Actual source code: plexorient.c
petsc-3.15.0 2021-03-30
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      1: #include <petsc/private/dmpleximpl.h>
      2: #include <petscsf.h>

      4: /*@
      5:   DMPlexCompareOrientations - Compare the cone of the given DAG point (cell) with the given reference cone (with the same cone points modulo order), and return relative orientation.

      7:   Not Collective

      9:   Input Parameters:
     10: + dm              - The DM (DMPLEX)
     11: . p               - The DAG point whose cone is compared
     12: . mainConeSize    - Number of the reference cone points passed (at least 2 and at most size of the cone of p)
     13: - mainCone        - The reference cone points

     15:   Output Parameters:
     16: + start           - The new starting point within the cone of p to make it conforming with the reference cone
     17: - reverse         - The flag whether the order of the cone points should be reversed

     19:   Level: advanced

     21: .seealso: DMPlexOrient(), DMPlexOrientCell()
     22: @*/
     23: PetscErrorCode DMPlexCompareOrientations(DM dm, PetscInt p, PetscInt mainConeSize, const PetscInt mainCone[], PetscInt *start, PetscBool *reverse)
     24: {
     25:   PetscInt        coneSize;
     26:   const PetscInt *cone;
     27:   PetscInt        i, start_;
     28:   PetscBool       reverse_;
     29:   PetscErrorCode  ierr;

     33:   DMPlexGetConeSize(dm, p, &coneSize);
     34:   if (coneSize < 2) SETERRQ1(PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Point %D has no cone", p);
     35:   DMPlexGetCone(dm, p, &cone);
     36:   if (mainConeSize < 2) SETERRQ1(PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Point %D: mainConeSize must be at least 2", p);
     37:   if (mainConeSize > coneSize) SETERRQ1(PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Point %D: mainConeSize must be at most coneSize", p);
     38:   start_ = 0;
     39:   for (i=0; i<coneSize; i++) {
     40:     if (cone[i] == mainCone[0]) {
     41:       start_ = i;
     42:       break;
     43:     }
     44:   }
     45:   if (PetscUnlikely(i==coneSize)) SETERRQ1(PETSC_COMM_SELF, PETSC_ERR_ARG_INCOMP, "Point %D: starting point of reference cone not found in worker cone", p);
     46:   reverse_ = PETSC_FALSE;
     47:   for (i=0; i<mainConeSize; i++) {if (cone[(start_+i)%coneSize] != mainCone[i]) break;}
     48:   if (i != mainConeSize) {
     49:     reverse_ = PETSC_TRUE;
     50:     for (i=0; i<mainConeSize; i++) {if (cone[(coneSize+start_-i)%coneSize] != mainCone[i]) break;}
     51:     if (i < mainConeSize) SETERRQ1(PETSC_COMM_SELF, PETSC_ERR_ARG_INCOMP, "Point %D: cone has non-conforming order of points with respect to reference cone", p);
     52:   }
     53:   if (start) *start = start_;
     54:   if (reverse) *reverse = reverse_;
     55:   if (PetscUnlikely(cone[start_] != mainCone[0])) SETERRQ4(PETSC_COMM_SELF, PETSC_ERR_PLIB, "Point %D: cone[%d] = %d != %d = mainCone[0]", p, start_, cone[start_], mainCone[0]);
     56:   return(0);
     57: }

     59: /*@
     60:   DMPlexOrientCell - Set the desired order of cone points of this DAG point, and fix orientations accordingly.

     62:   Not Collective

     64:   Input Parameters:
     65: + dm              - The DM
     66: . p               - The DAG point (from interval given by DMPlexGetChart())
     67: . mainConeSize    - Number of specified cone points (at least 2)
     68: - mainCone        - Specified cone points, i.e. ordered subset of current cone in DAG numbering (not cone-local numbering)

     70:   Level: intermediate

     72: .seealso: DMPlexOrient(), DMPlexGetCone(), DMPlexGetConeOrientation(), DMPlexInterpolate(), DMPlexGetChart()
     73: @*/
     74: PetscErrorCode DMPlexOrientCell(DM dm, PetscInt p, PetscInt mainConeSize, const PetscInt mainCone[])
     75: {
     76:   PetscInt        coneSize;
     77:   PetscInt        start1=0;
     78:   PetscBool       reverse1=PETSC_FALSE;
     79:   PetscErrorCode  ierr;

