1 /* Copyright 2007,2012 IPB, Universite de Bordeaux, INRIA & CNRS
2 **
3 ** This file is part of the Scotch software package for static mapping,
4 ** graph partitioning and sparse matrix ordering.
5 **
6 ** This software is governed by the CeCILL-C license under French law
7 ** and abiding by the rules of distribution of free software. You can
8 ** use, modify and/or redistribute the software under the terms of the
9 ** CeCILL-C license as circulated by CEA, CNRS and INRIA at the following
10 ** URL: "http://www.cecill.info".
11 **
12 ** As a counterpart to the access to the source code and rights to copy,
13 ** modify and redistribute granted by the license, users are provided
14 ** only with a limited warranty and the software's author, the holder of
15 ** the economic rights, and the successive licensors have only limited
16 ** liability.
17 **
18 ** In this respect, the user's attention is drawn to the risks associated
19 ** with loading, using, modifying and/or developing or reproducing the
20 ** software by the user in light of its specific status of free software,
21 ** that may mean that it is complicated to manipulate, and that also
22 ** therefore means that it is reserved for developers and experienced
23 ** professionals having in-depth computer knowledge. Users are therefore
24 ** encouraged to load and test the software's suitability as regards
25 ** their requirements in conditions enabling the security of their
26 ** systems and/or data to be ensured and, more generally, to use and
27 ** operate it in the same conditions as regards security.
28 **
29 ** The fact that you are presently reading this means that you have had
30 ** knowledge of the CeCILL-C license and that you accept its terms.
31 */
32 /************************************************************/
33 /** **/
34 /** NAME : library_dgraph_gather.c **/
35 /** **/
36 /** AUTHOR : Francois PELLEGRINI **/
37 /** **/
38 /** FUNCTION : This module is the API for the distri- **/
39 /** buted source graph handling routines of **/
40 /** the libSCOTCH library. **/
41 /** **/
42 /** DATES : # Version 5.0 : from : 12 jul 2007 **/
43 /** to 17 jul 2007 **/
44 /** # Version 6.0 : from : 29 nov 2012 **/
45 /** to 29 nov 2012 **/
46 /** **/
47 /************************************************************/
48
49 /*
50 ** The defines and includes.
51 */
52
53 #define LIBRARY
54
55 #include "module.h"
56 #include "common.h"
57 #include "graph.h"
58 #include "dgraph.h"
59 #include "ptscotch.h"
60
61 /************************************/
62 /* */
63 /* These routines are the C API for */
64 /* the graph handling routines. */
65 /* */
66 /************************************/
67
68 /*+ This routine gathers the data of a
69 *** distributed graph on a centralized graph.
70 *** It returns:
71 *** - 0 : if the centralization succeeded.
72 *** - !0 : on error.
73 +*/
74
75 int
SCOTCH_dgraphGather(const SCOTCH_Dgraph * const dgrfptr,SCOTCH_Graph * const cgrfptr)76 SCOTCH_dgraphGather (
77 const SCOTCH_Dgraph * const dgrfptr,
78 SCOTCH_Graph * const cgrfptr)
79 {
80 Dgraph * restrict srcdgrfptr;
81 Gnum reduloctab[3];
82 Gnum reduglbtab[3];
83
84 srcdgrfptr = (Dgraph *) dgrfptr;
85
86 if ((cgrfptr != NULL) && (((void *) cgrfptr) != ((void *) dgrfptr))) { /* If centralized graph provided */
87 reduloctab[0] = 1; /* Process is a potential root */
88 reduloctab[1] = (Gnum) srcdgrfptr->proclocnum;
89 }
90 else { /* Process is not a root */
91 reduloctab[0] = 0;
92 reduloctab[1] = 0;
93 }
94
95 if (srcdgrfptr->edloloctax == NULL) /* Compute sum of edge loads for access to low-level routines */
96 reduloctab[2] = srcdgrfptr->edgelocnbr;
97 else {
98 Gnum vertlocnum;
99 Gnum edlolocsum;
100
101 for (vertlocnum = srcdgrfptr->baseval, edlolocsum = 0;
102 vertlocnum < srcdgrfptr->vertlocnnd; vertlocnum ++) {
103 Gnum edgelocnum;
104 Gnum edgelocnnd;
105
106 for (edgelocnum = srcdgrfptr->vertloctax[vertlocnum],
107 edgelocnnd = srcdgrfptr->vendloctax[vertlocnum];
108 edgelocnum < edgelocnnd; edgelocnum ++)
109 edlolocsum += srcdgrfptr->edloloctax[edgelocnum];
110 }
111 reduloctab[2] = edlolocsum;
112 }
113
114 if (MPI_Allreduce (reduloctab, reduglbtab, 3, GNUM_MPI, MPI_SUM, srcdgrfptr->proccomm) != MPI_SUCCESS) {
115 errorPrint ("SCOTCH_dgraphGather: communication error");
116 return (1);
117 }
118 if (reduglbtab[0] == 1) /* If only one single root */
119 return (dgraphGatherAll2 (srcdgrfptr, (Graph *) cgrfptr, reduglbtab[2], (int) reduglbtab[1]));
120 else if (reduglbtab[0] == srcdgrfptr->procglbnbr) /* If all processes are roots */
121 return (dgraphGatherAll2 (srcdgrfptr, (Graph *) cgrfptr, reduglbtab[2], -1));
122
123 errorPrint ("SCOTCH_dgraphGather: invalid number of roots");
124 return (1);
125 }
126