LCOV - code coverage report
Current view: top level - storage_controller/src - compute_hook.rs (source / functions) Coverage Total Hit
Test: 53437f7e869ac68c86c7d3e4c20964c0156f158c.info Lines: 36.5 % 386 141
Test Date: 2024-09-20 16:14:12 Functions: 15.7 % 51 8

            Line data    Source code
       1              : use std::sync::Arc;
       2              : use std::{collections::HashMap, time::Duration};
       3              : 
       4              : use control_plane::endpoint::{ComputeControlPlane, EndpointStatus};
       5              : use control_plane::local_env::LocalEnv;
       6              : use futures::StreamExt;
       7              : use hyper::StatusCode;
       8              : use pageserver_api::shard::{ShardCount, ShardNumber, ShardStripeSize, TenantShardId};
       9              : use postgres_connection::parse_host_port;
      10              : use serde::{Deserialize, Serialize};
      11              : use tokio_util::sync::CancellationToken;
      12              : use tracing::{info_span, Instrument};
      13              : use utils::{
      14              :     backoff::{self},
      15              :     id::{NodeId, TenantId},
      16              : };
      17              : 
      18              : use crate::service::Config;
      19              : 
      20              : const SLOWDOWN_DELAY: Duration = Duration::from_secs(5);
      21              : 
      22              : const NOTIFY_REQUEST_TIMEOUT: Duration = Duration::from_secs(10);
      23              : 
      24              : pub(crate) const API_CONCURRENCY: usize = 32;
      25              : 
      26              : struct UnshardedComputeHookTenant {
      27              :     // Which node is this tenant attached to
      28              :     node_id: NodeId,
      29              : 
      30              :     // Must hold this lock to send a notification.
      31              :     send_lock: Arc<tokio::sync::Mutex<Option<ComputeHookNotifyRequest>>>,
      32              : }
      33              : struct ShardedComputeHookTenant {
      34              :     stripe_size: ShardStripeSize,
      35              :     shard_count: ShardCount,
      36              :     shards: Vec<(ShardNumber, NodeId)>,
      37              : 
      38              :     // Must hold this lock to send a notification.  The contents represent
      39              :     // the last successfully sent notification, and are used to coalesce multiple
      40              :     // updates by only sending when there is a chance since our last successful send.
      41              :     send_lock: Arc<tokio::sync::Mutex<Option<ComputeHookNotifyRequest>>>,
      42              : }
      43              : 
      44              : enum ComputeHookTenant {
      45              :     Unsharded(UnshardedComputeHookTenant),
      46              :     Sharded(ShardedComputeHookTenant),
      47              : }
      48              : 
      49              : impl ComputeHookTenant {
      50              :     /// Construct with at least one shard's information
      51            2 :     fn new(tenant_shard_id: TenantShardId, stripe_size: ShardStripeSize, node_id: NodeId) -> Self {
      52            2 :         if tenant_shard_id.shard_count.count() > 1 {
      53            1 :             Self::Sharded(ShardedComputeHookTenant {
      54            1 :                 shards: vec![(tenant_shard_id.shard_number, node_id)],
      55            1 :                 stripe_size,
      56            1 :                 shard_count: tenant_shard_id.shard_count,
      57            1 :                 send_lock: Arc::default(),
      58            1 :             })
      59              :         } else {
      60            1 :             Self::Unsharded(UnshardedComputeHookTenant {
      61            1 :                 node_id,
      62            1 :                 send_lock: Arc::default(),
      63            1 :             })
      64              :         }
      65            2 :     }
      66              : 
      67            4 :     fn get_send_lock(&self) -> &Arc<tokio::sync::Mutex<Option<ComputeHookNotifyRequest>>> {
      68            4 :         match self {
      69            2 :             Self::Unsharded(unsharded_tenant) => &unsharded_tenant.send_lock,
      70            2 :             Self::Sharded(sharded_tenant) => &sharded_tenant.send_lock,
      71              :         }
      72            4 :     }
      73              : 
      74              :     /// Set one shard's location.  If stripe size or shard count have changed, Self is reset
      75              :     /// and drops existing content.