     84:   if (mainConeSize == 1) SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "mainConeSize cannot be 1");
     85:   DMPlexGetConeSize(dm, p, &coneSize);
     86:   if (!coneSize) return(0); /* do nothing for points with no cone */
     87:   DMPlexCompareOrientations(dm, p, mainConeSize, mainCone, &start1, &reverse1);
     88:   DMPlexOrientCell_Internal(dm, p, start1, reverse1);
     89:   if (PetscDefined(USE_DEBUG)) {
     90:     PetscInt        c;
     91:     const PetscInt *cone;
     92:     DMPlexGetCone(dm, p, &cone);
     93:     for (c = 0; c < mainConeSize; c++) {
     94:       if (PetscUnlikely(cone[c] != mainCone[c])) SETERRQ4(PETSC_COMM_SELF, PETSC_ERR_PLIB, "The algorithm above is wrong as cone[%d] = %d != %d = mainCone[%d]", c, cone[c], mainCone[c], c);
     95:     }
     96:   }
     97:   return(0);
     98: }

    100: PetscErrorCode DMPlexOrientCell_Internal(DM dm, PetscInt p, PetscInt start1, PetscBool reverse1)
    101: {
    102:   PetscInt        i, j, k, maxConeSize, coneSize, coneConeSize, supportSize, supportConeSize;
    103:   PetscInt        start0, start;
    104:   PetscBool       reverse0, reverse;
    105:   PetscInt        newornt;
    106:   const PetscInt *cone=NULL, *support=NULL, *supportCone=NULL, *ornts=NULL;
    107:   PetscInt       *newcone=NULL, *newornts=NULL;
    108:   PetscErrorCode  ierr;

    111:   if (!start1 && !reverse1) return(0);
    112:   DMPlexGetConeSize(dm, p, &coneSize);
    113:   if (!coneSize) return(0); /* do nothing for points with no cone */
    114:   DMPlexGetCone(dm, p, &cone);
    115:   DMPlexGetMaxSizes(dm, &maxConeSize, NULL);
    116:   /* permute p's cone and orientations */
    117:   DMPlexGetConeOrientation(dm, p, &ornts);
    118:   DMGetWorkArray(dm, maxConeSize, MPIU_INT, &newcone);
    119:   DMGetWorkArray(dm, maxConeSize, MPIU_INT, &newornts);
    120:   DMPlexFixFaceOrientations_Permute_Private(coneSize, cone, start1, reverse1, newcone);
    121:   DMPlexFixFaceOrientations_Permute_Private(coneSize, ornts, start1, reverse1, newornts);
    122:   /* if direction of p (face) is flipped, flip also p's cone points (edges) */
    123:   if (reverse1) {
    124:     for (i=0; i<coneSize; i++) {
    125:       DMPlexGetConeSize(dm, cone[i], &coneConeSize);
    126:       DMPlexFixFaceOrientations_Translate_Private(newornts[i], &start0, &reverse0);
    127:       DMPlexFixFaceOrientations_Combine_Private(coneConeSize, start0, reverse0, 1, PETSC_FALSE, &start, &reverse);
    128:       DMPlexFixFaceOrientations_TranslateBack_Private(coneConeSize, start, reverse, &newornts[i]);
    129:     }
    130:   }
    131:   DMPlexSetConeOrientation(dm, p, newornts);
    132:   /* fix oriention of p within cones of p's support points */
    133:   DMPlexGetSupport(dm, p, &support);
    134:   DMPlexGetSupportSize(dm, p, &supportSize);
    135:   for (j=0; j<supportSize; j++) {
    136:     DMPlexGetCone(dm, support[j], &supportCone);
    137:     DMPlexGetConeSize(dm, support[j], &supportConeSize);
    138:     DMPlexGetConeOrientation(dm, support[j], &ornts);
    139:     for (k=0; k<supportConeSize; k++) {
    140:       if (supportCone[k] != p) continue;
    141:       DMPlexFixFaceOrientations_Translate_Private(ornts[k], &start0, &reverse0);
    142:       DMPlexFixFaceOrientations_Combine_Private(coneSize, start0, reverse0, start1, reverse1, &start, &reverse);
    143:       DMPlexFixFaceOrientations_TranslateBack_Private(coneSize, start, reverse, &newornt);
    144:       DMPlexInsertConeOrientation(dm, support[j], k, newornt);
    145:     }
    146:   }
    147:   /* rewrite cone */
    148:   DMPlexSetCone(dm, p, newcone);
    149:   DMRestoreWorkArray(dm, maxConeSize, MPIU_INT, &newcone);
    150:   DMRestoreWorkArray(dm, maxConeSize, MPIU_INT, &newornts);
    151:   return(0);
    152: }

    154: /*@
    155:   DMPlexReverseCell - Give a mesh cell the opposite orientation

    157:   Input Parameters:
    158: + dm   - The DM
    159: - cell - The cell number

    161:   Note: The modification of the DM is done in-place.

