[Backport 2.x] Make RemoteStoreReplicationSource#getSegmentFiles asynchronous

server/src/internalClusterTest/java/org/opensearch/remotestore/AbstractRemoteStoreMockRepositoryIntegTestCase.java

@@ -114,6 +114,10 @@ protected void cleanupRepo() {
     }
 
     protected String setup(Path repoLocation, double ioFailureRate, String skipExceptionBlobList, long maxFailure) {
+        return setup(repoLocation, ioFailureRate, skipExceptionBlobList, maxFailure, 0);
+    }
+
+    protected String setup(Path repoLocation, double ioFailureRate, String skipExceptionBlobList, long maxFailure, int replicaCount) {
         // The random_control_io_exception_rate setting ensures that 10-25% of all operations to remote store results in
         /// IOException. skip_exception_on_verification_file & skip_exception_on_list_blobs settings ensures that the
         // repository creation can happen without failure.
@@ -128,6 +132,7 @@ protected String setup(Path repoLocation, double ioFailureRate, String skipExcep
 
         internalCluster().startClusterManagerOnlyNode(settings.build());
         String dataNodeName = internalCluster().startDataOnlyNode(settings.build());
+        internalCluster().startDataOnlyNodes(replicaCount, settings.build());
         createIndex(INDEX_NAME);
         logger.info("--> Created index={}", INDEX_NAME);
         ensureYellowAndNoInitializingShards(INDEX_NAME);

server/src/internalClusterTest/java/org/opensearch/remotestore/SegmentReplicationUsingRemoteStoreDisruptionIT.java