      76            2 :     fn update(
      77            2 :         &mut self,
      78            2 :         tenant_shard_id: TenantShardId,
      79            2 :         stripe_size: ShardStripeSize,
      80            2 :         node_id: NodeId,
      81            2 :     ) {
      82            1 :         match self {
      83            1 :             Self::Unsharded(unsharded_tenant) if tenant_shard_id.shard_count.count() == 1 => {
      84            0 :                 unsharded_tenant.node_id = node_id
      85              :             }
      86            1 :             Self::Sharded(sharded_tenant)
      87            1 :                 if sharded_tenant.stripe_size == stripe_size
      88            1 :                     && sharded_tenant.shard_count == tenant_shard_id.shard_count =>
      89              :             {
      90            1 :                 if let Some(existing) = sharded_tenant
      91            1 :                     .shards
      92            1 :                     .iter()
      93            1 :                     .position(|s| s.0 == tenant_shard_id.shard_number)
      94            0 :                 {
      95            0 :                     sharded_tenant.shards.get_mut(existing).unwrap().1 = node_id;
      96            0 :                 } else {
      97            1 :                     sharded_tenant
      98            1 :                         .shards
      99            1 :                         .push((tenant_shard_id.shard_number, node_id));
     100            2 :                     sharded_tenant.shards.sort_by_key(|s| s.0)
     101              :                 }
     102              :             }
     103            1 :             _ => {
     104            1 :                 // Shard count changed: reset struct.
     105            1 :                 *self = Self::new(tenant_shard_id, stripe_size, node_id);
     106            1 :             }
     107              :         }
     108            2 :     }
     109              : }
     110              : 
     111            0 : #[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
     112              : struct ComputeHookNotifyRequestShard {
     113              :     node_id: NodeId,
     114              :     shard_number: ShardNumber,
     115              : }
     116              : 
     117              : /// Request body that we send to the control plane to notify it of where a tenant is attached
     118            0 : #[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
     119              : struct ComputeHookNotifyRequest {
     120              :     tenant_id: TenantId,
     121              :     stripe_size: Option<ShardStripeSize>,
     122              :     shards: Vec<ComputeHookNotifyRequestShard>,
     123              : }
     124              : 
     125              : /// Error type for attempts to call into the control plane compute notification hook
     126            0 : #[derive(thiserror::Error, Debug)]
     127              : pub(crate) enum NotifyError {
     128              :     // Request was not send successfully, e.g. transport error
     129              :     #[error("Sending request: {0}")]
     130              :     Request(#[from] reqwest::Error),
     131              :     // Request could not be serviced right now due to ongoing Operation in control plane, but should be possible soon.
     132              :     #[error("Control plane tenant busy")]
     133              :     Busy,
     134              :     // Explicit 429 response asking us to retry less frequently
     135              :     #[error("Control plane overloaded")]
     136              :     SlowDown,
     137              :     // A 503 response indicates the control plane can't handle the request right now
     138              :     #[error("Control plane unavailable (status {0})")]
     139              :     Unavailable(StatusCode),
     140              :     // API returned unexpected non-success status.  We will retry, but log a warning.
     141              :     #[error("Control plane returned unexpected status {0}")]
     142              :     Unexpected(StatusCode),
     143              :     // We shutdown while sending
     144              :     #[error("Shutting down")]
     145              :     ShuttingDown,
     146              :     // A response indicates we will never succeed, such as 400 or 404
     147              :     #[error("Non-retryable error {0}")]
     148              :     Fatal(StatusCode),
     149              : 
     150              :     #[error("neon_local error: {0}")]
     151              :     NeonLocal(anyhow::Error),
     152              : }
     153              : 
     154              : enum MaybeSendResult {
     155              :     // Please send this request while holding the lock, and if you succeed then write
     156              :     // the request into the lock.
     157              :     Transmit(
     158              :         (
     159              :             ComputeHookNotifyRequest,
     160              :             tokio::sync::OwnedMutexGuard<Option<ComputeHookNotifyRequest>>,
     161              :         ),
     162              :     ),
     163              :     // Something requires sending, but you must wait for a current sender then call again
     164              :     AwaitLock(Arc<tokio::sync::Mutex<Option<ComputeHookNotifyRequest>>>),
     165              :     // Nothing requires sending
     166              :     Noop,
     167              : }
     168              : 
     169              : impl ComputeHookTenant {
     170            4 :     fn maybe_send(
     171            4 :         &self,
     172            4 :         tenant_id: TenantId,
     173            4 :         lock: Option<tokio::sync::OwnedMutexGuard<Option<ComputeHookNotifyRequest>>>,
     174            4 :     ) -> MaybeSendResult {
     175            4 :         let locked = match lock {
     176            0 :             Some(already_locked) => already_locked,
     177              :             None => {
     178              :                 // Lock order: this _must_ be only a try_lock, because we are called inside of the [`ComputeHook::state`] lock.
