Address feedback

Author: lkts

server/src/main/java/org/elasticsearch/cluster/routing/ExpectedShardSizeEstimator.java

@@ -58,7 +58,7 @@ public static boolean shouldReserveSpaceForInitializingShard(ShardRouting shard,
             // shrink/split/clone operation is going to clone existing locally placed shards using file system hard links
             // so no additional space is going to be used until future merges
             case LOCAL_SHARDS -> false;
-            case RESHARD_SPLIT_TARGET -> false;
+            case RESHARD_SPLIT -> false;
         };
     }
 

server/src/main/java/org/elasticsearch/cluster/routing/RecoverySource.java

@@ -32,7 +32,7 @@
  * - {@link PeerRecoverySource} recovery from a primary on another node
  * - {@link SnapshotRecoverySource} recovery from a snapshot
  * - {@link LocalShardsRecoverySource} recovery from other shards of another index on the same node
- * - {@link ReshardSplitTargetRecoverySource} recovery of a shard that is created as a result of a resharding split
+ * - {@link ReshardSplitRecoverySource} recovery of a shard that is created as a result of a resharding split
  */
 public abstract class RecoverySource implements Writeable, ToXContentObject {
 
@@ -52,16 +52,14 @@ public void addAdditionalFields(XContentBuilder builder, ToXContent.Params param
     }
 
     public static RecoverySource readFrom(StreamInput in) throws IOException {
-        // TODO is transport version check needed?
-
         Type type = Type.values()[in.readByte()];
         return switch (type) {
             case EMPTY_STORE -> EmptyStoreRecoverySource.INSTANCE;
             case EXISTING_STORE -> ExistingStoreRecoverySource.read(in);
             case PEER -> PeerRecoverySource.INSTANCE;
             case SNAPSHOT -> new SnapshotRecoverySource(in);
             case LOCAL_SHARDS -> LocalShardsRecoverySource.INSTANCE;
-            case RESHARD_SPLIT_TARGET -> new ReshardSplitTargetRecoverySource(in);
+            case RESHARD_SPLIT -> new ReshardSplitRecoverySource(in);
         };
     }
 
@@ -84,7 +82,7 @@ public enum Type {
         PEER,
         SNAPSHOT,
         LOCAL_SHARDS,
-        RESHARD_SPLIT_TARGET
+        RESHARD_SPLIT
     }
 
     public abstract Type getType();
@@ -330,20 +328,20 @@ public boolean expectEmptyRetentionLeases() {
      * Recovery of a shard that is created as a result of a resharding split.
      * Not to be confused with _split API.
      */
-    public static class ReshardSplitTargetRecoverySource extends RecoverySource {
+    public static class ReshardSplitRecoverySource extends RecoverySource {
         private final ShardId sourceShardId;
 
-        public ReshardSplitTargetRecoverySource(ShardId sourceShardId) {
+        public ReshardSplitRecoverySource(ShardId sourceShardId) {
             this.sourceShardId = sourceShardId;
         }
 
-        ReshardSplitTargetRecoverySource(StreamInput in) throws IOException {
+        ReshardSplitRecoverySource(StreamInput in) throws IOException {
             sourceShardId = new ShardId(in);
         }
 
         @Override
         public Type getType() {
-            return Type.RESHARD_SPLIT_TARGET;
+            return Type.RESHARD_SPLIT;
         }
 
         public ShardId getSourceShardId() {

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

@@ -3501,7 +3501,7 @@ public void startRecovery(
         // }
         assert recoveryState.getRecoverySource().equals(shardRouting.recoverySource());
         switch (recoveryState.getRecoverySource().getType()) {
-            case EMPTY_STORE, EXISTING_STORE, RESHARD_SPLIT_TARGET -> executeRecovery(
+            case EMPTY_STORE, EXISTING_STORE, RESHARD_SPLIT -> executeRecovery(
                 "from store",
                 recoveryState,
                 recoveryListener,

server/src/main/java/org/elasticsearch/index/shard/StoreRecovery.java

@@ -91,8 +91,7 @@ void recoverFromStore(final IndexShard indexShard, ActionListener<Boolean> liste
             RecoverySource.Type recoveryType = indexShard.recoveryState().getRecoverySource().getType();
             assert recoveryType == RecoverySource.Type.EMPTY_STORE
                 || recoveryType == RecoverySource.Type.EXISTING_STORE
-                || recoveryType == RecoverySource.Type.RESHARD_SPLIT_TARGET
-                : "expected one of store recovery types but was: " + recoveryType;
+                || recoveryType == RecoverySource.Type.RESHARD_SPLIT : "expected one of store recovery types but was: " + recoveryType;
             logger.debug("starting recovery from store ...");
             final var recoveryListener = recoveryListener(indexShard, listener);
             try {

