/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */

/*

 *

 *  (C) 2001 by Argonne National Laboratory.

 *      See COPYRIGHT in top-level directory.

 */

#include "mpiimpl.h"

/* -- Begin Profiling Symbol Block for routine MPI_Comm_compare */

#if defined(HAVE_PRAGMA_WEAK)

#pragma weak MPI_Comm_compare = PMPI_Comm_compare

#elif defined(HAVE_PRAGMA_HP_SEC_DEF)

#pragma _HP_SECONDARY_DEF PMPI_Comm_compare  MPI_Comm_compare

#elif defined(HAVE_PRAGMA_CRI_DUP)

#pragma _CRI duplicate MPI_Comm_compare as PMPI_Comm_compare

#elif defined(HAVE_WEAK_ATTRIBUTE)

int MPI_Comm_compare(MPI_Comm comm1, MPI_Comm comm2, int *result)

    __attribute__ ((weak, alias("PMPI_Comm_compare")));

#endif

/* -- End Profiling Symbol Block */

/* Define MPICH_MPI_FROM_PMPI if weak symbols are not supported to build

   the MPI routines */

#ifndef MPICH_MPI_FROM_PMPI

#undef MPI_Comm_compare

#define MPI_Comm_compare PMPI_Comm_compare

#endif

#undef FUNCNAME

#define FUNCNAME MPI_Comm_compare

#undef FCNAME

#define FCNAME "MPI_Comm_compare"

/*@

MPI_Comm_compare - Compares two communicators

Input Parameters:

+ comm1 - comm1 (handle)

- comm2 - comm2 (handle)

Output Parameters:

. result - integer which is 'MPI_IDENT' if the contexts and groups are the

same, 'MPI_CONGRUENT' if different contexts but identical groups, 'MPI_SIMILAR'

if different contexts but similar groups, and 'MPI_UNEQUAL' otherwise

Using 'MPI_COMM_NULL' with 'MPI_Comm_compare':

It is an error to use 'MPI_COMM_NULL' as one of the arguments to

'MPI_Comm_compare'.  The relevant sections of the MPI standard are

$(2.4.1 Opaque Objects)

A null handle argument is an erroneous 'IN' argument in MPI calls, unless an

exception is explicitly stated in the text that defines the function.

$(5.4.1. Communicator Accessors)

where there is no text in 'MPI_COMM_COMPARE' allowing a null handle.

.N ThreadSafe

(To perform the communicator comparisions, this routine may need to

allocate some memory.  Memory allocation is not interrupt-safe, and hence

this routine is only thread-safe.)

.N Fortran

.N Errors

.N MPI_SUCCESS

.N MPI_ERR_ARG

@*/

int MPI_Comm_compare(MPI_Comm comm1, MPI_Comm comm2, int *result)

{

    int mpi_errno = MPI_SUCCESS;

    MPIR_Comm *comm_ptr1 = NULL;

    MPIR_Comm *comm_ptr2 = NULL;

    MPIR_FUNC_TERSE_STATE_DECL(MPID_STATE_MPI_COMM_COMPARE);

    MPIR_ERRTEST_INITIALIZED_ORDIE();

    MPID_THREAD_CS_ENTER(GLOBAL, MPIR_THREAD_GLOBAL_ALLFUNC_MUTEX);

    MPIR_FUNC_TERSE_ENTER(MPID_STATE_MPI_COMM_COMPARE);

#ifdef HAVE_ERROR_CHECKING

    {

        MPID_BEGIN_ERROR_CHECKS;

        {

            MPIR_ERRTEST_COMM(comm1, mpi_errno);

            MPIR_ERRTEST_COMM(comm2, mpi_errno);

        }

        MPID_END_ERROR_CHECKS;

    }

#endif /* HAVE_ERROR_CHECKING */

    /* Get handles to MPI objects. */

    MPIR_Comm_get_ptr(comm1, comm_ptr1);

    MPIR_Comm_get_ptr(comm2, comm_ptr2);

    /* Validate parameters and objects (post conversion) */

#ifdef HAVE_ERROR_CHECKING

    {

        MPID_BEGIN_ERROR_CHECKS;

        {

            /* Validate comm_ptr */

            MPIR_Comm_valid_ptr(comm_ptr1, mpi_errno, TRUE);

            if (mpi_errno)

                goto fn_fail;

            MPIR_Comm_valid_ptr(comm_ptr2, mpi_errno, TRUE);

            if (mpi_errno)

                goto fn_fail;

            MPIR_ERRTEST_ARGNULL(result, "result", mpi_errno);

        }

        MPID_END_ERROR_CHECKS;

    }

#endif /* HAVE_ERROR_CHECKING */

    /* ... body of routine ...  */

    if (comm_ptr1->comm_kind != comm_ptr2->comm_kind) {

        *result = MPI_UNEQUAL;

