cell.c 189 KB
Newer Older
1
/*******************************************************************************
2
 * This file is part of SWIFT.
3
 * Copyright (c) 2012 Pedro Gonnet (pedro.gonnet@durham.ac.uk)
4
5
6
7
 *                    Matthieu Schaller (matthieu.schaller@durham.ac.uk)
 *               2015 Peter W. Draper (p.w.draper@durham.ac.uk)
 *               2016 John A. Regan (john.a.regan@durham.ac.uk)
 *                    Tom Theuns (tom.theuns@durham.ac.uk)
8
 *
9
10
11
12
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
13
 *
14
15
16
17
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
18
 *
19
20
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
21
 *
22
23
24
25
26
27
28
29
30
 ******************************************************************************/

/* Config parameters. */
#include "../config.h"

/* Some standard headers. */
#include <float.h>
#include <limits.h>
#include <math.h>
31
32
33
34
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
35

36
37
/* MPI headers. */
#ifdef WITH_MPI
38
#include <mpi.h>
39
40
#endif

41
42
/* Switch off timers. */
#ifdef TIMER
43
#undef TIMER
44
45
#endif

46
47
48
/* This object's header. */
#include "cell.h"

49
/* Local headers. */
50
#include "active.h"
51
#include "atomic.h"
52
#include "black_holes.h"
53
#include "chemistry.h"
54
#include "drift.h"
55
#include "engine.h"
Matthieu Schaller's avatar
Matthieu Schaller committed
56
#include "entropy_floor.h"
57
#include "error.h"
58
#include "feedback.h"
59
#include "gravity.h"
60
#include "hydro.h"
Matthieu Schaller's avatar
Matthieu Schaller committed
61
#include "hydro_properties.h"
Pedro Gonnet's avatar
Pedro Gonnet committed
62
#include "memswap.h"
63
#include "minmax.h"
64
#include "pressure_floor.h"
65
#include "scheduler.h"
66
#include "space.h"
67
#include "space_getsid.h"
Loic Hausammann's avatar
Loic Hausammann committed
68
#include "star_formation.h"
Loic Hausammann's avatar
Loic Hausammann committed
69
#include "stars.h"
70
#include "timers.h"
71
#include "tools.h"
72
#include "tracers.h"
73

74
75
extern int engine_star_resort_task_depth;

76
77
78
/* Global variables. */
int cell_next_tag = 0;

Pedro Gonnet's avatar
Pedro Gonnet committed
79
/** List of cell pairs for sub-cell recursion. For any sid, the entries in
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
 * this array contain the number of sub-cell pairs and the indices and sid
 * of the sub-cell pairs themselves. */
struct cell_split_pair cell_split_pairs[13] = {
    {1, /* (  1 ,  1 ,  1 ) */
     {{7, 0, 0}}},

    {4, /* (  1 ,  1 ,  0 ) */
     {{6, 0, 1}, {7, 1, 1}, {6, 1, 0}, {7, 0, 2}}},

    {1, /* (  1 ,  1 , -1 ) */
     {{6, 1, 2}}},

    {4, /* (  1 ,  0 ,  1 ) */
     {{5, 0, 3}, {7, 2, 3}, {5, 2, 0}, {7, 0, 6}}},

    {16, /* (  1 ,  0 ,  0 ) */
     {{4, 0, 4},
      {5, 0, 5},
      {6, 0, 7},
      {7, 0, 8},
      {4, 1, 3},
      {5, 1, 4},
      {6, 1, 6},
      {7, 1, 7},
      {4, 2, 1},
      {5, 2, 2},
      {6, 2, 4},
      {7, 2, 5},
      {4, 3, 0},
      {5, 3, 1},
      {6, 3, 3},
      {7, 3, 4}}},