    163:   Level: advanced

    165: .seealso: DMPlexOrient(), DMCreate(), DMPLEX
    166: @*/
    167: PetscErrorCode DMPlexReverseCell(DM dm, PetscInt cell)
    168: {
    169:   /* Note that the reverse orientation ro of a face with orientation o is:

    171:        ro = o >= 0 ? -(faceSize - o) : faceSize + o

    173:      where faceSize is the size of the cone for the face.
    174:   */
    175:   const PetscInt *cone,    *coneO, *support;
    176:   PetscInt       *revcone, *revconeO;
    177:   PetscInt        maxConeSize, coneSize, supportSize, faceSize, cp, sp;
    178:   PetscErrorCode  ierr;

    181:   DMPlexGetMaxSizes(dm, &maxConeSize, NULL);
    182:   DMGetWorkArray(dm, maxConeSize, MPIU_INT, &revcone);
    183:   DMGetWorkArray(dm, maxConeSize, MPIU_INT, &revconeO);
    184:   /* Reverse cone, and reverse orientations of faces */
    185:   DMPlexGetConeSize(dm, cell, &coneSize);
    186:   DMPlexGetCone(dm, cell, &cone);
    187:   DMPlexGetConeOrientation(dm, cell, &coneO);
    188:   for (cp = 0; cp < coneSize; ++cp) {
    189:     const PetscInt rcp = coneSize-cp-1;

    191:     DMPlexGetConeSize(dm, cone[rcp], &faceSize);
    192:     revcone[cp]  = cone[rcp];
    193:     revconeO[cp] = coneO[rcp] >= 0 ? -(faceSize-coneO[rcp]) : faceSize+coneO[rcp];
    194:   }
    195:   DMPlexSetCone(dm, cell, revcone);
    196:   DMPlexSetConeOrientation(dm, cell, revconeO);
    197:   /* Reverse orientation of this cell in the support hypercells */
    198:   faceSize = coneSize;
    199:   DMPlexGetSupportSize(dm, cell, &supportSize);
    200:   DMPlexGetSupport(dm, cell, &support);
    201:   for (sp = 0; sp < supportSize; ++sp) {
    202:     DMPlexGetConeSize(dm, support[sp], &coneSize);
    203:     DMPlexGetCone(dm, support[sp], &cone);
    204:     DMPlexGetConeOrientation(dm, support[sp], &coneO);
    205:     for (cp = 0; cp < coneSize; ++cp) {
    206:       if (cone[cp] != cell) continue;
    207:       DMPlexInsertConeOrientation(dm, support[sp], cp, coneO[cp] >= 0 ? -(faceSize-coneO[cp]) : faceSize+coneO[cp]);
    208:     }
    209:   }
    210:   DMRestoreWorkArray(dm, maxConeSize, MPIU_INT, &revcone);
    211:   DMRestoreWorkArray(dm, maxConeSize, MPIU_INT, &revconeO);
    212:   return(0);
    213: }

    215: /*
    216:   - Checks face match
    217:     - Flips non-matching
    218:   - Inserts faces of support cells in FIFO
    219: */
    220: static PetscErrorCode DMPlexCheckFace_Internal(DM dm, PetscInt *faceFIFO, PetscInt *fTop, PetscInt *fBottom, PetscInt cStart, PetscInt fStart, PetscInt fEnd, PetscBT seenCells, PetscBT flippedCells, PetscBT seenFaces)
    221: {
    222:   const PetscInt *support, *coneA, *coneB, *coneOA, *coneOB;
    223:   PetscInt        supportSize, coneSizeA, coneSizeB, posA = -1, posB = -1;
    224:   PetscInt        face, dim, seenA, flippedA, seenB, flippedB, mismatch, c;
    225:   PetscErrorCode  ierr;

    228:   face = faceFIFO[(*fTop)++];
    229:   DMGetDimension(dm, &dim);
    230:   DMPlexGetSupportSize(dm, face, &supportSize);
    231:   DMPlexGetSupport(dm, face, &support);
    232:   if (supportSize < 2) return(0);
    233:   if (supportSize != 2) SETERRQ1(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Faces should separate only two cells, not %d", supportSize);
    234:   seenA    = PetscBTLookup(seenCells,    support[0]-cStart);
    235:   flippedA = PetscBTLookup(flippedCells, support[0]-cStart) ? 1 : 0;
    236:   seenB    = PetscBTLookup(seenCells,    support[1]-cStart);
    237:   flippedB = PetscBTLookup(flippedCells, support[1]-cStart) ? 1 : 0;

