code: public void abort() {
          if (asyncHandle != 0) {
              int handle = asyncHandle;
              asyncHandle = 0;
              broker.callRPCAbort(handle);
              ZKUtil.fireEvent(new AsyncRPCAbortEvent(rpcName, target, handle));
              rpcName = null;
          }
      }
docs: Abort any asynchronous RPC in progress.