@@ -0,0 +1,133 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.remotestore;
+
+import org.opensearch.common.settings.Settings;
+import org.opensearch.common.unit.TimeValue;
+import org.opensearch.core.index.Index;
+import org.opensearch.index.IndexService;
+import org.opensearch.index.shard.IndexShard;
+import org.opensearch.indices.IndicesService;
+import org.opensearch.indices.replication.SegmentReplicationState;
+import org.opensearch.indices.replication.SegmentReplicationTarget;
+import org.opensearch.indices.replication.SegmentReplicationTargetService;
+import org.opensearch.indices.replication.common.ReplicationCollection;
+import org.opensearch.test.InternalTestCluster;
+import org.opensearch.test.OpenSearchIntegTestCase;
+
+import java.nio.file.Path;
+import java.util.Optional;
+import java.util.Set;
+
+/**
+ * This class runs tests with remote store + segRep while blocking file downloads
+ */
+@OpenSearchIntegTestCase.ClusterScope(scope = OpenSearchIntegTestCase.Scope.TEST, numDataNodes = 0)
+public class SegmentReplicationUsingRemoteStoreDisruptionIT extends AbstractRemoteStoreMockRepositoryIntegTestCase {
+
+    @Override
+    public Settings indexSettings() {
+        return remoteStoreIndexSettings(1);
+    }
+
+    @Override
+    protected boolean addMockInternalEngine() {
+        return false;
+    }
+
+    public void testCancelReplicationWhileSyncingSegments() throws Exception {
+        Path location = randomRepoPath().toAbsolutePath();
+        setup(location, 0d, "metadata", Long.MAX_VALUE, 1);
+
+        final Set<String> dataNodeNames = internalCluster().getDataNodeNames();
+        final String replicaNode = getNode(dataNodeNames, false);
+        final String primaryNode = getNode(dataNodeNames, true);
+
+        SegmentReplicationTargetService targetService = internalCluster().getInstance(SegmentReplicationTargetService.class, replicaNode);
+        ensureGreen(INDEX_NAME);
+        blockNodeOnAnySegmentFile(REPOSITORY_NAME, replicaNode);
+        final IndexShard indexShard = getIndexShard(replicaNode, INDEX_NAME);
+        indexSingleDoc();
+        refresh(INDEX_NAME);
+        waitForBlock(replicaNode, REPOSITORY_NAME, TimeValue.timeValueSeconds(10));
+        final SegmentReplicationState state = targetService.getOngoingEventSegmentReplicationState(indexShard.shardId());
+        assertEquals(SegmentReplicationState.Stage.GET_FILES, state.getStage());
+        ReplicationCollection.ReplicationRef<SegmentReplicationTarget> segmentReplicationTargetReplicationRef = targetService.get(
+            state.getReplicationId()
+        );
+        final SegmentReplicationTarget segmentReplicationTarget = segmentReplicationTargetReplicationRef.get();
+        // close the target ref here otherwise it will hold a refcount
+        segmentReplicationTargetReplicationRef.close();
+        assertNotNull(segmentReplicationTarget);
+        assertTrue(segmentReplicationTarget.refCount() > 0);
+        internalCluster().stopRandomNode(InternalTestCluster.nameFilter(primaryNode));
+        assertBusy(() -> {
+            assertTrue(indexShard.routingEntry().primary());
+            assertNull(targetService.getOngoingEventSegmentReplicationState(indexShard.shardId()));
+            assertEquals("Target should be closed", 0, segmentReplicationTarget.refCount());
+        });
+        unblockNode(REPOSITORY_NAME, replicaNode);
+        cleanupRepo();
+    }
+
+    public void testCancelReplicationWhileFetchingMetadata() throws Exception {
+        Path location = randomRepoPath().toAbsolutePath();
+        setup(location, 0d, "metadata", Long.MAX_VALUE, 1);
+
+        final Set<String> dataNodeNames = internalCluster().getDataNodeNames();
+        final String replicaNode = getNode(dataNodeNames, false);
+        final String primaryNode = getNode(dataNodeNames, true);
+
+        SegmentReplicationTargetService targetService = internalCluster().getInstance(SegmentReplicationTargetService.class, replicaNode);
+        ensureGreen(INDEX_NAME);
+        blockNodeOnAnyFiles(REPOSITORY_NAME, replicaNode);
+        final IndexShard indexShard = getIndexShard(replicaNode, INDEX_NAME);
+        indexSingleDoc();
+        refresh(INDEX_NAME);
+        waitForBlock(replicaNode, REPOSITORY_NAME, TimeValue.timeValueSeconds(10));
+        final SegmentReplicationState state = targetService.getOngoingEventSegmentReplicationState(indexShard.shardId());
+        assertEquals(SegmentReplicationState.Stage.GET_CHECKPOINT_INFO, state.getStage());
+        ReplicationCollection.ReplicationRef<SegmentReplicationTarget> segmentReplicationTargetReplicationRef = targetService.get(
+            state.getReplicationId()
+        );
+        final SegmentReplicationTarget segmentReplicationTarget = segmentReplicationTargetReplicationRef.get();
+        // close the target ref here otherwise it will hold a refcount
+        segmentReplicationTargetReplicationRef.close();
+        assertNotNull(segmentReplicationTarget);
+        assertTrue(segmentReplicationTarget.refCount() > 0);
+        internalCluster().stopRandomNode(InternalTestCluster.nameFilter(primaryNode));
+        assertBusy(() -> {
+            assertTrue(indexShard.routingEntry().primary());
+            assertNull(targetService.getOngoingEventSegmentReplicationState(indexShard.shardId()));
+            assertEquals("Target should be closed", 0, segmentReplicationTarget.refCount());
+        });
+        unblockNode(REPOSITORY_NAME, replicaNode);
+        cleanupRepo();
+    }
+
+    private String getNode(Set<String> dataNodeNames, boolean primary) {
+        assertEquals(2, dataNodeNames.size());
+        for (String name : dataNodeNames) {
+            final IndexShard indexShard = getIndexShard(name, INDEX_NAME);
+            if (indexShard.routingEntry().primary() == primary) {
+                return name;
+            }
+        }
+        return null;
+    }
+
+    private IndexShard getIndexShard(String node, String indexName) {
+        final Index index = resolveIndex(indexName);
+        IndicesService indicesService = internalCluster().getInstance(IndicesService.class, node);
+        IndexService indexService = indicesService.indexService(index);
+        assertNotNull(indexService);
+        final Optional<Integer> shardId = indexService.shardIds().stream().findFirst();
+        return shardId.map(indexService::getShard).orElse(null);
+    }
+}

