Remove some abstractions from TransportReplicationAction (elastic#4…

…0706)

`TransportReplicationAction` is a rather complex beast, and some of its
concrete implementations do not need all of its features. More specifically, it
(a) chases a primary around the cluster until it manages to pin it down and
then (b) executes an action on that primary and all its replicas. There are
some actions that are coordinated by the primary itself, meaning that there is
no need for the chase-the-primary phases, and in the case of peer recovery
retention leases and primary/replica resync it is important to bypass these
first phases.

This commit is a step towards separating the `TransportReplicationAction` into
these two parts. It is a mostly mechanical sequence of steps to remove some
abstractions that are no longer in use.

server/src/main/java/org/elasticsearch/action/admin/indices/refresh/TransportShardRefreshAction.java

@@ -53,10 +53,11 @@ protected ReplicationResponse newResponseInstance() {
     }
 
     @Override
-    protected PrimaryResult shardOperationOnPrimary(BasicReplicationRequest shardRequest, IndexShard primary) {
+    protected PrimaryResult<BasicReplicationRequest, ReplicationResponse> shardOperationOnPrimary(
+            BasicReplicationRequest shardRequest, IndexShard primary) {
         primary.refresh("api");
         logger.trace("{} refresh request executed on primary", primary.shardId());
-        return new PrimaryResult(shardRequest, new ReplicationResponse());
+        return new PrimaryResult<>(shardRequest, new ReplicationResponse());
     }
 
     @Override

server/src/main/java/org/elasticsearch/action/resync/TransportResyncReplicationAction.java

@@ -66,16 +66,16 @@ public TransportResyncReplicationAction(Settings settings, TransportService tran
     @Override
     protected void registerRequestHandlers(String actionName, TransportService transportService, Supplier<ResyncReplicationRequest> request,
                                            Supplier<ResyncReplicationRequest> replicaRequest, String executor) {
-        transportService.registerRequestHandler(actionName, request, ThreadPool.Names.SAME, new OperationTransportHandler());
+        transportService.registerRequestHandler(actionName, request, ThreadPool.Names.SAME, this::handleOperationRequest);
         // we should never reject resync because of thread pool capacity on primary
         transportService.registerRequestHandler(transportPrimaryAction,
             () -> new ConcreteShardRequest<>(request),
             executor, true, true,
-            new PrimaryOperationTransportHandler());
+            this::handlePrimaryRequest);
         transportService.registerRequestHandler(transportReplicaAction,
             () -> new ConcreteReplicaRequest<>(replicaRequest),
             executor, true, true,
-            new ReplicaOperationTransportHandler());
+            this::handleReplicaRequest);
     }
 
     @Override

server/src/main/java/org/elasticsearch/action/support/ChannelActionListener.java

@@ -55,6 +55,7 @@ public void onFailure(Exception e) {
         try {
             channel.sendResponse(e);
         } catch (Exception e1) {
+            e1.addSuppressed(e);
             logger.warn(() -> new ParameterizedMessage(
                 "Failed to send error response for action [{}] and request [{}]", actionName, request), e1);
         }