Segment Replication - Implement segment replication event cancellation. (opensearch-project#4225)

* Segment Replication.  Fix Cancellation of replication events.

This PR updates segment replication paths to correctly cancel replication events on the primary and replica.
In the source service, any ongoing event for a primary that is sending to a replica that shuts down or is promoted as a new primary are cancelled.
In the target service, any ongoing event for a replica that is promoted as a new primary or is fetching from a primary that shuts down.
It wires up SegmentReplicationSourceService as an IndexEventListener so that it can respond to events and cancel any ongoing transfer state.
This change also includes some test cleanup for segment replication to rely on actual components over mocks.

Signed-off-by: Marc Handalian <handalm@amazon.com>

Fix to not start/stop SegmentReplicationSourceService as a lifecycle component with feature flag off.

Signed-off-by: Marc Handalian <handalm@amazon.com>

Update logic to properly mark SegmentReplicationTarget as cancelled when cancel initiated by primary.

Signed-off-by: Marc Handalian <handalm@amazon.com>

Minor updates from self review.

Signed-off-by: Marc Handalian <handalm@amazon.com>

* Add missing changelog entry.

Signed-off-by: Marc Handalian <handalm@amazon.com>

Signed-off-by: Marc Handalian <handalm@amazon.com>
(cherry picked from commit 19d1a2b)

Author: mch2

CHANGELOG.md

@@ -41,6 +41,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 ### Fixed
 - PR reference to checkout code for changelog verifier ([#4296](https://github.com/opensearch-project/OpenSearch/pull/4296))
 - Restore using the class ClusterInfoRequest and ClusterInfoRequestBuilder from package 'org.opensearch.action.support.master.info' for subclasses ([#4324](https://github.com/opensearch-project/OpenSearch/pull/4324))
+- Fixed cancellation of segment replication events ([#4225](https://github.com/opensearch-project/OpenSearch/pull/4225))
 
 ### Security
 

server/src/main/java/org/opensearch/indices/cluster/IndicesClusterStateService.java

@@ -81,6 +81,7 @@
 import org.opensearch.indices.recovery.PeerRecoveryTargetService;
 import org.opensearch.indices.recovery.RecoveryListener;
 import org.opensearch.indices.recovery.RecoveryState;
+import org.opensearch.indices.replication.SegmentReplicationSourceService;
 import org.opensearch.indices.replication.SegmentReplicationTargetService;
 import org.opensearch.indices.replication.checkpoint.SegmentReplicationCheckpointPublisher;
 import org.opensearch.indices.replication.common.ReplicationState;
@@ -152,6 +153,7 @@ public IndicesClusterStateService(
         final ThreadPool threadPool,
         final PeerRecoveryTargetService recoveryTargetService,
         final SegmentReplicationTargetService segmentReplicationTargetService,
+        final SegmentReplicationSourceService segmentReplicationSourceService,
         final ShardStateAction shardStateAction,
         final NodeMappingRefreshAction nodeMappingRefreshAction,
         final RepositoriesService repositoriesService,
@@ -170,6 +172,7 @@ public IndicesClusterStateService(
             threadPool,
             checkpointPublisher,
             segmentReplicationTargetService,
+            segmentReplicationSourceService,
             recoveryTargetService,
             shardStateAction,
             nodeMappingRefreshAction,
@@ -191,6 +194,7 @@ public IndicesClusterStateService(
         final ThreadPool threadPool,
         final SegmentReplicationCheckpointPublisher checkpointPublisher,
         final SegmentReplicationTargetService segmentReplicationTargetService,
+        final SegmentReplicationSourceService segmentReplicationSourceService,
         final PeerRecoveryTargetService recoveryTargetService,
         final ShardStateAction shardStateAction,
         final NodeMappingRefreshAction nodeMappingRefreshAction,
@@ -211,6 +215,7 @@ public IndicesClusterStateService(
         // if segrep feature flag is not enabled, don't wire the target serivce as an IndexEventListener.
         if (FeatureFlags.isEnabled(FeatureFlags.REPLICATION_TYPE)) {
             indexEventListeners.add(segmentReplicationTargetService);
+            indexEventListeners.add(segmentReplicationSourceService);
         }
         this.builtInIndexListener = Collections.unmodifiableList(indexEventListeners);
         this.indicesService = indicesService;

