kupl_shm_comm_create

Creates a KUPL communicator.

Interface Definition

int kupl_shm_comm_create(int size, int rank, int pid, kupl_shm_oob_cb_h oob_cbs, void *group, kupl_shm_comm_h *comm);

Parameters

**Table 1** Parameter definitions
Parameter	Type	Description	Input/Output
size	int	Size of the KUPL communicator to be created.	Input
rank	int	Rank (zero-indexed rank) of the current process.	Input
pid	int	Process identifier (PID) of the current process.	Input
oob_cbs	kupl_shm_oob_cb_h	Out-of-band function pointer. For details, see the following Table 2.	Input
group	void *	Parameters on which the out-of-band function pointer depends.	Input
comm	kupl_shm_comm_h	KUPL communicator to be created.	Output

**Table 2** shm out-of-band function structure
Parameter	Type	Description
oob_allgather	int (kupl_shm_oob_allgather_cb_t)(const void, void, int, void, kupl_shm_datatype_t)	Pointer to the out-of-band allgather function, which collects process-related information during the creation of kupl_comm.
oob_barrier	int (kupl_shm_oob_barrier_cb_t)(void )	Pointer to the out-of-band barrier function, which ensures the correct creation of kupl_comm.

Return Value

Success: KUPL_OK
Failure: KUPL_ERROR

Examples

#include <stdio.h>
#include <mpi.h>
#include <unistd.h>
#include "kupl.h"

// Callback 1 required for creating a KUPL communicator.
static int oob_barrier_callback(void *group)
{
    return MPI_Barrier((MPI_Comm)group);
}
// Callback 2 required for creating a KUPL communicator.
static int oob_allgather_callback(const void *sendbuf, void *recvbuf, int size, void *group,
                                  kupl_shm_datatype_t datatype)
{
    switch (datatype) {
        case KUPL_SHM_DATATYPE_CHAR:
            return MPI_Allgather(sendbuf, size, MPI_CHAR, recvbuf, size, MPI_CHAR, (MPI_Comm)group);
        default:
            fprintf(stderr, "not support datatype");
            return KUPL_ERROR;
    }
}
int main(int argc, char *argv[])
{
    // Initialize the MPI environment.
    MPI_Init(&argc, &argv);
    MPI_Comm comm = MPI_COMM_WORLD;
    // Obtain the size of the MPI communicator.
    int world_size;
    MPI_Comm_size(comm, &world_size);
    // Obtain the rank of the process.
    int world_rank;
    MPI_Comm_rank(comm, &world_rank);
    // Obtain the PID.
    int pid = getpid();
    // Create a KUPL communicator.
    kupl_shm_oob_cb_t oob_cbs;
    kupl_shm_oob_cb_h oob_cbs_h = &oob_cbs;
    oob_cbs_h->oob_allgather = oob_allgather_callback;
    oob_cbs_h->oob_barrier = oob_barrier_callback;
    kupl_shm_comm_h kupl_comm;
    int ret = kupl_shm_comm_create(world_size, world_rank, pid, oob_cbs_h, (void *)comm, &kupl_comm);
    if (ret != KUPL_OK || kupl_comm == NULL) {
        fprintf(stderr, "kupl shm comm create failed: %d\n", ret);
        return -1;
    }
    kupl_shm_comm_destroy(kupl_comm);
    MPI_Finalize();
    return 0;
}

The preceding example demonstrates how to create and destroy a KUPL communicator. The kupl_shm_comm_create function creates the KUPL communicator.

Parent topic: Shared Memory Communication Functions