     179            4 :                 let Ok(locked) = self.get_send_lock().clone().try_lock_owned() else {
     180            0 :                     return MaybeSendResult::AwaitLock(self.get_send_lock().clone());
     181              :                 };
     182            4 :                 locked
     183              :             }
     184              :         };
     185              : 
     186            4 :         let request = match self {
     187            2 :             Self::Unsharded(unsharded_tenant) => Some(ComputeHookNotifyRequest {
     188            2 :                 tenant_id,
     189            2 :                 shards: vec![ComputeHookNotifyRequestShard {
     190            2 :                     shard_number: ShardNumber(0),
     191            2 :                     node_id: unsharded_tenant.node_id,
     192            2 :                 }],
     193            2 :                 stripe_size: None,
     194            2 :             }),
     195            2 :             Self::Sharded(sharded_tenant)
     196            2 :                 if sharded_tenant.shards.len() == sharded_tenant.shard_count.count() as usize =>
     197            1 :             {
     198            1 :                 Some(ComputeHookNotifyRequest {
     199            1 :                     tenant_id,
     200            1 :                     shards: sharded_tenant
     201            1 :                         .shards
     202            1 :                         .iter()
     203            2 :                         .map(|(shard_number, node_id)| ComputeHookNotifyRequestShard {
     204            2 :                             shard_number: *shard_number,
     205            2 :                             node_id: *node_id,
     206            2 :                         })
     207            1 :                         .collect(),
     208            1 :                     stripe_size: Some(sharded_tenant.stripe_size),
     209            1 :                 })
     210              :             }
     211            1 :             Self::Sharded(sharded_tenant) => {
     212            1 :                 // Sharded tenant doesn't yet have information for all its shards
     213            1 : 
     214            1 :                 tracing::info!(
     215            0 :                     "ComputeHookTenant::maybe_send: not enough shards ({}/{})",
     216            0 :                     sharded_tenant.shards.len(),
     217            0 :                     sharded_tenant.shard_count.count()
     218              :                 );
     219            1 :                 None
     220              :             }
     221              :         };
     222              : 
     223            3 :         match request {
     224              :             None => {
     225              :                 // Not yet ready to emit a notification
     226            1 :                 tracing::info!("Tenant isn't yet ready to emit a notification");
     227            1 :                 MaybeSendResult::Noop
     228              :             }
     229            3 :             Some(request) if Some(&request) == locked.as_ref() => {
     230            1 :                 // No change from the last value successfully sent
     231            1 :                 MaybeSendResult::Noop
     232              :             }
     233            2 :             Some(request) => MaybeSendResult::Transmit((request, locked)),
     234              :         }
     235            4 :     }
     236              : }
     237              : 
     238              : /// The compute hook is a destination for notifications about changes to tenant:pageserver
     239              : /// mapping.  It aggregates updates for the shards in a tenant, and when appropriate reconfigures
     240              : /// the compute connection string.