    239:   DMPlexGetConeSize(dm, support[0], &coneSizeA);
    240:   DMPlexGetConeSize(dm, support[1], &coneSizeB);
    241:   DMPlexGetCone(dm, support[0], &coneA);
    242:   DMPlexGetCone(dm, support[1], &coneB);
    243:   DMPlexGetConeOrientation(dm, support[0], &coneOA);
    244:   DMPlexGetConeOrientation(dm, support[1], &coneOB);
    245:   for (c = 0; c < coneSizeA; ++c) {
    246:     if (!PetscBTLookup(seenFaces, coneA[c]-fStart)) {
    247:       faceFIFO[(*fBottom)++] = coneA[c];
    248:       PetscBTSet(seenFaces, coneA[c]-fStart);
    249:     }
    250:     if (coneA[c] == face) posA = c;
    251:     if (*fBottom > fEnd-fStart) SETERRQ3(PETSC_COMM_SELF, PETSC_ERR_PLIB, "Face %d was pushed exceeding capacity %d > %d", coneA[c], *fBottom, fEnd-fStart);
    252:   }
    253:   if (posA < 0) SETERRQ2(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Face %d could not be located in cell %d", face, support[0]);
    254:   for (c = 0; c < coneSizeB; ++c) {
    255:     if (!PetscBTLookup(seenFaces, coneB[c]-fStart)) {
    256:       faceFIFO[(*fBottom)++] = coneB[c];
    257:       PetscBTSet(seenFaces, coneB[c]-fStart);
    258:     }
    259:     if (coneB[c] == face) posB = c;
    260:     if (*fBottom > fEnd-fStart) SETERRQ3(PETSC_COMM_SELF, PETSC_ERR_PLIB, "Face %d was pushed exceeding capacity %d > %d", coneA[c], *fBottom, fEnd-fStart);
    261:   }
    262:   if (posB < 0) SETERRQ2(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Face %d could not be located in cell %d", face, support[1]);

    264:   if (dim == 1) {
    265:     mismatch = posA == posB;
    266:   } else {
    267:     mismatch = coneOA[posA] == coneOB[posB];
    268:   }

    270:   if (mismatch ^ (flippedA ^ flippedB)) {
    271:     if (seenA && seenB) SETERRQ2(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Previously seen cells %d and %d do not match: Fault mesh is non-orientable", support[0], support[1]);
    272:     if (!seenA && !flippedA) {
    273:       PetscBTSet(flippedCells, support[0]-cStart);
    274:     } else if (!seenB && !flippedB) {
    275:       PetscBTSet(flippedCells, support[1]-cStart);
    276:     } else SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Inconsistent mesh orientation: Fault mesh is non-orientable");
    277:   } else if (mismatch && flippedA && flippedB) SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Attempt to flip already flipped cell: Fault mesh is non-orientable");
    278:   PetscBTSet(seenCells, support[0]-cStart);
    279:   PetscBTSet(seenCells, support[1]-cStart);
    280:   return(0);
    281: }

    283: /*@
    284:   DMPlexOrient - Give a consistent orientation to the input mesh

    286:   Input Parameters:
    287: . dm - The DM

    289:   Note: The orientation data for the DM are change in-place.
    290: $ This routine will fail for non-orientable surfaces, such as the Moebius strip.

    292:   Level: advanced

    294: .seealso: DMCreate(), DMPLEX
    295: @*/
    296: PetscErrorCode DMPlexOrient(DM dm)
    297: {
    298:   MPI_Comm           comm;
    299:   PetscSF            sf;
    300:   const PetscInt    *lpoints;
    301:   const PetscSFNode *rpoints;
    302:   PetscSFNode       *rorntComp = NULL, *lorntComp = NULL;
    303:   PetscInt          *numNeighbors, **neighbors;
    304:   PetscSFNode       *nrankComp;
    305:   PetscBool         *match, *flipped;
    306:   PetscBT            seenCells, flippedCells, seenFaces;
    307:   PetscInt          *faceFIFO, fTop, fBottom, *cellComp, *faceComp;
    308:   PetscInt           numLeaves, numRoots, dim, h, cStart, cEnd, c, cell, fStart, fEnd, face, off, totNeighbors = 0;
    309:   PetscMPIInt        rank, size, numComponents, comp = 0;
    310:   PetscBool          flg, flg2;
    311:   PetscViewer        viewer = NULL, selfviewer = NULL;
    312:   PetscErrorCode     ierr;

