Actual source code: sf.c

petsc-3.10.4 2019-02-26
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  1:  #include <petsc/private/sfimpl.h>
  2:  #include <petscctable.h>

  4: #if defined(PETSC_USE_DEBUG)
  5: #  define PetscSFCheckGraphSet(sf,arg) do {                          \
  6:     if (PetscUnlikely(!(sf)->graphset))                              \
  7:       SETERRQ3(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"Must call PetscSFSetGraph() on argument %D \"%s\" before %s()",(arg),#sf,PETSC_FUNCTION_NAME); \
  8:   } while (0)
  9: #else
 10: #  define PetscSFCheckGraphSet(sf,arg) do {} while (0)
 11: #endif

 13: const char *const PetscSFDuplicateOptions[] = {"CONFONLY","RANKS","GRAPH","PetscSFDuplicateOption","PETSCSF_DUPLICATE_",0};

 15: /*@
 16:    PetscSFCreate - create a star forest communication context

 18:    Collective on MPI_Comm

 20:    Input Arguments:
 21: .  comm - communicator on which the star forest will operate

 23:    Output Arguments:
 24: .  sf - new star forest context

 26:    Level: intermediate

 28: .seealso: PetscSFSetGraph(), PetscSFDestroy()
 29: @*/
 30: PetscErrorCode PetscSFCreate(MPI_Comm comm,PetscSF *sf)
 31: {
 33:   PetscSF        b;

 37:   PetscSFInitializePackage();

 39:   PetscHeaderCreate(b,PETSCSF_CLASSID,"PetscSF","Star Forest","PetscSF",comm,PetscSFDestroy,PetscSFView);

 41:   b->nroots    = -1;
 42:   b->nleaves   = -1;
 43:   b->minleaf   = PETSC_MAX_INT;
 44:   b->maxleaf   = PETSC_MIN_INT;
 45:   b->nranks    = -1;
 46:   b->rankorder = PETSC_TRUE;
 47:   b->ingroup   = MPI_GROUP_NULL;
 48:   b->outgroup  = MPI_GROUP_NULL;
 49:   b->graphset  = PETSC_FALSE;

 51:   *sf = b;
 52:   return(0);
 53: }

 55: /*@
 56:    PetscSFReset - Reset a star forest so that different sizes or neighbors can be used

 58:    Collective

 60:    Input Arguments:
 61: .  sf - star forest

 63:    Level: advanced

 65: .seealso: PetscSFCreate(), PetscSFSetGraph(), PetscSFDestroy()
 66: @*/
 67: PetscErrorCode PetscSFReset(PetscSF sf)
 68: {

 73:   if (sf->ops->Reset) {(*sf->ops->Reset)(sf);}
 74:   sf->nroots   = -1;
 75:   sf->nleaves  = -1;
 76:   sf->minleaf  = PETSC_MAX_INT;
 77:   sf->maxleaf  = PETSC_MIN_INT;
 78:   sf->mine     = NULL;
 79:   sf->remote   = NULL;
 80:   sf->graphset = PETSC_FALSE;
 81:   PetscFree(sf->mine_alloc);
 82:   PetscFree(sf->remote_alloc);
 83:   sf->nranks = -1;
 84:   PetscFree4(sf->ranks,sf->roffset,sf->rmine,sf->rremote);
 85:   sf->degreeknown = PETSC_FALSE;
 86:   PetscFree(sf->degree);
 87:   if (sf->ingroup  != MPI_GROUP_NULL) {MPI_Group_free(&sf->ingroup);}
 88:   if (sf->outgroup != MPI_GROUP_NULL) {MPI_Group_free(&sf->outgroup);}
 89:   PetscSFDestroy(&sf->multi);
 90:   sf->setupcalled = PETSC_FALSE;
 91:   return(0);
 92: }

 94: /*@C
 95:    PetscSFSetType - Set the PetscSF communication implementation

 97:    Collective on PetscSF

 99:    Input Parameters:
100: +  sf - the PetscSF context
101: -  type - a known method

103:    Options Database Key:
104: .  -sf_type <type> - Sets the method; use -help for a list
105:    of available methods (for instance, window, pt2pt, neighbor)

107:    Notes:
108:    See "include/petscsf.h" for available methods (for instance)
109: +    PETSCSFWINDOW - MPI-2/3 one-sided
110: -    PETSCSFBASIC - basic implementation using MPI-1 two-sided

112:   Level: intermediate

114: .keywords: PetscSF, set, type

116: .seealso: PetscSFType, PetscSFCreate()
117: @*/
118: PetscErrorCode PetscSFSetType(PetscSF sf,PetscSFType type)
119: {
120:   PetscErrorCode ierr,(*r)(PetscSF);
121:   PetscBool      match;


127:   PetscObjectTypeCompare((PetscObject)sf,type,&match);
128:   if (match) return(0);

130:   PetscFunctionListFind(PetscSFList,type,&r);
131:   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested PetscSF type %s",type);
132:   /* Destroy the previous PetscSF implementation context */
133:   if (sf->ops->Destroy) {(*(sf)->ops->Destroy)(sf);}
134:   PetscMemzero(sf->ops,sizeof(*sf->ops));
135:   PetscObjectChangeTypeName((PetscObject)sf,type);
136:   (*r)(sf);
137:   return(0);
138: }

140: /*@C
141:   PetscSFGetType - Get the PetscSF communication implementation

143:   Not Collective

145:   Input Parameter:
146: . sf  - the PetscSF context

148:   Output Parameter:
149: . type - the PetscSF type name

151:   Level: intermediate

153: .keywords: PetscSF, get, type
154: .seealso: PetscSFSetType(), PetscSFCreate()
155: @*/
156: PetscErrorCode PetscSFGetType(PetscSF sf, PetscSFType *type)
157: {
161:   *type = ((PetscObject)sf)->type_name;
162:   return(0);
163: }

165: /*@
166:    PetscSFDestroy - destroy star forest

168:    Collective

170:    Input Arguments:
171: .  sf - address of star forest

173:    Level: intermediate

175: .seealso: PetscSFCreate(), PetscSFReset()
176: @*/
177: PetscErrorCode PetscSFDestroy(PetscSF *sf)
178: {

182:   if (!*sf) return(0);
184:   if (--((PetscObject)(*sf))->refct > 0) {*sf = NULL; return(0);}
185:   PetscSFReset(*sf);
186:   if ((*sf)->ops->Destroy) {(*(*sf)->ops->Destroy)(*sf);}
187:   PetscHeaderDestroy(sf);
188:   return(0);
189: }

191: /*@
192:    PetscSFSetUp - set up communication structures

194:    Collective

196:    Input Arguments:
197: .  sf - star forest communication object

199:    Level: beginner

201: .seealso: PetscSFSetFromOptions(), PetscSFSetType()
202: @*/
203: PetscErrorCode PetscSFSetUp(PetscSF sf)
204: {

209:   PetscSFCheckGraphSet(sf,1);
210:   if (sf->setupcalled) return(0);
211:   if (!((PetscObject)sf)->type_name) {PetscSFSetType(sf,PETSCSFBASIC);}
212:   PetscLogEventBegin(PETSCSF_SetUp,sf,0,0,0);
213:   if (sf->ops->SetUp) {(*sf->ops->SetUp)(sf);}
214:   PetscLogEventEnd(PETSCSF_SetUp,sf,0,0,0);
215:   sf->setupcalled = PETSC_TRUE;
216:   return(0);
217: }

219: /*@
220:    PetscSFSetFromOptions - set PetscSF options using the options database