     241              : pub(super) struct ComputeHook {
     242              :     config: Config,
     243              :     state: std::sync::Mutex<HashMap<TenantId, ComputeHookTenant>>,
     244              :     authorization_header: Option<String>,
     245              : 
     246              :     // Concurrency limiter, so that we do not overload the cloud control plane when updating
     247              :     // large numbers of tenants (e.g. when failing over after a node failure)
     248              :     api_concurrency: tokio::sync::Semaphore,
     249              : 
     250              :     // This lock is only used in testing enviroments, to serialize calls into neon_lock
     251              :     neon_local_lock: tokio::sync::Mutex<()>,
     252              : 
     253              :     // We share a client across all notifications to enable connection re-use etc when
     254              :     // sending large numbers of notifications
     255              :     client: reqwest::Client,
     256              : }
     257              : 
     258              : impl ComputeHook {
     259            0 :     pub(super) fn new(config: Config) -> Self {
     260            0 :         let authorization_header = config
     261            0 :             .control_plane_jwt_token
     262            0 :             .clone()
     263            0 :             .map(|jwt| format!("Bearer {}", jwt));
     264            0 : 
     265            0 :         let client = reqwest::ClientBuilder::new()
     266            0 :             .timeout(NOTIFY_REQUEST_TIMEOUT)
     267            0 :             .build()
     268            0 :             .expect("Failed to construct HTTP client");
     269            0 : 
     270            0 :         Self {
     271            0 :             state: Default::default(),
     272            0 :             config,
     273            0 :             authorization_header,
     274            0 :             neon_local_lock: Default::default(),
     275            0 :             api_concurrency: tokio::sync::Semaphore::new(API_CONCURRENCY),
     276            0 :             client,
     277            0 :         }
     278            0 :     }
     279              : 
     280              :     /// For test environments: use neon_local's LocalEnv to update compute
     281            0 :     async fn do_notify_local(
     282            0 :         &self,
     283            0 :         reconfigure_request: &ComputeHookNotifyRequest,
     284            0 :     ) -> Result<(), NotifyError> {
     285              :         // neon_local updates are not safe to call concurrently, use a lock to serialize
     286              :         // all calls to this function
     287            0 :         let _locked = self.neon_local_lock.lock().await;
     288              : 
     289            0 :         let Some(repo_dir) = self.config.neon_local_repo_dir.as_deref() else {
     290            0 :             tracing::warn!(
     291            0 :                 "neon_local_repo_dir not set, likely a bug in neon_local; skipping compute update"
     292              :             );
     293            0 :             return Ok(());
     294              :         };
     295            0 :         let env = match LocalEnv::load_config(repo_dir) {
     296            0 :             Ok(e) => e,
     297            0 :             Err(e) => {
     298            0 :                 tracing::warn!("Couldn't load neon_local config, skipping compute update ({e})");
     299            0 :                 return Ok(());
     300              :             }
     301              :         };
     302            0 :         let cplane =
     303            0 :             ComputeControlPlane::load(env.clone()).expect("Error loading compute control plane");
     304            0 :         let ComputeHookNotifyRequest {
     305            0 :             tenant_id,
     306            0 :             shards,
     307            0 :             stripe_size,
     308            0 :         } = reconfigure_request;
     309            0 : 
     310            0 :         let compute_pageservers = shards
     311            0 :             .iter()
     312            0 :             .map(|shard| {
     313            0 :                 let ps_conf = env
     314            0 :                     .get_pageserver_conf(shard.node_id)
     315            0 :                     .expect("Unknown pageserver");
     316            0 :                 let (pg_host, pg_port) = parse_host_port(&ps_conf.listen_pg_addr)
     317            0 :                     .expect("Unable to parse listen_pg_addr");
     318            0 :                 (pg_host, pg_port.unwrap_or(5432))
     319            0 :             })
     320            0 :             .collect::<Vec<_>>();
     321              : 
     322            0 :         for (endpoint_name, endpoint) in &cplane.endpoints {
     323            0 :             if endpoint.tenant_id == *tenant_id && endpoint.status() == EndpointStatus::Running {
     324            0 :                 tracing::info!("Reconfiguring endpoint {}", endpoint_name,);
     325            0 :                 endpoint
     326            0 :                     .reconfigure(compute_pageservers.clone(), *stripe_size, None)
     327            0 :                     .await
     328            0 :                     .map_err(NotifyError::NeonLocal)?;
     329            0 :             }
     330              :         }
     331              : 
     332            0 :         Ok(())
     333            0 :     }
     334              : 
     335            0 :     async fn do_notify_iteration(
     336            0 :         &self,
     337            0 :         url: &String,
     338            0 :         reconfigure_request: &ComputeHookNotifyRequest,
     339            0 :         cancel: &CancellationToken,
     340            0 :     ) -> Result<(), NotifyError> {
     341            0 :         let req = self.client.request(reqwest::Method::PUT, url);
     342            0 :         let req = if let Some(value) = &self.authorization_header {
     343            0 :             req.header(reqwest::header::AUTHORIZATION, value)
     344              :         } else {
     345            0 :             req
     346              :         };
     347              : 
     348            0 :         tracing::info!(
     349            0 :             "Sending notify request to {} ({:?})",
     350              :             url,
     351              :             reconfigure_request
     352              :         );
     353            0 :         let send_result = req.json(&reconfigure_request).send().await;
     354            0 :         let response = match send_result {
     355            0 :             Ok(r) => r,
     356            0 :             Err(e) => return Err(e.into()),
     357              :         };
     358              : 
     359              :         // Treat all 2xx responses as success
     360            0 :         if response.status() >= reqwest::StatusCode::OK
     361            0 :             && response.status() < reqwest::StatusCode::MULTIPLE_CHOICES
     362              :         {
     363            0 :             if response.status() != reqwest::StatusCode::OK {
     364              :                 // Non-200 2xx response: it doesn't make sense to retry, but this is unexpected, so
     365              :                 // log a warning.