    315:   PetscObjectGetComm((PetscObject) dm, &comm);
    316:   MPI_Comm_rank(comm, &rank);
    317:   MPI_Comm_size(comm, &size);
    318:   PetscOptionsHasName(((PetscObject) dm)->options,((PetscObject) dm)->prefix, "-orientation_view", &flg);
    319:   PetscOptionsHasName(((PetscObject) dm)->options,((PetscObject) dm)->prefix, "-orientation_view_synchronized", &flg2);
    320:   DMGetPointSF(dm, &sf);
    321:   PetscSFGetGraph(sf, &numRoots, &numLeaves, &lpoints, &rpoints);
    322:   /* Truth Table
    323:      mismatch    flips   do action   mismatch   flipA ^ flipB   action
    324:          F       0 flips     no         F             F           F
    325:          F       1 flip      yes        F             T           T
    326:          F       2 flips     no         T             F           T
    327:          T       0 flips     yes        T             T           F
    328:          T       1 flip      no
    329:          T       2 flips     yes
    330:   */
    331:   DMGetDimension(dm, &dim);
    332:   DMPlexGetVTKCellHeight(dm, &h);
    333:   DMPlexGetHeightStratum(dm, h,   &cStart, &cEnd);
    334:   DMPlexGetHeightStratum(dm, h+1, &fStart, &fEnd);
    335:   PetscBTCreate(cEnd - cStart, &seenCells);
    336:   PetscBTMemzero(cEnd - cStart, seenCells);
    337:   PetscBTCreate(cEnd - cStart, &flippedCells);
    338:   PetscBTMemzero(cEnd - cStart, flippedCells);
    339:   PetscBTCreate(fEnd - fStart, &seenFaces);
    340:   PetscBTMemzero(fEnd - fStart, seenFaces);
    341:   PetscCalloc3(fEnd - fStart, &faceFIFO, cEnd-cStart, &cellComp, fEnd-fStart, &faceComp);
    342:   /*
    343:    OLD STYLE
    344:    - Add an integer array over cells and faces (component) for connected component number
    345:    Foreach component
    346:      - Mark the initial cell as seen
    347:      - Process component as usual
    348:      - Set component for all seenCells
    349:      - Wipe seenCells and seenFaces (flippedCells can stay)
    350:    - Generate parallel adjacency for component using SF and seenFaces
    351:    - Collect numComponents adj data from each proc to 0
    352:    - Build same serial graph
    353:    - Use same solver
    354:    - Use Scatterv to to send back flipped flags for each component
    355:    - Negate flippedCells by component

    357:    NEW STYLE
    358:    - Create the adj on each process
    359:    - Bootstrap to complete graph on proc 0
    360:   */
    361:   /* Loop over components */
    362:   for (cell = cStart; cell < cEnd; ++cell) cellComp[cell-cStart] = -1;
    363:   do {
    364:     /* Look for first unmarked cell */
    365:     for (cell = cStart; cell < cEnd; ++cell) if (cellComp[cell-cStart] < 0) break;
    366:     if (cell >= cEnd) break;
    367:     /* Initialize FIFO with first cell in component */
    368:     {
    369:       const PetscInt *cone;
    370:       PetscInt        coneSize;

    372:       fTop = fBottom = 0;
    373:       DMPlexGetConeSize(dm, cell, &coneSize);
    374:       DMPlexGetCone(dm, cell, &cone);
    375:       for (c = 0; c < coneSize; ++c) {
    376:         faceFIFO[fBottom++] = cone[c];
    377:         PetscBTSet(seenFaces, cone[c]-fStart);
    378:       }
    379:       PetscBTSet(seenCells, cell-cStart);
    380:     }
    381:     /* Consider each face in FIFO */
    382:     while (fTop < fBottom) {
    383:       DMPlexCheckFace_Internal(dm, faceFIFO, &fTop, &fBottom, cStart, fStart, fEnd, seenCells, flippedCells, seenFaces);
    384:     }
    385:     /* Set component for cells and faces */
    386:     for (cell = 0; cell < cEnd-cStart; ++cell) {
    387:       if (PetscBTLookup(seenCells, cell)) cellComp[cell] = comp;
    388:     }
    389:     for (face = 0; face < fEnd-fStart; ++face) {
    390:       if (PetscBTLookup(seenFaces, face)) faceComp[face] = comp;
    391:     }
    392:     /* Wipe seenCells and seenFaces for next component */
    393:     PetscBTMemzero(fEnd - fStart, seenFaces);
    394:     PetscBTMemzero(cEnd - cStart, seenCells);
    395:     ++comp;
    396:   } while (1);
    397:   numComponents = comp;
    398:   if (flg) {
    399:     PetscViewer v;

    401:     PetscViewerASCIIGetStdout(comm, &v);
    402:     PetscViewerASCIIPushSynchronized(v);
    403:     PetscViewerASCIISynchronizedPrintf(v, "[%d]BT for serial flipped cells:\n", rank);
    404:     PetscBTView(cEnd-cStart, flippedCells, v);
    405:     PetscViewerFlush(v);
    406:     PetscViewerASCIIPopSynchronized(v);
    407:   }
    408:   /* Now all subdomains are oriented, but we need a consistent parallel orientation */
    409:   if (numLeaves >= 0) {
    410:     /* Store orientations of boundary faces*/
    411:     PetscCalloc2(numRoots,&rorntComp,numRoots,&lorntComp);
    412:     for (face = fStart; face < fEnd; ++face) {
    413:       const PetscInt *cone, *support, *ornt;
    414:       PetscInt        coneSize, supportSize;