222:    Logically Collective

224:    Input Arguments:
225: .  sf - star forest

227:    Options Database Keys:
228: +  -sf_type - implementation type, see PetscSFSetType()
229: -  -sf_rank_order - sort composite points for gathers and scatters in rank order, gathers are non-deterministic otherwise

231:    Level: intermediate

233: .keywords: KSP, set, from, options, database

235: .seealso: PetscSFWindowSetSyncType()
236: @*/
237: PetscErrorCode PetscSFSetFromOptions(PetscSF sf)
238: {
239:   PetscSFType    deft;
240:   char           type[256];
242:   PetscBool      flg;

246:   PetscObjectOptionsBegin((PetscObject)sf);
247:   deft = ((PetscObject)sf)->type_name ? ((PetscObject)sf)->type_name : PETSCSFBASIC;
248:   PetscOptionsFList("-sf_type","PetscSF implementation type","PetscSFSetType",PetscSFList,deft,type,sizeof(type),&flg);
249:   PetscSFSetType(sf,flg ? type : deft);
250:   PetscOptionsBool("-sf_rank_order","sort composite points for gathers and scatters in rank order, gathers are non-deterministic otherwise","PetscSFSetRankOrder",sf->rankorder,&sf->rankorder,NULL);
251:   if (sf->ops->SetFromOptions) {(*sf->ops->SetFromOptions)(PetscOptionsObject,sf);}
252:   PetscOptionsEnd();
253:   return(0);
254: }

256: /*@
257:    PetscSFSetRankOrder - sort multi-points for gathers and scatters by rank order

259:    Logically Collective

261:    Input Arguments:
262: +  sf - star forest
263: -  flg - PETSC_TRUE to sort, PETSC_FALSE to skip sorting (lower setup cost, but non-deterministic)

265:    Level: advanced

267: .seealso: PetscSFGatherBegin(), PetscSFScatterBegin()
268: @*/
269: PetscErrorCode PetscSFSetRankOrder(PetscSF sf,PetscBool flg)
270: {

275:   if (sf->multi) SETERRQ(PetscObjectComm((PetscObject)sf),PETSC_ERR_ARG_WRONGSTATE,"Rank ordering must be set before first call to PetscSFGatherBegin() or PetscSFScatterBegin()");
276:   sf->rankorder = flg;
277:   return(0);
278: }

280: /*@
281:    PetscSFSetGraph - Set a parallel star forest

283:    Collective

285:    Input Arguments:
286: +  sf - star forest
287: .  nroots - number of root vertices on the current process (these are possible targets for other process to attach leaves)
288: .  nleaves - number of leaf vertices on the current process, each of these references a root on any process
289: .  ilocal - locations of leaves in leafdata buffers, pass NULL for contiguous storage
290: .  localmode - copy mode for ilocal
291: .  iremote - remote locations of root vertices for each leaf on the current process
292: -  remotemode - copy mode for iremote

294:    Level: intermediate

296:    Notes:
297:     In Fortran you must use PETSC_COPY_VALUES for localmode and remotemode

299:    Developers Note: Local indices which are the identity permutation in the range [0,nleaves) are discarded as they
300:    encode contiguous storage. In such case, if localmode is PETSC_OWN_POINTER, the memory is deallocated as it is not
301:    needed

303: .seealso: PetscSFCreate(), PetscSFView(), PetscSFGetGraph()
304: @*/
305: PetscErrorCode PetscSFSetGraph(PetscSF sf,PetscInt nroots,PetscInt nleaves,const PetscInt *ilocal,PetscCopyMode localmode,const PetscSFNode *iremote,PetscCopyMode remotemode)
306: {

313:   if (nroots  < 0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"nroots %D, cannot be negative",nroots);
314:   if (nleaves < 0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"nleaves %D, cannot be negative",nleaves);

316:   PetscSFReset(sf);
317:   PetscLogEventBegin(PETSCSF_SetGraph,sf,0,0,0);

319:   sf->nroots  = nroots;
320:   sf->nleaves = nleaves;

322:   if (nleaves && ilocal) {
323:     PetscInt i;
324:     PetscInt minleaf = PETSC_MAX_INT;
325:     PetscInt maxleaf = PETSC_MIN_INT;
326:     int      contiguous = 1;
327:     for (i=0; i<nleaves; i++) {
328:       minleaf = PetscMin(minleaf,ilocal[i]);
329:       maxleaf = PetscMax(maxleaf,ilocal[i]);
330:       contiguous &= (ilocal[i] == i);
331:     }
332:     sf->minleaf = minleaf;
333:     sf->maxleaf = maxleaf;
334:     if (contiguous) {
335:       if (localmode == PETSC_OWN_POINTER) {
336:         PetscFree(ilocal);
337:       }
338:       ilocal = NULL;
339:     }
340:   } else {
341:     sf->minleaf = 0;
342:     sf->maxleaf = nleaves - 1;
343:   }

345:   if (ilocal) {
346:     switch (localmode) {
347:     case PETSC_COPY_VALUES:
348:       PetscMalloc1(nleaves,&sf->mine_alloc);
349:       PetscMemcpy(sf->mine_alloc,ilocal,nleaves*sizeof(*ilocal));
350:       sf->mine = sf->mine_alloc;
351:       break;
352:     case PETSC_OWN_POINTER:
353:       sf->mine_alloc = (PetscInt*)ilocal;
354:       sf->mine       = sf->mine_alloc;
355:       break;
356:     case PETSC_USE_POINTER:
357:       sf->mine_alloc = NULL;
358:       sf->mine       = (PetscInt*)ilocal;
359:       break;
360:     default: SETERRQ(PetscObjectComm((PetscObject)sf),PETSC_ERR_ARG_OUTOFRANGE,"Unknown localmode");
361:     }
362:   }

364:   switch (remotemode) {
365:   case PETSC_COPY_VALUES:
366:     PetscMalloc1(nleaves,&sf->remote_alloc);
367:     PetscMemcpy(sf->remote_alloc,iremote,nleaves*sizeof(*iremote));
368:     sf->remote = sf->remote_alloc;
369:     break;
370:   case PETSC_OWN_POINTER:
371:     sf->remote_alloc = (PetscSFNode*)iremote;
372:     sf->remote       = sf->remote_alloc;
373:     break;
374:   case PETSC_USE_POINTER:
375:     sf->remote_alloc = NULL;
376:     sf->remote       = (PetscSFNode*)iremote;
377:     break;
378:   default: SETERRQ(PetscObjectComm((PetscObject)sf),PETSC_ERR_ARG_OUTOFRANGE,"Unknown remotemode");
379:   }

381:   PetscLogEventEnd(PETSCSF_SetGraph,sf,0,0,0);
382:   sf->graphset = PETSC_TRUE;
383:   return(0);
384: }

386: /*@
387:    PetscSFCreateInverseSF - given a PetscSF in which all vertices have degree 1, creates the inverse map

389:    Collective

391:    Input Arguments:
392: .  sf - star forest to invert

394:    Output Arguments:
395: .  isf - inverse of sf

397:    Level: advanced

399:    Notes:
400:    All roots must have degree 1.

402:    The local space may be a permutation, but cannot be sparse.