     366            0 :                 tracing::warn!(
     367            0 :                     "Unexpected 2xx response code {} from control plane",
     368            0 :                     response.status()
     369              :                 );
     370            0 :             }
     371              : 
     372            0 :             return Ok(());
     373            0 :         }
     374            0 : 
     375            0 :         // Error response codes
     376            0 :         match response.status() {
     377              :             reqwest::StatusCode::TOO_MANY_REQUESTS => {
     378              :                 // TODO: 429 handling should be global: set some state visible to other requests
     379              :                 // so that they will delay before starting, rather than all notifications trying
     380              :                 // once before backing off.
     381            0 :                 tokio::time::timeout(SLOWDOWN_DELAY, cancel.cancelled())
     382            0 :                     .await
     383            0 :                     .ok();
     384            0 :                 Err(NotifyError::SlowDown)
     385              :             }
     386              :             reqwest::StatusCode::LOCKED => {
     387              :                 // We consider this fatal, because it's possible that the operation blocking the control one is
     388              :                 // also the one that is waiting for this reconcile.  We should let the reconciler calling
     389              :                 // this hook fail, to give control plane a chance to un-lock.
     390            0 :                 tracing::info!("Control plane reports tenant is locked, dropping out of notify");
     391            0 :                 Err(NotifyError::Busy)
     392              :             }
     393              :             reqwest::StatusCode::SERVICE_UNAVAILABLE => {
     394            0 :                 Err(NotifyError::Unavailable(StatusCode::SERVICE_UNAVAILABLE))
     395              :             }
     396              :             reqwest::StatusCode::GATEWAY_TIMEOUT => {
     397            0 :                 Err(NotifyError::Unavailable(StatusCode::GATEWAY_TIMEOUT))
     398              :             }
     399              :             reqwest::StatusCode::BAD_GATEWAY => {
     400            0 :                 Err(NotifyError::Unavailable(StatusCode::BAD_GATEWAY))
     401              :             }
     402              : 
     403            0 :             reqwest::StatusCode::BAD_REQUEST => Err(NotifyError::Fatal(StatusCode::BAD_REQUEST)),
     404            0 :             reqwest::StatusCode::UNAUTHORIZED => Err(NotifyError::Fatal(StatusCode::UNAUTHORIZED)),
     405            0 :             reqwest::StatusCode::FORBIDDEN => Err(NotifyError::Fatal(StatusCode::FORBIDDEN)),
     406            0 :             status => Err(NotifyError::Unexpected(
     407            0 :                 hyper::StatusCode::from_u16(status.as_u16())
     408            0 :                     .unwrap_or(StatusCode::INTERNAL_SERVER_ERROR),
     409            0 :             )),
     410              :         }
     411            0 :     }
     412              : 
     413            0 :     async fn do_notify(
     414            0 :         &self,
     415            0 :         url: &String,
     416            0 :         reconfigure_request: &ComputeHookNotifyRequest,
     417            0 :         cancel: &CancellationToken,
     418            0 :     ) -> Result<(), NotifyError> {
     419              :         // We hold these semaphore units across all retries, rather than only across each
     420              :         // HTTP request: this is to preserve fairness and avoid a situation where a retry might
     421              :         // time out waiting for a semaphore.