    416:       DMPlexGetSupportSize(dm, face, &supportSize);
    417:       if (supportSize != 1) continue;
    418:       DMPlexGetSupport(dm, face, &support);

    420:       DMPlexGetCone(dm, support[0], &cone);
    421:       DMPlexGetConeSize(dm, support[0], &coneSize);
    422:       DMPlexGetConeOrientation(dm, support[0], &ornt);
    423:       for (c = 0; c < coneSize; ++c) if (cone[c] == face) break;
    424:       if (dim == 1) {
    425:         /* Use cone position instead, shifted to -1 or 1 */
    426:         if (PetscBTLookup(flippedCells, support[0]-cStart)) rorntComp[face].rank = 1-c*2;
    427:         else                                                rorntComp[face].rank = c*2-1;
    428:       } else {
    429:         if (PetscBTLookup(flippedCells, support[0]-cStart)) rorntComp[face].rank = ornt[c] < 0 ? -1 :  1;
    430:         else                                                rorntComp[face].rank = ornt[c] < 0 ?  1 : -1;
    431:       }
    432:       rorntComp[face].index = faceComp[face-fStart];
    433:     }
    434:     /* Communicate boundary edge orientations */
    435:     PetscSFBcastBegin(sf, MPIU_2INT, rorntComp, lorntComp,MPI_REPLACE);
    436:     PetscSFBcastEnd(sf, MPIU_2INT, rorntComp, lorntComp,MPI_REPLACE);
    437:   }
    438:   /* Get process adjacency */
    439:   PetscMalloc2(numComponents, &numNeighbors, numComponents, &neighbors);
    440:   viewer = PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)dm));
    441:   if (flg2) {PetscViewerASCIIPushSynchronized(viewer);}
    442:   PetscViewerGetSubViewer(viewer,PETSC_COMM_SELF,&selfviewer);
    443:   for (comp = 0; comp < numComponents; ++comp) {
    444:     PetscInt  l, n;

    446:     numNeighbors[comp] = 0;
    447:     PetscMalloc1(PetscMax(numLeaves, 0), &neighbors[comp]);
    448:     /* I know this is p^2 time in general, but for bounded degree its alright */
    449:     for (l = 0; l < numLeaves; ++l) {
    450:       const PetscInt face = lpoints[l];

    452:       /* Find a representative face (edge) separating pairs of procs */
    453:       if ((face >= fStart) && (face < fEnd) && (faceComp[face-fStart] == comp)) {
    454:         const PetscInt rrank = rpoints[l].rank;
    455:         const PetscInt rcomp = lorntComp[face].index;

    457:         for (n = 0; n < numNeighbors[comp]; ++n) if ((rrank == rpoints[neighbors[comp][n]].rank) && (rcomp == lorntComp[lpoints[neighbors[comp][n]]].index)) break;
    458:         if (n >= numNeighbors[comp]) {
    459:           PetscInt supportSize;

    461:           DMPlexGetSupportSize(dm, face, &supportSize);
    462:           if (supportSize != 1) SETERRQ1(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Boundary faces should see one cell, not %d", supportSize);
    463:           if (flg) {PetscViewerASCIIPrintf(selfviewer, "[%d]: component %d, Found representative leaf %d (face %d) connecting to face %d on (%d, %d) with orientation %d\n", rank, comp, l, face, rpoints[l].index, rrank, rcomp, lorntComp[face].rank);}
    464:           neighbors[comp][numNeighbors[comp]++] = l;
    465:         }
    466:       }
    467:     }
    468:     totNeighbors += numNeighbors[comp];
    469:   }
    470:   PetscViewerRestoreSubViewer(viewer,PETSC_COMM_SELF,&selfviewer);
    471:   PetscViewerFlush(viewer);
    472:   if (flg2) {PetscViewerASCIIPopSynchronized(viewer);}
    473:   PetscMalloc2(totNeighbors, &nrankComp, totNeighbors, &match);
    474:   for (comp = 0, off = 0; comp < numComponents; ++comp) {
    475:     PetscInt n;

    477:     for (n = 0; n < numNeighbors[comp]; ++n, ++off) {
    478:       const PetscInt face = lpoints[neighbors[comp][n]];
    479:       const PetscInt o    = rorntComp[face].rank*lorntComp[face].rank;

