DeinoMPI

The Great and Terrible implementation of MPI-2

MPI_File_create_errhandler

Create a file error handler

int MPI_File_create_errhandler(
  MPI_File_errhandler_fn *function,
  MPI_Errhandler *errhandler
);

Parameters

function: [in] user defined error handling procedure (function)
errhandler: [out] MPI error handler (handle)

Remarks

The user routine should be, in C, a function of type MPI_File_errhandler_fn, which is defined as

typedef void MPI_File_errhandler_fn(MPI_File *, int *, ...);

The first argument is the file in use, the second is the error code to be returned.

In Fortran, the user routine should be of the form:

SUBROUTINE FILE_ERRHANDLER_FN(FILE, ERROR_CODE, ... ) INTEGER FILE, ERROR_CODE

In C++, the user routine should be of the form:

typedef void MPI::File::Errhandler_fn(MPI::File &, int *, ... );

Thread and Interrupt Safety

This routine is thread-safe. This means that this routine may be safely used by multiple threads without the need for any user-provided thread locks. However, the routine is not interrupt safe. Typically, this is due to the use of memory allocation routines such as mallocor other non-MPICH runtime routines that are themselves not interrupt-safe.

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_File_create_errhandler.

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

static int ncalls = 0;
void efn( MPI_File *fh, int *code, ... );
void efn( MPI_File *fh, int *code, ... )
{
    ncalls ++;
    *code = MPI_SUCCESS;
}

int main( int argc, char *argv[] )
{
    MPI_File fh;
    MPI_Errhandler eh;
    char filename[10];
    int errs = 0, toterrs, rank, rc;

    MPI_Init( &argc, &argv );
    /* Test that the default error handler is errors return for files */
    strncpy( filename, "t1", sizeof(filename) );
    rc = MPI_File_open( MPI_COMM_WORLD, filename, MPI_MODE_RDWR, MPI_INFO_NULL, &fh );
    if (!rc) {
        errs++;
        printf( "Did not get error from open for writing without CREATE\n" );fflush(stdout);
    }
    /* Test that we can change the default error handler by changing the error handler on MPI_FILE_NULL. */
    MPI_File_create_errhandler( efn, &eh );
    MPI_File_set_errhandler( MPI_FILE_NULL, eh );
    rc = MPI_File_open(MPI_COMM_WORLD, filename, MPI_MODE_RDWR, MPI_INFO_NULL, &fh );
    if (rc) {
        printf( "Returned error from open (should have called error handler instead)\n");fflush(stdout);
    }
    if (ncalls != 1) {
        errs++;
        printf( "Did not invoke error handler when opening a non-existent file for writing and reading (without MODE_CREATE)\n" );fflush(stdout);
    }
    MPI_Finalize();
    return errs;
}

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