xref: /petsc/src/dm/impls/plex/plexorient.c (revision 2da392cc7c10228af19ad9843ce5155178acb644) 
1 #include <petsc/private/dmpleximpl.h>   /*I      "petscdmplex.h"   I*/
2 #include <petscsf.h>
3 
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.
6 
7   Not Collective
8 
9   Input Parameters:
10 + dm              - The DM (DMPLEX)
11 . p               - The DAG point whose cone is compared
12 . masterConeSize  - Number of the reference cone points passed (at least 2 and at most size of the cone of p)
13 - masterCone      - The reference cone points
14 
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
18 
19   Level: advanced
20 
21 .seealso: DMPlexOrient(), DMPlexOrientCell()
22 @*/
23 PetscErrorCode DMPlexCompareOrientations(DM dm, PetscInt p, PetscInt masterConeSize, const PetscInt masterCone[], PetscInt *start, PetscBool *reverse)
24 {
25   PetscInt        coneSize;
26   const PetscInt *cone;
27   PetscInt        i, start_;
28   PetscBool       reverse_;
29   PetscErrorCode  ierr;
30 
31   PetscFunctionBegin;
32   PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
33   ierr = DMPlexGetConeSize(dm, p, &coneSize);CHKERRQ(ierr);
34   if (coneSize < 2) SETERRQ1(PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Point %D has no cone", p);
35   ierr = DMPlexGetCone(dm, p, &cone);CHKERRQ(ierr);
36   if (masterConeSize < 2) SETERRQ1(PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Point %D: masterConeSize must be at least 2", p);
37   if (masterConeSize > coneSize) SETERRQ1(PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Point %D: masterConeSize must be at most coneSize", p);
38   start_ = 0;
39   for (i=0; i<coneSize; i++) {
40     if (cone[i] == masterCone[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 slave cone", p);
46   reverse_ = PETSC_FALSE;
47   for (i=0; i<masterConeSize; i++) {if (cone[(start_+i)%coneSize] != masterCone[i]) break;}
48   if (i != masterConeSize) {
49     reverse_ = PETSC_TRUE;
50     for (i=0; i<masterConeSize; i++) {if (cone[(coneSize+start_-i)%coneSize] != masterCone[i]) break;}
51     if (i < masterConeSize) 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_] != masterCone[0])) SETERRQ4(PETSC_COMM_SELF, PETSC_ERR_PLIB, "Point %D: cone[%d] = %d != %d = masterCone[0]", p, start_, cone[start_], masterCone[0]);
56   PetscFunctionReturn(0);
57 }
58 
59 /*@
60   DMPlexOrientCell - Set the desired order of cone points of this DAG point, and fix orientations accordingly.
61 
62   Not Collective
63 
64   Input Parameters:
65 + dm              - The DM
66 . p               - The DAG point (from interval given by DMPlexGetChart())
67 . masterConeSize  - Number of specified cone points (at least 2)
68 - masterCone      - Specified cone points, i.e. ordered subset of current cone in DAG numbering (not cone-local numbering)
69 
70   Level: intermediate
71 
72 .seealso: DMPlexOrient(), DMPlexGetCone(), DMPlexGetConeOrientation(), DMPlexInterpolate(), DMPlexGetChart()
73 @*/
74 PetscErrorCode DMPlexOrientCell(DM dm, PetscInt p, PetscInt masterConeSize, const PetscInt masterCone[])
75 {
76   PetscInt        coneSize;
77   PetscInt        start1=0;
78   PetscBool       reverse1=PETSC_FALSE;
79   PetscErrorCode  ierr;
80 
81   PetscFunctionBegin;
82   PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
83   if (masterConeSize) PetscValidIntPointer(masterCone,4);
84   if (masterConeSize == 1) SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "masterConeSize cannot be 1");
85   ierr = DMPlexGetConeSize(dm, p, &coneSize);CHKERRQ(ierr);