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

@@ -37,7 +37,6 @@
  * @opensearch.internal
  */
 class OngoingSegmentReplications {
-
     private final RecoverySettings recoverySettings;
     private final IndicesService indicesService;
     private final Map<ReplicationCheckpoint, CopyState> copyStateMap;
@@ -161,14 +160,27 @@ synchronized void cancel(IndexShard shard, String reason) {
         cancelHandlers(handler -> handler.getCopyState().getShard().shardId().equals(shard.shardId()), reason);
     }
 
+    /**
+     * Cancel all Replication events for the given allocation ID, intended to be called when a primary is shutting down.
+     *
+     * @param allocationId  {@link String} - Allocation ID.
+     * @param reason {@link String} - Reason for the cancel
+     */
+    synchronized void cancel(String allocationId, String reason) {
+        final SegmentReplicationSourceHandler handler = allocationIdToHandlers.remove(allocationId);
+        if (handler != null) {
+            handler.cancel(reason);
+            removeCopyState(handler.getCopyState());
+        }
+    }
+
     /**
      * Cancel any ongoing replications for a given {@link DiscoveryNode}
      *
      * @param node {@link DiscoveryNode} node for which to cancel replication events.
      */
     void cancelReplication(DiscoveryNode node) {
         cancelHandlers(handler -> handler.getTargetNode().equals(node), "Node left");
-
     }
 
     /**
@@ -243,11 +255,7 @@ private void cancelHandlers(Predicate<? super SegmentReplicationSourceHandler> p
             .map(SegmentReplicationSourceHandler::getAllocationId)
             .collect(Collectors.toList());
         for (String allocationId : allocationIds) {
-            final SegmentReplicationSourceHandler handler = allocationIdToHandlers.remove(allocationId);
-            if (handler != null) {
-                handler.cancel(reason);
-                removeCopyState(handler.getCopyState());
-            }
+            cancel(allocationId, reason);
         }
     }
 }

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

@@ -87,4 +87,10 @@ public void getSegmentFiles(
         );
         transportClient.executeRetryableAction(GET_SEGMENT_FILES, request, responseListener, reader);
     }
+
+    @Override
+    public void cancel() {
+        transportClient.cancel();
+    }
+
 }

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

@@ -9,6 +9,7 @@
 package org.opensearch.indices.replication;
 
 import org.opensearch.action.ActionListener;
+import org.opensearch.common.util.CancellableThreads.ExecutionCancelledException;
 import org.opensearch.index.store.Store;
 import org.opensearch.index.store.StoreFileMetadata;
 import org.opensearch.indices.replication.checkpoint.ReplicationCheckpoint;
@@ -47,4 +48,9 @@ void getSegmentFiles(
         Store store,
         ActionListener<GetSegmentFilesResponse> listener
     );
+
+    /**
+     * Cancel any ongoing requests, should resolve any ongoing listeners with onFailure with a {@link ExecutionCancelledException}.
+     */
+    default void cancel() {}
 }

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

@@ -113,6 +113,16 @@ public synchronized void sendFiles(GetSegmentFilesRequest request, ActionListene
         final Closeable releaseResources = () -> IOUtils.close(resources);
         try {
             timer.start();
+            cancellableThreads.setOnCancel((reason, beforeCancelEx) -> {
+                final RuntimeException e = new CancellableThreads.ExecutionCancelledException(
+                    "replication was canceled reason [" + reason + "]"
+                );
+                if (beforeCancelEx != null) {
+                    e.addSuppressed(beforeCancelEx);
+                }
+                IOUtils.closeWhileHandlingException(releaseResources, () -> future.onFailure(e));
+                throw e;
+            });
             final Consumer<Exception> onFailure = e -> {
                 assert Transports.assertNotTransportThread(SegmentReplicationSourceHandler.this + "[onFailure]");
                 IOUtils.closeWhileHandlingException(releaseResources, () -> future.onFailure(e));
@@ -153,6 +163,7 @@ public synchronized void sendFiles(GetSegmentFilesRequest request, ActionListene
             final MultiChunkTransfer<StoreFileMetadata, SegmentFileTransferHandler.FileChunk> transfer = segmentFileTransferHandler
                 .createTransfer(shard.store(), storeFileMetadata, () -> 0, sendFileStep);
             resources.add(transfer);
+            cancellableThreads.checkForCancel();
             transfer.start();
 
