Add ElasticsearchIndexDeletionPolicy and EngineConfig policy wrapper (elastic#130442)

This change adds a new abstract class ElasticsearchIndexDeletionPolicy that allows using different policy implementations for InternalEngine.

It also adds an index deletion policy wrapper to the EngineConfig to allow wrapping the default CombinedDeletionPolicy by inheritors of InternalEngine.

Relates ES-10929

---------

Co-authored-by: Francisco Fernández Castaño <[email protected]>

Author: tlrx

server/src/internalClusterTest/java/org/elasticsearch/indices/IndexingMemoryControllerIT.java

@@ -89,7 +89,8 @@ EngineConfig engineConfigWithLargerIndexingMemory(EngineConfig config) {
                 config.isPromotableToPrimary(),
                 config.getMapperService(),
                 config.getEngineResetLock(),
-                config.getMergeMetrics()
+                config.getMergeMetrics(),
+                config.getIndexDeletionPolicyWrapper()
             );
         }
 

server/src/main/java/org/elasticsearch/common/lucene/FilterIndexCommit.java

@@ -71,4 +71,11 @@ public Map<String, String> getUserData() throws IOException {
     public String toString() {
         return "FilterIndexCommit{" + "in=" + in + '}';
     }
+
+    public static IndexCommit unwrap(IndexCommit in) {
+        while (in instanceof FilterIndexCommit) {
+            in = ((FilterIndexCommit) in).getIndexCommit();
+        }
+        return in;
+    }
 }

server/src/main/java/org/elasticsearch/index/engine/CombinedDeletionPolicy.java

@@ -38,7 +38,7 @@
  * In particular, this policy will delete index commits whose max sequence number is at most
  * the current global checkpoint except the index commit which has the highest max sequence number among those.
  */
-public class CombinedDeletionPolicy extends IndexDeletionPolicy {
+public class CombinedDeletionPolicy extends ElasticsearchIndexDeletionPolicy {
     private final Logger logger;
     private final TranslogDeletionPolicy translogDeletionPolicy;
     private final SoftDeletesPolicy softDeletesPolicy;
@@ -48,13 +48,6 @@ public class CombinedDeletionPolicy extends IndexDeletionPolicy {
     // when checking for externally acquired index commits that haven't been released
     private final Set<IndexCommit> internallyAcquiredIndexCommits;
 
-    interface CommitsListener {
-
-        void onNewAcquiredCommit(IndexCommit commit, Set<String> additionalFiles);
-
-        void onDeletedCommit(IndexCommit commit);
-    }
-
     @Nullable
     private final CommitsListener commitsListener;
 
@@ -187,7 +180,6 @@ private void deleteCommit(IndexCommit commit) throws IOException {
         assert commit.isDeleted() == false : "Index commit [" + commitDescription(commit) + "] is deleted twice";
         logger.debug("Delete index commit [{}]", commitDescription(commit));
         commit.delete();
-        assert commit.isDeleted() : "Deletion commit [" + commitDescription(commit) + "] was suppressed";
     }
 
     private void updateRetentionPolicy() throws IOException {
@@ -204,7 +196,8 @@ protected int getDocCountOfCommit(IndexCommit indexCommit) throws IOException {
         return SegmentInfos.readCommit(indexCommit.getDirectory(), indexCommit.getSegmentsFileName()).totalMaxDoc();
     }
 
-    SafeCommitInfo getSafeCommitInfo() {
+    @Override
+    public SafeCommitInfo getSafeCommitInfo() {
         return safeCommitInfo;
     }
 
@@ -214,7 +207,8 @@ SafeCommitInfo getSafeCommitInfo() {
      *
      * @param acquiringSafeCommit captures the most recent safe commit point if true; otherwise captures the most recent commit point.
      */
-    synchronized IndexCommit acquireIndexCommit(boolean acquiringSafeCommit) {
+    @Override
+    public synchronized IndexCommit acquireIndexCommit(boolean acquiringSafeCommit) {
         return acquireIndexCommit(acquiringSafeCommit, false);
     }
 