86   if (!coneSize) PetscFunctionReturn(0); /* do nothing for points with no cone */
87   ierr = DMPlexCompareOrientations(dm, p, masterConeSize, masterCone, &start1, &reverse1);CHKERRQ(ierr);
88   ierr = DMPlexOrientCell_Internal(dm, p, start1, reverse1);CHKERRQ(ierr);
89   if (PetscDefined(USE_DEBUG)) {
90     PetscInt        c;
91     const PetscInt *cone;
92     ierr = DMPlexGetCone(dm, p, &cone);CHKERRQ(ierr);
93     for (c = 0; c < masterConeSize; c++) {
94       if (PetscUnlikely(cone[c] != masterCone[c])) SETERRQ4(PETSC_COMM_SELF, PETSC_ERR_PLIB, "The algorithm above is wrong as cone[%d] = %d != %d = masterCone[%d]", c, cone[c], masterCone[c], c);
95     }
96   }
97   PetscFunctionReturn(0);
98 }
99 
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;
109 
110   PetscFunctionBegin;
111   if (!start1 && !reverse1) PetscFunctionReturn(0);
112   ierr = DMPlexGetConeSize(dm, p, &coneSize);CHKERRQ(ierr);
113   if (!coneSize) PetscFunctionReturn(0); /* do nothing for points with no cone */
114   ierr = DMPlexGetCone(dm, p, &cone);CHKERRQ(ierr);
115   ierr = DMPlexGetMaxSizes(dm, &maxConeSize, NULL);CHKERRQ(ierr);
116   /* permute p's cone and orientations */
117   ierr = DMPlexGetConeOrientation(dm, p, &ornts);CHKERRQ(ierr);
118   ierr = DMGetWorkArray(dm, maxConeSize, MPIU_INT, &newcone);CHKERRQ(ierr);
119   ierr = DMGetWorkArray(dm, maxConeSize, MPIU_INT, &newornts);CHKERRQ(ierr);
120   ierr = DMPlexFixFaceOrientations_Permute_Private(coneSize, cone, start1, reverse1, newcone);CHKERRQ(ierr);
121   ierr = DMPlexFixFaceOrientations_Permute_Private(coneSize, ornts, start1, reverse1, newornts);CHKERRQ(ierr);
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       ierr = DMPlexGetConeSize(dm, cone[i], &coneConeSize);CHKERRQ(ierr);
126       ierr = DMPlexFixFaceOrientations_Translate_Private(newornts[i], &start0, &reverse0);CHKERRQ(ierr);
127       ierr = DMPlexFixFaceOrientations_Combine_Private(coneConeSize, start0, reverse0, 1, PETSC_FALSE, &start, &reverse);CHKERRQ(ierr);
128       ierr = DMPlexFixFaceOrientations_TranslateBack_Private(coneConeSize, start, reverse, &newornts[i]);CHKERRQ(ierr);
129     }
130   }
131   ierr = DMPlexSetConeOrientation(dm, p, newornts);CHKERRQ(ierr);
132   /* fix oriention of p within cones of p's support points */
133   ierr = DMPlexGetSupport(dm, p, &support);CHKERRQ(ierr);
134   ierr = DMPlexGetSupportSize(dm, p, &supportSize);CHKERRQ(ierr);
135   for (j=0; j<supportSize; j++) {
136     ierr = DMPlexGetCone(dm, support[j], &supportCone);CHKERRQ(ierr);
137     ierr = DMPlexGetConeSize(dm, support[j], &supportConeSize);CHKERRQ(ierr);
138     ierr = DMPlexGetConeOrientation(dm, support[j], &ornts);CHKERRQ(ierr);
139     for (k=0; k<supportConeSize; k++) {
140       if (supportCone[k] != p) continue;
141       ierr = DMPlexFixFaceOrientations_Translate_Private(ornts[k], &start0, &reverse0);CHKERRQ(ierr);
142       ierr = DMPlexFixFaceOrientations_Combine_Private(coneSize, start0, reverse0, start1, reverse1, &start, &reverse);CHKERRQ(ierr);
143       ierr = DMPlexFixFaceOrientations_TranslateBack_Private(coneSize, start, reverse, &newornt);CHKERRQ(ierr);
144       ierr = DMPlexInsertConeOrientation(dm, support[j], k, newornt);CHKERRQ(ierr);
145     }
146   }
147   /* rewrite cone */
148   ierr = DMPlexSetCone(dm, p, newcone);CHKERRQ(ierr);
149   ierr = DMRestoreWorkArray(dm, maxConeSize, MPIU_INT, &newcone);CHKERRQ(ierr);
150   ierr = DMRestoreWorkArray(dm, maxConeSize, MPIU_INT, &newornts);CHKERRQ(ierr);
