xref: /petsc/src/dm/impls/plex/plexorient.c (revision 6a98f8dc3f2c9149905a87dc2e9d0fedaf64e09a) 
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 defined(PETSC_USE_DEBUG)
90   {
91     PetscInt        c;
92     const PetscInt *cone;
93     ierr = DMPlexGetCone(dm, p, &cone);CHKERRQ(ierr);
94     for (c = 0; c < masterConeSize; c++) {
95       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);
96     }
97   }
98 #endif
99   PetscFunctionReturn(0);
100 }
101 
102 PetscErrorCode DMPlexOrientCell_Internal(DM dm, PetscInt p, PetscInt start1, PetscBool reverse1)
103 {
104   PetscInt        i, j, k, maxConeSize, coneSize, coneConeSize, supportSize, supportConeSize;
105   PetscInt        start0, start;
106   PetscBool       reverse0, reverse;
107   PetscInt        newornt;
108   const PetscInt *cone=NULL, *support=NULL, *supportCone=NULL, *ornts=NULL;
109   PetscInt       *newcone=NULL, *newornts=NULL;
110   PetscErrorCode  ierr;
111 
112   PetscFunctionBegin;
113   if (!start1 && !reverse1) PetscFunctionReturn(0);
114   ierr = DMPlexGetConeSize(dm, p, &coneSize);CHKERRQ(ierr);
115   if (!coneSize) PetscFunctionReturn(0); /* do nothing for points with no cone */
116   ierr = DMPlexGetCone(dm, p, &cone);CHKERRQ(ierr);
117   ierr = DMPlexGetMaxSizes(dm, &maxConeSize, NULL);CHKERRQ(ierr);
118   /* permute p's cone and orientations */
119   ierr = DMPlexGetConeOrientation(dm, p, &ornts);CHKERRQ(ierr);
120   ierr = DMGetWorkArray(dm, maxConeSize, MPIU_INT, &newcone);CHKERRQ(ierr);
121   ierr = DMGetWorkArray(dm, maxConeSize, MPIU_INT, &newornts);CHKERRQ(ierr);
122   ierr = DMPlexFixFaceOrientations_Permute_Private(coneSize, cone, start1, reverse1, newcone);CHKERRQ(ierr);
123   ierr = DMPlexFixFaceOrientations_Permute_Private(coneSize, ornts, start1, reverse1, newornts);CHKERRQ(ierr);
124   /* if direction of p (face) is flipped, flip also p's cone points (edges) */
125   if (reverse1) {
126     for (i=0; i<coneSize; i++) {
127       ierr = DMPlexGetConeSize(dm, cone[i], &coneConeSize);CHKERRQ(ierr);
128       ierr = DMPlexFixFaceOrientations_Translate_Private(newornts[i], &start0, &reverse0);CHKERRQ(ierr);
129       ierr = DMPlexFixFaceOrientations_Combine_Private(coneConeSize, start0, reverse0, 1, PETSC_FALSE, &start, &reverse);CHKERRQ(ierr);
130       ierr = DMPlexFixFaceOrientations_TranslateBack_Private(coneConeSize, start, reverse, &newornts[i]);CHKERRQ(ierr);
131     }
132   }
133   ierr = DMPlexSetConeOrientation(dm, p, newornts);CHKERRQ(ierr);
134   /* fix oriention of p within cones of p's support points */
135   ierr = DMPlexGetSupport(dm, p, &support);CHKERRQ(ierr);
136   ierr = DMPlexGetSupportSize(dm, p, &supportSize);CHKERRQ(ierr);
137   for (j=0; j<supportSize; j++) {
138     ierr = DMPlexGetCone(dm, support[j], &supportCone);CHKERRQ(ierr);
139     ierr = DMPlexGetConeSize(dm, support[j], &supportConeSize);CHKERRQ(ierr);
140     ierr = DMPlexGetConeOrientation(dm, support[j], &ornts);CHKERRQ(ierr);
141     for (k=0; k<supportConeSize; k++) {
142       if (supportCone[k] != p) continue;
143       ierr = DMPlexFixFaceOrientations_Translate_Private(ornts[k], &start0, &reverse0);CHKERRQ(ierr);
144       ierr = DMPlexFixFaceOrientations_Combine_Private(coneSize, start0, reverse0, start1, reverse1, &start, &reverse);CHKERRQ(ierr);
145       ierr = DMPlexFixFaceOrientations_TranslateBack_Private(coneSize, start, reverse, &newornt);CHKERRQ(ierr);
146       ierr = DMPlexInsertConeOrientation(dm, support[j], k, newornt);CHKERRQ(ierr);
147     }
148   }
149   /* rewrite cone */
150   ierr = DMPlexSetCone(dm, p, newcone);CHKERRQ(ierr);
151   ierr = DMRestoreWorkArray(dm, maxConeSize, MPIU_INT, &newcone);CHKERRQ(ierr);
152   ierr = DMRestoreWorkArray(dm, maxConeSize, MPIU_INT, &newornts);CHKERRQ(ierr);
