if (status!=MPI_STATUS_IGNORE)
status->cancelled=1;
if(req->detached_sender_ != nullptr)
unref(&(req->detached_sender_));
unref(request);
return;
if (status!=MPI_STATUS_IGNORE)
status->cancelled=1;
if(req->detached_sender_ != nullptr)
unref(&(req->detached_sender_));
unref(request);
return;