text: /* Copyright 2007-2009 IPB, Universite de Bordeaux, INRIA & CNRS
  **
  ** This file is part of the Scotch software package for static mapping,
  ** graph partitioning and sparse matrix ordering.
  **
  ** This software is governed by the CeCILL-C license under French law
  ** and abiding by the rules of distribution of free software. You can
  ** use, modify and/or redistribute the software under the terms of the
  ** CeCILL-C license as circulated by CEA, CNRS and INRIA at the following
  ** URL: "http://www.cecill.info".
  ** 
  ** As a counterpart to the access to the source code and rights to copy,
  ** modify and redistribute granted by the license, users are provided
  ** only with a limited warranty and the software's author, the holder of
  ** the economic rights, and the successive licensors have only limited
  ** liability.
  ** 
  ** In this respect, the user's attention is drawn to the risks associated
  ** with loading, using, modifying and/or developing or reproducing the
  ** software by the user in light of its specific status of free software,
  ** that may mean that it is complicated to manipulate, and that also
  ** therefore means that it is reserved for developers and experienced
  ** professionals having in-depth computer knowledge. Users are therefore
  ** encouraged to load and test the software's suitability as regards
  ** their requirements in conditions enabling the security of their
  ** systems and/or data to be ensured and, more generally, to use and
  ** operate it in the same conditions as regards security.
  ** 
  ** The fact that you are presently reading this means that you have had
  ** knowledge of the CeCILL-C license and that you accept its terms.
  */
  /************************************************************/
  /**                                                        **/
  /**   NAME       : dgraph_fold_dup.c                       **/
  /**                                                        **/
  /**   AUTHOR     : Francois PELLEGRINI                     **/
  /**                                                        **/
  /**   FUNCTION   : This module folds a distributed graph   **/
  /**                into two distinct copies, which may     **/
  /**                be different when the number of         **/
  /**                processes is odd.                       **/
  /**                                                        **/
  /**   DATES      : # Version 5.0  : from : 10 aug 2006     **/
  /**                                 to   : 20 jun 2007     **/
  /**                # Version 5.1  : from : 14 nov 2008     **/
  /**                                 to   : 28 oct 2009     **/
  /**                # Version 6.0  : from : 28 sep 2014     **/
  /**                                 to   : 28 sep 2014     **/
  /**                                                        **/
  /************************************************************/
  
  #define DGRAPH
  #define DGRAPH_FOLD_DUP
  
  #include "module.h"
  #include "common.h"
  #include "dgraph.h"
  #include "dgraph_fold_dup.h"
  
  /******************************/
  /*                            */
  /* This routine handles       */
  /* distributed source graphs. */
  /*                            */
  /******************************/
  
  /* This routine builds two folded graphs of
  ** a given graph on each of the two halves
  ** of the processes. The number of processes
  ** does not need to be even. There is a
  ** multi-threaded version, as well as a
  ** sequential one.
  ** It returns:
  ** - 0   : on success.
  ** - !0  : on error.
  */
  
  #ifdef SCOTCH_PTHREAD
  static
  void *
  dgraphFoldDup2 (
  void * const                    dataptr)          /* Pointer to thread data */
  {
    DgraphFoldDupData *             fldthrdptr;
  
    fldthrdptr = (DgraphFoldDupData *) dataptr;
  
    return ((void *) (intptr_t) dgraphFold2 (fldthrdptr->orggrafptr, fldthrdptr->partval, fldthrdptr->fldgrafptr,
                                             fldthrdptr->fldproccomm, fldthrdptr->orgdataptr,
                                             fldthrdptr->flddataptr, fldthrdptr->datatype));
  }
  #endif /* SCOTCH_PTHREAD */
  
