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Prevent NPE when generating snapshot metrics before initial cluster state is set #136350
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b3c35ce
Fix checkstyle
nicktindall 4214472
Generate snapshot metrics from last applied state
nicktindall f46ef6e
Merge remote-tracking branch 'origin/main' into fix_npe_snapshot_metrics
nicktindall 4d7ab3d
Update docs/changelog/136350.yaml
nicktindall f1c7b95
Split out metrics calculation
nicktindall 9e926ae
Merge remote-tracking branch 'origin/main' into fix_npe_snapshot_metrics
nicktindall b312683
Merge branch 'fix_npe_snapshot_metrics' of github.com:nicktindall/ela…
nicktindall 8c72da5
Fix changelog
nicktindall 3c5bb9e
Clean up remnants
nicktindall 3684b57
Remove redundant staleness check
nicktindall a9e46fe
Add test for no-longer master
nicktindall 1a79b92
Use ClusterService lifecycle to decide when to poll
nicktindall 6f8978c
Test whole lifecyle
nicktindall ee4a21c
Merge remote-tracking branch 'origin/main' into fix_npe_snapshot_metrics
nicktindall e3146c6
Make minimum nodes 2
nicktindall 20715a3
Use original cluster state when creating snapshotsInProgress
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,5 @@ | ||
| pr: 136350 | ||
| summary: Prevent NPE when generating snapshot metrics before initial cluster state is set | ||
| area: Snapshot/Restore | ||
| type: bug | ||
| issues: [] |
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139 changes: 139 additions & 0 deletions
139
server/src/main/java/org/elasticsearch/snapshots/SnapshotMetricsService.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,139 @@ | ||
| /* | ||
| * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one | ||
| * or more contributor license agreements. Licensed under the "Elastic License | ||
| * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side | ||
| * Public License v 1"; you may not use this file except in compliance with, at | ||
| * your election, the "Elastic License 2.0", the "GNU Affero General Public | ||
| * License v3.0 only", or the "Server Side Public License, v 1". | ||
| */ | ||
|
|
||
| package org.elasticsearch.snapshots; | ||
|
|
||
| import org.elasticsearch.cluster.ClusterChangedEvent; | ||
| import org.elasticsearch.cluster.ClusterState; | ||
| import org.elasticsearch.cluster.ClusterStateListener; | ||
| import org.elasticsearch.cluster.SnapshotsInProgress; | ||
| import org.elasticsearch.cluster.metadata.RepositoriesMetadata; | ||
| import org.elasticsearch.cluster.metadata.RepositoryMetadata; | ||
| import org.elasticsearch.cluster.service.ClusterService; | ||
| import org.elasticsearch.common.util.Maps; | ||
| import org.elasticsearch.core.Tuple; | ||
| import org.elasticsearch.gateway.GatewayService; | ||
| import org.elasticsearch.repositories.SnapshotMetrics; | ||
| import org.elasticsearch.telemetry.metric.LongWithAttributes; | ||
|
|
||
| import java.util.ArrayList; | ||
| import java.util.Collection; | ||
| import java.util.List; | ||
| import java.util.Map; | ||
| import java.util.Objects; | ||
|
|
||
| /** | ||
| * Generates the snapshots-by-state and shards-by-state metrics when polled. Only produces | ||
| * metrics on the master node, and only after it's seen a cluster state applied. | ||
| */ | ||
| public class SnapshotMetricsService implements ClusterStateListener { | ||
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| private final ClusterService clusterService; | ||
| private volatile boolean shouldReturnSnapshotMetrics; | ||
| private CachedSnapshotStateMetrics cachedSnapshotStateMetrics; | ||
|
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| public SnapshotMetricsService(SnapshotMetrics snapshotMetrics, ClusterService clusterService) { | ||
| this.clusterService = clusterService; | ||
| snapshotMetrics.createSnapshotShardsByStateMetric(this::getShardsByState); | ||
| snapshotMetrics.createSnapshotsByStateMetric(this::getSnapshotsByState); | ||
| } | ||
|
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| @Override | ||
| public void clusterChanged(ClusterChangedEvent event) { | ||
| final ClusterState clusterState = event.state(); | ||
| // Only return metrics when the state is recovered and we are the master | ||
| shouldReturnSnapshotMetrics = clusterState.nodes().isLocalNodeElectedMaster() | ||