@@ -241,7 +235,8 @@ protected IndexCommit wrapCommit(IndexCommit indexCommit, boolean acquiredIntern
      *
      * @return true if the acquired commit can be clean up.
      */
-    synchronized boolean releaseCommit(final IndexCommit acquiredCommit) {
+    @Override
+    public synchronized boolean releaseIndexCommit(final IndexCommit acquiredCommit) {
         final SnapshotIndexCommit snapshotIndexCommit = (SnapshotIndexCommit) acquiredCommit;
         final IndexCommit releasingCommit = snapshotIndexCommit.getIndexCommit();
         assert acquiredIndexCommits.containsKey(releasingCommit)
@@ -316,7 +311,8 @@ private static Set<String> listOfNewFileNames(IndexCommit previous, IndexCommit
     /**
      * Checks whether the deletion policy is holding on to externally acquired index commits
      */
-    synchronized boolean hasAcquiredIndexCommitsForTesting() {
+    @Override
+    public synchronized boolean hasAcquiredIndexCommitsForTesting() {
         // We explicitly check only external commits and disregard internal commits acquired by the commits listener
         for (var e : acquiredIndexCommits.entrySet()) {
             if (internallyAcquiredIndexCommits.contains(e.getKey()) == false || e.getValue() > 1) {
@@ -329,7 +325,8 @@ synchronized boolean hasAcquiredIndexCommitsForTesting() {
     /**
      * Checks if the deletion policy can delete some index commits with the latest global checkpoint.
      */
-    boolean hasUnreferencedCommits() {
+    @Override
+    public boolean hasUnreferencedCommits() {
         return maxSeqNoOfNextSafeCommit <= globalCheckpointSupplier.getAsLong();
     }
 

server/src/main/java/org/elasticsearch/index/engine/ElasticsearchIndexDeletionPolicy.java

@@ -0,0 +1,49 @@
+/*
+ * 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.index.engine;
+
+import org.apache.lucene.index.IndexCommit;
+import org.apache.lucene.index.IndexDeletionPolicy;
+
+import java.util.Set;
+
+public abstract class ElasticsearchIndexDeletionPolicy extends IndexDeletionPolicy {
+
+    /**
+     * Captures the most recent commit point or the most recent safe commit point.
+     * Index files of the capturing commit point won't be released until the commit reference is closed.
+     *
+     * @param acquiringSafeCommit captures the most recent safe commit point if true; otherwise captures the most recent commit point.
+     */
+    public abstract IndexCommit acquireIndexCommit(boolean acquiringSafeCommit);
+
+    /**
+     * Releases an index commit that was acquired by {@link #acquireIndexCommit(boolean)}.
+     *
+     * @return true if the acquired commit can be clean up.
+     */
+    public abstract boolean releaseIndexCommit(IndexCommit acquiredIndexCommit);
+
+    /**
+     * @return information about the safe commit
+     */
+    public abstract SafeCommitInfo getSafeCommitInfo();
+
+    public abstract boolean hasAcquiredIndexCommitsForTesting();
+
+    public abstract boolean hasUnreferencedCommits();
+
+    public interface CommitsListener {
+
+        void onNewAcquiredCommit(IndexCommit commit, Set<String> additionalFiles);
+
+        void onDeletedCommit(IndexCommit commit);
+    }
+}

server/src/main/java/org/elasticsearch/index/engine/EngineConfig.java

@@ -41,6 +41,7 @@
 import java.util.Comparator;
 import java.util.List;
 import java.util.Objects;
+import java.util.function.Function;
 import java.util.function.LongSupplier;
 import java.util.function.Supplier;
 
@@ -151,6 +152,11 @@ public Supplier<RetentionLeases> retentionLeasesSupplier() {
 
     private final MergeMetrics mergeMetrics;
 
