Merge pull request #15468 from jasontedor/master-side-of-wait-on-shard-failures

Master should wait on cluster state publication when failing a shard

Author: jasontedor

core/src/main/java/org/elasticsearch/cluster/action/shard/ShardStateAction.java

@@ -25,6 +25,7 @@
 import org.elasticsearch.cluster.ClusterStateTaskConfig;
 import org.elasticsearch.cluster.ClusterStateTaskExecutor;
 import org.elasticsearch.cluster.ClusterStateTaskListener;
+import org.elasticsearch.cluster.NotMasterException;
 import org.elasticsearch.cluster.metadata.IndexMetaData;
 import org.elasticsearch.cluster.node.DiscoveryNode;
 import org.elasticsearch.cluster.routing.RoutingService;
@@ -53,6 +54,7 @@
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Locale;
 
 import static org.elasticsearch.cluster.routing.ShardRouting.readShardRoutingEntry;
 
@@ -113,7 +115,7 @@ public void handleResponse(TransportResponse.Empty response) {
 
                 @Override
                 public void handleException(TransportException exp) {
-                    logger.warn("failed to send failed shard to {}", exp, masterNode);
+                    logger.warn("unexpected failure while sending request to [{}] to fail shard [{}]", exp, masterNode, shardRoutingEntry);
                     listener.onShardFailedFailure(masterNode, exp);
                 }
             });
@@ -122,22 +124,62 @@ public void handleException(TransportException exp) {
     private class ShardFailedTransportHandler implements TransportRequestHandler<ShardRoutingEntry> {
         @Override
         public void messageReceived(ShardRoutingEntry request, TransportChannel channel) throws Exception {
-            handleShardFailureOnMaster(request);
-            channel.sendResponse(TransportResponse.Empty.INSTANCE);
+            handleShardFailureOnMaster(request, new ClusterStateTaskListener() {
+                    @Override
+                    public void onFailure(String source, Throwable t) {
+                        logger.error("unexpected failure while failing shard [{}]", t, request.shardRouting);
+                        try {
+                            channel.sendResponse(t);
+                        } catch (Throwable channelThrowable) {
+                            logger.warn("failed to send failure [{}] while failing shard [{}]", channelThrowable, t, request.shardRouting);
+                        }
+                    }
+
+                    @Override
+                    public void onNoLongerMaster(String source) {
+                        logger.error("no longer master while failing shard [{}]", request.shardRouting);
+                        try {
+                            channel.sendResponse(new NotMasterException(source));
+                        } catch (Throwable channelThrowable) {
+                            logger.warn("failed to send no longer master while failing shard [{}]", channelThrowable, request.shardRouting);
+                        }
+                    }
+
+                    @Override
+                    public void clusterStateProcessed(String source, ClusterState oldState, ClusterState newState) {
+                        try {
+                            int numberOfUnassignedShards = newState.getRoutingNodes().unassigned().size();
+                            if (oldState != newState && numberOfUnassignedShards > 0) {
+                                String reason = String.format(Locale.ROOT, "[%d] unassigned shards after failing shard [%s]", numberOfUnassignedShards, request.shardRouting);
+                                if (logger.isTraceEnabled()) {
+                                    logger.trace(reason + ", scheduling a reroute");
+                                }
+                                routingService.reroute(reason);
+                            }
+                        } finally {
+                            try {
+                                channel.sendResponse(TransportResponse.Empty.INSTANCE);
+                            } catch (Throwable channelThrowable) {
+                                logger.warn("failed to send response while failing shard [{}]", channelThrowable, request.shardRouting);
+                            }
+                        }
+                    }
+                }
+            );
         }
     }
 
-    class ShardFailedClusterStateHandler implements ClusterStateTaskExecutor<ShardRoutingEntry>, ClusterStateTaskListener {
+    class ShardFailedClusterStateHandler implements ClusterStateTaskExecutor<ShardRoutingEntry> {
         @Override
         public BatchResult<ShardRoutingEntry> execute(ClusterState currentState, List<ShardRoutingEntry> tasks) throws Exception {
             BatchResult.Builder<ShardRoutingEntry> batchResultBuilder = BatchResult.builder();
-            List<FailedRerouteAllocation.FailedShard> shardRoutingsToBeApplied = new ArrayList<>(tasks.size());
+            List<FailedRerouteAllocation.FailedShard> failedShards = new ArrayList<>(tasks.size());
             for (ShardRoutingEntry task : tasks) {
-                shardRoutingsToBeApplied.add(new FailedRerouteAllocation.FailedShard(task.shardRouting, task.message, task.failure));
+                failedShards.add(new FailedRerouteAllocation.FailedShard(task.shardRouting, task.message, task.failure));
             }
             ClusterState maybeUpdatedState = currentState;
             try {
-                RoutingAllocation.Result result = allocationService.applyFailedShards(currentState, shardRoutingsToBeApplied);
+                RoutingAllocation.Result result = allocationService.applyFailedShards(currentState, failedShards);
                 if (result.changed()) {
                     maybeUpdatedState = ClusterState.builder(currentState).routingResult(result).build();
                 }
@@ -147,31 +189,18 @@ public BatchResult<ShardRoutingEntry> execute(ClusterState currentState, List<Sh
             }
             return batchResultBuilder.build(maybeUpdatedState);
         }
-
-        @Override
-        public void clusterStateProcessed(String source, ClusterState oldState, ClusterState newState) {
-            if (oldState != newState && newState.getRoutingNodes().unassigned().size() > 0) {
-                logger.trace("unassigned shards after shard failures. scheduling a reroute.");
-                routingService.reroute("unassigned shards after shard failures, scheduling a reroute");
-            }
-        }
-
-        @Override
-        public void onFailure(String source, Throwable t) {
-            logger.error("unexpected failure during [{}]", t, source);
-        }
     }
 
     private final ShardFailedClusterStateHandler shardFailedClusterStateHandler = new ShardFailedClusterStateHandler();
 
-    private void handleShardFailureOnMaster(final ShardRoutingEntry shardRoutingEntry) {
+    private void handleShardFailureOnMaster(final ShardRoutingEntry shardRoutingEntry, ClusterStateTaskListener listener) {
         logger.warn("{} received shard failed for {}", shardRoutingEntry.failure, shardRoutingEntry.shardRouting.shardId(), shardRoutingEntry);
         clusterService.submitStateUpdateTask(
             "shard-failed (" + shardRoutingEntry.shardRouting + "), message [" + shardRoutingEntry.message + "]",
             shardRoutingEntry,
             ClusterStateTaskConfig.build(Priority.HIGH),
             shardFailedClusterStateHandler,
-            shardFailedClusterStateHandler);
+            listener);
     }
 
     public void shardStarted(final ShardRouting shardRouting, String indexUUID, final String reason) {