeMessage {
    Exists(PagestreamExistsRequest),
    Nblocks(PagestreamNblocksRequest),
    GetPage(PagestreamGetPageRequest),
    DbSize(PagestreamDbSizeRequest),
}

// Wrapped in libpq CopyData
pub enum PagestreamBeMessage {
    Exists(PagestreamExistsResponse),
    Nblocks(PagestreamNblocksResponse),
    GetPage(PagestreamGetPageResponse),
    Error(PagestreamErrorResponse),
    DbSize(PagestreamDbSizeResponse),
}

#[derive(Debug, PartialEq, Eq)]
pub struct PagestreamExistsRequest {
    pub latest: bool,
    pub lsn: Lsn,
    pub rel: RelTag,
}

#[derive(Debug, PartialEq, Eq)]
pub struct PagestreamNblocksRequest {
    pub latest: bool,
    pub lsn: Lsn,
    pub rel: RelTag,
}

#[derive(Debug, PartialEq, Eq)]
pub struct PagestreamGetPageRequest {
    pub latest: bool,
    pub lsn: Lsn,
    pub rel: RelTag,
    pub blkno: u32,
}

#[derive(Debug, PartialEq, Eq)]
pub struct PagestreamDbSizeRequest {
    pub latest: bool,
    pub lsn: Lsn,
    pub dbnode: u32,
}

#[derive(Debug)]
pub struct PagestreamExistsResponse {
    pub exists: bool,
}

#[derive(Debug)]
pub struct PagestreamNblocksResponse {
    pub n_blocks: u32,
}

#[derive(Debug)]
pub struct PagestreamGetPageResponse {
    pub page: Bytes,
}

#[derive(Debug)]
pub struct PagestreamErrorResponse {
    pub message: String,
}

#[derive(Debug)]
pub struct PagestreamDbSizeResponse {
    pub db_size: i64,
}

impl PagestreamFeMessage {
    pub fn serialize(&self) -> Bytes {
        let mut bytes = BytesMut::new();

        match self {
            Self::Exists(req) => {
                bytes.put_u8(0);
                bytes.put_u8(u8::from(req.latest));
                bytes.put_u64(req.lsn.0);
                bytes.put_u32(req.rel.spcnode);
                bytes.put_u32(req.rel.dbnode);
                bytes.put_u32(req.rel.relnode);
                bytes.put_u8(req.rel.forknum);
            }

            Self::Nblocks(req) => {
                bytes.put_u8(1);
                bytes.put_u8(u8::from(req.latest));
                bytes.put_u64(req.lsn.0);
                bytes.put_u32(req.rel.spcnode);
                bytes.put_u32(req.rel.dbnode);
                bytes.put_u32(req.rel.relnode);
                bytes.put_u8(req.rel.forknum);
            }

            Self::GetPage(req) => {
                bytes.put_u8(2);
                bytes.put_u8(u8::from(req.latest));
                bytes.put_u64(req.lsn.0);
                bytes.put_u32(req.rel.spcnode);
                bytes.put_u32(req.rel.dbnode);
                bytes.put_u32(req.rel.relnode);
                bytes.put_u8(req.rel.forknum);
                bytes.put_u32(req.blkno);
            }

            Self::DbSize(req) => {
                bytes.put_u8(3);
                bytes.put_u8(u8::from(req.latest));
                bytes.put_u64(req.lsn.0);
                bytes.put_u32(req.dbnode);
            }
        }

        bytes.into()
    }

    pub fn parse<R: std::io::Read>(body: &mut R) -> anyhow::Result<PagestreamFeMessage> {
        // TODO these gets can fail