404: .seealso: PetscSFSetGraph()
405: @*/
406: PetscErrorCode PetscSFCreateInverseSF(PetscSF sf,PetscSF *isf)
407: {
409:   PetscMPIInt    rank;
410:   PetscInt       i,nroots,nleaves,maxlocal,count,*newilocal;
411:   const PetscInt *ilocal;
412:   PetscSFNode    *roots,*leaves;

416:   PetscSFCheckGraphSet(sf,1);

419:   PetscSFGetGraph(sf,&nroots,&nleaves,&ilocal,NULL);
420:   maxlocal = sf->maxleaf+1; /* TODO: We should use PetscSFGetLeafRange() */

422:   MPI_Comm_rank(PetscObjectComm((PetscObject)sf),&rank);
423:   PetscMalloc2(nroots,&roots,maxlocal,&leaves);
424:   for (i=0; i<maxlocal; i++) {
425:     leaves[i].rank  = rank;
426:     leaves[i].index = i;
427:   }
428:   for (i=0; i <nroots; i++) {
429:     roots[i].rank  = -1;
430:     roots[i].index = -1;
431:   }
432:   PetscSFReduceBegin(sf,MPIU_2INT,leaves,roots,MPIU_REPLACE);
433:   PetscSFReduceEnd(sf,MPIU_2INT,leaves,roots,MPIU_REPLACE);

435:   /* Check whether our leaves are sparse */
436:   for (i=0,count=0; i<nroots; i++) if (roots[i].rank >= 0) count++;
437:   if (count == nroots) newilocal = NULL;
438:   else {                        /* Index for sparse leaves and compact "roots" array (which is to become our leaves). */
439:     PetscMalloc1(count,&newilocal);
440:     for (i=0,count=0; i<nroots; i++) {
441:       if (roots[i].rank >= 0) {
442:         newilocal[count]   = i;
443:         roots[count].rank  = roots[i].rank;
444:         roots[count].index = roots[i].index;
445:         count++;
446:       }
447:     }
448:   }

450:   PetscSFDuplicate(sf,PETSCSF_DUPLICATE_CONFONLY,isf);
451:   PetscSFSetGraph(*isf,maxlocal,count,newilocal,PETSC_OWN_POINTER,roots,PETSC_COPY_VALUES);
452:   PetscFree2(roots,leaves);
453:   return(0);
454: }

456: /*@
457:    PetscSFDuplicate - duplicate a PetscSF, optionally preserving rank connectivity and graph

459:    Collective

461:    Input Arguments:
462: +  sf - communication object to duplicate
463: -  opt - PETSCSF_DUPLICATE_CONFONLY, PETSCSF_DUPLICATE_RANKS, or PETSCSF_DUPLICATE_GRAPH (see PetscSFDuplicateOption)

465:    Output Arguments:
466: .  newsf - new communication object

468:    Level: beginner

470: .seealso: PetscSFCreate(), PetscSFSetType(), PetscSFSetGraph()
471: @*/
472: PetscErrorCode PetscSFDuplicate(PetscSF sf,PetscSFDuplicateOption opt,PetscSF *newsf)
473: {
474:   PetscSFType    type;

481:   PetscSFCreate(PetscObjectComm((PetscObject)sf),newsf);
482:   PetscSFGetType(sf,&type);
483:   if (type) {PetscSFSetType(*newsf,type);}
484:   if (opt == PETSCSF_DUPLICATE_GRAPH) {
485:     PetscInt          nroots,nleaves;
486:     const PetscInt    *ilocal;
487:     const PetscSFNode *iremote;
488:     PetscSFCheckGraphSet(sf,1);
489:     PetscSFGetGraph(sf,&nroots,&nleaves,&ilocal,&iremote);
490:     PetscSFSetGraph(*newsf,nroots,nleaves,ilocal,PETSC_COPY_VALUES,iremote,PETSC_COPY_VALUES);
491:   }
492:   if (sf->ops->Duplicate) {(*sf->ops->Duplicate)(sf,opt,*newsf);}
493:   return(0);
494: }

496: /*@C
497:    PetscSFGetGraph - Get the graph specifying a parallel star forest

499:    Not Collective

501:    Input Arguments:
502: .  sf - star forest

504:    Output Arguments:
505: +  nroots - number of root vertices on the current process (these are possible targets for other process to attach leaves)
506: .  nleaves - number of leaf vertices on the current process, each of these references a root on any process
507: .  ilocal - locations of leaves in leafdata buffers
508: -  iremote - remote locations of root vertices for each leaf on the current process

510:    Notes:
511:    We are not currently requiring that the graph is set, thus returning nroots=-1 if it has not been set yet

513:    Level: intermediate

515: .seealso: PetscSFCreate(), PetscSFView(), PetscSFSetGraph()
516: @*/
517: PetscErrorCode PetscSFGetGraph(PetscSF sf,PetscInt *nroots,PetscInt *nleaves,const PetscInt **ilocal,const PetscSFNode **iremote)
518: {

522:   if (nroots) *nroots = sf->nroots;
523:   if (nleaves) *nleaves = sf->nleaves;
524:   if (ilocal) *ilocal = sf->mine;
525:   if (iremote) *iremote = sf->remote;
526:   return(0);
527: }

529: /*@
530:    PetscSFGetLeafRange - Get the active leaf ranges

532:    Not Collective

534:    Input Arguments:
535: .  sf - star forest

537:    Output Arguments:
538: +  minleaf - minimum active leaf on this process
539: -  maxleaf - maximum active leaf on this process

541:    Level: developer

543: .seealso: PetscSFCreate(), PetscSFView(), PetscSFSetGraph(), PetscSFGetGraph()
544: @*/
545: PetscErrorCode PetscSFGetLeafRange(PetscSF sf,PetscInt *minleaf,PetscInt *maxleaf)
546: {

550:   PetscSFCheckGraphSet(sf,1);
551:   if (minleaf) *minleaf = sf->minleaf;
552:   if (maxleaf) *maxleaf = sf->maxleaf;
553:   return(0);
554: }

556: /*@C
557:    PetscSFView - view a star forest

559:    Collective

561:    Input Arguments:
562: +  sf - star forest
563: -  viewer - viewer to display graph, for example PETSC_VIEWER_STDOUT_WORLD

565:    Level: beginner

567: .seealso: PetscSFCreate(), PetscSFSetGraph()
568: @*/
569: PetscErrorCode PetscSFView(PetscSF sf,PetscViewer viewer)
570: {
571:   PetscErrorCode    ierr;
572:   PetscBool         iascii;
573:   PetscViewerFormat format;

577:   if (!viewer) {PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)sf),&viewer);}
580:   if (sf->graphset) {PetscSFSetUp(sf);}
581:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
582:   if (iascii) {
583:     PetscMPIInt rank;
584:     PetscInt    ii,i,j;