    481:       if      (o < 0) match[off] = PETSC_TRUE;
    482:       else if (o > 0) match[off] = PETSC_FALSE;
    483:       else SETERRQ5(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Invalid face %d (%d, %d) neighbor: %d comp: %d", face, rorntComp[face], lorntComp[face], neighbors[comp][n], comp);
    484:       nrankComp[off].rank  = rpoints[neighbors[comp][n]].rank;
    485:       nrankComp[off].index = lorntComp[lpoints[neighbors[comp][n]]].index;
    486:     }
    487:     PetscFree(neighbors[comp]);
    488:   }
    489:   /* Collect the graph on 0 */
    490:   if (numLeaves >= 0) {
    491:     Mat          G;
    492:     PetscBT      seenProcs, flippedProcs;
    493:     PetscInt    *procFIFO, pTop, pBottom;
    494:     PetscInt    *N   = NULL, *Noff;
    495:     PetscSFNode *adj = NULL;
    496:     PetscBool   *val = NULL;
    497:     PetscMPIInt *recvcounts = NULL, *displs = NULL, *Nc, p, o;
    498:     PetscMPIInt  size = 0;

    500:     PetscCalloc1(numComponents, &flipped);
    501:     if (!rank) {MPI_Comm_size(comm, &size);}
    502:     PetscCalloc4(size, &recvcounts, size+1, &displs, size, &Nc, size+1, &Noff);
    503:     MPI_Gather(&numComponents, 1, MPI_INT, Nc, 1, MPI_INT, 0, comm);
    504:     for (p = 0; p < size; ++p) {
    505:       displs[p+1] = displs[p] + Nc[p];
    506:     }
    507:     if (!rank) {PetscMalloc1(displs[size],&N);}
    508:     MPI_Gatherv(numNeighbors, numComponents, MPIU_INT, N, Nc, displs, MPIU_INT, 0, comm);
    509:     for (p = 0, o = 0; p < size; ++p) {
    510:       recvcounts[p] = 0;
    511:       for (c = 0; c < Nc[p]; ++c, ++o) recvcounts[p] += N[o];
    512:       displs[p+1] = displs[p] + recvcounts[p];
    513:     }
    514:     if (!rank) {PetscMalloc2(displs[size], &adj, displs[size], &val);}
    515:     MPI_Gatherv(nrankComp, totNeighbors, MPIU_2INT, adj, recvcounts, displs, MPIU_2INT, 0, comm);
    516:     MPI_Gatherv(match, totNeighbors, MPIU_BOOL, val, recvcounts, displs, MPIU_BOOL, 0, comm);
    517:     PetscFree2(numNeighbors, neighbors);
    518:     if (!rank) {
    519:       for (p = 1; p <= size; ++p) {Noff[p] = Noff[p-1] + Nc[p-1];}
    520:       if (flg) {
    521:         PetscInt n;

    523:         for (p = 0, off = 0; p < size; ++p) {
    524:           for (c = 0; c < Nc[p]; ++c) {
    525:             PetscPrintf(PETSC_COMM_SELF, "Proc %d Comp %d:\n", p, c);
    526:             for (n = 0; n < N[Noff[p]+c]; ++n, ++off) {
    527:               PetscPrintf(PETSC_COMM_SELF, "  edge (%d, %d) (%d):\n", adj[off].rank, adj[off].index, val[off]);
    528:             }
    529:           }
    530:         }
    531:       }
    532:       /* Symmetrize the graph */
    533:       MatCreate(PETSC_COMM_SELF, &G);
    534:       MatSetSizes(G, Noff[size], Noff[size], Noff[size], Noff[size]);
    535:       MatSetUp(G);
    536:       for (p = 0, off = 0; p < size; ++p) {
    537:         for (c = 0; c < Nc[p]; ++c) {
    538:           const PetscInt r = Noff[p]+c;
    539:           PetscInt       n;

    541:           for (n = 0; n < N[r]; ++n, ++off) {
    542:             const PetscInt    q = Noff[adj[off].rank] + adj[off].index;
    543:             const PetscScalar o = val[off] ? 1.0 : 0.0;

    545:             MatSetValues(G, 1, &r, 1, &q, &o, INSERT_VALUES);
    546:             MatSetValues(G, 1, &q, 1, &r, &o, INSERT_VALUES);
    547:           }
    548:         }
    549:       }
    550:       MatAssemblyBegin(G, MAT_FINAL_ASSEMBLY);
    551:       MatAssemblyEnd(G, MAT_FINAL_ASSEMBLY);

