Function receiveArray

quest/src/comm/comm_routines.cpp:269–290

void receiveArray(qcomp* dest, qindex numElems, int pairRank) {
#if COMPILE_MPI

    // expect the data in multiple messages
    auto [messageSize, numMessages] = dividePow2PayloadIntoMessages(numElems);

    // create a request for each asynch receive below
    vector<MPI_Request> requests(numMessages, MPI_REQUEST_NULL);

    // listen to receive each uniquely-tagged message asynchronously (as per arxiv.org/abs/2308.07402)
    for (qindex m=0; m<numMessages; m++) {
        int tag = static_cast<int>(m); // gauranteed int, but m*messageSize needs qindex
        MPI_Irecv(&dest[m*messageSize], messageSize, MPI_QCOMP, pairRank, tag, MPI_COMM_WORLD, &requests[m]);
    }

    // receivers wait for all messages to be received (while sender asynch proceeds)
    MPI_Waitall(requests.size(), requests.data(), MPI_STATUSES_IGNORE);

#else
    error_commButEnvNotDistributed();
#endif
}