        // these correspond to the NeonMessageTag enum in pagestore_client.h
        //
        // TODO: consider using protobuf or serde bincode for less error prone
        // serialization.
        let msg_tag = body.read_u8()?;
        match msg_tag {
            0 => Ok(PagestreamFeMessage::Exists(PagestreamExistsRequest {
                latest: body.read_u8()? != 0,
                lsn: Lsn::from(body.read_u64::<BigEndian>()?),
                rel: RelTag {
                    spcnode: body.read_u32::<BigEndian>()?,
                    dbnode: body.read_u32::<BigEndian>()?,
                    relnode: body.read_u32::<BigEndian>()?,
                    forknum: body.read_u8()?,
                },
            })),
            1 => Ok(PagestreamFeMessage::Nblocks(PagestreamNblocksRequest {
                latest: body.read_u8()? != 0,
                lsn: Lsn::from(body.read_u64::<BigEndian>()?),
                rel: RelTag {
                    spcnode: body.read_u32::<BigEndian>()?,
                    dbnode: body.read_u32::<BigEndian>()?,
                    relnode: body.read_u32::<BigEndian>()?,
                    forknum: body.read_u8()?,
                },
            })),
            2 => Ok(PagestreamFeMessage::GetPage(PagestreamGetPageRequest {
                latest: body.read_u8()? != 0,
                lsn: Lsn::from(body.read_u64::<BigEndian>()?),
                rel: RelTag {
                    spcnode: body.read_u32::<BigEndian>()?,
                    dbnode: body.read_u32::<BigEndian>()?,
                    relnode: body.read_u32::<BigEndian>()?,
                    forknum: body.read_u8()?,
                },
                blkno: body.read_u32::<BigEndian>()?,
            })),
            3 => Ok(PagestreamFeMessage::DbSize(PagestreamDbSizeRequest {
                latest: body.read_u8()? != 0,
                lsn: Lsn::from(body.read_u64::<BigEndian>()?),
                dbnode: body.read_u32::<BigEndian>()?,
            })),
            _ => bail!("unknown smgr message tag: {:?}", msg_tag),
        }
    }
}

impl PagestreamBeMessage {
    pub fn serialize(&self) -> Bytes {
        let mut bytes = BytesMut::new();

        match self {
            Self::Exists(resp) => {
                bytes.put_u8(100); /* tag from pagestore_client.h */
                bytes.put_u8(resp.exists as u8);
            }

            Self::Nblocks(resp) => {
                bytes.put_u8(101); /* tag from pagestore_client.h */
                bytes.put_u32(resp.n_blocks);
            }

            Self::GetPage(resp) => {
                bytes.put_u8(102); /* tag from pagestore_client.h */
                bytes.put(&resp.page[..]);
            }

            Self::Error(resp) => {
                bytes.put_u8(103); /* tag from pagestore_client.h */
                bytes.put(resp.message.as_bytes());
                bytes.put_u8(0); // null terminator
            }
            Self::DbSize(resp) => {
                bytes.put_u8(104); /* tag from pagestore_client.h */
                bytes.put_i64(resp.db_size);
            }
        }

        bytes.into()
    }
}

#[cfg(test)]
mod tests {
    use bytes::Buf;

    use super::*;

    #[test]
    fn test_pagestream() {
        // Test serialization/deserialization of PagestreamFeMessage
        let messages = vec![
            PagestreamFeMessage::Exists(PagestreamExistsRequest {
                latest: true,
                lsn: Lsn(4),
                rel: RelTag {
                    forknum: 1,
                    spcnode: 2,
                    dbnode: 3,
                    relnode: 4,
                },
            }),
            PagestreamFeMessage::Nblocks(PagestreamNblocksRequest {
                latest: false,
                lsn: Lsn(4),
                rel: RelTag {
                    forknum: 1,
                    spcnode: 2,
                    dbnode: 3,
                    relnode: 4,
                },
            }),
            PagestreamFeMessage::GetPage(PagestreamGetPageRequest {
                latest: true,
                lsn: Lsn(4),
                rel: RelTag {
                    forknum: 1,
                    spcnode: 2,
                    dbnode: 3,
                    relnode: 4,
                },
                blkno: 7,
            }),
            PagestreamFeMessage::DbSize(PagestreamDbSizeRequest {
                latest: true,
                lsn: Lsn(4),
                dbnode: 7,
            }),
        ];
        for msg in messages {
            let bytes = msg.serialize();
            let reconstructed = PagestreamFeMessage::parse(&mut bytes.reader()).unwrap();
            assert!(msg == reconstructed);
        }
    }
}