    553:       PetscBTCreate(Noff[size], &seenProcs);
    554:       PetscBTMemzero(Noff[size], seenProcs);
    555:       PetscBTCreate(Noff[size], &flippedProcs);
    556:       PetscBTMemzero(Noff[size], flippedProcs);
    557:       PetscMalloc1(Noff[size], &procFIFO);
    558:       pTop = pBottom = 0;
    559:       for (p = 0; p < Noff[size]; ++p) {
    560:         if (PetscBTLookup(seenProcs, p)) continue;
    561:         /* Initialize FIFO with next proc */
    562:         procFIFO[pBottom++] = p;
    563:         PetscBTSet(seenProcs, p);
    564:         /* Consider each proc in FIFO */
    565:         while (pTop < pBottom) {
    566:           const PetscScalar *ornt;
    567:           const PetscInt    *neighbors;
    568:           PetscInt           proc, nproc, seen, flippedA, flippedB, mismatch, numNeighbors, n;

    570:           proc     = procFIFO[pTop++];
    571:           flippedA = PetscBTLookup(flippedProcs, proc) ? 1 : 0;
    572:           MatGetRow(G, proc, &numNeighbors, &neighbors, &ornt);
    573:           /* Loop over neighboring procs */
    574:           for (n = 0; n < numNeighbors; ++n) {
    575:             nproc    = neighbors[n];
    576:             mismatch = PetscRealPart(ornt[n]) > 0.5 ? 0 : 1;
    577:             seen     = PetscBTLookup(seenProcs, nproc);
    578:             flippedB = PetscBTLookup(flippedProcs, nproc) ? 1 : 0;

    580:             if (mismatch ^ (flippedA ^ flippedB)) {
    581:               if (seen) SETERRQ2(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Previously seen procs %d and %d do not match: Fault mesh is non-orientable", proc, nproc);
    582:               if (!flippedB) {
    583:                 PetscBTSet(flippedProcs, nproc);
    584:               } else SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Inconsistent mesh orientation: Fault mesh is non-orientable");
    585:             } else if (mismatch && flippedA && flippedB) SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Attempt to flip already flipped cell: Fault mesh is non-orientable");
    586:             if (!seen) {
    587:               procFIFO[pBottom++] = nproc;
    588:               PetscBTSet(seenProcs, nproc);
    589:             }
    590:           }
    591:         }
    592:       }
    593:       PetscFree(procFIFO);
    594:       MatDestroy(&G);
    595:       PetscFree2(adj, val);
    596:       PetscBTDestroy(&seenProcs);
    597:     }
    598:     /* Scatter flip flags */
    599:     {
    600:       PetscBool *flips = NULL;

    602:       if (!rank) {
    603:         PetscMalloc1(Noff[size], &flips);
    604:         for (p = 0; p < Noff[size]; ++p) {
    605:           flips[p] = PetscBTLookup(flippedProcs, p) ? PETSC_TRUE : PETSC_FALSE;
    606:           if (flg && flips[p]) {PetscPrintf(comm, "Flipping Proc+Comp %d:\n", p);}
    607:         }
    608:         for (p = 0; p < size; ++p) {
    609:           displs[p+1] = displs[p] + Nc[p];
    610:         }
    611:       }
    612:       MPI_Scatterv(flips, Nc, displs, MPIU_BOOL, flipped, numComponents, MPIU_BOOL, 0, comm);
    613:       PetscFree(flips);
    614:     }
    615:     if (!rank) {PetscBTDestroy(&flippedProcs);}
    616:     PetscFree(N);
    617:     PetscFree4(recvcounts, displs, Nc, Noff);
    618:     PetscFree2(nrankComp, match);

    620:     /* Decide whether to flip cells in each component */
    621:     for (c = 0; c < cEnd-cStart; ++c) {if (flipped[cellComp[c]]) {PetscBTNegate(flippedCells, c);}}
    622:     PetscFree(flipped);
    623:   }
    624:   if (flg) {
    625:     PetscViewer v;

    627:     PetscViewerASCIIGetStdout(comm, &v);
    628:     PetscViewerASCIIPushSynchronized(v);
    629:     PetscViewerASCIISynchronizedPrintf(v, "[%d]BT for parallel flipped cells:\n", rank);
    630:     PetscBTView(cEnd-cStart, flippedCells, v);
    631:     PetscViewerFlush(v);
    632:     PetscViewerASCIIPopSynchronized(v);
    633:   }
    634:   /* Reverse flipped cells in the mesh */
    635:   for (c = cStart; c < cEnd; ++c) {
    636:     if (PetscBTLookup(flippedCells, c-cStart)) {
    637:       DMPlexReverseCell(dm, c);
    638:     }
    639:   }
    640:   PetscBTDestroy(&seenCells);
    641:   PetscBTDestroy(&flippedCells);
    642:   PetscBTDestroy(&seenFaces);
    643:   PetscFree2(numNeighbors, neighbors);
    644:   PetscFree2(rorntComp, lorntComp);
    645:   PetscFree3(faceFIFO, cellComp, faceComp);
    646:   return(0);
    647: }