153   PetscFunctionReturn(0);
154 }
155 
156 /*@
157   DMPlexReverseCell - Give a mesh cell the opposite orientation
158 
159   Input Parameters:
160 + dm   - The DM
161 - cell - The cell number
162 
163   Note: The modification of the DM is done in-place.
164 
165   Level: advanced
166 
167 .seealso: DMPlexOrient(), DMCreate(), DMPLEX
168 @*/
169 PetscErrorCode DMPlexReverseCell(DM dm, PetscInt cell)
170 {
171   /* Note that the reverse orientation ro of a face with orientation o is:
172 
173        ro = o >= 0 ? -(faceSize - o) : faceSize + o
174 
175      where faceSize is the size of the cone for the face.
176   */
177   const PetscInt *cone,    *coneO, *support;
178   PetscInt       *revcone, *revconeO;
179   PetscInt        maxConeSize, coneSize, supportSize, faceSize, cp, sp;
180   PetscErrorCode  ierr;
181 
182   PetscFunctionBegin;
183   ierr = DMPlexGetMaxSizes(dm, &maxConeSize, NULL);CHKERRQ(ierr);
184   ierr = DMGetWorkArray(dm, maxConeSize, MPIU_INT, &revcone);CHKERRQ(ierr);
185   ierr = DMGetWorkArray(dm, maxConeSize, MPIU_INT, &revconeO);CHKERRQ(ierr);
186   /* Reverse cone, and reverse orientations of faces */
187   ierr = DMPlexGetConeSize(dm, cell, &coneSize);CHKERRQ(ierr);
188   ierr = DMPlexGetCone(dm, cell, &cone);CHKERRQ(ierr);
189   ierr = DMPlexGetConeOrientation(dm, cell, &coneO);CHKERRQ(ierr);
190   for (cp = 0; cp < coneSize; ++cp) {
191     const PetscInt rcp = coneSize-cp-1;
192 
193     ierr = DMPlexGetConeSize(dm, cone[rcp], &faceSize);CHKERRQ(ierr);
194     revcone[cp]  = cone[rcp];
195     revconeO[cp] = coneO[rcp] >= 0 ? -(faceSize-coneO[rcp]) : faceSize+coneO[rcp];
196   }
197   ierr = DMPlexSetCone(dm, cell, revcone);CHKERRQ(ierr);
198   ierr = DMPlexSetConeOrientation(dm, cell, revconeO);CHKERRQ(ierr);
199   /* Reverse orientation of this cell in the support hypercells */
200   faceSize = coneSize;
201   ierr = DMPlexGetSupportSize(dm, cell, &supportSize);CHKERRQ(ierr);
202   ierr = DMPlexGetSupport(dm, cell, &support);CHKERRQ(ierr);
203   for (sp = 0; sp < supportSize; ++sp) {
204     ierr = DMPlexGetConeSize(dm, support[sp], &coneSize);CHKERRQ(ierr);
205     ierr = DMPlexGetCone(dm, support[sp], &cone);CHKERRQ(ierr);
206     ierr = DMPlexGetConeOrientation(dm, support[sp], &coneO);CHKERRQ(ierr);
207     for (cp = 0; cp < coneSize; ++cp) {
208       if (cone[cp] != cell) continue;
209       ierr = DMPlexInsertConeOrientation(dm, support[sp], cp, coneO[cp] >= 0 ? -(faceSize-coneO[cp]) : faceSize+coneO[cp]);CHKERRQ(ierr);
210     }
211   }
212   ierr = DMRestoreWorkArray(dm, maxConeSize, MPIU_INT, &revcone);CHKERRQ(ierr);
213   ierr = DMRestoreWorkArray(dm, maxConeSize, MPIU_INT, &revconeO);CHKERRQ(ierr);
214   PetscFunctionReturn(0);
215 }
216 
217 /*
218   - Checks face match
219     - Flips non-matching
220   - Inserts faces of support cells in FIFO
221 */
222 static PetscErrorCode DMPlexCheckFace_Internal(DM dm, PetscInt *faceFIFO, PetscInt *fTop, PetscInt *fBottom, PetscInt cStart, PetscInt fStart, PetscInt fEnd, PetscBT seenCells, PetscBT flippedCells, PetscBT seenFaces)
223 {
224   const PetscInt *support, *coneA, *coneB, *coneOA, *coneOB;
225   PetscInt        supportSize, coneSizeA, coneSizeB, posA = -1, posB = -1;
226   PetscInt        face, dim, seenA, flippedA, seenB, flippedB, mismatch, c;
227   PetscErrorCode  ierr;
228 
229   PetscFunctionBegin;
230   face = faceFIFO[(*fTop)++];
231   ierr = DMGetDimension(dm, &dim);CHKERRQ(ierr);