             sendFileStep.whenComplete(r -> {

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

@@ -15,6 +15,7 @@
 import org.opensearch.cluster.ClusterChangedEvent;
 import org.opensearch.cluster.ClusterStateListener;
 import org.opensearch.cluster.node.DiscoveryNode;
+import org.opensearch.cluster.routing.ShardRouting;
 import org.opensearch.cluster.service.ClusterService;
 import org.opensearch.common.Nullable;
 import org.opensearch.common.component.AbstractLifecycleComponent;
@@ -42,7 +43,25 @@
  *
  * @opensearch.internal
  */
-public final class SegmentReplicationSourceService extends AbstractLifecycleComponent implements ClusterStateListener, IndexEventListener {
+public class SegmentReplicationSourceService extends AbstractLifecycleComponent implements ClusterStateListener, IndexEventListener {
+
+    // Empty Implementation, only required while Segment Replication is under feature flag.
+    public static final SegmentReplicationSourceService NO_OP = new SegmentReplicationSourceService() {
+        @Override
+        public void clusterChanged(ClusterChangedEvent event) {
+            // NoOp;
+        }
+
+        @Override
+        public void beforeIndexShardClosed(ShardId shardId, IndexShard indexShard, Settings indexSettings) {
+            // NoOp;
+        }
+
+        @Override
+        public void shardRoutingChanged(IndexShard indexShard, @Nullable ShardRouting oldRouting, ShardRouting newRouting) {
+            // NoOp;
+        }
+    };
 
     private static final Logger logger = LogManager.getLogger(SegmentReplicationSourceService.class);
     private final RecoverySettings recoverySettings;
@@ -62,6 +81,14 @@ public static class Actions {
 
     private final OngoingSegmentReplications ongoingSegmentReplications;
 
+    // Used only for empty implementation.
+    private SegmentReplicationSourceService() {
+        recoverySettings = null;
+        ongoingSegmentReplications = null;
+        transportService = null;
+        indicesService = null;
+    }
+
     public SegmentReplicationSourceService(
         IndicesService indicesService,
         TransportService transportService,
@@ -163,10 +190,25 @@ protected void doClose() throws IOException {
 
     }
 
+    /**
+     *
+     * Cancels any replications on this node to a replica shard that is about to be closed.
+     */
     @Override
     public void beforeIndexShardClosed(ShardId shardId, @Nullable IndexShard indexShard, Settings indexSettings) {
         if (indexShard != null) {
             ongoingSegmentReplications.cancel(indexShard, "shard is closed");
         }
     }
+
+    /**
+     * Cancels any replications on this node to a replica that has been promoted as primary.
+     */
+    @Override
+    public void shardRoutingChanged(IndexShard indexShard, @Nullable ShardRouting oldRouting, ShardRouting newRouting) {
+        if (indexShard != null && oldRouting.primary() == false && newRouting.primary()) {
+            ongoingSegmentReplications.cancel(indexShard.routingEntry().allocationId().getId(), "Relocating primary shard.");
+        }
+    }
+
 }

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

@@ -35,7 +35,8 @@ public enum Stage {
         GET_CHECKPOINT_INFO((byte) 3),
         FILE_DIFF((byte) 4),
         GET_FILES((byte) 5),
-        FINALIZE_REPLICATION((byte) 6);
+        FINALIZE_REPLICATION((byte) 6),
+        CANCELLED((byte) 7);
 
         private static final Stage[] STAGES = new Stage[Stage.values().length];
 
@@ -118,6 +119,10 @@ protected void validateAndSetStage(Stage expected, Stage next) {
                 "can't move replication to stage [" + next + "]. current stage: [" + stage + "] (expected [" + expected + "])"
             );
         }
+        stopTimersAndSetStage(next);
+    }
+
+    private void stopTimersAndSetStage(Stage next) {
         // save the timing data for the current step
         stageTimer.stop();
         timingData.add(new Tuple<>(stage.name(), stageTimer.time()));
@@ -155,6 +160,14 @@ public void setStage(Stage stage) {
                 overallTimer.stop();
                 timingData.add(new Tuple<>("OVERALL", overallTimer.time()));
                 break;
+            case CANCELLED:
+                if (this.stage == Stage.DONE) {
+                    throw new IllegalStateException("can't move replication to Cancelled state from Done.");
+                }
+                stopTimersAndSetStage(Stage.CANCELLED);
+                overallTimer.stop();
+                timingData.add(new Tuple<>("OVERALL", overallTimer.time()));
+                break;
             default:
                 throw new IllegalArgumentException("unknown SegmentReplicationState.Stage [" + stage + "]");
         }