151   PetscFunctionReturn(0);
152 }
153 
154 /*@
155   DMPlexReverseCell - Give a mesh cell the opposite orientation
156 
157   Input Parameters:
158 + dm   - The DM
159 - cell - The cell number
160 
161   Note: The modification of the DM is done in-place.
162 
163   Level: advanced
164 
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:
170 
171        ro = o >= 0 ? -(faceSize - o) : faceSize + o
172 
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;
179 
180   PetscFunctionBegin;
181   ierr = DMPlexGetMaxSizes(dm, &maxConeSize, NULL);CHKERRQ(ierr);
182   ierr = DMGetWorkArray(dm, maxConeSize, MPIU_INT, &revcone);CHKERRQ(ierr);
183   ierr = DMGetWorkArray(dm, maxConeSize, MPIU_INT, &revconeO);CHKERRQ(ierr);
184   /* Reverse cone, and reverse orientations of faces */
185   ierr = DMPlexGetConeSize(dm, cell, &coneSize);CHKERRQ(ierr);
186   ierr = DMPlexGetCone(dm, cell, &cone);CHKERRQ(ierr);
187   ierr = DMPlexGetConeOrientation(dm, cell, &coneO);CHKERRQ(ierr);
188   for (cp = 0; cp < coneSize; ++cp) {
189     const PetscInt rcp = coneSize-cp-1;
190 
191     ierr = DMPlexGetConeSize(dm, cone[rcp], &faceSize);CHKERRQ(ierr);
192     revcone[cp]  = cone[rcp];
193     revconeO[cp] = coneO[rcp] >= 0 ? -(faceSize-coneO[rcp]) : faceSize+coneO[rcp];
194   }
195   ierr = DMPlexSetCone(dm, cell, revcone);CHKERRQ(ierr);
196   ierr = DMPlexSetConeOrientation(dm, cell, revconeO);CHKERRQ(ierr);
197   /* Reverse orientation of this cell in the support hypercells */
198   faceSize = coneSize;
199   ierr = DMPlexGetSupportSize(dm, cell, &supportSize);CHKERRQ(ierr);
200   ierr = DMPlexGetSupport(dm, cell, &support);CHKERRQ(ierr);
201   for (sp = 0; sp < supportSize; ++sp) {
202     ierr = DMPlexGetConeSize(dm, support[sp], &coneSize);CHKERRQ(ierr);
203     ierr = DMPlexGetCone(dm, support[sp], &cone);CHKERRQ(ierr);
204     ierr = DMPlexGetConeOrientation(dm, support[sp], &coneO);CHKERRQ(ierr);
205     for (cp = 0; cp < coneSize; ++cp) {
206       if (cone[cp] != cell) continue;
207       ierr = DMPlexInsertConeOrientation(dm, support[sp], cp, coneO[cp] >= 0 ? -(faceSize-coneO[cp]) : faceSize+coneO[cp]);CHKERRQ(ierr);
208     }
209   }
210   ierr = DMRestoreWorkArray(dm, maxConeSize, MPIU_INT, &revcone);CHKERRQ(ierr);
211   ierr = DMRestoreWorkArray(dm, maxConeSize, MPIU_INT, &revconeO);CHKERRQ(ierr);
212   PetscFunctionReturn(0);
213 }
214 
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;
226 
227   PetscFunctionBegin;
228   face = faceFIFO[(*fTop)++];
229   ierr = DMGetDimension(dm, &dim);CHKERRQ(ierr);
230   ierr = DMPlexGetSupportSize(dm, face, &supportSize);CHKERRQ(ierr);
231   ierr = DMPlexGetSupport(dm, face, &support);CHKERRQ(ierr);
232   if (supportSize < 2) PetscFunctionReturn(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;
238 
239   ierr = DMPlexGetConeSize(dm, support[0], &coneSizeA);CHKERRQ(ierr);
240   ierr = DMPlexGetConeSize(dm, support[1], &coneSizeB);CHKERRQ(ierr);
241   ierr = DMPlexGetCone(dm, support[0], &coneA);CHKERRQ(ierr);
242   ierr = DMPlexGetCone(dm, support[1], &coneB);CHKERRQ(ierr);
243   ierr = DMPlexGetConeOrientation(dm, support[0], &coneOA);CHKERRQ(ierr);
244   ierr = DMPlexGetConeOrientation(dm, support[1], &coneOB);CHKERRQ(ierr);
245   for (c = 0; c < coneSizeA; ++c) {