232   ierr = DMPlexGetSupportSize(dm, face, &supportSize);CHKERRQ(ierr);
233   ierr = DMPlexGetSupport(dm, face, &support);CHKERRQ(ierr);
234   if (supportSize < 2) PetscFunctionReturn(0);
235   if (supportSize != 2) SETERRQ1(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Faces should separate only two cells, not %d", supportSize);
236   seenA    = PetscBTLookup(seenCells,    support[0]-cStart);
237   flippedA = PetscBTLookup(flippedCells, support[0]-cStart) ? 1 : 0;
238   seenB    = PetscBTLookup(seenCells,    support[1]-cStart);
239   flippedB = PetscBTLookup(flippedCells, support[1]-cStart) ? 1 : 0;
240 
241   ierr = DMPlexGetConeSize(dm, support[0], &coneSizeA);CHKERRQ(ierr);
242   ierr = DMPlexGetConeSize(dm, support[1], &coneSizeB);CHKERRQ(ierr);
243   ierr = DMPlexGetCone(dm, support[0], &coneA);CHKERRQ(ierr);
244   ierr = DMPlexGetCone(dm, support[1], &coneB);CHKERRQ(ierr);
245   ierr = DMPlexGetConeOrientation(dm, support[0], &coneOA);CHKERRQ(ierr);
246   ierr = DMPlexGetConeOrientation(dm, support[1], &coneOB);CHKERRQ(ierr);
247   for (c = 0; c < coneSizeA; ++c) {
248     if (!PetscBTLookup(seenFaces, coneA[c]-fStart)) {
249       faceFIFO[(*fBottom)++] = coneA[c];
250       ierr = PetscBTSet(seenFaces, coneA[c]-fStart);CHKERRQ(ierr);
251     }
252     if (coneA[c] == face) posA = c;
253     if (*fBottom > fEnd-fStart) SETERRQ3(PETSC_COMM_SELF, PETSC_ERR_PLIB, "Face %d was pushed exceeding capacity %d > %d", coneA[c], *fBottom, fEnd-fStart);
254   }
255   if (posA < 0) SETERRQ2(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Face %d could not be located in cell %d", face, support[0]);
256   for (c = 0; c < coneSizeB; ++c) {
257     if (!PetscBTLookup(seenFaces, coneB[c]-fStart)) {
258       faceFIFO[(*fBottom)++] = coneB[c];
259       ierr = PetscBTSet(seenFaces, coneB[c]-fStart);CHKERRQ(ierr);
260     }
261     if (coneB[c] == face) posB = c;
262     if (*fBottom > fEnd-fStart) SETERRQ3(PETSC_COMM_SELF, PETSC_ERR_PLIB, "Face %d was pushed exceeding capacity %d > %d", coneA[c], *fBottom, fEnd-fStart);
263   }
264   if (posB < 0) SETERRQ2(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Face %d could not be located in cell %d", face, support[1]);
265 
266   if (dim == 1) {
267     mismatch = posA == posB;
268   } else {
269     mismatch = coneOA[posA] == coneOB[posB];
270   }
271 
272   if (mismatch ^ (flippedA ^ flippedB)) {
273     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]);
274     if (!seenA && !flippedA) {
275       ierr = PetscBTSet(flippedCells, support[0]-cStart);CHKERRQ(ierr);
276     } else if (!seenB && !flippedB) {
277       ierr = PetscBTSet(flippedCells, support[1]-cStart);CHKERRQ(ierr);
278     } else SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Inconsistent mesh orientation: Fault mesh is non-orientable");
279   } else if (mismatch && flippedA && flippedB) SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Attempt to flip already flipped cell: Fault mesh is non-orientable");
280   ierr = PetscBTSet(seenCells, support[0]-cStart);CHKERRQ(ierr);
281   ierr = PetscBTSet(seenCells, support[1]-cStart);CHKERRQ(ierr);
282   PetscFunctionReturn(0);
283 }
284 
285 /*@
286   DMPlexOrient - Give a consistent orientation to the input mesh
287 
288   Input Parameters:
289 . dm - The DM
290 
291   Note: The orientation data for the DM are change in-place.
292 $ This routine will fail for non-orientable surfaces, such as the Moebius strip.