server/src/main/java/org/opensearch/index/store/RemoteStoreFileDownloader.java

@@ -16,7 +16,7 @@
 import org.opensearch.common.Nullable;
 import org.opensearch.common.annotation.InternalApi;
 import org.opensearch.common.logging.Loggers;
-import org.opensearch.common.util.concurrent.UncategorizedExecutionException;
+import org.opensearch.common.util.CancellableThreads;
 import org.opensearch.core.action.ActionListener;
 import org.opensearch.core.index.shard.ShardId;
 import org.opensearch.indices.recovery.RecoverySettings;
@@ -51,9 +51,16 @@ public RemoteStoreFileDownloader(ShardId shardId, ThreadPool threadPool, Recover
      * @param source The remote directory to copy segment files from
      * @param destination The local directory to copy segment files to
      * @param toDownloadSegments The list of segment files to download
+     * @param listener Callback listener to be notified upon completion
      */
-    public void download(Directory source, Directory destination, Collection<String> toDownloadSegments) throws IOException {
-        downloadInternal(source, destination, null, toDownloadSegments, () -> {});
+    public void downloadAsync(
+        CancellableThreads cancellableThreads,
+        Directory source,
+        Directory destination,
+        Collection<String> toDownloadSegments,
+        ActionListener<Void> listener
+    ) {
+        downloadInternal(cancellableThreads, source, destination, null, toDownloadSegments, () -> {}, listener);
     }
 
     /**
@@ -74,17 +81,37 @@ public void download(
         Directory secondDestination,
         Collection<String> toDownloadSegments,
         Runnable onFileCompletion
-    ) throws IOException {
-        downloadInternal(source, destination, secondDestination, toDownloadSegments, onFileCompletion);
+    ) throws InterruptedException, IOException {
+        final CancellableThreads cancellableThreads = new CancellableThreads();
+        final PlainActionFuture<Void> listener = PlainActionFuture.newFuture();
+        downloadInternal(cancellableThreads, source, destination, secondDestination, toDownloadSegments, onFileCompletion, listener);
+        try {
+            listener.get();
+        } catch (ExecutionException e) {
+            if (e.getCause() instanceof RuntimeException) {
+                throw (RuntimeException) e.getCause();
+            } else if (e.getCause() instanceof IOException) {
+                throw (IOException) e.getCause();
+            }
+            throw new RuntimeException(e);
+        } catch (InterruptedException e) {
+            // If the blocking call on the PlainActionFuture itself is interrupted, then we must
+            // cancel the asynchronous work we were waiting on
+            cancellableThreads.cancel(e.getMessage());
+            Thread.currentThread().interrupt();
+            throw e;
+        }
     }
 