246     if (!PetscBTLookup(seenFaces, coneA[c]-fStart)) {
247       faceFIFO[(*fBottom)++] = coneA[c];
248       ierr = PetscBTSet(seenFaces, coneA[c]-fStart);CHKERRQ(ierr);
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       ierr = PetscBTSet(seenFaces, coneB[c]-fStart);CHKERRQ(ierr);
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]);
263 
264   if (dim == 1) {
265     mismatch = posA == posB;
266   } else {
267     mismatch = coneOA[posA] == coneOB[posB];
268   }
269 
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       ierr = PetscBTSet(flippedCells, support[0]-cStart);CHKERRQ(ierr);
274     } else if (!seenB && !flippedB) {
275       ierr = PetscBTSet(flippedCells, support[1]-cStart);CHKERRQ(ierr);
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   ierr = PetscBTSet(seenCells, support[0]-cStart);CHKERRQ(ierr);
279   ierr = PetscBTSet(seenCells, support[1]-cStart);CHKERRQ(ierr);
280   PetscFunctionReturn(0);
281 }
282 
283 /*@
284   DMPlexOrient - Give a consistent orientation to the input mesh
285 
286   Input Parameters:
287 . dm - The DM
288 
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.
291 
292   Level: advanced
293 
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;
313 
314   PetscFunctionBegin;
315   ierr = PetscObjectGetComm((PetscObject) dm, &comm);CHKERRQ(ierr);
316   ierr = MPI_Comm_rank(comm, &rank);CHKERRQ(ierr);
317   ierr = MPI_Comm_size(comm, &size);CHKERRQ(ierr);
318   ierr = PetscOptionsHasName(((PetscObject) dm)->options,((PetscObject) dm)->prefix, "-orientation_view", &flg);CHKERRQ(ierr);
319   ierr = PetscOptionsHasName(((PetscObject) dm)->options,((PetscObject) dm)->prefix, "-orientation_view_synchronized", &flg2);CHKERRQ(ierr);
320   ierr = DMGetPointSF(dm, &sf);CHKERRQ(ierr);
321   ierr = PetscSFGetGraph(sf, &numRoots, &numLeaves, &lpoints, &rpoints);CHKERRQ(ierr);
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   ierr = DMGetDimension(dm, &dim);CHKERRQ(ierr);
332   ierr = DMPlexGetVTKCellHeight(dm, &h);CHKERRQ(ierr);
333   ierr = DMPlexGetHeightStratum(dm, h,   &cStart, &cEnd);CHKERRQ(ierr);
334   ierr = DMPlexGetHeightStratum(dm, h+1, &fStart, &fEnd);CHKERRQ(ierr);
335   ierr = PetscBTCreate(cEnd - cStart, &seenCells);CHKERRQ(ierr);
336   ierr = PetscBTMemzero(cEnd - cStart, seenCells);CHKERRQ(ierr);
337   ierr = PetscBTCreate(cEnd - cStart, &flippedCells);CHKERRQ(ierr);
338   ierr = PetscBTMemzero(cEnd - cStart, flippedCells);CHKERRQ(ierr);
339   ierr = PetscBTCreate(fEnd - fStart, &seenFaces);CHKERRQ(ierr);
340   ierr = PetscBTMemzero(fEnd - fStart, seenFaces);CHKERRQ(ierr);
341   ierr = PetscCalloc3(fEnd - fStart, &faceFIFO, cEnd-cStart, &cellComp, fEnd-fStart, &faceComp);CHKERRQ(ierr);
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
356 
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;
371 
372       fTop = fBottom = 0;
373       ierr = DMPlexGetConeSize(dm, cell, &coneSize);CHKERRQ(ierr);
374       ierr = DMPlexGetCone(dm, cell, &cone);CHKERRQ(ierr);
375       for (c = 0; c < coneSize; ++c) {
376         faceFIFO[fBottom++] = cone[c];
377         ierr = PetscBTSet(seenFaces, cone[c]-fStart);CHKERRQ(ierr);
378       }
379       ierr = PetscBTSet(seenCells, cell-cStart);CHKERRQ(ierr);
380     }