293 
294   Level: advanced
295 
296 .seealso: DMCreate(), DMPLEX
297 @*/
298 PetscErrorCode DMPlexOrient(DM dm)
299 {
300   MPI_Comm           comm;
301   PetscSF            sf;
302   const PetscInt    *lpoints;
303   const PetscSFNode *rpoints;
304   PetscSFNode       *rorntComp = NULL, *lorntComp = NULL;
305   PetscInt          *numNeighbors, **neighbors;
306   PetscSFNode       *nrankComp;
307   PetscBool         *match, *flipped;
308   PetscBT            seenCells, flippedCells, seenFaces;
309   PetscInt          *faceFIFO, fTop, fBottom, *cellComp, *faceComp;
310   PetscInt           numLeaves, numRoots, dim, h, cStart, cEnd, c, cell, fStart, fEnd, face, off, totNeighbors = 0;
311   PetscMPIInt        rank, size, numComponents, comp = 0;
312   PetscBool          flg, flg2;
313   PetscViewer        viewer = NULL, selfviewer = NULL;
314   PetscErrorCode     ierr;
315 
316   PetscFunctionBegin;
317   ierr = PetscObjectGetComm((PetscObject) dm, &comm);CHKERRQ(ierr);
318   ierr = MPI_Comm_rank(comm, &rank);CHKERRQ(ierr);
319   ierr = MPI_Comm_size(comm, &size);CHKERRQ(ierr);
320   ierr = PetscOptionsHasName(((PetscObject) dm)->options,((PetscObject) dm)->prefix, "-orientation_view", &flg);CHKERRQ(ierr);
321   ierr = PetscOptionsHasName(((PetscObject) dm)->options,((PetscObject) dm)->prefix, "-orientation_view_synchronized", &flg2);CHKERRQ(ierr);
322   ierr = DMGetPointSF(dm, &sf);CHKERRQ(ierr);
323   ierr = PetscSFGetGraph(sf, &numRoots, &numLeaves, &lpoints, &rpoints);CHKERRQ(ierr);
324   /* Truth Table
325      mismatch    flips   do action   mismatch   flipA ^ flipB   action
326          F       0 flips     no         F             F           F
327          F       1 flip      yes        F             T           T
328          F       2 flips     no         T             F           T
329          T       0 flips     yes        T             T           F
330          T       1 flip      no
331          T       2 flips     yes
332   */
333   ierr = DMGetDimension(dm, &dim);CHKERRQ(ierr);
334   ierr = DMPlexGetVTKCellHeight(dm, &h);CHKERRQ(ierr);
335   ierr = DMPlexGetHeightStratum(dm, h,   &cStart, &cEnd);CHKERRQ(ierr);
336   ierr = DMPlexGetHeightStratum(dm, h+1, &fStart, &fEnd);CHKERRQ(ierr);
337   ierr = PetscBTCreate(cEnd - cStart, &seenCells);CHKERRQ(ierr);
338   ierr = PetscBTMemzero(cEnd - cStart, seenCells);CHKERRQ(ierr);
339   ierr = PetscBTCreate(cEnd - cStart, &flippedCells);CHKERRQ(ierr);
340   ierr = PetscBTMemzero(cEnd - cStart, flippedCells);CHKERRQ(ierr);
341   ierr = PetscBTCreate(fEnd - fStart, &seenFaces);CHKERRQ(ierr);
342   ierr = PetscBTMemzero(fEnd - fStart, seenFaces);CHKERRQ(ierr);
343   ierr = PetscCalloc3(fEnd - fStart, &faceFIFO, cEnd-cStart, &cellComp, fEnd-fStart, &faceComp);CHKERRQ(ierr);
344   /*
345    OLD STYLE
346    - Add an integer array over cells and faces (component) for connected component number
347    Foreach component
348      - Mark the initial cell as seen
349      - Process component as usual
350      - Set component for all seenCells
351      - Wipe seenCells and seenFaces (flippedCells can stay)
352    - Generate parallel adjacency for component using SF and seenFaces
353    - Collect numComponents adj data from each proc to 0
354    - Build same serial graph
355    - Use same solver
356    - Use Scatterv to to send back flipped flags for each component
357    - Negate flippedCells by component
358 
359    NEW STYLE
360    - Create the adj on each process
361    - Bootstrap to complete graph on proc 0
362   */
363   /* Loop over components */
364   for (cell = cStart; cell < cEnd; ++cell) cellComp[cell-cStart] = -1;
