[Segment Replication] Override segment replication handler for duplicate request from replica (opensearch-project#6693) (opensearch-project#6699)

* [Segment Replication] Override segment replication handler for new request from same replica



* Spotless and use map.compute



---------


(cherry picked from commit 6bbe31a)

Signed-off-by: Suraj Singh <surajrider@gmail.com>
Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: opensearch-trigger-bot[bot]

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

@@ -147,16 +147,13 @@ void startSegmentCopy(GetSegmentFilesRequest request, ActionListener<GetSegmentF
      */
     CopyState prepareForReplication(CheckpointInfoRequest request, FileChunkWriter fileChunkWriter) throws IOException {
         final CopyState copyState = getCachedCopyState(request.getCheckpoint());
-        if (allocationIdToHandlers.putIfAbsent(
-            request.getTargetAllocationId(),
-            createTargetHandler(request.getTargetNode(), copyState, request.getTargetAllocationId(), fileChunkWriter)
-        ) != null) {
-            throw new OpenSearchException(
-                "Shard copy {} on node {} already replicating",
-                request.getCheckpoint().getShardId(),
-                request.getTargetNode()
-            );
-        }
+        allocationIdToHandlers.compute(request.getTargetAllocationId(), (allocationId, segrepHandler) -> {
+            if (segrepHandler != null) {
+                logger.warn("Override handler for allocation id {}", request.getTargetAllocationId());
+                cancelHandlers(handler -> handler.getAllocationId().equals(request.getTargetAllocationId()), "cancel due to retry");
+            }
+            return createTargetHandler(request.getTargetNode(), copyState, request.getTargetAllocationId(), fileChunkWriter);
+        });
         return copyState;
     }
 

server/src/test/java/org/opensearch/indices/replication/OngoingSegmentReplicationsTests.java

@@ -9,7 +9,6 @@
 package org.opensearch.indices.replication;
 
 import org.junit.Assert;
-import org.opensearch.OpenSearchException;
 import org.opensearch.action.ActionListener;
 import org.opensearch.cluster.metadata.IndexMetadata;
 import org.opensearch.cluster.node.DiscoveryNode;
@@ -277,7 +276,8 @@ public void testShardAlreadyReplicatingToNode() throws IOException {
             listener.onResponse(null);
         };
         replications.prepareForReplication(request, segmentSegmentFileChunkWriter);
-        assertThrows(OpenSearchException.class, () -> { replications.prepareForReplication(request, segmentSegmentFileChunkWriter); });
+        CopyState copyState = replications.prepareForReplication(request, segmentSegmentFileChunkWriter);
+        assertEquals(1, copyState.refCount());
     }
 
     public void testStartReplicationWithNoFilesToFetch() throws IOException {