381     /* Consider each face in FIFO */
382     while (fTop < fBottom) {
383       ierr = DMPlexCheckFace_Internal(dm, faceFIFO, &fTop, &fBottom, cStart, fStart, fEnd, seenCells, flippedCells, seenFaces);CHKERRQ(ierr);
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     ierr = PetscBTMemzero(fEnd - fStart, seenFaces);CHKERRQ(ierr);
394     ierr = PetscBTMemzero(cEnd - cStart, seenCells);CHKERRQ(ierr);
395     ++comp;
396   } while (1);
397   numComponents = comp;
398   if (flg) {
399     PetscViewer v;
400 
401     ierr = PetscViewerASCIIGetStdout(comm, &v);CHKERRQ(ierr);
402     ierr = PetscViewerASCIIPushSynchronized(v);CHKERRQ(ierr);
403     ierr = PetscViewerASCIISynchronizedPrintf(v, "[%d]BT for serial flipped cells:\n", rank);CHKERRQ(ierr);
404     ierr = PetscBTView(cEnd-cStart, flippedCells, v);CHKERRQ(ierr);
405     ierr = PetscViewerFlush(v);CHKERRQ(ierr);
406     ierr = PetscViewerASCIIPopSynchronized(v);CHKERRQ(ierr);
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     ierr = PetscCalloc2(numRoots,&rorntComp,numRoots,&lorntComp);CHKERRQ(ierr);
412     for (face = fStart; face < fEnd; ++face) {
413       const PetscInt *cone, *support, *ornt;
414       PetscInt        coneSize, supportSize;
415 
416       ierr = DMPlexGetSupportSize(dm, face, &supportSize);CHKERRQ(ierr);
417       if (supportSize != 1) continue;
418       ierr = DMPlexGetSupport(dm, face, &support);CHKERRQ(ierr);
419 
420       ierr = DMPlexGetCone(dm, support[0], &cone);CHKERRQ(ierr);
421       ierr = DMPlexGetConeSize(dm, support[0], &coneSize);CHKERRQ(ierr);
422       ierr = DMPlexGetConeOrientation(dm, support[0], &ornt);CHKERRQ(ierr);
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     ierr = PetscSFBcastBegin(sf, MPIU_2INT, rorntComp, lorntComp);CHKERRQ(ierr);
436     ierr = PetscSFBcastEnd(sf, MPIU_2INT, rorntComp, lorntComp);CHKERRQ(ierr);
437   }
438   /* Get process adjacency */
439   ierr = PetscMalloc2(numComponents, &numNeighbors, numComponents, &neighbors);CHKERRQ(ierr);
440   viewer = PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)dm));
441   if (flg2) {ierr = PetscViewerASCIIPushSynchronized(viewer);CHKERRQ(ierr);}
442   ierr = PetscViewerGetSubViewer(viewer,PETSC_COMM_SELF,&selfviewer);CHKERRQ(ierr);
443   for (comp = 0; comp < numComponents; ++comp) {
444     PetscInt  l, n;
445 
446     numNeighbors[comp] = 0;
447     ierr = PetscMalloc1(PetscMax(numLeaves, 0), &neighbors[comp]);CHKERRQ(ierr);
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];
451 
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;
456 
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;
460 
461           ierr = DMPlexGetSupportSize(dm, face, &supportSize);CHKERRQ(ierr);
462           if (supportSize != 1) SETERRQ1(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Boundary faces should see one cell, not %d", supportSize);
463           if (flg) {ierr = 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);CHKERRQ(ierr);}
464           neighbors[comp][numNeighbors[comp]++] = l;
465         }
466       }
467     }
468     totNeighbors += numNeighbors[comp];
469   }
470   ierr = PetscViewerRestoreSubViewer(viewer,PETSC_COMM_SELF,&selfviewer);CHKERRQ(ierr);
471   ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