     private void downloadInternal(
+        CancellableThreads cancellableThreads,
         Directory source,
         Directory destination,
         @Nullable Directory secondDestination,
         Collection<String> toDownloadSegments,
-        Runnable onFileCompletion
-    ) throws IOException {
+        Runnable onFileCompletion,
+        ActionListener<Void> listener
+    ) {
         final Queue<String> queue = new ConcurrentLinkedQueue<>(toDownloadSegments);
         // Choose the minimum of:
         // - number of files to download
@@ -95,25 +122,14 @@ private void downloadInternal(
             Math.min(threadPool.info(ThreadPool.Names.REMOTE_RECOVERY).getMax(), recoverySettings.getMaxConcurrentRemoteStoreStreams())
         );
         logger.trace("Starting download of {} files with {} threads", queue.size(), threads);
-        final PlainActionFuture<Collection<Void>> listener = PlainActionFuture.newFuture();
-        final ActionListener<Void> allFilesListener = new GroupedActionListener<>(listener, threads);
+        final ActionListener<Void> allFilesListener = new GroupedActionListener<>(ActionListener.map(listener, r -> null), threads);
         for (int i = 0; i < threads; i++) {
-            copyOneFile(source, destination, secondDestination, queue, onFileCompletion, allFilesListener);
-        }
-        try {
-            listener.actionGet();
-        } catch (UncategorizedExecutionException e) {
-            // Any IOException will be double-wrapped so dig it out and throw it
-            if (e.getCause() instanceof ExecutionException) {
-                if (e.getCause().getCause() instanceof IOException) {
-                    throw (IOException) e.getCause().getCause();
-                }
-            }
-            throw e;
+            copyOneFile(cancellableThreads, source, destination, secondDestination, queue, onFileCompletion, allFilesListener);
         }
     }
 
     private void copyOneFile(
+        CancellableThreads cancellableThreads,
         Directory source,
         Directory destination,
         @Nullable Directory secondDestination,
@@ -129,18 +145,20 @@ private void copyOneFile(
             threadPool.executor(ThreadPool.Names.REMOTE_RECOVERY).submit(() -> {
                 logger.trace("Downloading file {}", file);
                 try {
-                    destination.copyFrom(source, file, file, IOContext.DEFAULT);
-                    onFileCompletion.run();
-                    if (secondDestination != null) {
-                        secondDestination.copyFrom(destination, file, file, IOContext.DEFAULT);
-                    }
+                    cancellableThreads.executeIO(() -> {
+                        destination.copyFrom(source, file, file, IOContext.DEFAULT);
+                        onFileCompletion.run();
+                        if (secondDestination != null) {
+                            secondDestination.copyFrom(destination, file, file, IOContext.DEFAULT);
+                        }
+                    });
                 } catch (Exception e) {
                     // Clear the queue to stop any future processing, report the failure, then return
                     queue.clear();
                     listener.onFailure(e);
                     return;
                 }
-                copyOneFile(source, destination, secondDestination, queue, onFileCompletion, listener);
+                copyOneFile(cancellableThreads, source, destination, secondDestination, queue, onFileCompletion, listener);
             });
         }
     }

server/src/main/java/org/opensearch/indices/replication/RemoteStoreReplicationSource.java

@@ -15,6 +15,7 @@
 import org.apache.lucene.store.FilterDirectory;
 import org.apache.lucene.util.Version;
 import org.opensearch.common.concurrent.GatedCloseable;
+import org.opensearch.common.util.CancellableThreads;
 import org.opensearch.core.action.ActionListener;
 import org.opensearch.index.shard.IndexShard;
 import org.opensearch.index.shard.IndexShardState;
@@ -24,11 +25,14 @@
 import org.opensearch.index.store.remote.metadata.RemoteSegmentMetadata;
 import org.opensearch.indices.replication.checkpoint.ReplicationCheckpoint;
 
+import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.BiConsumer;
 import java.util.stream.Collectors;
 
@@ -43,6 +47,7 @@ public class RemoteStoreReplicationSource implements SegmentReplicationSource {
 
     private final IndexShard indexShard;
     private final RemoteSegmentStoreDirectory remoteDirectory;
+    private final CancellableThreads cancellableThreads = new CancellableThreads();
 
