DeinoMPI

The Great and Terrible implementation of MPI-2

MPI_Info_delete

Deletes a (key,value) pair from info

int MPI_Info_delete(
  MPI_Info info,
  char *key
);

int MPI_Info_delete(
  MPI_Info info,
  wchar_t *key
);

Parameters

info: [in] info object (handle)
key: [in] key (string)

Remarks

MPI_INFO_DELETE deletes a (key,value) pair from info. If key is not defined in info, the call raises an error of class MPI_ERR_INFO_NOKEY.

Thread and Interrupt Safety

The user is responsible for ensuring that multiple threads do not try to update the same MPI object from different threads. This routine should not be used from within a signal handler.

The MPI standard defined a thread-safe interface but this does not mean that all routines may be called without any thread locks. For example, two threads must not attempt to change the contents of the same MPI_Info object concurrently. The user is responsible in this case for using some mechanism, such as thread locks, to ensure that only one thread at a time makes use of this routine.

Notes for Fortran

All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK) have an additional argument ierr at the end of the argument list. ierris an integer and has the same meaning as the return value of the routine in C. In Fortran, MPI routines are subroutines, and are invoked with the call statement.

All MPI objects (e.g., MPI_Datatype, MPI_Comm) are of type INTEGERin Fortran.

Errors

All MPI routines (except MPI_Wtime and MPI_Wtick) return an error value; C routines as the value of the function and Fortran routines in the last argument. Before the value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job. The error handler may be changed with MPI_Comm_set_errhandler (for communicators), MPI_File_set_errhandler (for files), and MPI_Win_set_errhandler (for RMA windows). The MPI-1 routine MPI_Errhandler_set may be used but its use is deprecated. The predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarentee that an MPI program can continue past an error; however, MPI implementations will attempt to continue whenever possible.

MPI_SUCCESS: No error; MPI routine completed successfully.

Example Code

The following sample code illustrates MPI_Info_delete.

#include "mpi.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define NKEYS 3
int main( int argc, char *argv[] )
{
    int errs = 0;
    MPI_Info info;
    char *keys[NKEYS] = { "file", "soft", "host" };
    char *values[NKEYS] = { "runfile.txt", "2:1000:4,3:1000:7", "myhost.myorg.org" };
    char value[MPI_MAX_INFO_VAL];
    int i, flag, nkeys;

    MPI_Init( &argc, &argv );

    MPI_Info_create( &info );
    for (i=0; i<NKEYS; i++) {
        MPI_Info_set( info, keys[i], values[i] );
    }

    /* Check that all values are present */
    for (i=0; i<NKEYS; i++) {
        MPI_Info_get( info, keys[i], MPI_MAX_INFO_VAL, value, &flag );
        if (!flag) {
            errs++;
            printf( "No value for key %s\n", keys[i] );fflush(stdout);
        }
        if (strcmp( value, values[i] )) {
            errs++;
            printf( "Incorrect value for key %s, got %s expected %s\n", keys[i], value, values[i] );fflush(stdout);
        }
    }

    /* Now, change one value and remove another, then check again */
    MPI_Info_delete( info, keys[NKEYS-1] );
    MPI_Info_get_nkeys( info, &nkeys );
    if (nkeys != NKEYS - 1) {
        errs++;
        printf( "Deleting a key did not change the number of keys\n" );fflush(stdout);
    }

    values[0] = "backfile.txt";
    MPI_Info_set( info, keys[0], values[0] );
    for (i=0; i<NKEYS-1; i++) {
        MPI_Info_get( info, keys[i], MPI_MAX_INFO_VAL, value, &flag );
        if (!flag) {
            errs++;
            printf( "(after reset) No value for key %s\n", keys[i] );fflush(stdout);
        }
        if (strcmp( value, values[i] )) {
            errs++;
            printf( "(after reset) Incorrect value for key %s, got %s expected %s\n", keys[i], value, values[i] );fflush(stdout);
        }
    }

    MPI_Info_free( &info );
    if (info != MPI_INFO_NULL) {
        errs++;
        printf( "MPI_Info_free should set info to MPI_INFO_NULL\n" );fflush(stdout);
    }

    MPI_Finalize();
    return errs;
}

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