     422            0 :         let _units = self
     423            0 :             .api_concurrency
     424            0 :             .acquire()
     425            0 :             .await
     426              :             // Interpret closed semaphore as shutdown
     427            0 :             .map_err(|_| NotifyError::ShuttingDown)?;
     428              : 
     429            0 :         backoff::retry(
     430            0 :             || self.do_notify_iteration(url, reconfigure_request, cancel),
     431            0 :             |e| {
     432            0 :                 matches!(
     433            0 :                     e,
     434              :                     NotifyError::Fatal(_) | NotifyError::Unexpected(_) | NotifyError::Busy
     435              :                 )
     436            0 :             },
     437            0 :             3,
     438            0 :             10,
     439            0 :             "Send compute notification",
     440            0 :             cancel,
     441            0 :         )
     442            0 :         .await
     443            0 :         .ok_or_else(|| NotifyError::ShuttingDown)
     444            0 :         .and_then(|x| x)
     445            0 :     }
     446              : 
     447              :     /// Synchronous phase: update the per-tenant state for the next intended notification
     448            0 :     fn notify_prepare(
     449            0 :         &self,
     450            0 :         tenant_shard_id: TenantShardId,
     451            0 :         node_id: NodeId,
     452            0 :         stripe_size: ShardStripeSize,
     453            0 :     ) -> MaybeSendResult {
     454            0 :         let mut state_locked = self.state.lock().unwrap();
     455              : 
     456              :         use std::collections::hash_map::Entry;
     457            0 :         let tenant = match state_locked.entry(tenant_shard_id.tenant_id) {
     458            0 :             Entry::Vacant(e) => e.insert(ComputeHookTenant::new(
     459            0 :                 tenant_shard_id,
     460            0 :                 stripe_size,
     461            0 :                 node_id,
     462            0 :             )),
     463            0 :             Entry::Occupied(e) => {
     464            0 :                 let tenant = e.into_mut();
     465            0 :                 tenant.update(tenant_shard_id, stripe_size, node_id);
     466            0 :                 tenant
     467              :             }
     468              :         };
     469            0 :         tenant.maybe_send(tenant_shard_id.tenant_id, None)
     470            0 :     }
     471              : 
     472            0 :     async fn notify_execute(
     473            0 :         &self,
     474            0 :         maybe_send_result: MaybeSendResult,
     475            0 :         tenant_shard_id: TenantShardId,
     476            0 :         cancel: &CancellationToken,
     477            0 :     ) -> Result<(), NotifyError> {
     478              :         // Process result: we may get an update to send, or we may have to wait for a lock
     479              :         // before trying again.
     480            0 :         let (request, mut send_lock_guard) = match maybe_send_result {
     481              :             MaybeSendResult::Noop => {
     482            0 :                 return Ok(());
     483              :             }
     484            0 :             MaybeSendResult::AwaitLock(send_lock) => {
     485            0 :                 let send_locked = tokio::select! {
     486            0 :                     guard = send_lock.lock_owned() => {guard},
     487            0 :                     _ = cancel.cancelled() => {
     488            0 :                         return Err(NotifyError::ShuttingDown)
     489              :                     }
     490              :                 };
     491              : 
     492              :                 // Lock order: maybe_send is called within the `[Self::state]` lock, and takes the send lock, but here
     493              :                 // we have acquired the send lock and take `[Self::state]` lock.  This is safe because maybe_send only uses
     494              :                 // try_lock.
     495            0 :                 let state_locked = self.state.lock().unwrap();
     496            0 :                 let Some(tenant) = state_locked.get(&tenant_shard_id.tenant_id) else {
     497            0 :                     return Ok(());
     498              :                 };
     499            0 :                 match tenant.maybe_send(tenant_shard_id.tenant_id, Some(send_locked)) {
     500              :                     MaybeSendResult::AwaitLock(_) => {
     501            0 :                         unreachable!("We supplied lock guard")
     502              :                     }
     503              :                     MaybeSendResult::Noop => {
     504            0 :                         return Ok(());
     505              :                     }
     506            0 :                     MaybeSendResult::Transmit((request, lock)) => (request, lock),
     507              :                 }
     508              :             }
     509            0 :             MaybeSendResult::Transmit((request, lock)) => (request, lock),
     510              :         };
     511              : 
     512            0 :         let result = if let Some(notify_url) = &self.config.compute_hook_url {
     513            0 :             self.do_notify(notify_url, &request, cancel).await
     514              :         } else {
     515            0 :             self.do_notify_local(&request).await.map_err(|e| {
     516            0 :                 // This path is for testing only, so munge the error into our prod-style error type.
     517            0 :                 tracing::error!("neon_local notification hook failed: {e}");
     518            0 :                 NotifyError::Fatal(StatusCode::INTERNAL_SERVER_ERROR)
     519            0 :             })
     520              :         };
     521              : 
     522            0 :         if result.is_ok() {
     523            0 :             // Before dropping the send lock, stash the request we just sent so that
     524            0 :             // subsequent callers can avoid redundantly re-sending the same thing.
