public boolean cancel() {
    assert op != null : "No operation";
    op.cancel();
    notifyListeners();
    return op.getState() == OperationState.WRITE_QUEUED;
  }
Cancel this operation, if possible.

@return true if the operation has not yet been written to the network
src/main/java/net/spy/memcached/internal/OperationFuture.java