586:     PetscObjectPrintClassNamePrefixType((PetscObject)sf,viewer);
587:     PetscViewerASCIIPushTab(viewer);
588:     if (sf->ops->View) {(*sf->ops->View)(sf,viewer);}
589:     if (!sf->graphset) {
590:       PetscViewerASCIIPrintf(viewer,"PetscSFSetGraph() has not been called yet\n");
591:       PetscViewerASCIIPopTab(viewer);
592:       return(0);
593:     }
594:     MPI_Comm_rank(PetscObjectComm((PetscObject)sf),&rank);
595:     PetscViewerASCIIPushSynchronized(viewer);
596:     PetscViewerASCIISynchronizedPrintf(viewer,"[%d] Number of roots=%D, leaves=%D, remote ranks=%D\n",rank,sf->nroots,sf->nleaves,sf->nranks);
597:     for (i=0; i<sf->nleaves; i++) {
598:       PetscViewerASCIISynchronizedPrintf(viewer,"[%d] %D <- (%D,%D)\n",rank,sf->mine ? sf->mine[i] : i,sf->remote[i].rank,sf->remote[i].index);
599:     }
600:     PetscViewerFlush(viewer);
601:     PetscViewerGetFormat(viewer,&format);
602:     if (format == PETSC_VIEWER_ASCII_INFO_DETAIL) {
603:       PetscMPIInt *tmpranks,*perm;
604:       PetscMalloc2(sf->nranks,&tmpranks,sf->nranks,&perm);
605:       PetscMemcpy(tmpranks,sf->ranks,sf->nranks*sizeof(tmpranks[0]));
606:       for (i=0; i<sf->nranks; i++) perm[i] = i;
607:       PetscSortMPIIntWithArray(sf->nranks,tmpranks,perm);
608:       PetscViewerASCIISynchronizedPrintf(viewer,"[%d] Roots referenced by my leaves, by rank\n",rank);
609:       for (ii=0; ii<sf->nranks; ii++) {
610:         i = perm[ii];
611:         PetscViewerASCIISynchronizedPrintf(viewer,"[%d] %d: %D edges\n",rank,sf->ranks[i],sf->roffset[i+1]-sf->roffset[i]);
612:         for (j=sf->roffset[i]; j<sf->roffset[i+1]; j++) {
613:           PetscViewerASCIISynchronizedPrintf(viewer,"[%d]    %D <- %D\n",rank,sf->rmine[j],sf->rremote[j]);
614:         }
615:       }
616:       PetscFree2(tmpranks,perm);
617:     }
618:     PetscViewerFlush(viewer);
619:     PetscViewerASCIIPopSynchronized(viewer);
620:     PetscViewerASCIIPopTab(viewer);
621:   }
622:   return(0);
623: }

625: /*@C
626:    PetscSFGetRanks - Get ranks and number of vertices referenced by leaves on this process

628:    Not Collective

630:    Input Arguments:
631: .  sf - star forest

633:    Output Arguments:
634: +  nranks - number of ranks referenced by local part
635: .  ranks - array of ranks
636: .  roffset - offset in rmine/rremote for each rank (length nranks+1)
637: .  rmine - concatenated array holding local indices referencing each remote rank
638: -  rremote - concatenated array holding remote indices referenced for each remote rank

640:    Level: developer

642: .seealso: PetscSFSetGraph()
643: @*/
644: PetscErrorCode PetscSFGetRanks(PetscSF sf,PetscInt *nranks,const PetscMPIInt **ranks,const PetscInt **roffset,const PetscInt **rmine,const PetscInt **rremote)
645: {

649:   if (!sf->setupcalled) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"Must call PetscSFSetUp() before obtaining ranks");
650:   if (nranks)  *nranks  = sf->nranks;
651:   if (ranks)   *ranks   = sf->ranks;
652:   if (roffset) *roffset = sf->roffset;
653:   if (rmine)   *rmine   = sf->rmine;
654:   if (rremote) *rremote = sf->rremote;
655:   return(0);
656: }

658: static PetscBool InList(PetscMPIInt needle,PetscMPIInt n,const PetscMPIInt *list) {
659:   PetscInt i;
660:   for (i=0; i<n; i++) {
661:     if (needle == list[i]) return PETSC_TRUE;
662:   }
663:   return PETSC_FALSE;
664: }

666: /*@C
667:    PetscSFSetUpRanks - Set up data structures associated with ranks; this is for internal use by PetscSF implementations.

669:    Collective

671:    Input Arguments:
672: +  sf - PetscSF to set up; PetscSFSetGraph() must have been called
673: -  dgroup - MPI_Group of ranks to be distinguished (e.g., for self or shared memory exchange)

675:    Level: developer

677: .seealso: PetscSFGetRanks()
678: @*/
679: PetscErrorCode PetscSFSetUpRanks(PetscSF sf,MPI_Group dgroup)
680: {
681:   PetscErrorCode     ierr;
682:   PetscTable         table;
683:   PetscTablePosition pos;
684:   PetscMPIInt        size,groupsize,*groupranks;
685:   PetscInt           i,*rcount,*ranks;

689:   PetscSFCheckGraphSet(sf,1);
690:   MPI_Comm_size(PetscObjectComm((PetscObject)sf),&size);
691:   PetscTableCreate(10,size,&table);
692:   for (i=0; i<sf->nleaves; i++) {
693:     /* Log 1-based rank */
694:     PetscTableAdd(table,sf->remote[i].rank+1,1,ADD_VALUES);
695:   }
696:   PetscTableGetCount(table,&sf->nranks);
697:   PetscMalloc4(sf->nranks,&sf->ranks,sf->nranks+1,&sf->roffset,sf->nleaves,&sf->rmine,sf->nleaves,&sf->rremote);
698:   PetscMalloc2(sf->nranks,&rcount,sf->nranks,&ranks);
699:   PetscTableGetHeadPosition(table,&pos);
700:   for (i=0; i<sf->nranks; i++) {
701:     PetscTableGetNext(table,&pos,&ranks[i],&rcount[i]);
702:     ranks[i]--;             /* Convert back to 0-based */
703:   }
704:   PetscTableDestroy(&table);

706:   /* We expect that dgroup is reliably "small" while nranks could be large */
707:   {
708:     MPI_Group group = MPI_GROUP_NULL;
709:     PetscMPIInt *dgroupranks;
710:     MPI_Comm_group(PetscObjectComm((PetscObject)sf),&group);
711:     MPI_Group_size(dgroup,&groupsize);
712:     PetscMalloc1(groupsize,&dgroupranks);
713:     PetscMalloc1(groupsize,&groupranks);
714:     for (i=0; i<groupsize; i++) dgroupranks[i] = i;
715:     if (groupsize) {MPI_Group_translate_ranks(dgroup,groupsize,dgroupranks,group,groupranks);}
716:     MPI_Group_free(&group);
717:     PetscFree(dgroupranks);
718:   }

720:   /* Partition ranks[] into distinguished (first sf->ndranks) followed by non-distinguished */
721:   for (sf->ndranks=0,i=sf->nranks; sf->ndranks<i; ) {
722:     for (i--; sf->ndranks<i; i--) { /* Scan i backward looking for distinguished rank */
723:       if (InList(ranks[i],groupsize,groupranks)) break;
724:     }
725:     for ( ; sf->ndranks<=i; sf->ndranks++) { /* Scan sf->ndranks forward looking for non-distinguished rank */
726:       if (!InList(ranks[sf->ndranks],groupsize,groupranks)) break;
727:     }
728:     if (sf->ndranks < i) {                         /* Swap ranks[sf->ndranks] with ranks[i] */
729:       PetscInt    tmprank,tmpcount;
730:       tmprank = ranks[i];
731:       tmpcount = rcount[i];
732:       ranks[i] = ranks[sf->ndranks];
733:       rcount[i] = rcount[sf->ndranks];
734:       ranks[sf->ndranks] = tmprank;
735:       rcount[sf->ndranks] = tmpcount;
736:       sf->ndranks++;
737:     }
738:   }
739:   PetscFree(groupranks);
740:   PetscSortIntWithArray(sf->ndranks,ranks,rcount);
741:   PetscSortIntWithArray(sf->nranks-sf->ndranks,ranks+sf->ndranks,rcount+sf->ndranks);
742:   sf->roffset[0] = 0;
743:   for (i=0; i<sf->nranks; i++) {
744:     PetscMPIIntCast(ranks[i],sf->ranks+i);
745:     sf->roffset[i+1] = sf->roffset[i] + rcount[i];
746:     rcount[i]        = 0;
747:   }
748:   for (i=0; i<sf->nleaves; i++) {
749:     PetscInt irank;
750:     /* Search for index of iremote[i].rank in sf->ranks */
751:     PetscFindMPIInt(sf->remote[i].rank,sf->ndranks,sf->ranks,&irank);
752:     if (irank < 0) {
753:       PetscFindMPIInt(sf->remote[i].rank,sf->nranks-sf->ndranks,sf->ranks+sf->ndranks,&irank);
754:       if (irank >= 0) irank += sf->ndranks;
755:     }
756:     if (irank < 0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Could not find rank %D in array",sf->remote[i].rank);
757:     sf->rmine[sf->roffset[irank] + rcount[irank]]   = sf->mine ? sf->mine[i] : i;
758:     sf->rremote[sf->roffset[irank] + rcount[irank]] = sf->remote[i].index;
759:     rcount[irank]++;
760:   }
761:   PetscFree2(rcount,ranks);
762:   return(0);
763: }