472   if (flg2) {ierr = PetscViewerASCIIPopSynchronized(viewer);CHKERRQ(ierr);}
473   ierr = PetscMalloc2(totNeighbors, &nrankComp, totNeighbors, &match);CHKERRQ(ierr);
474   for (comp = 0, off = 0; comp < numComponents; ++comp) {
475     PetscInt n;
476 
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;
480 
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     ierr = PetscFree(neighbors[comp]);CHKERRQ(ierr);
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;
499 
500     ierr = PetscCalloc1(numComponents, &flipped);CHKERRQ(ierr);
501     if (!rank) {ierr = MPI_Comm_size(comm, &size);CHKERRQ(ierr);}
502     ierr = PetscCalloc4(size, &recvcounts, size+1, &displs, size, &Nc, size+1, &Noff);CHKERRQ(ierr);
503     ierr = MPI_Gather(&numComponents, 1, MPI_INT, Nc, 1, MPI_INT, 0, comm);CHKERRQ(ierr);
504     for (p = 0; p < size; ++p) {
505       displs[p+1] = displs[p] + Nc[p];
506     }
507     if (!rank) {ierr = PetscMalloc1(displs[size],&N);CHKERRQ(ierr);}
508     ierr = MPI_Gatherv(numNeighbors, numComponents, MPIU_INT, N, Nc, displs, MPIU_INT, 0, comm);CHKERRQ(ierr);
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) {ierr = PetscMalloc2(displs[size], &adj, displs[size], &val);CHKERRQ(ierr);}
515     ierr = MPI_Gatherv(nrankComp, totNeighbors, MPIU_2INT, adj, recvcounts, displs, MPIU_2INT, 0, comm);CHKERRQ(ierr);
516     ierr = MPI_Gatherv(match, totNeighbors, MPIU_BOOL, val, recvcounts, displs, MPIU_BOOL, 0, comm);CHKERRQ(ierr);
517     ierr = PetscFree2(numNeighbors, neighbors);CHKERRQ(ierr);
518     if (!rank) {
519       for (p = 1; p <= size; ++p) {Noff[p] = Noff[p-1] + Nc[p-1];}
520       if (flg) {
521         PetscInt n;
522 
523         for (p = 0, off = 0; p < size; ++p) {
524           for (c = 0; c < Nc[p]; ++c) {
525             ierr = PetscPrintf(PETSC_COMM_SELF, "Proc %d Comp %d:\n", p, c);CHKERRQ(ierr);
526             for (n = 0; n < N[Noff[p]+c]; ++n, ++off) {
527               ierr = PetscPrintf(PETSC_COMM_SELF, "  edge (%d, %d) (%d):\n", adj[off].rank, adj[off].index, val[off]);CHKERRQ(ierr);
528             }
529           }
530         }
531       }
532       /* Symmetrize the graph */
533       ierr = MatCreate(PETSC_COMM_SELF, &G);CHKERRQ(ierr);
534       ierr = MatSetSizes(G, Noff[size], Noff[size], Noff[size], Noff[size]);CHKERRQ(ierr);
535       ierr = MatSetUp(G);CHKERRQ(ierr);
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;
540 
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;
544 
545             ierr = MatSetValues(G, 1, &r, 1, &q, &o, INSERT_VALUES);CHKERRQ(ierr);
546             ierr = MatSetValues(G, 1, &q, 1, &r, &o, INSERT_VALUES);CHKERRQ(ierr);
547           }
548         }
549       }
550       ierr = MatAssemblyBegin(G, MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
551       ierr = MatAssemblyEnd(G, MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
552 
553       ierr = PetscBTCreate(Noff[size], &seenProcs);CHKERRQ(ierr);
554       ierr = PetscBTMemzero(Noff[size], seenProcs);CHKERRQ(ierr);
555       ierr = PetscBTCreate(Noff[size], &flippedProcs);CHKERRQ(ierr);
556       ierr = PetscBTMemzero(Noff[size], flippedProcs);CHKERRQ(ierr);
557       ierr = PetscMalloc1(Noff[size], &procFIFO);CHKERRQ(ierr);