+    /**
+     * Allows to pass an {@link ElasticsearchIndexDeletionPolicy} wrapper to egine implementations.
+     */
+    private final Function<ElasticsearchIndexDeletionPolicy, ElasticsearchIndexDeletionPolicy> indexDeletionPolicyWrapper;
+
     /**
      * Creates a new {@link org.elasticsearch.index.engine.EngineConfig}
      */
@@ -184,7 +190,8 @@ public EngineConfig(
         boolean promotableToPrimary,
         MapperService mapperService,
         EngineResetLock engineResetLock,
-        MergeMetrics mergeMetrics
+        MergeMetrics mergeMetrics,
+        Function<ElasticsearchIndexDeletionPolicy, ElasticsearchIndexDeletionPolicy> indexDeletionPolicyWrapper
     ) {
         this.shardId = shardId;
         this.indexSettings = indexSettings;
@@ -233,6 +240,7 @@ public EngineConfig(
         this.useCompoundFile = indexSettings.getSettings().getAsBoolean(USE_COMPOUND_FILE, true);
         this.engineResetLock = engineResetLock;
         this.mergeMetrics = mergeMetrics;
+        this.indexDeletionPolicyWrapper = indexDeletionPolicyWrapper;
     }
 
     /**
@@ -485,4 +493,11 @@ public EngineResetLock getEngineResetLock() {
     public MergeMetrics getMergeMetrics() {
         return mergeMetrics;
     }
+
+    /**
+     * @return an {@link ElasticsearchIndexDeletionPolicy} wrapper, to be use by engine implementations.
+     */
+    public Function<ElasticsearchIndexDeletionPolicy, ElasticsearchIndexDeletionPolicy> getIndexDeletionPolicyWrapper() {
+        return indexDeletionPolicyWrapper;
+    }
 }

server/src/main/java/org/elasticsearch/index/engine/InternalEngine.java

@@ -170,7 +170,7 @@ public class InternalEngine extends Engine {
 
     private final LocalCheckpointTracker localCheckpointTracker;
 
-    private final CombinedDeletionPolicy combinedDeletionPolicy;
+    private final ElasticsearchIndexDeletionPolicy indexDeletionPolicy;
 
     // How many callers are currently requesting index throttling. Currently there are only two situations where we do this: when merges
     // are falling behind and when writing indexing buffer to disk is too slow. When this is 0, there is no throttling, else we throttle
@@ -277,13 +277,7 @@ public InternalEngine(EngineConfig engineConfig) {
                 this.totalDiskSpace = ByteSizeValue.of(Environment.getFileStore(translog.location()).getTotalSpace(), ByteSizeUnit.BYTES);
                 this.lastCommittedSegmentInfos = store.readLastCommittedSegmentsInfo();
                 this.softDeletesPolicy = newSoftDeletesPolicy();
-                this.combinedDeletionPolicy = new CombinedDeletionPolicy(
-                    logger,
-                    translogDeletionPolicy,
-                    softDeletesPolicy,
-                    translog::getLastSyncedGlobalCheckpoint,
-                    newCommitsListener()
-                );
+                this.indexDeletionPolicy = newIndexDeletionPolicy(engineConfig, logger, translog, softDeletesPolicy);
                 this.localCheckpointTracker = createLocalCheckpointTracker(localCheckpointTrackerSupplier);
                 writer = createWriter();
                 bootstrapAppendOnlyInfoFromWriter(writer);
@@ -391,6 +385,25 @@ private SoftDeletesPolicy newSoftDeletesPolicy() throws IOException {
         );
     }
 
+    protected ElasticsearchIndexDeletionPolicy newIndexDeletionPolicy(
+        EngineConfig engineConfig,
+        Logger logger,
+        Translog translog,
+        SoftDeletesPolicy softDeletesPolicy
+    ) {
+        var wrapper = engineConfig.getIndexDeletionPolicyWrapper();
+        assert wrapper != null : "no index deletion policy wrapper for " + engineConfig.getShardId();
+        return wrapper.apply(
+            new CombinedDeletionPolicy(
+                logger,
+                translog.getDeletionPolicy(),
+                softDeletesPolicy,
+                translog::getLastSyncedGlobalCheckpoint,
+                newCommitsListener()
+            )
+        );
+    }
+
     @Nullable
     private CombinedDeletionPolicy.CommitsListener newCommitsListener() {
         IndexCommitListener listener = engineConfig.getIndexCommitListener();
@@ -682,7 +695,7 @@ Translog getTranslog() {
 