765: /*@C
766:    PetscSFGetGroups - gets incoming and outgoing process groups

768:    Collective

770:    Input Argument:
771: .  sf - star forest

773:    Output Arguments:
774: +  incoming - group of origin processes for incoming edges (leaves that reference my roots)
775: -  outgoing - group of destination processes for outgoing edges (roots that I reference)

777:    Level: developer

779: .seealso: PetscSFGetWindow(), PetscSFRestoreWindow()
780: @*/
781: PetscErrorCode PetscSFGetGroups(PetscSF sf,MPI_Group *incoming,MPI_Group *outgoing)
782: {
784:   MPI_Group      group = MPI_GROUP_NULL;

787:   if (!sf->setupcalled) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"Must call PetscSFSetUp() before obtaining groups");
788:   if (sf->ingroup == MPI_GROUP_NULL) {
789:     PetscInt       i;
790:     const PetscInt *indegree;
791:     PetscMPIInt    rank,*outranks,*inranks;
792:     PetscSFNode    *remote;
793:     PetscSF        bgcount;

795:     /* Compute the number of incoming ranks */
796:     PetscMalloc1(sf->nranks,&remote);
797:     for (i=0; i<sf->nranks; i++) {
798:       remote[i].rank  = sf->ranks[i];
799:       remote[i].index = 0;
800:     }
801:     PetscSFDuplicate(sf,PETSCSF_DUPLICATE_CONFONLY,&bgcount);
802:     PetscSFSetGraph(bgcount,1,sf->nranks,NULL,PETSC_COPY_VALUES,remote,PETSC_OWN_POINTER);
803:     PetscSFComputeDegreeBegin(bgcount,&indegree);
804:     PetscSFComputeDegreeEnd(bgcount,&indegree);

806:     /* Enumerate the incoming ranks */
807:     PetscMalloc2(indegree[0],&inranks,sf->nranks,&outranks);
808:     MPI_Comm_rank(PetscObjectComm((PetscObject)sf),&rank);
809:     for (i=0; i<sf->nranks; i++) outranks[i] = rank;
810:     PetscSFGatherBegin(bgcount,MPI_INT,outranks,inranks);
811:     PetscSFGatherEnd(bgcount,MPI_INT,outranks,inranks);
812:     MPI_Comm_group(PetscObjectComm((PetscObject)sf),&group);
813:     MPI_Group_incl(group,indegree[0],inranks,&sf->ingroup);
814:     MPI_Group_free(&group);
815:     PetscFree2(inranks,outranks);
816:     PetscSFDestroy(&bgcount);
817:   }
818:   *incoming = sf->ingroup;

820:   if (sf->outgroup == MPI_GROUP_NULL) {
821:     MPI_Comm_group(PetscObjectComm((PetscObject)sf),&group);
822:     MPI_Group_incl(group,sf->nranks,sf->ranks,&sf->outgroup);
823:     MPI_Group_free(&group);
824:   }
825:   *outgoing = sf->outgroup;
826:   return(0);
827: }

829: /*@
830:    PetscSFGetMultiSF - gets the inner SF implemeting gathers and scatters

832:    Collective

834:    Input Argument:
835: .  sf - star forest that may contain roots with 0 or with more than 1 vertex

837:    Output Arguments:
838: .  multi - star forest with split roots, such that each root has degree exactly 1

840:    Level: developer

842:    Notes:

844:    In most cases, users should use PetscSFGatherBegin() and PetscSFScatterBegin() instead of manipulating multi
845:    directly. Since multi satisfies the stronger condition that each entry in the global space has exactly one incoming
846:    edge, it is a candidate for future optimization that might involve its removal.

848: .seealso: PetscSFSetGraph(), PetscSFGatherBegin(), PetscSFScatterBegin()
849: @*/
850: PetscErrorCode PetscSFGetMultiSF(PetscSF sf,PetscSF *multi)
851: {

857:   if (sf->nroots < 0) {         /* Graph has not been set yet; why do we need this? */
858:     PetscSFDuplicate(sf,PETSCSF_DUPLICATE_RANKS,&sf->multi);
859:     *multi = sf->multi;
860:     return(0);
861:   }
862:   if (!sf->multi) {
863:     const PetscInt *indegree;
864:     PetscInt       i,*inoffset,*outones,*outoffset,maxlocal;
865:     PetscSFNode    *remote;
866:     maxlocal = sf->maxleaf+1; /* TODO: We should use PetscSFGetLeafRange() */
867:     PetscSFComputeDegreeBegin(sf,&indegree);
868:     PetscSFComputeDegreeEnd(sf,&indegree);
869:     PetscMalloc3(sf->nroots+1,&inoffset,maxlocal,&outones,maxlocal,&outoffset);
870:     inoffset[0] = 0;
871:     for (i=0; i<sf->nroots; i++) inoffset[i+1] = inoffset[i] + indegree[i];
872:     for (i=0; i<maxlocal; i++) outones[i] = 1;
873:     PetscSFFetchAndOpBegin(sf,MPIU_INT,inoffset,outones,outoffset,MPI_SUM);
874:     PetscSFFetchAndOpEnd(sf,MPIU_INT,inoffset,outones,outoffset,MPI_SUM);
875:     for (i=0; i<sf->nroots; i++) inoffset[i] -= indegree[i]; /* Undo the increment */
876: #if 0
877: #if defined(PETSC_USE_DEBUG)                                 /* Check that the expected number of increments occurred */
878:     for (i=0; i<sf->nroots; i++) {
879:       if (inoffset[i] + indegree[i] != inoffset[i+1]) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Incorrect result after PetscSFFetchAndOp");
880:     }
881: #endif
882: #endif
883:     PetscMalloc1(sf->nleaves,&remote);
884:     for (i=0; i<sf->nleaves; i++) {
885:       remote[i].rank  = sf->remote[i].rank;
886:       remote[i].index = outoffset[sf->mine ? sf->mine[i] : i];
887:     }
888:     PetscSFDuplicate(sf,PETSCSF_DUPLICATE_RANKS,&sf->multi);
889:     PetscSFSetGraph(sf->multi,inoffset[sf->nroots],sf->nleaves,sf->mine,PETSC_COPY_VALUES,remote,PETSC_OWN_POINTER);
890:     if (sf->rankorder) {        /* Sort the ranks */
891:       PetscMPIInt rank;
892:       PetscInt    *inranks,*newoffset,*outranks,*newoutoffset,*tmpoffset,maxdegree;
893:       PetscSFNode *newremote;
894:       MPI_Comm_rank(PetscObjectComm((PetscObject)sf),&rank);
895:       for (i=0,maxdegree=0; i<sf->nroots; i++) maxdegree = PetscMax(maxdegree,indegree[i]);
896:       PetscMalloc5(sf->multi->nroots,&inranks,sf->multi->nroots,&newoffset,maxlocal,&outranks,maxlocal,&newoutoffset,maxdegree,&tmpoffset);
897:       for (i=0; i<maxlocal; i++) outranks[i] = rank;
898:       PetscSFReduceBegin(sf->multi,MPIU_INT,outranks,inranks,MPIU_REPLACE);
899:       PetscSFReduceEnd(sf->multi,MPIU_INT,outranks,inranks,MPIU_REPLACE);
900:       /* Sort the incoming ranks at each vertex, build the inverse map */
901:       for (i=0; i<sf->nroots; i++) {
902:         PetscInt j;
903:         for (j=0; j<indegree[i]; j++) tmpoffset[j] = j;
904:         PetscSortIntWithArray(indegree[i],inranks+inoffset[i],tmpoffset);
905:         for (j=0; j<indegree[i]; j++) newoffset[inoffset[i] + tmpoffset[j]] = inoffset[i] + j;
906:       }
907:       PetscSFBcastBegin(sf->multi,MPIU_INT,newoffset,newoutoffset);
908:       PetscSFBcastEnd(sf->multi,MPIU_INT,newoffset,newoutoffset);
909:       PetscMalloc1(sf->nleaves,&newremote);
910:       for (i=0; i<sf->nleaves; i++) {
911:         newremote[i].rank  = sf->remote[i].rank;
912:         newremote[i].index = newoutoffset[sf->mine ? sf->mine[i] : i];
913:       }
914:       PetscSFSetGraph(sf->multi,inoffset[sf->nroots],sf->nleaves,sf->mine,PETSC_COPY_VALUES,newremote,PETSC_OWN_POINTER);
915:       PetscFree5(inranks,newoffset,outranks,newoutoffset,tmpoffset);
916:     }
917:     PetscFree3(inoffset,outones,outoffset);
918:   }
919:   *multi = sf->multi;
920:   return(0);
921: }

