[Backport 2.x] [Remote Migration] Make remote seeding a low priority upload

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

@@ -459,8 +459,8 @@ private void uploadNewSegments(
         }
     }
 
-    private boolean isLowPriorityUpload() {
-        return isLocalOrSnapshotRecovery();
+    boolean isLowPriorityUpload() {
+        return isLocalOrSnapshotRecoveryOrSeeding();
     }
 
     /**
@@ -550,7 +550,7 @@ private void initializeRemoteDirectoryOnTermUpdate() throws IOException {
      * @return true iff the shard is a started with primary mode true or it is local or snapshot recovery.
      */
     private boolean isReadyForUpload() {
-        boolean isReady = indexShard.isStartedPrimary() || isLocalOrSnapshotRecovery() || indexShard.shouldSeedRemoteStore();
+        boolean isReady = indexShard.isStartedPrimary() || isLocalOrSnapshotRecoveryOrSeeding();
 
         if (isReady == false) {
             StringBuilder sb = new StringBuilder("Skipped syncing segments with");
@@ -572,14 +572,15 @@ private boolean isReadyForUpload() {
         return isReady;
     }
 
-    private boolean isLocalOrSnapshotRecovery() {
+    boolean isLocalOrSnapshotRecoveryOrSeeding() {
         // In this case when the primary mode is false, we need to upload segments to Remote Store
-        // This is required in case of snapshots/shrink/ split/clone where we need to durable persist
+        // This is required in case of remote migration seeding/snapshots/shrink/ split/clone where we need to durable persist
         // all segments to remote before completing the recovery to ensure durability.
         return (indexShard.state() == IndexShardState.RECOVERING && indexShard.shardRouting.primary())
             && indexShard.recoveryState() != null
             && (indexShard.recoveryState().getRecoverySource().getType() == RecoverySource.Type.LOCAL_SHARDS
-                || indexShard.recoveryState().getRecoverySource().getType() == RecoverySource.Type.SNAPSHOT);
+                || indexShard.recoveryState().getRecoverySource().getType() == RecoverySource.Type.SNAPSHOT
+                || indexShard.shouldSeedRemoteStore());
     }
 
     /**

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

@@ -16,6 +16,7 @@
 import org.apache.lucene.tests.store.BaseDirectoryWrapper;
 import org.opensearch.cluster.metadata.IndexMetadata;
 import org.opensearch.cluster.routing.IndexShardRoutingTable;
+import org.opensearch.cluster.routing.RecoverySource;
 import org.opensearch.cluster.routing.ShardRouting;
 import org.opensearch.cluster.service.ClusterService;
 import org.opensearch.common.collect.Tuple;
@@ -37,6 +38,7 @@
 import org.opensearch.index.store.lockmanager.RemoteStoreLockManager;
 import org.opensearch.indices.DefaultRemoteStoreSettings;
 import org.opensearch.indices.RemoteStoreSettings;
+import org.opensearch.indices.recovery.RecoveryState;
 import org.opensearch.indices.replication.checkpoint.SegmentReplicationCheckpointPublisher;
 import org.opensearch.indices.replication.common.ReplicationType;
 import org.opensearch.threadpool.ThreadPool;
@@ -125,6 +127,52 @@ public void tearDown() throws Exception {
         super.tearDown();
     }
 
+    public void testIsLowPriorityUpload() throws IOException {
+        setup(true, 3);
+
+        // Mocking the IndexShard methods and dependent classes.
+        IndexShard shard = mock(IndexShard.class);
+        Store store = mock(Store.class);
+        ShardId shardId = new ShardId("index1", "_na_", 1);
+        ShardRouting shardRouting = mock(ShardRouting.class);
+        shard.shardRouting = shardRouting;
+        when(shard.shouldSeedRemoteStore()).thenReturn(true);
+        when(shard.state()).thenReturn(IndexShardState.RECOVERING);
+        when(shardRouting.primary()).thenReturn(true);
+        when(shard.shardId()).thenReturn(shardId);
+        when(shard.store()).thenReturn(store);
+        when(shard.routingEntry()).thenReturn(shardRouting);
+        when(shard.getThreadPool()).thenReturn(mock(ThreadPool.class));
+        RecoveryState recoveryState = mock(RecoveryState.class);
+        when(recoveryState.getRecoverySource()).thenReturn(RecoverySource.PeerRecoverySource.INSTANCE);
+        when(shard.recoveryState()).thenReturn(recoveryState);
+
+        // Mock the Store, Directory and RemoteSegmentStoreDirectory classes
+        Store remoteStore = mock(Store.class);
+        when(shard.remoteStore()).thenReturn(remoteStore);
+        RemoteDirectory remoteMetadataDirectory = mock(RemoteDirectory.class);
+        RemoteSegmentStoreDirectory remoteSegmentStoreDirectory = new RemoteSegmentStoreDirectory(
+            mock(RemoteDirectory.class),
+            remoteMetadataDirectory,
+            mock(RemoteStoreLockManager.class),
+            mock(ThreadPool.class),
+            shardId
+        );
+        FilterDirectory remoteStoreFilterDirectory = new RemoteStoreRefreshListenerTests.TestFilterDirectory(
+            new RemoteStoreRefreshListenerTests.TestFilterDirectory(remoteSegmentStoreDirectory)
+        );
+        when(remoteStore.directory()).thenReturn(remoteStoreFilterDirectory);
+
+        RemoteStoreRefreshListener remoteStoreRefreshListener = new RemoteStoreRefreshListener(
+            shard,
+            SegmentReplicationCheckpointPublisher.EMPTY,
+            mock(RemoteSegmentTransferTracker.class),
+            DefaultRemoteStoreSettings.INSTANCE
+        );
+        assertTrue(remoteStoreRefreshListener.isLocalOrSnapshotRecoveryOrSeeding());
+        assertTrue(remoteStoreRefreshListener.isLowPriorityUpload());
+    }
+
     public void testRemoteDirectoryInitThrowsException() throws IOException {
         // Methods used in the constructor of RemoteSegmentTrackerListener have been mocked to reproduce specific exceptions
         // to test the failure modes possible during construction of RemoteSegmentTrackerListener object.