| && clusterState.blocks().hasGlobalBlock(GatewayService.STATE_NOT_RECOVERED_BLOCK) == false; | ||
| } | ||
|
|
||
| private Collection<LongWithAttributes> getShardsByState() { | ||
| if (shouldReturnSnapshotMetrics == false) { | ||
| return List.of(); | ||
| } | ||
| return recalculateIfStale(clusterService.state()).shardStateMetrics(); | ||
| } | ||
|
|
||
| private Collection<LongWithAttributes> getSnapshotsByState() { | ||
| if (shouldReturnSnapshotMetrics == false) { | ||
| return List.of(); | ||
| } | ||
| return recalculateIfStale(clusterService.state()).snapshotStateMetrics(); | ||
| } | ||
|
|
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| private CachedSnapshotStateMetrics recalculateIfStale(ClusterState currentState) { | ||
| if (cachedSnapshotStateMetrics == null || cachedSnapshotStateMetrics.isStale(currentState)) { | ||
| cachedSnapshotStateMetrics = recalculateSnapshotStats(currentState); | ||
| } | ||
| return cachedSnapshotStateMetrics; | ||
| } | ||
|
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| private CachedSnapshotStateMetrics recalculateSnapshotStats(ClusterState currentState) { | ||
| final SnapshotsInProgress snapshotsInProgress = SnapshotsInProgress.get(currentState); | ||
| final List<LongWithAttributes> snapshotStateMetrics = new ArrayList<>(); | ||
| final List<LongWithAttributes> shardStateMetrics = new ArrayList<>(); | ||
|
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||
| currentState.metadata().projects().forEach((projectId, project) -> { | ||
| final RepositoriesMetadata repositoriesMetadata = RepositoriesMetadata.get(project); | ||
| if (repositoriesMetadata != null) { | ||
| for (RepositoryMetadata repository : repositoriesMetadata.repositories()) { | ||
| final Tuple<Map<SnapshotsInProgress.State, Integer>, Map<SnapshotsInProgress.ShardState, Integer>> stateSummaries = | ||
| snapshotsInProgress.shardStateSummaryForRepository(projectId, repository.name()); | ||
| final Map<String, Object> attributesMap = SnapshotMetrics.createAttributesMap(projectId, repository); | ||
| stateSummaries.v1() | ||
| .forEach( | ||
| (snapshotState, count) -> snapshotStateMetrics.add( | ||
| new LongWithAttributes(count, Maps.copyMapWithAddedEntry(attributesMap, "state", snapshotState.name())) | ||
| ) | ||
| ); | ||
| stateSummaries.v2() | ||
| .forEach( | ||
| (shardState, count) -> shardStateMetrics.add( | ||
| new LongWithAttributes(count, Maps.copyMapWithAddedEntry(attributesMap, "state", shardState.name())) | ||
| ) | ||
| ); | ||
| } | ||
| } | ||
| }); | ||
| return new CachedSnapshotStateMetrics(currentState, snapshotStateMetrics, shardStateMetrics); | ||
| } | ||
|
|
||
| /** | ||
| * A cached copy of the snapshot and shard state metrics | ||
| */ | ||
| private record CachedSnapshotStateMetrics( | ||
| String clusterStateId, | ||
| int snapshotsInProgressIdentityHashcode, | ||
| Collection<LongWithAttributes> snapshotStateMetrics, | ||
| Collection<LongWithAttributes> shardStateMetrics | ||
| ) { | ||
| CachedSnapshotStateMetrics( | ||
| ClusterState sourceState, | ||
| Collection<LongWithAttributes> snapshotStateMetrics, | ||
| Collection<LongWithAttributes> shardStateMetrics | ||
| ) { | ||
| this( | ||
| sourceState.stateUUID(), | ||
| System.identityHashCode(SnapshotsInProgress.get(sourceState)), | ||
| snapshotStateMetrics, | ||
| shardStateMetrics | ||
| ); | ||
| } | ||
|
|
||
| /** | ||
| * Are these metrics stale? | ||
| * | ||
| * @param currentClusterState The current cluster state | ||
| * @return true if these metrics were calculated from a prior cluster state and need to be recalculated, false otherwise | ||
| */ | ||
| public boolean isStale(ClusterState currentClusterState) { | ||
| return (Objects.equals(clusterStateId, currentClusterState.stateUUID()) == false | ||
| && System.identityHashCode(SnapshotsInProgress.get(currentClusterState)) != snapshotsInProgressIdentityHashcode); | ||
| } | ||
| } | ||
| } | ||
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There is a slight race if the node is demoted from master, it could happen just after we evaluate
shouldReturnSnapshotMetrics == true, but it's no big deal and definitely not worth synchronizing.There was a problem hiding this comment.
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We have the same issue with other Gauge metrics. I don't think it's important enough to address.