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

@@ -702,10 +702,9 @@ private void createShard(ShardRouting shardRouting, ClusterState state) {
                     logger.trace("ignoring initializing shard {} - no source node can be found.", shardId);
                     return;
                 }
-            } else if (shardRouting.recoverySource().getType() == Type.RESHARD_SPLIT_TARGET) {
-                ShardId sourceShardId = ((RecoverySource.ReshardSplitTargetRecoverySource) shardRouting.recoverySource())
-                    .getSourceShardId();
-                sourceNode = findSourceNodeForSplitTargetRecovery(state.routingTable(project.id()), state.nodes(), sourceShardId);
+            } else if (shardRouting.recoverySource() instanceof RecoverySource.ReshardSplitRecoverySource reshardSplitRecoverySource) {
+                ShardId sourceShardId = reshardSplitRecoverySource.getSourceShardId();
+                sourceNode = findSourceNodeForReshardSplitRecovery(state.routingTable(project.id()), state.nodes(), sourceShardId);
                 if (sourceNode == null) {
                     logger.trace("ignoring initializing reshard target shard {} - no source node can be found.", shardId);
                     return;
@@ -997,7 +996,7 @@ private static DiscoveryNode findSourceNodeForPeerRecovery(RoutingTable routingT
         return sourceNode;
     }
 
-    private static DiscoveryNode findSourceNodeForSplitTargetRecovery(
+    private static DiscoveryNode findSourceNodeForReshardSplitRecovery(
         RoutingTable routingTable,
         DiscoveryNodes nodes,
         ShardId sourceShardId

server/src/main/java/org/elasticsearch/indices/recovery/RecoveryState.java

@@ -112,7 +112,7 @@ public RecoveryState(ShardRouting shardRouting, DiscoveryNode targetNode, @Nulla
         assert shardRouting.initializing() : "only allow initializing shard routing to be recovered: " + shardRouting;
         assert shardRouting.recoverySource().getType() != RecoverySource.Type.PEER || sourceNode != null
             : "peer recovery requires source node but it is null";
-        assert shardRouting.recoverySource().getType() != RecoverySource.Type.RESHARD_SPLIT_TARGET || sourceNode != null
+        assert shardRouting.recoverySource().getType() != RecoverySource.Type.RESHARD_SPLIT || sourceNode != null
             : "reshard split target recovery requires source node but it is null";
         timer.start();
     }

server/src/test/java/org/elasticsearch/cluster/routing/RecoverySourceTests.java

@@ -34,7 +34,7 @@ public void testRecoverySourceTypeOrder() {
         assertEquals(RecoverySource.Type.PEER.ordinal(), 2);
         assertEquals(RecoverySource.Type.SNAPSHOT.ordinal(), 3);
         assertEquals(RecoverySource.Type.LOCAL_SHARDS.ordinal(), 4);
-        assertEquals(RecoverySource.Type.RESHARD_SPLIT_TARGET.ordinal(), 5);
+        assertEquals(RecoverySource.Type.RESHARD_SPLIT.ordinal(), 5);
         // check exhaustiveness
         for (RecoverySource.Type type : RecoverySource.Type.values()) {
             assertThat(type.ordinal(), greaterThanOrEqualTo(0));

test/framework/src/main/java/org/elasticsearch/cluster/routing/TestShardRouting.java

@@ -276,7 +276,7 @@ public static RecoverySource buildRecoverySource() {
                 IndexVersion.current(),
                 new IndexId("some_index", randomUUID())
             ),
-            new RecoverySource.ReshardSplitTargetRecoverySource(new ShardId("some_index", randomUUID(), randomIntBetween(0, 1000)))
+            new RecoverySource.ReshardSplitRecoverySource(new ShardId("some_index", randomUUID(), randomIntBetween(0, 1000)))
         );
     }
 }