@Override
  public boolean dispatch(final CallRunner callTask) {
    RpcCall call = callTask.getRpcCall();
    boolean shouldDispatchToWriteQueue = isWriteRequest(call.getHeader(), call.getParam());
    boolean shouldDispatchToScanQueue = shouldDispatchToScanQueue(callTask);
    FastPathRpcHandler handler = shouldDispatchToWriteQueue ? writeHandlerStack.poll()
      : shouldDispatchToScanQueue ? scanHandlerStack.poll()
      : readHandlerStack.poll();
    return handler != null
      ? handler.loadCallRunner(callTask)
      : dispatchTo(shouldDispatchToWriteQueue, shouldDispatchToScanQueue, callTask);
  }
RPC Executor that extends {@link RWQueueRpcExecutor} with fast-path feature, used in
{@link FastPathBalancedQueueRpcExecutor}.
hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/FastPathRWQueueRpcExecutor.java