365   do {
366     /* Look for first unmarked cell */
367     for (cell = cStart; cell < cEnd; ++cell) if (cellComp[cell-cStart] < 0) break;
368     if (cell >= cEnd) break;
369     /* Initialize FIFO with first cell in component */
370     {
371       const PetscInt *cone;
372       PetscInt        coneSize;
373 
374       fTop = fBottom = 0;
375       ierr = DMPlexGetConeSize(dm, cell, &coneSize);CHKERRQ(ierr);
376       ierr = DMPlexGetCone(dm, cell, &cone);CHKERRQ(ierr);
377       for (c = 0; c < coneSize; ++c) {
378         faceFIFO[fBottom++] = cone[c];
379         ierr = PetscBTSet(seenFaces, cone[c]-fStart);CHKERRQ(ierr);
380       }
381       ierr = PetscBTSet(seenCells, cell-cStart);CHKERRQ(ierr);
382     }
383     /* Consider each face in FIFO */
384     while (fTop < fBottom) {
385       ierr = DMPlexCheckFace_Internal(dm, faceFIFO, &fTop, &fBottom, cStart, fStart, fEnd, seenCells, flippedCells, seenFaces);CHKERRQ(ierr);
386     }
387     /* Set component for cells and faces */
388     for (cell = 0; cell < cEnd-cStart; ++cell) {
389       if (PetscBTLookup(seenCells, cell)) cellComp[cell] = comp;
390     }
391     for (face = 0; face < fEnd-fStart; ++face) {
392       if (PetscBTLookup(seenFaces, face)) faceComp[face] = comp;
393     }
394     /* Wipe seenCells and seenFaces for next component */
395     ierr = PetscBTMemzero(fEnd - fStart, seenFaces);CHKERRQ(ierr);
396     ierr = PetscBTMemzero(cEnd - cStart, seenCells);CHKERRQ(ierr);
397     ++comp;
398   } while (1);
399   numComponents = comp;
400   if (flg) {
401     PetscViewer v;
402 
403     ierr = PetscViewerASCIIGetStdout(comm, &v);CHKERRQ(ierr);
404     ierr = PetscViewerASCIIPushSynchronized(v);CHKERRQ(ierr);
405     ierr = PetscViewerASCIISynchronizedPrintf(v, "[%d]BT for serial flipped cells:\n", rank);CHKERRQ(ierr);
406     ierr = PetscBTView(cEnd-cStart, flippedCells, v);CHKERRQ(ierr);
407     ierr = PetscViewerFlush(v);CHKERRQ(ierr);
408     ierr = PetscViewerASCIIPopSynchronized(v);CHKERRQ(ierr);
409   }
410   /* Now all subdomains are oriented, but we need a consistent parallel orientation */
411   if (numLeaves >= 0) {
412     /* Store orientations of boundary faces*/
413     ierr = PetscCalloc2(numRoots,&rorntComp,numRoots,&lorntComp);CHKERRQ(ierr);
414     for (face = fStart; face < fEnd; ++face) {
415       const PetscInt *cone, *support, *ornt;
416       PetscInt        coneSize, supportSize;
417 
418       ierr = DMPlexGetSupportSize(dm, face, &supportSize);CHKERRQ(ierr);
419       if (supportSize != 1) continue;
420       ierr = DMPlexGetSupport(dm, face, &support);CHKERRQ(ierr);
421 
422       ierr = DMPlexGetCone(dm, support[0], &cone);CHKERRQ(ierr);
423       ierr = DMPlexGetConeSize(dm, support[0], &coneSize);CHKERRQ(ierr);
424       ierr = DMPlexGetConeOrientation(dm, support[0], &ornt);CHKERRQ(ierr);
425       for (c = 0; c < coneSize; ++c) if (cone[c] == face) break;
426       if (dim == 1) {
427         /* Use cone position instead, shifted to -1 or 1 */
428         if (PetscBTLookup(flippedCells, support[0]-cStart)) rorntComp[face].rank = 1-c*2;
429         else                                                rorntComp[face].rank = c*2-1;
430       } else {
431         if (PetscBTLookup(flippedCells, support[0]-cStart)) rorntComp[face].rank = ornt[c] < 0 ? -1 :  1;
432         else                                                rorntComp[face].rank = ornt[c] < 0 ?  1 : -1;
433       }
434       rorntComp[face].index = faceComp[face-fStart];
435     }
436     /* Communicate boundary edge orientations */