     525            0 :             *send_lock_guard = Some(request);
     526            0 :         }
     527            0 :         result
     528            0 :     }
     529              : 
     530              :     /// Infallible synchronous fire-and-forget version of notify(), that sends its results to
     531              :     /// a channel.  Something should consume the channel and arrange to try notifying again
     532              :     /// if something failed.
     533            0 :     pub(super) fn notify_background(
     534            0 :         self: &Arc<Self>,
     535            0 :         notifications: Vec<(TenantShardId, NodeId, ShardStripeSize)>,
     536            0 :         result_tx: tokio::sync::mpsc::Sender<Result<(), (TenantShardId, NotifyError)>>,
     537            0 :         cancel: &CancellationToken,
     538            0 :     ) {
     539            0 :         let mut maybe_sends = Vec::new();
     540            0 :         for (tenant_shard_id, node_id, stripe_size) in notifications {
     541            0 :             let maybe_send_result = self.notify_prepare(tenant_shard_id, node_id, stripe_size);
     542            0 :             maybe_sends.push((tenant_shard_id, maybe_send_result))
     543              :         }
     544              : 
     545            0 :         let this = self.clone();
     546            0 :         let cancel = cancel.clone();
     547            0 : 
     548            0 :         tokio::task::spawn(async move {
     549            0 :             // Construct an async stream of futures to invoke the compute notify function: we do this
     550            0 :             // in order to subsequently use .buffered() on the stream to execute with bounded parallelism.  The
     551            0 :             // ComputeHook semaphore already limits concurrency, but this way we avoid constructing+polling lots of futures which
     552            0 :             // would mostly just be waiting on that semaphore.
     553            0 :             let mut stream = futures::stream::iter(maybe_sends)
     554            0 :                 .map(|(tenant_shard_id, maybe_send_result)| {
     555            0 :                     let this = this.clone();
     556            0 :                     let cancel = cancel.clone();
     557              : 
     558            0 :                     async move {
     559            0 :                         this
     560            0 :                             .notify_execute(maybe_send_result, tenant_shard_id, &cancel)
     561            0 :                             .await.map_err(|e| (tenant_shard_id, e))
     562            0 :                     }.instrument(info_span!(
     563            0 :                         "notify_background", tenant_id=%tenant_shard_id.tenant_id, shard_id=%tenant_shard_id.shard_slug()
     564              :                     ))
     565            0 :                 })
     566            0 :                 .buffered(API_CONCURRENCY);
     567              : 
     568              :             loop {
     569            0 :                 tokio::select! {
     570            0 :                     next = stream.next() => {
     571            0 :                         match next {
     572            0 :                             Some(r) => {
     573            0 :                                 result_tx.send(r).await.ok();
     574              :                             },
     575              :                             None => {
     576            0 :                                 tracing::info!("Finished sending background compute notifications");
     577            0 :                                 break;
     578              :                             }
     579              :                         }
     580              :                     },
     581            0 :                     _ = cancel.cancelled() => {
     582            0 :                         tracing::info!("Shutdown while running background compute notifications");
     583            0 :                         break;
     584              :                     }
     585              :                 };
     586              :             }
     587            0 :         });
     588            0 :     }
     589              : 
     590              :     /// Call this to notify the compute (postgres) tier of new pageservers to use
     591              :     /// for a tenant.  notify() is called by each shard individually, and this function
     592              :     /// will decide whether an update to the tenant is sent.  An update is sent on the
     593              :     /// condition that:
     594              :     /// - We know a pageserver for every shard.
     595              :     /// - All the shards have the same shard_count (i.e. we are not mid-split)
     596              :     ///
     597              :     /// Cancellation token enables callers to drop out, e.g. if calling from a Reconciler
     598              :     /// that is cancelled.
     599              :     ///
     600              :     /// This function is fallible, including in the case that the control plane is transiently
     601              :     /// unavailable.  A limited number of retries are done internally to efficiently hide short unavailability
     602              :     /// periods, but we don't retry forever.  The **caller** is responsible for handling failures and
     603              :     /// ensuring that they eventually call again to ensure that the compute is eventually notified of
     604              :     /// the proper pageserver nodes for a tenant.
