Removes BWC snapshot status handler used in 6.x (#27443)

We introduced a new snapshot status update handler in 6.1.0. We will
keep the old handler along with this new one in all 6.x. This commit
removes the old handler from 7.0.

Relates #27151

Author: dnhatn

core/src/main/java/org/elasticsearch/snapshots/SnapshotShardsService.java

@@ -23,7 +23,6 @@
 import org.apache.logging.log4j.message.ParameterizedMessage;
 import org.apache.logging.log4j.util.Supplier;
 import org.elasticsearch.ExceptionsHelper;
-import org.elasticsearch.Version;
 import org.elasticsearch.action.ActionListener;
 import org.elasticsearch.action.ActionRequestValidationException;
 import org.elasticsearch.action.ActionResponse;
@@ -68,10 +67,6 @@
 import org.elasticsearch.repositories.Repository;
 import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.transport.EmptyTransportResponseHandler;
-import org.elasticsearch.transport.TransportChannel;
-import org.elasticsearch.transport.TransportRequest;
-import org.elasticsearch.transport.TransportRequestHandler;
-import org.elasticsearch.transport.TransportResponse;
 import org.elasticsearch.transport.TransportService;
 
 import java.io.IOException;
@@ -97,10 +92,8 @@
  */
 public class SnapshotShardsService extends AbstractLifecycleComponent implements ClusterStateListener, IndexEventListener {
 
-    public static final String UPDATE_SNAPSHOT_STATUS_ACTION_NAME_V6 = "internal:cluster/snapshot/update_snapshot";
     public static final String UPDATE_SNAPSHOT_STATUS_ACTION_NAME = "internal:cluster/snapshot/update_snapshot_status";
 
-
     private final ClusterService clusterService;
 
     private final IndicesService indicesService;
@@ -138,21 +131,12 @@ public SnapshotShardsService(Settings settings, ClusterService clusterService, S
         // The constructor of UpdateSnapshotStatusAction will register itself to the TransportService.
         this.updateSnapshotStatusHandler = new UpdateSnapshotStatusAction(settings, UPDATE_SNAPSHOT_STATUS_ACTION_NAME,
             transportService, clusterService, threadPool, actionFilters, indexNameExpressionResolver);
-
-        if (DiscoveryNode.isMasterNode(settings)) {
-            // This needs to run only on nodes that can become masters
-            transportService.registerRequestHandler(UPDATE_SNAPSHOT_STATUS_ACTION_NAME_V6, UpdateSnapshotStatusRequestV6::new, ThreadPool.Names.SAME, new UpdateSnapshotStateRequestHandlerV6());
-        }
-
     }
 
     @Override
     protected void doStart() {
         assert this.updateSnapshotStatusHandler != null;
         assert transportService.getRequestHandler(UPDATE_SNAPSHOT_STATUS_ACTION_NAME) != null;
-        if (DiscoveryNode.isMasterNode(settings)) {
-            assert transportService.getRequestHandler(UPDATE_SNAPSHOT_STATUS_ACTION_NAME_V6) != null;
-        }
     }
 
     @Override
@@ -531,13 +515,8 @@ public String toString() {
      */
     public void updateIndexShardSnapshotStatus(Snapshot snapshot, ShardId shardId, ShardSnapshotStatus status, DiscoveryNode master) {
         try {
-            if (master.getVersion().onOrAfter(Version.V_7_0_0_alpha1)) {
-                UpdateIndexShardSnapshotStatusRequest request = new UpdateIndexShardSnapshotStatusRequest(snapshot, shardId, status);
-                transportService.sendRequest(transportService.getLocalNode(), UPDATE_SNAPSHOT_STATUS_ACTION_NAME, request, EmptyTransportResponseHandler.INSTANCE_SAME);
-            } else {
-                UpdateSnapshotStatusRequestV6 requestV6 = new UpdateSnapshotStatusRequestV6(snapshot, shardId, status);
-                transportService.sendRequest(master, UPDATE_SNAPSHOT_STATUS_ACTION_NAME_V6, requestV6, EmptyTransportResponseHandler.INSTANCE_SAME);
-            }
+            UpdateIndexShardSnapshotStatusRequest request = new UpdateIndexShardSnapshotStatusRequest(snapshot, shardId, status);
+            transportService.sendRequest(transportService.getLocalNode(), UPDATE_SNAPSHOT_STATUS_ACTION_NAME, request, EmptyTransportResponseHandler.INSTANCE_SAME);
         } catch (Exception e) {
             logger.warn((Supplier<?>) () -> new ParameterizedMessage("[{}] [{}] failed to update snapshot state", snapshot, status), e);
         }
@@ -651,78 +630,4 @@ protected ClusterBlockException checkBlock(UpdateIndexShardSnapshotStatusRequest
         }
     }
 
-    /**
-     * A BWC version of {@link UpdateIndexShardSnapshotStatusRequest}
-     */
-    static class UpdateSnapshotStatusRequestV6 extends TransportRequest {
-        private Snapshot snapshot;
-        private ShardId shardId;
-        private ShardSnapshotStatus status;
-
-        UpdateSnapshotStatusRequestV6() {
-
-        }
-
-        UpdateSnapshotStatusRequestV6(Snapshot snapshot, ShardId shardId, ShardSnapshotStatus status) {
-            this.snapshot = snapshot;
-            this.shardId = shardId;
-            this.status = status;
-        }
-
-        @Override
-        public void readFrom(StreamInput in) throws IOException {
-            super.readFrom(in);
-            snapshot = new Snapshot(in);
-            shardId = ShardId.readShardId(in);
-            status = new ShardSnapshotStatus(in);
-        }
-
-        @Override
-        public void writeTo(StreamOutput out) throws IOException {
-            super.writeTo(out);
-            snapshot.writeTo(out);
-            shardId.writeTo(out);
-            status.writeTo(out);
-        }
-
-        Snapshot snapshot() {
-            return snapshot;
-        }
-
-        ShardId shardId() {
-            return shardId;
-        }
-
-        ShardSnapshotStatus status() {
-            return status;
-        }
-
-        @Override
-        public String toString() {
-            return snapshot + ", shardId [" + shardId + "], status [" + status.state() + "]";
-        }
-    }
-
-    /**
-     * A BWC version of {@link UpdateSnapshotStatusAction}
-     */
-    class UpdateSnapshotStateRequestHandlerV6 implements TransportRequestHandler<UpdateSnapshotStatusRequestV6> {
-        @Override
-        public void messageReceived(UpdateSnapshotStatusRequestV6 requestV6, final TransportChannel channel) throws Exception {
-            final UpdateIndexShardSnapshotStatusRequest request = new UpdateIndexShardSnapshotStatusRequest(requestV6.snapshot(), requestV6.shardId(), requestV6.status());
-            innerUpdateSnapshotState(request, new ActionListener<UpdateIndexShardSnapshotStatusResponse>() {
-                @Override
-                public void onResponse(UpdateIndexShardSnapshotStatusResponse updateSnapshotStatusResponse) {
-
-                }
-
-                @Override
-                public void onFailure(Exception e) {
-                    logger.warn("Failed to update snapshot status", e);
-                }
-            });
-            channel.sendResponse(TransportResponse.Empty.INSTANCE);
-        }
-    }
-
 }