437     ierr = PetscSFBcastBegin(sf, MPIU_2INT, rorntComp, lorntComp);CHKERRQ(ierr);
438     ierr = PetscSFBcastEnd(sf, MPIU_2INT, rorntComp, lorntComp);CHKERRQ(ierr);
439   }
440   /* Get process adjacency */
441   ierr = PetscMalloc2(numComponents, &numNeighbors, numComponents, &neighbors);CHKERRQ(ierr);
442   viewer = PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)dm));
443   if (flg2) {ierr = PetscViewerASCIIPushSynchronized(viewer);CHKERRQ(ierr);}
444   ierr = PetscViewerGetSubViewer(viewer,PETSC_COMM_SELF,&selfviewer);CHKERRQ(ierr);
445   for (comp = 0; comp < numComponents; ++comp) {
446     PetscInt  l, n;
447 
448     numNeighbors[comp] = 0;
449     ierr = PetscMalloc1(PetscMax(numLeaves, 0), &neighbors[comp]);CHKERRQ(ierr);
450     /* I know this is p^2 time in general, but for bounded degree its alright */
451     for (l = 0; l < numLeaves; ++l) {
452       const PetscInt face = lpoints[l];
453 
454       /* Find a representative face (edge) separating pairs of procs */
455       if ((face >= fStart) && (face < fEnd) && (faceComp[face-fStart] == comp)) {
456         const PetscInt rrank = rpoints[l].rank;
457         const PetscInt rcomp = lorntComp[face].index;
458 
459         for (n = 0; n < numNeighbors[comp]; ++n) if ((rrank == rpoints[neighbors[comp][n]].rank) && (rcomp == lorntComp[lpoints[neighbors[comp][n]]].index)) break;
460         if (n >= numNeighbors[comp]) {
461           PetscInt supportSize;
462 
463           ierr = DMPlexGetSupportSize(dm, face, &supportSize);CHKERRQ(ierr);
464           if (supportSize != 1) SETERRQ1(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Boundary faces should see one cell, not %d", supportSize);
465           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);}
466           neighbors[comp][numNeighbors[comp]++] = l;
467         }
468       }
469     }
470     totNeighbors += numNeighbors[comp];
471   }
472   ierr = PetscViewerRestoreSubViewer(viewer,PETSC_COMM_SELF,&selfviewer);CHKERRQ(ierr);
473   ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
474   if (flg2) {ierr = PetscViewerASCIIPopSynchronized(viewer);CHKERRQ(ierr);}
475   ierr = PetscMalloc2(totNeighbors, &nrankComp, totNeighbors, &match);CHKERRQ(ierr);
476   for (comp = 0, off = 0; comp < numComponents; ++comp) {
477     PetscInt n;
478 
479     for (n = 0; n < numNeighbors[comp]; ++n, ++off) {
480       const PetscInt face = lpoints[neighbors[comp][n]];
481       const PetscInt o    = rorntComp[face].rank*lorntComp[face].rank;
482 
483       if      (o < 0) match[off] = PETSC_TRUE;
484       else if (o > 0) match[off] = PETSC_FALSE;
485       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);
486       nrankComp[off].rank  = rpoints[neighbors[comp][n]].rank;
487       nrankComp[off].index = lorntComp[lpoints[neighbors[comp][n]]].index;
488     }
489     ierr = PetscFree(neighbors[comp]);CHKERRQ(ierr);
490   }
491   /* Collect the graph on 0 */
492   if (numLeaves >= 0) {
493     Mat          G;
494     PetscBT      seenProcs, flippedProcs;
495     PetscInt    *procFIFO, pTop, pBottom;
496     PetscInt    *N   = NULL, *Noff;
497     PetscSFNode *adj = NULL;
498     PetscBool   *val = NULL;
499     PetscMPIInt *recvcounts = NULL, *displs = NULL, *Nc, p, o;
500     PetscMPIInt  size = 0;
501 
502     ierr = PetscCalloc1(numComponents, &flipped);CHKERRQ(ierr);
503     if (!rank) {ierr = MPI_Comm_size(comm, &size);CHKERRQ(ierr);}
504     ierr = PetscCalloc4(size, &recvcounts, size+1, &displs, size, &Nc, size+1, &Noff);CHKERRQ(ierr);
505     ierr = MPI_Gather(&numComponents, 1, MPI_INT, Nc, 1, MPI_INT, 0, comm);CHKERRQ(ierr);