     // Package private for testing purposes only
     boolean hasAcquiredIndexCommitsForTesting() {
-        return combinedDeletionPolicy.hasAcquiredIndexCommitsForTesting();
+        return indexDeletionPolicy.hasAcquiredIndexCommitsForTesting();
     }
 
     @Override
@@ -748,7 +761,7 @@ public Translog.Location getTranslogLastWriteLocation() {
     }
 
     private void revisitIndexDeletionPolicyOnTranslogSynced() throws IOException {
-        if (combinedDeletionPolicy.hasUnreferencedCommits()) {
+        if (indexDeletionPolicy.hasUnreferencedCommits()) {
             indexWriter.deleteUnusedFiles();
         }
         translog.trimUnreferencedReaders();
@@ -2555,17 +2568,17 @@ public IndexCommitRef acquireLastIndexCommit(final boolean flushFirst) throws En
             future.actionGet();
             logger.trace("finish flush for snapshot");
         }
-        return acquireIndexCommitRef(() -> combinedDeletionPolicy.acquireIndexCommit(false));
+        return acquireIndexCommitRef(() -> indexDeletionPolicy.acquireIndexCommit(false));
     }
 
     @Override
     public IndexCommitRef acquireSafeIndexCommit() throws EngineException {
-        return acquireIndexCommitRef(() -> combinedDeletionPolicy.acquireIndexCommit(true));
+        return acquireIndexCommitRef(() -> indexDeletionPolicy.acquireIndexCommit(true));
     }
 
     private void releaseIndexCommit(IndexCommit snapshot) throws IOException {
         // Revisit the deletion policy if we can clean up the snapshotting commit.
-        if (combinedDeletionPolicy.releaseCommit(snapshot)) {
+        if (indexDeletionPolicy.releaseIndexCommit(snapshot)) {
             try {
                 // Here we don't have to trim translog because snapshotting an index commit
                 // does not lock translog or prevents unreferenced files from trimming.
@@ -2578,7 +2591,7 @@ private void releaseIndexCommit(IndexCommit snapshot) throws IOException {
 
     @Override
     public SafeCommitInfo getSafeCommitInfo() {
-        return combinedDeletionPolicy.getSafeCommitInfo();
+        return indexDeletionPolicy.getSafeCommitInfo();
     }
 
     private boolean failOnTragicEvent(AlreadyClosedException ex) {
@@ -2756,7 +2769,7 @@ private IndexWriterConfig getIndexWriterConfig() {
         final IndexWriterConfig iwc = new IndexWriterConfig(engineConfig.getAnalyzer());
         iwc.setCommitOnClose(false); // we by default don't commit on close
         iwc.setOpenMode(IndexWriterConfig.OpenMode.APPEND);
-        iwc.setIndexDeletionPolicy(combinedDeletionPolicy);
+        iwc.setIndexDeletionPolicy(indexDeletionPolicy);
         iwc.setInfoStream(TESTS_VERBOSE ? InfoStream.getDefault() : new LoggerInfoStream(logger));
         iwc.setMergeScheduler(mergeScheduler.getMergeScheduler());
         // Give us the opportunity to upgrade old segments while performing

server/src/main/java/org/elasticsearch/index/shard/IndexShard.java

@@ -3765,7 +3765,8 @@ private EngineConfig newEngineConfig(LongSupplier globalCheckpointSupplier) {
             routingEntry().isPromotableToPrimary(),
             mapperService(),
             engineResetLock,
-            mergeMetrics
+            mergeMetrics,
+            Function.identity()
         );
     }
 

server/src/test/java/org/elasticsearch/index/engine/CombinedDeletionPolicyTests.java