923: /*@C
924:    PetscSFCreateEmbeddedSF - removes edges from all but the selected roots, does not remap indices

926:    Collective

928:    Input Arguments:
929: +  sf - original star forest
930: .  nroots - number of roots to select on this process
931: -  selected - selected roots on this process

933:    Output Arguments:
934: .  newsf - new star forest

936:    Level: advanced

938:    Note:
939:    To use the new PetscSF, it may be necessary to know the indices of the leaves that are still participating. This can
940:    be done by calling PetscSFGetGraph().

942: .seealso: PetscSFSetGraph(), PetscSFGetGraph()
943: @*/
944: PetscErrorCode PetscSFCreateEmbeddedSF(PetscSF sf,PetscInt nroots,const PetscInt *selected,PetscSF *newsf)
945: {
946:   PetscInt      *rootdata, *leafdata, *ilocal;
947:   PetscSFNode   *iremote;
948:   PetscInt       leafsize = 0, nleaves = 0, n, i;

953:   PetscSFCheckGraphSet(sf,1);
956:   if (sf->mine) for (i = 0; i < sf->nleaves; ++i) {leafsize = PetscMax(leafsize, sf->mine[i]+1);}
957:   else leafsize = sf->nleaves;
958:   PetscCalloc2(sf->nroots,&rootdata,leafsize,&leafdata);
959:   for (i=0; i<nroots; ++i) rootdata[selected[i]] = 1;
960:   PetscSFBcastBegin(sf,MPIU_INT,rootdata,leafdata);
961:   PetscSFBcastEnd(sf,MPIU_INT,rootdata,leafdata);
962:   for (i = 0; i < leafsize; ++i) nleaves += leafdata[i];
963:   PetscMalloc1(nleaves,&ilocal);
964:   PetscMalloc1(nleaves,&iremote);
965:   for (i = 0, n = 0; i < sf->nleaves; ++i) {
966:     const PetscInt lidx = sf->mine ? sf->mine[i] : i;

968:     if (leafdata[lidx]) {
969:       ilocal[n]        = lidx;
970:       iremote[n].rank  = sf->remote[i].rank;
971:       iremote[n].index = sf->remote[i].index;
972:       ++n;
973:     }
974:   }
975:   if (n != nleaves) SETERRQ2(PETSC_COMM_SELF, PETSC_ERR_PLIB, "There is a size mismatch in the SF embedding, %d != %d", n, nleaves);
976:   PetscSFDuplicate(sf,PETSCSF_DUPLICATE_RANKS,newsf);
977:   PetscSFSetGraph(*newsf,sf->nroots,nleaves,ilocal,PETSC_OWN_POINTER,iremote,PETSC_OWN_POINTER);
978:   PetscFree2(rootdata,leafdata);
979:   return(0);
980: }

982: /*@C
983:   PetscSFCreateEmbeddedLeafSF - removes edges from all but the selected leaves, does not remap indices

985:   Collective

987:   Input Arguments:
988: + sf - original star forest
989: . nleaves - number of leaves to select on this process
990: - selected - selected leaves on this process

992:   Output Arguments:
993: .  newsf - new star forest

995:   Level: advanced

997: .seealso: PetscSFCreateEmbeddedSF(), PetscSFSetGraph(), PetscSFGetGraph()
998: @*/
999: PetscErrorCode PetscSFCreateEmbeddedLeafSF(PetscSF sf, PetscInt nleaves, const PetscInt *selected, PetscSF *newsf)
1000: {
1001:   PetscSFNode   *iremote;
1002:   PetscInt      *ilocal;
1003:   PetscInt       i;

1008:   PetscSFCheckGraphSet(sf, 1);
1011:   PetscMalloc1(nleaves, &ilocal);
1012:   PetscMalloc1(nleaves, &iremote);
1013:   for (i = 0; i < nleaves; ++i) {
1014:     const PetscInt l = selected[i];

1016:     ilocal[i]        = sf->mine ? sf->mine[l] : l;
1017:     iremote[i].rank  = sf->remote[l].rank;
1018:     iremote[i].index = sf->remote[l].index;
1019:   }
1020:   PetscSFDuplicate(sf, PETSCSF_DUPLICATE_RANKS, newsf);
1021:   PetscSFSetGraph(*newsf, sf->nroots, nleaves, ilocal, PETSC_OWN_POINTER, iremote, PETSC_OWN_POINTER);
1022:   return(0);
1023: }

1025: /*@C
1026:    PetscSFBcastBegin - begin pointwise broadcast to be concluded with call to PetscSFBcastEnd()

1028:    Collective on PetscSF

1030:    Input Arguments:
1031: +  sf - star forest on which to communicate
1032: .  unit - data type associated with each node
1033: -  rootdata - buffer to broadcast

1035:    Output Arguments:
1036: .  leafdata - buffer to update with values from each leaf's respective root

1038:    Level: intermediate

1040: .seealso: PetscSFCreate(), PetscSFSetGraph(), PetscSFView(), PetscSFBcastEnd(), PetscSFReduceBegin()
1041: @*/
1042: PetscErrorCode PetscSFBcastBegin(PetscSF sf,MPI_Datatype unit,const void *rootdata,void *leafdata)
1043: {