    } else if (comm1 == comm2) {

        *result = MPI_IDENT;

    } else if (comm_ptr1->comm_kind == MPIR_COMM_KIND__INTRACOMM) {

        MPIR_Group *group_ptr1, *group_ptr2;

        mpi_errno = MPIR_Comm_group_impl(comm_ptr1, &group_ptr1);

        if (mpi_errno)

            MPIR_ERR_POP(mpi_errno);

        mpi_errno = MPIR_Comm_group_impl(comm_ptr2, &group_ptr2);

        if (mpi_errno)

            MPIR_ERR_POP(mpi_errno);

        mpi_errno = MPIR_Group_compare_impl(group_ptr1, group_ptr2, result);

        if (mpi_errno)

            MPIR_ERR_POP(mpi_errno);

        /* If the groups are the same but the contexts are different, then

         * the communicators are congruent */

        if (*result == MPI_IDENT)

            *result = MPI_CONGRUENT;

        mpi_errno = MPIR_Group_free_impl(group_ptr1);

        if (mpi_errno)

            MPIR_ERR_POP(mpi_errno);

        mpi_errno = MPIR_Group_free_impl(group_ptr2);

        if (mpi_errno)

            MPIR_ERR_POP(mpi_errno);

    } else {

        /* INTER_COMM */

        int lresult, rresult;

        MPIR_Group *group_ptr1, *group_ptr2;

        MPIR_Group *rgroup_ptr1, *rgroup_ptr2;

        /* Get the groups and see what their relationship is */

        mpi_errno = MPIR_Comm_group_impl(comm_ptr1, &group_ptr1);

        if (mpi_errno)

            MPIR_ERR_POP(mpi_errno);

        mpi_errno = MPIR_Comm_group_impl(comm_ptr2, &group_ptr2);

        if (mpi_errno)

            MPIR_ERR_POP(mpi_errno);

        mpi_errno = MPIR_Group_compare_impl(group_ptr1, group_ptr2, &lresult);

        if (mpi_errno)

            MPIR_ERR_POP(mpi_errno);

        mpi_errno = MPIR_Comm_remote_group_impl(comm_ptr1, &rgroup_ptr1);

        if (mpi_errno)

            MPIR_ERR_POP(mpi_errno);

        mpi_errno = MPIR_Comm_remote_group_impl(comm_ptr2, &rgroup_ptr2);

        if (mpi_errno)

            MPIR_ERR_POP(mpi_errno);

        mpi_errno = MPIR_Group_compare_impl(rgroup_ptr1, rgroup_ptr2, &rresult);

        if (mpi_errno)

            MPIR_ERR_POP(mpi_errno);

        /* Choose the result that is "least" strong. This works

         * due to the ordering of result types in mpi.h */

        (*result) = (rresult > lresult) ? rresult : lresult;

        /* They can't be identical since they're not the same

         * handle, they are congruent instead */

        if ((*result) == MPI_IDENT)

            (*result) = MPI_CONGRUENT;

        /* Free the groups */

        mpi_errno = MPIR_Group_free_impl(group_ptr1);

        if (mpi_errno)

            MPIR_ERR_POP(mpi_errno);

        mpi_errno = MPIR_Group_free_impl(group_ptr2);

        if (mpi_errno)

            MPIR_ERR_POP(mpi_errno);

        mpi_errno = MPIR_Group_free_impl(rgroup_ptr1);

        if (mpi_errno)

            MPIR_ERR_POP(mpi_errno);

        mpi_errno = MPIR_Group_free_impl(rgroup_ptr2);

        if (mpi_errno)

            MPIR_ERR_POP(mpi_errno);

    }

    /* ... end of body of routine ... */

  fn_exit:

    MPIR_FUNC_TERSE_EXIT(MPID_STATE_MPI_COMM_COMPARE);

    MPID_THREAD_CS_EXIT(GLOBAL, MPIR_THREAD_GLOBAL_ALLFUNC_MUTEX);

    return mpi_errno;

    /* --BEGIN ERROR HANDLING-- */

  fn_fail:

#ifdef HAVE_ERROR_CHECKING

    {

        mpi_errno =

            MPIR_Err_create_code(mpi_errno, MPIR_ERR_RECOVERABLE, FCNAME, __LINE__, MPI_ERR_OTHER,

                                 "**mpi_comm_compare", "**mpi_comm_compare %C %C %p", comm1, comm2,

                                 result);

    }

    /* Use whichever communicator is non-null if possible */

#endif

    mpi_errno = MPIR_Err_return_comm(comm_ptr1 ? comm_ptr1 : comm_ptr2, FCNAME, mpi_errno);

    goto fn_exit;

    /* --END ERROR HANDLING-- */

}