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         ierr = PetscBTSet(seenProcs, p);CHKERRQ(ierr);
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;
569 
570           proc     = procFIFO[pTop++];
571           flippedA = PetscBTLookup(flippedProcs, proc) ? 1 : 0;
572           ierr = MatGetRow(G, proc, &numNeighbors, &neighbors, &ornt);CHKERRQ(ierr);
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;
579 
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                 ierr = PetscBTSet(flippedProcs, nproc);CHKERRQ(ierr);
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               ierr = PetscBTSet(seenProcs, nproc);CHKERRQ(ierr);
589             }
590           }
591         }
592       }
593       ierr = PetscFree(procFIFO);CHKERRQ(ierr);
594       ierr = MatDestroy(&G);CHKERRQ(ierr);
595       ierr = PetscFree2(adj, val);CHKERRQ(ierr);
596       ierr = PetscBTDestroy(&seenProcs);CHKERRQ(ierr);
597     }
598     /* Scatter flip flags */
599     {
600       PetscBool *flips = NULL;
601 
602       if (!rank) {
603         ierr = PetscMalloc1(Noff[size], &flips);CHKERRQ(ierr);
604         for (p = 0; p < Noff[size]; ++p) {
605           flips[p] = PetscBTLookup(flippedProcs, p) ? PETSC_TRUE : PETSC_FALSE;
606           if (flg && flips[p]) {ierr = PetscPrintf(comm, "Flipping Proc+Comp %d:\n", p);CHKERRQ(ierr);}
607         }
608         for (p = 0; p < size; ++p) {
609           displs[p+1] = displs[p] + Nc[p];
610         }
611       }
612       ierr = MPI_Scatterv(flips, Nc, displs, MPIU_BOOL, flipped, numComponents, MPIU_BOOL, 0, comm);CHKERRQ(ierr);
613       ierr = PetscFree(flips);CHKERRQ(ierr);
614     }
615     if (!rank) {ierr = PetscBTDestroy(&flippedProcs);CHKERRQ(ierr);}
616     ierr = PetscFree(N);CHKERRQ(ierr);
617     ierr = PetscFree4(recvcounts, displs, Nc, Noff);CHKERRQ(ierr);
618     ierr = PetscFree2(nrankComp, match);CHKERRQ(ierr);
619 
620     /* Decide whether to flip cells in each component */
621     for (c = 0; c < cEnd-cStart; ++c) {if (flipped[cellComp[c]]) {ierr = PetscBTNegate(flippedCells, c);CHKERRQ(ierr);}}
622     ierr = PetscFree(flipped);CHKERRQ(ierr);
623   }
624   if (flg) {
625     PetscViewer v;
626 
627     ierr = PetscViewerASCIIGetStdout(comm, &v);CHKERRQ(ierr);
628     ierr = PetscViewerASCIIPushSynchronized(v);CHKERRQ(ierr);
629     ierr = PetscViewerASCIISynchronizedPrintf(v, "[%d]BT for parallel flipped cells:\n", rank);CHKERRQ(ierr);
630     ierr = PetscBTView(cEnd-cStart, flippedCells, v);CHKERRQ(ierr);
631     ierr = PetscViewerFlush(v);CHKERRQ(ierr);
632     ierr = PetscViewerASCIIPopSynchronized(v);CHKERRQ(ierr);
633   }
634   /* Reverse flipped cells in the mesh */
635   for (c = cStart; c < cEnd; ++c) {
636     if (PetscBTLookup(flippedCells, c-cStart)) {
637       ierr = DMPlexReverseCell(dm, c);CHKERRQ(ierr);
638     }
639   }
640   ierr = PetscBTDestroy(&seenCells);CHKERRQ(ierr);
641   ierr = PetscBTDestroy(&flippedCells);CHKERRQ(ierr);
642   ierr = PetscBTDestroy(&seenFaces);CHKERRQ(ierr);
643   ierr = PetscFree2(numNeighbors, neighbors);CHKERRQ(ierr);
644   ierr = PetscFree2(rorntComp, lorntComp);CHKERRQ(ierr);
645   ierr = PetscFree3(faceFIFO, cellComp, faceComp);CHKERRQ(ierr);
646   PetscFunctionReturn(0);
647 }
648