@Override
    public void messageReceived(Request request, final TransportChannel channel) throws Exception {
      // if we have a local operation, execute it on a thread since we don't spawn
      request.operationThreaded(true);
      execute(
          request,
          new ActionListener<Response>() {
            @Override
            public void onResponse(Response result) {
              try {
                channel.sendResponse(result);
              } catch (Throwable e) {
                onFailure(e);
              }
            }

            @Override
            public void onFailure(Throwable e) {
              try {
                channel.sendResponse(e);
              } catch (Exception e1) {
                logger.warn("failed to send response for get", e1);
              }
            }
          });
    }
    void retry(boolean fromClusterEvent, @Nullable final Throwable failure) {
      if (!fromClusterEvent) {
        // make it threaded operation so we fork on the discovery listener thread
        request.beforeLocalFork();
        request.operationThreaded(true);
        clusterService.add(
            request.timeout(),
            new TimeoutClusterStateListener() {
              @Override
              public void postAdded() {
                if (start(true)) {
                  // if we managed to start and perform the operation on the primary, we can remove
                  // this listener
                  clusterService.remove(this);
                }
              }

              @Override
              public void onClose() {
                clusterService.remove(this);
                listener.onFailure(new NodeClosedException(nodes.localNode()));
              }

              @Override
              public void clusterChanged(ClusterChangedEvent event) {
                if (start(true)) {
                  // if we managed to start and perform the operation on the primary, we can remove
                  // this listener
                  clusterService.remove(this);
                }
              }

              @Override
              public void onTimeout(TimeValue timeValue) {
                // just to be on the safe side, see if we can start it now?
                if (start(true)) {
                  clusterService.remove(this);
                  return;
                }
                clusterService.remove(this);
                Throwable listenerFailure = failure;
                if (listenerFailure == null) {
                  if (shardIt == null) {
                    listenerFailure =
                        new UnavailableShardsException(
                            null,
                            "no available shards: Timeout waiting for ["
                                + timeValue
                                + "], request: "
                                + request.toString());
                  } else {
                    listenerFailure =
                        new UnavailableShardsException(
                            shardIt.shardId(),
                            "["
                                + shardIt.size()
                                + "] shardIt, ["
                                + shardIt.sizeActive()
                                + "] active : Timeout waiting for ["
                                + timeValue
                                + "], request: "
                                + request.toString());
                  }
                }
                listener.onFailure(listenerFailure);
              }
            });
      }
    }
    void performOnReplica(
        final PrimaryResponse<Response, ReplicaRequest> response,
        final AtomicInteger counter,
        final ShardRouting shard,
        String nodeId) {
      // if we don't have that node, it means that it might have failed and will be created again,
      // in
      // this case, we don't have to do the operation, and just let it failover
      if (!nodes.nodeExists(nodeId)) {
        if (counter.decrementAndGet() == 0) {
          listener.onResponse(response.response());
        }
        return;
      }

      final ReplicaOperationRequest shardRequest =
          new ReplicaOperationRequest(shardIt.shardId().id(), response.replicaRequest());
      if (!nodeId.equals(nodes.localNodeId())) {
        DiscoveryNode node = nodes.get(nodeId);
        transportService.sendRequest(
            node,
            transportReplicaAction,
            shardRequest,
            transportOptions,
            new VoidTransportResponseHandler(ThreadPool.Names.SAME) {
              @Override
              public void handleResponse(VoidStreamable vResponse) {
                finishIfPossible();
              }

              @Override
              public void handleException(TransportException exp) {
                if (!ignoreReplicaException(exp.unwrapCause())) {
                  logger.warn(
                      "Failed to perform " + transportAction + " on replica " + shardIt.shardId(),
                      exp);
                  shardStateAction.shardFailed(
                      shard,
                      "Failed to perform ["
                          + transportAction
                          + "] on replica, message ["
                          + detailedMessage(exp)
                          + "]");
                }
                finishIfPossible();
              }