     public RemoteStoreReplicationSource(IndexShard indexShard) {
         this.indexShard = indexShard;
@@ -61,7 +66,7 @@ public void getCheckpointMetadata(
         // TODO: Need to figure out a way to pass this information for segment metadata via remote store.
         try (final GatedCloseable<SegmentInfos> segmentInfosSnapshot = indexShard.getSegmentInfosSnapshot()) {
             final Version version = segmentInfosSnapshot.get().getCommitLuceneVersion();
-            RemoteSegmentMetadata mdFile = remoteDirectory.init();
+            final RemoteSegmentMetadata mdFile = getRemoteSegmentMetadata();
             // During initial recovery flow, the remote store might not
             // have metadata as primary hasn't uploaded anything yet.
             if (mdFile == null && indexShard.state().equals(IndexShardState.STARTED) == false) {
@@ -106,39 +111,50 @@ public void getSegmentFiles(
             }
             logger.debug("Downloading segment files from remote store {}", filesToFetch);
 
-            RemoteSegmentMetadata remoteSegmentMetadata = remoteDirectory.readLatestMetadataFile();
-            Collection<String> directoryFiles = List.of(indexShard.store().directory().listAll());
-            if (remoteSegmentMetadata != null) {
-                try {
-                    indexShard.store().incRef();
-                    indexShard.remoteStore().incRef();
-                    final Directory storeDirectory = indexShard.store().directory();
-                    final List<String> toDownloadSegmentNames = new ArrayList<>();
-                    for (StoreFileMetadata fileMetadata : filesToFetch) {
-                        String file = fileMetadata.name();
-                        assert directoryFiles.contains(file) == false : "Local store already contains the file " + file;
-                        toDownloadSegmentNames.add(file);
-                    }
-                    indexShard.getFileDownloader()
-                        .download(
-                            remoteDirectory,
-                            new ReplicationStatsDirectoryWrapper(storeDirectory, fileProgressTracker),
-                            toDownloadSegmentNames
-                        );
-                    logger.debug("Downloaded segment files from remote store {}", filesToFetch);
-                } finally {
-                    indexShard.store().decRef();
-                    indexShard.remoteStore().decRef();
+            if (remoteMetadataExists()) {
+                final Directory storeDirectory = indexShard.store().directory();
+                final Collection<String> directoryFiles = List.of(storeDirectory.listAll());
+                final List<String> toDownloadSegmentNames = new ArrayList<>();
+                for (StoreFileMetadata fileMetadata : filesToFetch) {
+                    String file = fileMetadata.name();
+                    assert directoryFiles.contains(file) == false : "Local store already contains the file " + file;
+                    toDownloadSegmentNames.add(file);
                 }
+                indexShard.getFileDownloader()
+                    .downloadAsync(
+                        cancellableThreads,
+                        remoteDirectory,
+                        new ReplicationStatsDirectoryWrapper(storeDirectory, fileProgressTracker),
+                        toDownloadSegmentNames,
+                        ActionListener.map(listener, r -> new GetSegmentFilesResponse(filesToFetch))
+                    );
+            } else {
+                listener.onResponse(new GetSegmentFilesResponse(filesToFetch));
             }
-            listener.onResponse(new GetSegmentFilesResponse(filesToFetch));
-        } catch (Exception e) {
+        } catch (IOException | RuntimeException e) {
             listener.onFailure(e);
         }
     }
 
+    @Override
+    public void cancel() {
+        this.cancellableThreads.cancel("Canceled by target");
+    }
+
     @Override
     public String getDescription() {
         return "RemoteStoreReplicationSource";
     }
+
+    private boolean remoteMetadataExists() throws IOException {
+        final AtomicBoolean metadataExists = new AtomicBoolean(false);
+        cancellableThreads.executeIO(() -> metadataExists.set(remoteDirectory.readLatestMetadataFile() != null));
+        return metadataExists.get();
+    }
+
+    private RemoteSegmentMetadata getRemoteSegmentMetadata() throws IOException {
+        AtomicReference<RemoteSegmentMetadata> mdFile = new AtomicReference<>();
+        cancellableThreads.executeIO(() -> mdFile.set(remoteDirectory.init()));
+        return mdFile.get();
+    }
 }