1048:   PetscSFSetUp(sf);
1049:   PetscLogEventBegin(PETSCSF_BcastBegin,sf,0,0,0);
1050:   (*sf->ops->BcastBegin)(sf,unit,rootdata,leafdata);
1051:   PetscLogEventEnd(PETSCSF_BcastBegin,sf,0,0,0);
1052:   return(0);
1053: }

1055: /*@C
1056:    PetscSFBcastEnd - end a broadcast operation started with PetscSFBcastBegin()

1058:    Collective

1060:    Input Arguments:
1061: +  sf - star forest
1062: .  unit - data type
1063: -  rootdata - buffer to broadcast

1065:    Output Arguments:
1066: .  leafdata - buffer to update with values from each leaf's respective root

1068:    Level: intermediate

1070: .seealso: PetscSFSetGraph(), PetscSFReduceEnd()
1071: @*/
1072: PetscErrorCode PetscSFBcastEnd(PetscSF sf,MPI_Datatype unit,const void *rootdata,void *leafdata)
1073: {

1078:   PetscSFSetUp(sf);
1079:   PetscLogEventBegin(PETSCSF_BcastEnd,sf,0,0,0);
1080:   (*sf->ops->BcastEnd)(sf,unit,rootdata,leafdata);
1081:   PetscLogEventEnd(PETSCSF_BcastEnd,sf,0,0,0);
1082:   return(0);
1083: }

1085: /*@C
1086:    PetscSFReduceBegin - begin reduction of leafdata into rootdata, to be completed with call to PetscSFReduceEnd()

1088:    Collective

1090:    Input Arguments:
1091: +  sf - star forest
1092: .  unit - data type
1093: .  leafdata - values to reduce
1094: -  op - reduction operation

1096:    Output Arguments:
1097: .  rootdata - result of reduction of values from all leaves of each root

1099:    Level: intermediate

1101: .seealso: PetscSFBcastBegin()
1102: @*/
1103: PetscErrorCode PetscSFReduceBegin(PetscSF sf,MPI_Datatype unit,const void *leafdata,void *rootdata,MPI_Op op)
1104: {

1109:   PetscSFSetUp(sf);
1110:   PetscLogEventBegin(PETSCSF_ReduceBegin,sf,0,0,0);
1111:   (sf->ops->ReduceBegin)(sf,unit,leafdata,rootdata,op);
1112:   PetscLogEventEnd(PETSCSF_ReduceBegin,sf,0,0,0);
1113:   return(0);
1114: }

1116: /*@C
1117:    PetscSFReduceEnd - end a reduction operation started with PetscSFReduceBegin()

1119:    Collective

1121:    Input Arguments:
1122: +  sf - star forest
1123: .  unit - data type
1124: .  leafdata - values to reduce
1125: -  op - reduction operation

1127:    Output Arguments:
1128: .  rootdata - result of reduction of values from all leaves of each root

1130:    Level: intermediate

1132: .seealso: PetscSFSetGraph(), PetscSFBcastEnd()
1133: @*/
1134: PetscErrorCode PetscSFReduceEnd(PetscSF sf,MPI_Datatype unit,const void *leafdata,void *rootdata,MPI_Op op)
1135: {

1140:   PetscSFSetUp(sf);
1141:   PetscLogEventBegin(PETSCSF_ReduceEnd,sf,0,0,0);
1142:   (*sf->ops->ReduceEnd)(sf,unit,leafdata,rootdata,op);
1143:   PetscLogEventEnd(PETSCSF_ReduceEnd,sf,0,0,0);
1144:   return(0);
1145: }

1147: /*@C
1148:    PetscSFComputeDegreeBegin - begin computation of degree for each root vertex, to be completed with PetscSFComputeDegreeEnd()

1150:    Collective

1152:    Input Arguments:
1153: .  sf - star forest

1155:    Output Arguments:
1156: .  degree - degree of each root vertex

1158:    Level: advanced

1160: .seealso: PetscSFGatherBegin()
1161: @*/
1162: PetscErrorCode PetscSFComputeDegreeBegin(PetscSF sf,const PetscInt **degree)
1163: {

1168:   PetscSFCheckGraphSet(sf,1);
1170:   if (!sf->degreeknown) {
1171:     PetscInt i, nroots = sf->nroots, maxlocal = sf->maxleaf+1;  /* TODO: We should use PetscSFGetLeafRange() */
1172:     if (sf->degree) SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "Calls to PetscSFComputeDegreeBegin() cannot be nested.");
1173:     PetscMalloc1(nroots,&sf->degree);
1174:     PetscMalloc1(PetscMax(maxlocal,1),&sf->degreetmp); /* allocate at least one entry, see check in PetscSFComputeDegreeEnd() */
1175:     for (i=0; i<nroots; i++) sf->degree[i] = 0;
1176:     for (i=0; i<maxlocal; i++) sf->degreetmp[i] = 1;
1177:     PetscSFReduceBegin(sf,MPIU_INT,sf->degreetmp,sf->degree,MPI_SUM);
1178:   }
1179:   *degree = NULL;
1180:   return(0);
1181: }

1183: /*@C
1184:    PetscSFComputeDegreeEnd - complete computation of degree for each root vertex, started with PetscSFComputeDegreeBegin()

1186:    Collective

1188:    Input Arguments:
1189: .  sf - star forest

1191:    Output Arguments:
1192: .  degree - degree of each root vertex

1194:    Level: developer

1196: .seealso:
1197: @*/
1198: PetscErrorCode PetscSFComputeDegreeEnd(PetscSF sf,const PetscInt **degree)
1199: {

1204:   PetscSFCheckGraphSet(sf,1);
1206:   if (!sf->degreeknown) {
1207:     if (!sf->degreetmp) SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "Must call PetscSFComputeDegreeBegin() before PetscSFComputeDegreeEnd()");
1208:     PetscSFReduceEnd(sf,MPIU_INT,sf->degreetmp,sf->degree,MPI_SUM);
1209:     PetscFree(sf->degreetmp);
1210:     sf->degreeknown = PETSC_TRUE;
1211:   }
1212:   *degree = sf->degree;
1213:   return(0);
1214: }

1216: /*@C
1217:    PetscSFFetchAndOpBegin - begin operation that fetches values from root and updates atomically by applying operation using my leaf value, to be completed with PetscSFFetchAndOpEnd()

1219:    Collective

1221:    Input Arguments:
1222: +  sf - star forest
1223: .  unit - data type
1224: .  leafdata - leaf values to use in reduction
1225: -  op - operation to use for reduction

1227:    Output Arguments:
1228: +  rootdata - root values to be updated, input state is seen by first process to perform an update
1229: -  leafupdate - state at each leaf's respective root immediately prior to my atomic update

1231:    Level: advanced

1233:    Note:
1234:    The update is only atomic at the granularity provided by the hardware. Different roots referenced by the same process
1235:    might be updated in a different order. Furthermore, if a composite type is used for the unit datatype, atomicity is
1236:    not guaranteed across the whole vertex. Therefore, this function is mostly only used with primitive types such as
1237:    integers.