     605            0 :     #[tracing::instrument(skip_all, fields(tenant_id=%tenant_shard_id.tenant_id, shard_id=%tenant_shard_id.shard_slug(), node_id))]
     606              :     pub(super) async fn notify(
     607              :         &self,
     608              :         tenant_shard_id: TenantShardId,
     609              :         node_id: NodeId,
     610              :         stripe_size: ShardStripeSize,
     611              :         cancel: &CancellationToken,
     612              :     ) -> Result<(), NotifyError> {
     613              :         let maybe_send_result = self.notify_prepare(tenant_shard_id, node_id, stripe_size);
     614              :         self.notify_execute(maybe_send_result, tenant_shard_id, cancel)
     615              :             .await
     616              :     }
     617              : }
     618              : 
     619              : #[cfg(test)]
     620              : pub(crate) mod tests {
     621              :     use pageserver_api::shard::{ShardCount, ShardNumber};
     622              :     use utils::id::TenantId;
     623              : 
     624              :     use super::*;
     625              : 
     626              :     #[test]
     627            1 :     fn tenant_updates() -> anyhow::Result<()> {
     628            1 :         let tenant_id = TenantId::generate();
     629            1 :         let mut tenant_state = ComputeHookTenant::new(
     630            1 :             TenantShardId {
     631            1 :                 tenant_id,
     632            1 :                 shard_count: ShardCount::new(0),
     633            1 :                 shard_number: ShardNumber(0),
     634            1 :             },
     635            1 :             ShardStripeSize(12345),
     636            1 :             NodeId(1),
     637            1 :         );
     638            1 : 
     639            1 :         // An unsharded tenant is always ready to emit a notification, but won't
     640            1 :         // send the same one twice
     641            1 :         let send_result = tenant_state.maybe_send(tenant_id, None);
     642            1 :         let MaybeSendResult::Transmit((request, mut guard)) = send_result else {
     643            0 :             anyhow::bail!("Wrong send result");
     644              :         };
     645            1 :         assert_eq!(request.shards.len(), 1);
     646            1 :         assert!(request.stripe_size.is_none());
     647              : 
     648              :         // Simulate successful send
     649            1 :         *guard = Some(request);
     650            1 :         drop(guard);
     651            1 : 
     652            1 :         // Try asking again: this should be a no-op
     653            1 :         let send_result = tenant_state.maybe_send(tenant_id, None);
     654            1 :         assert!(matches!(send_result, MaybeSendResult::Noop));
     655              : 
     656              :         // Writing the first shard of a multi-sharded situation (i.e. in a split)
     657              :         // resets the tenant state and puts it in an non-notifying state (need to
     658              :         // see all shards)
     659            1 :         tenant_state.update(
     660            1 :             TenantShardId {
     661            1 :                 tenant_id,
     662            1 :                 shard_count: ShardCount::new(2),
     663            1 :                 shard_number: ShardNumber(1),
     664            1 :             },
     665            1 :             ShardStripeSize(32768),
     666            1 :             NodeId(1),
     667            1 :         );
     668            1 :         assert!(matches!(
     669            1 :             tenant_state.maybe_send(tenant_id, None),
     670              :             MaybeSendResult::Noop
     671              :         ));
     672              : 
     673              :         // Writing the second shard makes it ready to notify
     674            1 :         tenant_state.update(
     675            1 :             TenantShardId {
     676            1 :                 tenant_id,
     677            1 :                 shard_count: ShardCount::new(2),
     678            1 :                 shard_number: ShardNumber(0),
     679            1 :             },
     680            1 :             ShardStripeSize(32768),
     681            1 :             NodeId(1),
     682            1 :         );
     683            1 : 
     684            1 :         let send_result = tenant_state.maybe_send(tenant_id, None);
     685            1 :         let MaybeSendResult::Transmit((request, mut guard)) = send_result else {
     686            0 :             anyhow::bail!("Wrong send result");
     687              :         };
     688            1 :         assert_eq!(request.shards.len(), 2);
     689            1 :         assert_eq!(request.stripe_size, Some(ShardStripeSize(32768)));
     690              : 
     691              :         // Simulate successful send
     692            1 :         *guard = Some(request);
     693            1 :         drop(guard);
     694            1 : 
     695            1 :         Ok(())
     696            1 :     }
     697              : }
        

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