@@ -193,7 +193,7 @@ public void testAcquireIndexCommit() throws Exception {
                 final IndexCommit lastCommit = commitList.get(commitList.size() - 1);
                 safeCommit = CombinedDeletionPolicy.findSafeCommitPoint(commitList, globalCheckpoint.get());
                 assertThat(
-                    indexPolicy.releaseCommit(snapshot),
+                    indexPolicy.releaseIndexCommit(snapshot),
                     equalTo(pendingSnapshots == 0 && snapshot.equals(lastCommit) == false && snapshot.equals(safeCommit) == false)
                 );
             }
@@ -211,7 +211,7 @@ public void testAcquireIndexCommit() throws Exception {
                 )
             );
         }
-        snapshottingCommits.forEach(indexPolicy::releaseCommit);
+        snapshottingCommits.forEach(indexPolicy::releaseIndexCommit);
         globalCheckpoint.set(randomLongBetween(lastMaxSeqNo, Long.MAX_VALUE));
         commitList.forEach(this::resetDeletion);
         indexPolicy.onCommit(commitList);
@@ -350,8 +350,8 @@ protected int getDocCountOfCommit(IndexCommit indexCommit) {
             }
 
             @Override
-            synchronized boolean releaseCommit(IndexCommit acquiredCommit) {
-                return super.releaseCommit(wrapCommit(acquiredCommit));
+            public synchronized boolean releaseIndexCommit(IndexCommit acquiredCommit) {
+                return super.releaseIndexCommit(wrapCommit(acquiredCommit));
             }
         };
 
@@ -383,7 +383,7 @@ synchronized boolean releaseCommit(IndexCommit acquiredCommit) {
         assertThat(deletedCommits, hasSize(0));
         assertThat(newCommitFiles, containsInAnyOrder(equalTo("_1.cfe"), equalTo("_1.si"), equalTo("_1.cfs"), equalTo("segments_2")));
 
-        boolean maybeCleanUpCommits = combinedDeletionPolicy.releaseCommit(commit0);
+        boolean maybeCleanUpCommits = combinedDeletionPolicy.releaseIndexCommit(commit0);
         assertThat(maybeCleanUpCommits, equalTo(true));
 
         globalCheckpoint.set(20L);
@@ -454,7 +454,7 @@ synchronized boolean releaseCommit(IndexCommit acquiredCommit) {
             )
         );
 
-        maybeCleanUpCommits = combinedDeletionPolicy.releaseCommit(commit2);
+        maybeCleanUpCommits = combinedDeletionPolicy.releaseIndexCommit(commit2);
         assertThat("No commits to clean up (commit #2 is the safe commit)", maybeCleanUpCommits, equalTo(false));
 
         globalCheckpoint.set(30L);
@@ -499,13 +499,13 @@ synchronized boolean releaseCommit(IndexCommit acquiredCommit) {
         assertThat(deletedCommits, contains(commit0, commit2));
         assertThat(newCommitFiles, containsInAnyOrder(equalTo("_4.cfe"), equalTo("_4.si"), equalTo("_4.cfs"), equalTo("segments_4")));
 
-        maybeCleanUpCommits = combinedDeletionPolicy.releaseCommit(commit3);
+        maybeCleanUpCommits = combinedDeletionPolicy.releaseIndexCommit(commit3);
         assertThat("No commits to clean up (commit #3 is the safe commit)", maybeCleanUpCommits, equalTo(false));
 
-        maybeCleanUpCommits = combinedDeletionPolicy.releaseCommit(commit4);
+        maybeCleanUpCommits = combinedDeletionPolicy.releaseIndexCommit(commit4);
         assertThat("No commits to clean up (commit #4 is the last commit)", maybeCleanUpCommits, equalTo(false));
 
-        maybeCleanUpCommits = combinedDeletionPolicy.releaseCommit(commit1);
+        maybeCleanUpCommits = combinedDeletionPolicy.releaseIndexCommit(commit1);
         assertThat(maybeCleanUpCommits, equalTo(true));
 
         final boolean globalCheckpointCatchUp = randomBoolean();
@@ -560,7 +560,7 @@ synchronized boolean releaseCommit(IndexCommit acquiredCommit) {
         }
         assertThat(newCommitFiles, containsInAnyOrder(equalTo("_5.cfe"), equalTo("_5.si"), equalTo("_5.cfs"), equalTo("segments_5")));
 
-        maybeCleanUpCommits = combinedDeletionPolicy.releaseCommit(commit5);
+        maybeCleanUpCommits = combinedDeletionPolicy.releaseIndexCommit(commit5);
         assertThat("No commits to clean up (commit #5 is the last commit)", maybeCleanUpCommits, equalTo(false));
     }