506     for (p = 0; p < size; ++p) {
507       displs[p+1] = displs[p] + Nc[p];
508     }
509     if (!rank) {ierr = PetscMalloc1(displs[size],&N);CHKERRQ(ierr);}
510     ierr = MPI_Gatherv(numNeighbors, numComponents, MPIU_INT, N, Nc, displs, MPIU_INT, 0, comm);CHKERRQ(ierr);
511     for (p = 0, o = 0; p < size; ++p) {
512       recvcounts[p] = 0;
513       for (c = 0; c < Nc[p]; ++c, ++o) recvcounts[p] += N[o];
514       displs[p+1] = displs[p] + recvcounts[p];
515     }
516     if (!rank) {ierr = PetscMalloc2(displs[size], &adj, displs[size], &val);CHKERRQ(ierr);}
517     ierr = MPI_Gatherv(nrankComp, totNeighbors, MPIU_2INT, adj, recvcounts, displs, MPIU_2INT, 0, comm);CHKERRQ(ierr);
518     ierr = MPI_Gatherv(match, totNeighbors, MPIU_BOOL, val, recvcounts, displs, MPIU_BOOL, 0, comm);CHKERRQ(ierr);
519     ierr = PetscFree2(numNeighbors, neighbors);CHKERRQ(ierr);
520     if (!rank) {
521       for (p = 1; p <= size; ++p) {Noff[p] = Noff[p-1] + Nc[p-1];}
522       if (flg) {
523         PetscInt n;
524 
525         for (p = 0, off = 0; p < size; ++p) {
526           for (c = 0; c < Nc[p]; ++c) {
527             ierr = PetscPrintf(PETSC_COMM_SELF, "Proc %d Comp %d:\n", p, c);CHKERRQ(ierr);
528             for (n = 0; n < N[Noff[p]+c]; ++n, ++off) {
529               ierr = PetscPrintf(PETSC_COMM_SELF, "  edge (%d, %d) (%d):\n", adj[off].rank, adj[off].index, val[off]);CHKERRQ(ierr);
530             }
531           }
532         }
533       }
534       /* Symmetrize the graph */
535       ierr = MatCreate(PETSC_COMM_SELF, &G);CHKERRQ(ierr);
536       ierr = MatSetSizes(G, Noff[size], Noff[size], Noff[size], Noff[size]);CHKERRQ(ierr);
537       ierr = MatSetUp(G);CHKERRQ(ierr);
538       for (p = 0, off = 0; p < size; ++p) {
539         for (c = 0; c < Nc[p]; ++c) {
540           const PetscInt r = Noff[p]+c;
541           PetscInt       n;
542 
543           for (n = 0; n < N[r]; ++n, ++off) {
544             const PetscInt    q = Noff[adj[off].rank] + adj[off].index;
545             const PetscScalar o = val[off] ? 1.0 : 0.0;
546 
547             ierr = MatSetValues(G, 1, &r, 1, &q, &o, INSERT_VALUES);CHKERRQ(ierr);
548             ierr = MatSetValues(G, 1, &q, 1, &r, &o, INSERT_VALUES);CHKERRQ(ierr);
549           }
550         }
551       }
552       ierr = MatAssemblyBegin(G, MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
553       ierr = MatAssemblyEnd(G, MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
554 
555       ierr = PetscBTCreate(Noff[size], &seenProcs);CHKERRQ(ierr);
556       ierr = PetscBTMemzero(Noff[size], seenProcs);CHKERRQ(ierr);
557       ierr = PetscBTCreate(Noff[size], &flippedProcs);CHKERRQ(ierr);
558       ierr = PetscBTMemzero(Noff[size], flippedProcs);CHKERRQ(ierr);
559       ierr = PetscMalloc1(Noff[size], &procFIFO);CHKERRQ(ierr);
560       pTop = pBottom = 0;
561       for (p = 0; p < Noff[size]; ++p) {
562         if (PetscBTLookup(seenProcs, p)) continue;
563         /* Initialize FIFO with next proc */
564         procFIFO[pBottom++] = p;
565         ierr = PetscBTSet(seenProcs, p);CHKERRQ(ierr);
566         /* Consider each proc in FIFO */
567         while (pTop < pBottom) {
568           const PetscScalar *ornt;
569           const PetscInt    *neighbors;
570           PetscInt           proc, nproc, seen, flippedA, flippedB, mismatch, numNeighbors, n;
571 
572           proc     = procFIFO[pTop++];
573           flippedA = PetscBTLookup(flippedProcs, proc) ? 1 : 0;
574           ierr = MatGetRow(G, proc, &numNeighbors, &neighbors, &ornt);CHKERRQ(ierr);
575           /* Loop over neighboring procs */