1239: .seealso: PetscSFComputeDegreeBegin(), PetscSFReduceBegin(), PetscSFSetGraph()
1240: @*/
1241: PetscErrorCode PetscSFFetchAndOpBegin(PetscSF sf,MPI_Datatype unit,void *rootdata,const void *leafdata,void *leafupdate,MPI_Op op)
1242: {

1247:   PetscSFSetUp(sf);
1248:   PetscLogEventBegin(PETSCSF_FetchAndOpBegin,sf,0,0,0);
1249:   (*sf->ops->FetchAndOpBegin)(sf,unit,rootdata,leafdata,leafupdate,op);
1250:   PetscLogEventEnd(PETSCSF_FetchAndOpBegin,sf,0,0,0);
1251:   return(0);
1252: }

1254: /*@C
1255:    PetscSFFetchAndOpEnd - end operation started in matching call to PetscSFFetchAndOpBegin() to fetch values from roots and update atomically by applying operation using my leaf value

1257:    Collective

1259:    Input Arguments:
1260: +  sf - star forest
1261: .  unit - data type
1262: .  leafdata - leaf values to use in reduction
1263: -  op - operation to use for reduction

1265:    Output Arguments:
1266: +  rootdata - root values to be updated, input state is seen by first process to perform an update
1267: -  leafupdate - state at each leaf's respective root immediately prior to my atomic update

1269:    Level: advanced

1271: .seealso: PetscSFComputeDegreeEnd(), PetscSFReduceEnd(), PetscSFSetGraph()
1272: @*/
1273: PetscErrorCode PetscSFFetchAndOpEnd(PetscSF sf,MPI_Datatype unit,void *rootdata,const void *leafdata,void *leafupdate,MPI_Op op)
1274: {

1279:   PetscSFSetUp(sf);
1280:   PetscLogEventBegin(PETSCSF_FetchAndOpEnd,sf,0,0,0);
1281:   (*sf->ops->FetchAndOpEnd)(sf,unit,rootdata,leafdata,leafupdate,op);
1282:   PetscLogEventEnd(PETSCSF_FetchAndOpEnd,sf,0,0,0);
1283:   return(0);
1284: }

1286: /*@C
1287:    PetscSFGatherBegin - begin pointwise gather of all leaves into multi-roots, to be completed with PetscSFGatherEnd()

1289:    Collective

1291:    Input Arguments:
1292: +  sf - star forest
1293: .  unit - data type
1294: -  leafdata - leaf data to gather to roots

1296:    Output Argument:
1297: .  multirootdata - root buffer to gather into, amount of space per root is equal to its degree

1299:    Level: intermediate

1301: .seealso: PetscSFComputeDegreeBegin(), PetscSFScatterBegin()
1302: @*/
1303: PetscErrorCode PetscSFGatherBegin(PetscSF sf,MPI_Datatype unit,const void *leafdata,void *multirootdata)
1304: {
1306:   PetscSF        multi;

1310:   PetscSFSetUp(sf);
1311:   PetscSFGetMultiSF(sf,&multi);
1312:   PetscSFReduceBegin(multi,unit,leafdata,multirootdata,MPIU_REPLACE);
1313:   return(0);
1314: }

1316: /*@C
1317:    PetscSFGatherEnd - ends pointwise gather operation that was started with PetscSFGatherBegin()

1319:    Collective

1321:    Input Arguments:
1322: +  sf - star forest
1323: .  unit - data type
1324: -  leafdata - leaf data to gather to roots

1326:    Output Argument:
1327: .  multirootdata - root buffer to gather into, amount of space per root is equal to its degree

1329:    Level: intermediate

1331: .seealso: PetscSFComputeDegreeEnd(), PetscSFScatterEnd()
1332: @*/
1333: PetscErrorCode PetscSFGatherEnd(PetscSF sf,MPI_Datatype unit,const void *leafdata,void *multirootdata)
1334: {
1336:   PetscSF        multi;

1340:   PetscSFSetUp(sf);
1341:   PetscSFGetMultiSF(sf,&multi);
1342:   PetscSFReduceEnd(multi,unit,leafdata,multirootdata,MPIU_REPLACE);
1343:   return(0);
1344: }

1346: /*@C
1347:    PetscSFScatterBegin - begin pointwise scatter operation from multi-roots to leaves, to be completed with PetscSFScatterEnd()

1349:    Collective

1351:    Input Arguments:
1352: +  sf - star forest
1353: .  unit - data type
1354: -  multirootdata - root buffer to send to each leaf, one unit of data per leaf

1356:    Output Argument:
1357: .  leafdata - leaf data to be update with personal data from each respective root

1359:    Level: intermediate

1361: .seealso: PetscSFComputeDegreeBegin(), PetscSFScatterBegin()
1362: @*/
1363: PetscErrorCode PetscSFScatterBegin(PetscSF sf,MPI_Datatype unit,const void *multirootdata,void *leafdata)
1364: {
1366:   PetscSF        multi;

1370:   PetscSFSetUp(sf);
1371:   PetscSFGetMultiSF(sf,&multi);
1372:   PetscSFBcastBegin(multi,unit,multirootdata,leafdata);
1373:   return(0);
1374: }

1376: /*@C
1377:    PetscSFScatterEnd - ends pointwise scatter operation that was started with PetscSFScatterBegin()

1379:    Collective

1381:    Input Arguments:
1382: +  sf - star forest
1383: .  unit - data type
1384: -  multirootdata - root buffer to send to each leaf, one unit of data per leaf

1386:    Output Argument:
1387: .  leafdata - leaf data to be update with personal data from each respective root

1389:    Level: intermediate

1391: .seealso: PetscSFComputeDegreeEnd(), PetscSFScatterEnd()
1392: @*/
1393: PetscErrorCode PetscSFScatterEnd(PetscSF sf,MPI_Datatype unit,const void *multirootdata,void *leafdata)
1394: {
1396:   PetscSF        multi;

1400:   PetscSFSetUp(sf);
1401:   PetscSFGetMultiSF(sf,&multi);
1402:   PetscSFBcastEnd(multi,unit,multirootdata,leafdata);
1403:   return(0);
1404: }

1406: /*@
1407:   PetscSFCompose - Compose a new PetscSF equivalent to action to PetscSFs

1409:   Input Parameters:
1410: + sfA - The first PetscSF
1411: - sfB - The second PetscSF

1413:   Output Parameters:
1414: . sfBA - equvalent PetscSF for applying A then B

1416:   Level: developer

1418: .seealso: PetscSF, PetscSFGetGraph(), PetscSFSetGraph()
1419: @*/
1420: PetscErrorCode PetscSFCompose(PetscSF sfA, PetscSF sfB, PetscSF *sfBA)
1421: {
1422:   MPI_Comm           comm;
1423:   const PetscSFNode *remotePointsA, *remotePointsB;
1424:   PetscSFNode       *remotePointsBA;
1425:   const PetscInt    *localPointsA, *localPointsB;
1426:   PetscInt           numRootsA, numLeavesA, numRootsB, numLeavesB;
1427:   PetscErrorCode     ierr;

1431:   PetscSFCheckGraphSet(sfA, 1);
1433:   PetscSFCheckGraphSet(sfB, 2);
1435:   PetscObjectGetComm((PetscObject) sfA, &comm);
1436:   PetscSFGetGraph(sfA, &numRootsA, &numLeavesA, &localPointsA, &remotePointsA);
1437:   PetscSFGetGraph(sfB, &numRootsB, &numLeavesB, &localPointsB, &remotePointsB);
1438:   PetscMalloc1(numLeavesB, &remotePointsBA);
1439:   PetscSFBcastBegin(sfB, MPIU_2INT, remotePointsA, remotePointsBA);
1440:   PetscSFBcastEnd(sfB, MPIU_2INT, remotePointsA, remotePointsBA);
1441:   PetscSFCreate(comm, sfBA);
1442:   PetscSFSetGraph(*sfBA, numRootsA, numLeavesB, localPointsB, PETSC_COPY_VALUES, remotePointsBA, PETSC_OWN_POINTER);
1443:   return(0);
1444: }