Addressing PR comments

Signed-off-by: Ankit Kala <[email protected]>

Author: ankitkala

CHANGELOG.md

@@ -29,6 +29,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Plugin ZIP publication groupId value is configurable ([#4156](https://github.com/opensearch-project/OpenSearch/pull/4156))
 - Add index specific setting for remote repository ([#4253](https://github.com/opensearch-project/OpenSearch/pull/4253))
 - [Segment Replication] Update replicas to commit SegmentInfos instead of relying on SIS files from primary shards. ([#4402](https://github.com/opensearch-project/OpenSearch/pull/4402))
+- [CCR] Add getHistoryOperationsFromTranslog method to fetch the history snapshot from translogs ([#3948](https://github.com/opensearch-project/OpenSearch/pull/3948))
 
 ### Deprecated
 
@@ -78,4 +79,4 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 
 
 [Unreleased]: https://github.com/opensearch-project/OpenSearch/compare/2.2.0...HEAD
-[2.x]: https://github.com/opensearch-project/OpenSearch/compare/2.2.0...2.x
+[2.x]: https://github.com/opensearch-project/OpenSearch/compare/2.2.0...2.x

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

@@ -2360,10 +2360,12 @@ public Translog.Snapshot getHistoryOperations(String reason, long startingSeqNo,
     /**
      * Creates a new history snapshot from the translog instead of the lucene index. Required for cross cluster replication.
      * Use the recommended {@link #getHistoryOperations(String, long, long, boolean)} method for other cases.
-     * Depending on how translog durability is configured, this method might/might not return the snapshot. For e.g,
-     * If the translog has been configured with no-durability, it'll return UnsupportedOperationException.
+     * This method should only be invoked if Segment Replication or Remote Store is not enabled.
      */
     public Translog.Snapshot getHistoryOperationsFromTranslog(long startingSeqNo, long endSeqNo) throws IOException {
+        if (indexSettings.isSegRepEnabled() || indexSettings.isRemoteStoreEnabled()) {
+            throw new AssertionError("unsupported operation for segment replication enabled indices or remote store backed indices");
+        }
         return getEngine().translogManager().newChangesSnapshot(startingSeqNo, endSeqNo, true);
     }
 

server/src/test/java/org/opensearch/index/shard/IndexShardTests.java

@@ -1196,6 +1196,66 @@ public void testAcquireReplicaPermitAdvanceMaxSeqNoOfUpdates() throws Exception
         closeShards(replica);
     }
 
+    public void testGetChangesSnapshotThrowsAssertForSegRep() throws IOException {
+        final ShardId shardId = new ShardId("index", "_na_", 0);
+        final ShardRouting shardRouting = TestShardRouting.newShardRouting(
+            shardId,
+            randomAlphaOfLength(8),
+            true,
+            ShardRoutingState.INITIALIZING,
+            RecoverySource.EmptyStoreRecoverySource.INSTANCE
+        );
+        final Settings settings = Settings.builder()
+            .put(IndexMetadata.SETTING_VERSION_CREATED, Version.CURRENT)
+            .put(IndexMetadata.SETTING_NUMBER_OF_REPLICAS, 2)
+            .put(IndexMetadata.SETTING_NUMBER_OF_SHARDS, 1)
+            .put(IndexMetadata.SETTING_REPLICATION_TYPE, ReplicationType.SEGMENT.toString())
+            .build();
+        final IndexMetadata.Builder indexMetadata = IndexMetadata.builder(shardRouting.getIndexName()).settings(settings).primaryTerm(0, 1);
+        final AtomicBoolean synced = new AtomicBoolean();
+        final IndexShard primaryShard = newShard(
+            shardRouting,
+            indexMetadata.build(),
+            null,
+            new InternalEngineFactory(),
+            () -> synced.set(true),
+            RetentionLeaseSyncer.EMPTY,
+            null
+        );
+        expectThrows(AssertionError.class, () -> primaryShard.getHistoryOperationsFromTranslog(0, 1));
+        closeShard(primaryShard, false);
+    }
+
+    public void testGetChangesSnapshotThrowsAssertForRemoteStore() throws IOException {
+        final ShardId shardId = new ShardId("index", "_na_", 0);
+        final ShardRouting shardRouting = TestShardRouting.newShardRouting(
+            shardId,
+            randomAlphaOfLength(8),
+            true,
+            ShardRoutingState.INITIALIZING,
+            RecoverySource.EmptyStoreRecoverySource.INSTANCE
+        );
+        final Settings settings = Settings.builder()
+            .put(IndexMetadata.SETTING_VERSION_CREATED, Version.CURRENT)
+            .put(IndexMetadata.SETTING_NUMBER_OF_REPLICAS, 2)
+            .put(IndexMetadata.SETTING_NUMBER_OF_SHARDS, 1)
+            .put(IndexMetadata.SETTING_REMOTE_STORE_ENABLED, true)
+            .build();
+        final IndexMetadata.Builder indexMetadata = IndexMetadata.builder(shardRouting.getIndexName()).settings(settings).primaryTerm(0, 1);
+        final AtomicBoolean synced = new AtomicBoolean();
+        final IndexShard primaryShard = newShard(
+            shardRouting,
+            indexMetadata.build(),
+            null,
+            new InternalEngineFactory(),
+            () -> synced.set(true),
+            RetentionLeaseSyncer.EMPTY,
+            null
+        );
+        expectThrows(AssertionError.class, () -> primaryShard.getHistoryOperationsFromTranslog(0, 1));
+        closeShard(primaryShard, false);
+    }
+
     public void testGlobalCheckpointSync() throws IOException {
         // create the primary shard with a callback that sets a boolean when the global checkpoint sync is invoked
         final ShardId shardId = new ShardId("index", "_na_", 0);