576           for (n = 0; n < numNeighbors; ++n) {
577             nproc    = neighbors[n];
578             mismatch = PetscRealPart(ornt[n]) > 0.5 ? 0 : 1;
579             seen     = PetscBTLookup(seenProcs, nproc);
580             flippedB = PetscBTLookup(flippedProcs, nproc) ? 1 : 0;
581 
582             if (mismatch ^ (flippedA ^ flippedB)) {
583               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);
584               if (!flippedB) {
585                 ierr = PetscBTSet(flippedProcs, nproc);CHKERRQ(ierr);
586               } else SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Inconsistent mesh orientation: Fault mesh is non-orientable");
587             } else if (mismatch && flippedA && flippedB) SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Attempt to flip already flipped cell: Fault mesh is non-orientable");
588             if (!seen) {
589               procFIFO[pBottom++] = nproc;
590               ierr = PetscBTSet(seenProcs, nproc);CHKERRQ(ierr);
591             }
592           }
593         }
594       }
595       ierr = PetscFree(procFIFO);CHKERRQ(ierr);
596       ierr = MatDestroy(&G);CHKERRQ(ierr);
597       ierr = PetscFree2(adj, val);CHKERRQ(ierr);
598       ierr = PetscBTDestroy(&seenProcs);CHKERRQ(ierr);
599     }
600     /* Scatter flip flags */
601     {
602       PetscBool *flips = NULL;
603 
604       if (!rank) {
605         ierr = PetscMalloc1(Noff[size], &flips);CHKERRQ(ierr);
606         for (p = 0; p < Noff[size]; ++p) {
607           flips[p] = PetscBTLookup(flippedProcs, p) ? PETSC_TRUE : PETSC_FALSE;
608           if (flg && flips[p]) {ierr = PetscPrintf(comm, "Flipping Proc+Comp %d:\n", p);CHKERRQ(ierr);}
609         }
610         for (p = 0; p < size; ++p) {
611           displs[p+1] = displs[p] + Nc[p];
612         }
613       }
614       ierr = MPI_Scatterv(flips, Nc, displs, MPIU_BOOL, flipped, numComponents, MPIU_BOOL, 0, comm);CHKERRQ(ierr);
615       ierr = PetscFree(flips);CHKERRQ(ierr);
616     }
617     if (!rank) {ierr = PetscBTDestroy(&flippedProcs);CHKERRQ(ierr);}
618     ierr = PetscFree(N);CHKERRQ(ierr);
619     ierr = PetscFree4(recvcounts, displs, Nc, Noff);CHKERRQ(ierr);
620     ierr = PetscFree2(nrankComp, match);CHKERRQ(ierr);
621 
622     /* Decide whether to flip cells in each component */
623     for (c = 0; c < cEnd-cStart; ++c) {if (flipped[cellComp[c]]) {ierr = PetscBTNegate(flippedCells, c);CHKERRQ(ierr);}}
624     ierr = PetscFree(flipped);CHKERRQ(ierr);
625   }
626   if (flg) {
627     PetscViewer v;
628 
629     ierr = PetscViewerASCIIGetStdout(comm, &v);CHKERRQ(ierr);
630     ierr = PetscViewerASCIIPushSynchronized(v);CHKERRQ(ierr);
631     ierr = PetscViewerASCIISynchronizedPrintf(v, "[%d]BT for parallel flipped cells:\n", rank);CHKERRQ(ierr);
632     ierr = PetscBTView(cEnd-cStart, flippedCells, v);CHKERRQ(ierr);
633     ierr = PetscViewerFlush(v);CHKERRQ(ierr);
634     ierr = PetscViewerASCIIPopSynchronized(v);CHKERRQ(ierr);
635   }
636   /* Reverse flipped cells in the mesh */
637   for (c = cStart; c < cEnd; ++c) {
638     if (PetscBTLookup(flippedCells, c-cStart)) {
639       ierr = DMPlexReverseCell(dm, c);CHKERRQ(ierr);
640     }
641   }
642   ierr = PetscBTDestroy(&seenCells);CHKERRQ(ierr);
643   ierr = PetscBTDestroy(&flippedCells);CHKERRQ(ierr);
644   ierr = PetscBTDestroy(&seenFaces);CHKERRQ(ierr);
645   ierr = PetscFree2(numNeighbors, neighbors);CHKERRQ(ierr);
646   ierr = PetscFree2(rorntComp, lorntComp);CHKERRQ(ierr);
647   ierr = PetscFree3(faceFIFO, cellComp, faceComp);CHKERRQ(ierr);
648   PetscFunctionReturn(0);
649 }
650