  int
  dgraphFoldDup (
  const Dgraph * RESTRICT const orggrafptr,
  Dgraph * RESTRICT const       fldgrafptr,
  void * RESTRICT const         orgdataptr,         /* Un-based array of data which must be folded, e.g. coarmulttab */
  void ** RESTRICT const        flddataptr,         /* Un-based array of data which must be folded, e.g. coarmulttab */
  MPI_Datatype                  datatype)
  {
    int                       fldprocnbr;
    int                       fldprocnum;
    int                       fldproccol;
    MPI_Comm                  fldproccommtab[2];
  #ifdef SCOTCH_PTHREAD
    Dgraph                    orggrafdat;
    DgraphFoldDupData         fldthrdtab[2];
    pthread_t                 thrdval;              /* Data of second thread */
  #endif /* SCOTCH_PTHREAD */
    int                       o;
  
    fldprocnbr = (orggrafptr->procglbnbr + 1) / 2;  /* Median cut on number of processors     */
    if (orggrafptr->proclocnum < fldprocnbr) {      /* Compute color and rank in two subparts */
      fldproccol = 0;
      fldprocnum = orggrafptr->proclocnum;
      fldproccommtab[1] = MPI_COMM_NULL;
    }
    else {
      fldproccol = 1;
      fldprocnum = orggrafptr->proclocnum - fldprocnbr;
      fldproccommtab[0] = MPI_COMM_NULL;
    }
    if (MPI_Comm_split (orggrafptr->proccomm, fldproccol, fldprocnum, &fldproccommtab[fldproccol]) != MPI_SUCCESS) {
      errorPrint  ("dgraphFoldDup: communication error (1)");
      return      (1);
    }
  
  #ifdef SCOTCH_PTHREAD
    orggrafdat = *orggrafptr;                       /* Create a separate graph structure to change its communicator */
  
    fldthrdtab[0].orggrafptr  = orggrafptr;
    fldthrdtab[0].fldgrafptr  = fldgrafptr;
    fldthrdtab[0].fldproccomm = fldproccommtab[0];
    fldthrdtab[0].partval     = 0;
    fldthrdtab[0].orgdataptr  = orgdataptr;
    fldthrdtab[0].flddataptr  = flddataptr;
    fldthrdtab[0].datatype    = datatype;
    fldthrdtab[1].orggrafptr  = &orggrafdat;
    fldthrdtab[1].fldgrafptr  = fldgrafptr;
    fldthrdtab[1].fldproccomm = fldproccommtab[1];
    fldthrdtab[1].partval     = 1;
    fldthrdtab[1].orgdataptr  = orgdataptr;
    fldthrdtab[1].flddataptr  = flddataptr;
    fldthrdtab[1].datatype    = datatype;
  
    if (MPI_Comm_dup (orggrafptr->proccomm, &orggrafdat.proccomm) != MPI_SUCCESS) { /* Duplicate communicator to avoid interferences in communications */
      errorPrint ("dgraphFoldDup: communication error (2)");
      return     (1);
    }
  
    if (pthread_create (&thrdval, NULL, dgraphFoldDup2, (void *) &fldthrdtab[1]) != 0) /* If could not create thread */
      o = (int) (intptr_t) dgraphFold2 (orggrafptr, 0, fldgrafptr, fldproccommtab[0], orgdataptr, flddataptr, datatype) || /* Call routines in sequence */
          (int) (intptr_t) dgraphFold2 (orggrafptr, 1, fldgrafptr, fldproccommtab[1], orgdataptr, flddataptr, datatype);
    else {                                          /* Newly created thread is processing subgraph 1, so let's process subgraph 0 */
      void *                    o2;
  
      o = (int) (intptr_t) dgraphFoldDup2 ((void *) &fldthrdtab[0]); /* Work on copy with private communicator */
  
      pthread_join (thrdval, &o2);
      o |= (int) (intptr_t) o2;
    }
    MPI_Comm_free (&orggrafdat.proccomm);
  
  #else /* SCOTCH_PTHREAD */
    o = (dgraphFold2 (orggrafptr, 0, fldgrafptr, fldproccommtab[0], orgdataptr, flddataptr, datatype) || /* Call routines in sequence */
         dgraphFold2 (orggrafptr, 1, fldgrafptr, fldproccommtab[1], orgdataptr, flddataptr, datatype));
  #endif /* SCOTCH_PTHREAD */
  
    fldgrafptr->prockeyval = fldproccol;            /* Discriminate between folded communicators at same level */
  
    return (o);
  }
  