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

@@ -17,6 +17,7 @@
 import org.apache.lucene.store.ByteBuffersDataInput;
 import org.apache.lucene.store.ByteBuffersIndexInput;
 import org.apache.lucene.store.ChecksumIndexInput;
+import org.opensearch.ExceptionsHelper;
 import org.opensearch.OpenSearchException;
 import org.opensearch.action.ActionListener;
 import org.opensearch.action.StepListener;
@@ -103,7 +104,15 @@ public String description() {
 
     @Override
     public void notifyListener(OpenSearchException e, boolean sendShardFailure) {
-        listener.onFailure(state(), e, sendShardFailure);
+        // Cancellations still are passed to our SegmentReplicationListner as failures, if we have failed because of cancellation
+        // update the stage.
+        final Throwable cancelledException = ExceptionsHelper.unwrap(e, CancellableThreads.ExecutionCancelledException.class);
+        if (cancelledException != null) {
+            state.setStage(SegmentReplicationState.Stage.CANCELLED);
+            listener.onFailure(state(), (CancellableThreads.ExecutionCancelledException) cancelledException, sendShardFailure);
+        } else {
+            listener.onFailure(state(), e, sendShardFailure);
+        }
     }
 
     @Override
@@ -134,13 +143,22 @@ public void writeFileChunk(
      * @param listener {@link ActionListener} listener.
      */
     public void startReplication(ActionListener<Void> listener) {
+        cancellableThreads.setOnCancel((reason, beforeCancelEx) -> {
+            // This method only executes when cancellation is triggered by this node and caught by a call to checkForCancel,
+            // SegmentReplicationSource does not share CancellableThreads.
+            final CancellableThreads.ExecutionCancelledException executionCancelledException =
+                new CancellableThreads.ExecutionCancelledException("replication was canceled reason [" + reason + "]");
+            notifyListener(executionCancelledException, false);
+            throw executionCancelledException;
+        });
         state.setStage(SegmentReplicationState.Stage.REPLICATING);
         final StepListener<CheckpointInfoResponse> checkpointInfoListener = new StepListener<>();
         final StepListener<GetSegmentFilesResponse> getFilesListener = new StepListener<>();
         final StepListener<Void> finalizeListener = new StepListener<>();
 
         logger.trace("[shardId {}] Replica starting replication [id {}]", shardId().getId(), getId());
         // Get list of files to copy from this checkpoint.
+        cancellableThreads.checkForCancel();
         state.setStage(SegmentReplicationState.Stage.GET_CHECKPOINT_INFO);
         source.getCheckpointMetadata(getId(), checkpoint, checkpointInfoListener);
 
@@ -154,6 +172,7 @@ public void startReplication(ActionListener<Void> listener) {
 
     private void getFiles(CheckpointInfoResponse checkpointInfo, StepListener<GetSegmentFilesResponse> getFilesListener)
         throws IOException {
+        cancellableThreads.checkForCancel();
         state.setStage(SegmentReplicationState.Stage.FILE_DIFF);
         final Store.MetadataSnapshot snapshot = checkpointInfo.getSnapshot();
         Store.MetadataSnapshot localMetadata = getMetadataSnapshot();
@@ -188,12 +207,14 @@ private void getFiles(CheckpointInfoResponse checkpointInfo, StepListener<GetSeg
         }
         // always send a req even if not fetching files so the primary can clear the copyState for this shard.
         state.setStage(SegmentReplicationState.Stage.GET_FILES);
+        cancellableThreads.checkForCancel();
         source.getSegmentFiles(getId(), checkpointInfo.getCheckpoint(), filesToFetch, store, getFilesListener);
     }
 
     private void finalizeReplication(CheckpointInfoResponse checkpointInfoResponse, ActionListener<Void> listener) {
-        state.setStage(SegmentReplicationState.Stage.FINALIZE_REPLICATION);
         ActionListener.completeWith(listener, () -> {
+            cancellableThreads.checkForCancel();
+            state.setStage(SegmentReplicationState.Stage.FINALIZE_REPLICATION);
             multiFileWriter.renameAllTempFiles();
             final Store store = store();
             store.incRef();
@@ -261,4 +282,10 @@ Store.MetadataSnapshot getMetadataSnapshot() throws IOException {
         }
         return store.getMetadata(indexShard.getSegmentInfosSnapshot().get());
     }
+
+    @Override
+    protected void onCancel(String reason) {
+        cancellableThreads.cancel(reason);
+        source.cancel();
+    }
 }