DeinoMPI

The Great and Terrible implementation of MPI-2

MPI_Info_get_valuelen

Retrieves the length of the value associated with a key

int MPI_Info_get_valuelen(
  MPI_Info info,
  char *key,
  int *valuelen,
  int *flag
);

int MPI_Info_get_valuelen(
  MPI_Info info,
  wchar_t *key,
  int *valuelen,
  int *flag
);

Parameters

info: [in] info object (handle)
key: [in] key (string)
valuelen: [out] length of value argument (integer)
flag: [out] true if key defined, false if not (boolean)

Remarks

Retrieves the length of the value associated with key. If key is defined, valuelen is set to the length of its associated value and flag is set to true. If key is not defined, valuelen is not touched and flag is set to false. The length returned in C or C++ does not include the end-of-string character.

If key is larger than MPI_MAX_INFO_KEY, the call is erroneous.

Thread and Interrupt Safety

This routine is thread and interrupt safe only if no MPI routine that updates or frees the same MPI_Info object may be called concurrently with this routine.

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.

MPI_ERR_INFO_KEY: Invalid or null key string for info.

MPI_ERR_OTHER: Other error; use MPI_Error_string to get more information about this error code.

Example Code

The following sample code illustrates MPI_Info_get_valuelen.

#include "mpi.h"
#include <stdio.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, vallen;

    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_valuelen( info, keys[i], &vallen, &flag );
        if (!flag) {
            errs++;
            printf( "get_valuelen failed for valid key %s\n", keys[i] );fflush(stdout);
        }
        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\n", keys[i] );fflush(stdout);
        }
        if (strlen(value) != vallen) {
            errs++;
            printf( "value_len returned %d but actual len is %d\n", vallen, (int) strlen(value) );fflush(stdout);
        }
    }

    MPI_Info_free( &info );

    MPI_Finalize();
    return errs;
}

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