              private void finishIfPossible() {
                if (counter.decrementAndGet() == 0) {
                  listener.onResponse(response.response());
                }
              }
            });
      } else {
        if (request.operationThreaded()) {
          request.beforeLocalFork();
          threadPool
              .executor(executor)
              .execute(
                  new Runnable() {
                    @Override
                    public void run() {
                      try {
                        shardOperationOnReplica(shardRequest);
                      } catch (Exception e) {
                        if (!ignoreReplicaException(e)) {
                          logger.warn(
                              "Failed to perform "
                                  + transportAction
                                  + " on replica "
                                  + shardIt.shardId(),
                              e);
                          shardStateAction.shardFailed(
                              shard,
                              "Failed to perform ["
                                  + transportAction
                                  + "] on replica, message ["
                                  + detailedMessage(e)
                                  + "]");
                        }
                      }
                      if (counter.decrementAndGet() == 0) {
                        listener.onResponse(response.response());
                      }
                    }
                  });
        } else {
          try {
            shardOperationOnReplica(shardRequest);
          } catch (Exception e) {
            if (!ignoreReplicaException(e)) {
              logger.warn(
                  "Failed to perform " + transportAction + " on replica" + shardIt.shardId(), e);
              shardStateAction.shardFailed(
                  shard,
                  "Failed to perform ["
                      + transportAction
                      + "] on replica, message ["
                      + detailedMessage(e)
                      + "]");
            }
          }
          if (counter.decrementAndGet() == 0) {
            listener.onResponse(response.response());
          }
        }
      }
    }
    /** Returns <tt>true</tt> if the action starting to be performed on the primary (or is done). */
    public boolean start(final boolean fromClusterEvent) throws ElasticSearchException {
      final ClusterState clusterState = clusterService.state();
      nodes = clusterState.nodes();
      try {
        ClusterBlockException blockException = checkGlobalBlock(clusterState, request);
        if (blockException != null) {
          if (blockException.retryable()) {
            retry(fromClusterEvent, blockException);
            return false;
          } else {
            throw blockException;
          }
        }
        // check if we need to execute, and if not, return
        if (!resolveRequest(clusterState, request, listener)) {
          return true;
        }
        blockException = checkRequestBlock(clusterState, request);
        if (blockException != null) {
          if (blockException.retryable()) {
            retry(fromClusterEvent, blockException);
            return false;
          } else {
            throw blockException;
          }
        }
        shardIt = shards(clusterState, request);
      } catch (Exception e) {
        listener.onFailure(e);
        return true;
      }

      // no shardIt, might be in the case between index gateway recovery and shardIt initialization
      if (shardIt.size() == 0) {
        retry(fromClusterEvent, null);
        return false;
      }

      boolean foundPrimary = false;
      ShardRouting shardX;
      while ((shardX = shardIt.nextOrNull()) != null) {
        final ShardRouting shard = shardX;
        // we only deal with primary shardIt here...
        if (!shard.primary()) {
          continue;
        }
        if (!shard.active() || !nodes.nodeExists(shard.currentNodeId())) {
          retry(fromClusterEvent, null);
          return false;
        }

        // check here for consistency
        if (checkWriteConsistency) {
          WriteConsistencyLevel consistencyLevel = defaultWriteConsistencyLevel;
          if (request.consistencyLevel() != WriteConsistencyLevel.DEFAULT) {
            consistencyLevel = request.consistencyLevel();
          }
          int requiredNumber = 1;
          if (consistencyLevel == WriteConsistencyLevel.QUORUM && shardIt.size() > 2) {
            // only for more than 2 in the number of shardIt it makes sense, otherwise its 1 shard
            // with 1 replica, quorum is 1 (which is what it is initialized to)
            requiredNumber = (shardIt.size() / 2) + 1;
          } else if (consistencyLevel == WriteConsistencyLevel.ALL) {
            requiredNumber = shardIt.size();
          }

          if (shardIt.sizeActive() < requiredNumber) {
            retry(fromClusterEvent, null);
            return false;
          }
        }

        if (!primaryOperationStarted.compareAndSet(false, true)) {
          return true;
        }

        foundPrimary = true;
        if (shard.currentNodeId().equals(nodes.localNodeId())) {
          if (request.operationThreaded()) {
            request.beforeLocalFork();
            threadPool
                .executor(executor)
                .execute(
                    new Runnable() {
                      @Override
                      public void run() {
                        performOnPrimary(shard.id(), fromClusterEvent, shard, clusterState);
                      }
                    });
          } else {
            performOnPrimary(shard.id(), fromClusterEvent, shard, clusterState);
          }
        } else {
          DiscoveryNode node = nodes.get(shard.currentNodeId());
          transportService.sendRequest(
              node,
              transportAction,
              request,
              transportOptions,
              new BaseTransportResponseHandler<Response>() {

                @Override
                public Response newInstance() {
                  return newResponseInstance();
                }

                @Override
                public String executor() {
                  return ThreadPool.Names.SAME;
                }

                @Override
                public void handleResponse(Response response) {
                  listener.onResponse(response);
                }

                @Override
                public void handleException(TransportException exp) {
                  // if we got disconnected from the node, or the node / shard is not in the right
                  // state (being closed)
                  if (exp.unwrapCause() instanceof ConnectTransportException
                      || exp.unwrapCause() instanceof NodeClosedException
                      || retryPrimaryException(exp)) {
                    primaryOperationStarted.set(false);
                    // we already marked it as started when we executed it (removed the listener) so
                    // pass false
                    // to re-add to the cluster listener
                    retry(false, null);
                  } else {
                    listener.onFailure(exp);
                  }
                }
              });
        }
        break;
      }
      // we should never get here, but here we go
      if (!foundPrimary) {
        retry(fromClusterEvent, null);
        return false;
      }
      return true;
    }