    {4, /* (  1 ,  0 , -1 ) */
     {{4, 1, 5}, {6, 3, 5}, {4, 3, 2}, {6, 1, 8}}},

    {1, /* (  1 , -1 ,  1 ) */
     {{5, 2, 6}}},

    {4, /* (  1 , -1 ,  0 ) */
     {{4, 3, 6}, {5, 2, 8}, {4, 2, 7}, {5, 3, 7}}},

    {1, /* (  1 , -1 , -1 ) */
     {{4, 3, 8}}},

    {4, /* (  0 ,  1 ,  1 ) */
     {{3, 0, 9}, {7, 4, 9}, {3, 4, 0}, {7, 0, 8}}},

    {16, /* (  0 ,  1 ,  0 ) */
     {{2, 0, 10},
      {3, 0, 11},
      {6, 0, 7},
      {7, 0, 6},
      {2, 1, 9},
      {3, 1, 10},
      {6, 1, 8},
      {7, 1, 7},
      {2, 4, 1},
      {3, 4, 2},
      {6, 4, 10},
      {7, 4, 11},
      {2, 5, 0},
      {3, 5, 1},
      {6, 5, 9},
      {7, 5, 10}}},

    {4, /* (  0 ,  1 , -1 ) */
     {{2, 1, 11}, {6, 5, 11}, {2, 5, 2}, {6, 1, 6}}},

    {16, /* (  0 ,  0 ,  1 ) */
     {{1, 0, 12},
      {3, 0, 11},
      {5, 0, 5},
      {7, 0, 2},
      {1, 2, 9},
      {3, 2, 12},
      {5, 2, 8},
      {7, 2, 5},
      {1, 4, 3},
      {3, 4, 6},
      {5, 4, 12},
      {7, 4, 11},
      {1, 6, 0},
      {3, 6, 3},
      {5, 6, 9},
      {7, 6, 12}}}};

167
168
169
170
171
/**
 * @brief Get the size of the cell subtree.
 *
 * @param c The #cell.
 */
172
int cell_getsize(struct cell *c) {
Pedro Gonnet's avatar
Pedro Gonnet committed
173
174
  /* Number of cells in this subtree. */
  int count = 1;
175

176
177
  /* Sum up the progeny if split. */
  if (c->split)
Pedro Gonnet's avatar
Pedro Gonnet committed
178
    for (int k = 0; k < 8; k++)
179
180
181
182
183
184
      if (c->progeny[k] != NULL) count += cell_getsize(c->progeny[k]);

  /* Return the final count. */
  return count;
}

185
/**
186
 * @brief Link the cells recursively to the given #part array.
187
188
189
190
191
192
 *
 * @param c The #cell.
 * @param parts The #part array.
 *
 * @return The number of particles linked.
 */
193
int cell_link_parts(struct cell *c, struct part *parts) {
194
#ifdef SWIFT_DEBUG_CHECKS
195
196
197
  if (c->nodeID == engine_rank)
    error("Linking foreign particles in a local cell!");

198
  if (c->hydro.parts != NULL)
199
200
201
    error("Linking parts into a cell that was already linked");
#endif

202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
  c->hydro.parts = parts;

  /* Fill the progeny recursively, depth-first. */
  if (c->split) {
    int offset = 0;
    for (int k = 0; k < 8; k++) {
      if (c->progeny[k] != NULL)
        offset += cell_link_parts(c->progeny[k], &parts[offset]);
    }
  }

  /* Return the total number of linked particles. */
  return c->hydro.count;
}

/**
218
 * @brief Link the cells recursively to the given #gpart array.
219
220
 *
 * @param c The #cell.
221
 * @param gparts The #gpart array.
222
223
224
 *
 * @return The number of particles linked.
 */
225
int cell_link_gparts(struct cell *c, struct gpart *gparts) {
226
227
228
229
#ifdef SWIFT_DEBUG_CHECKS
  if (c->nodeID == engine_rank)
    error("Linking foreign particles in a local cell!");

230
  if (c->grav.parts != NULL)
231
    error("Linking gparts into a cell that was already linked");
232
#endif
233

234
  c->grav.parts = gparts;
235
236
237
238
239
240
241
242
243
244
245

  /* Fill the progeny recursively, depth-first. */
  if (c->split) {
    int offset = 0;
    for (int k = 0; k < 8; k++) {
      if (c->progeny[k] != NULL)
        offset += cell_link_gparts(c->progeny[k], &gparts[offset]);
    }
  }

  /* Return the total number of linked particles. */
246
  return c->grav.count;
247
248
}

249
250
251
252
253
254
255
256
257
/**
 * @brief Link the cells recursively to the given #spart array.
 *
 * @param c The #cell.
 * @param sparts The #spart array.
 *
 * @return The number of particles linked.
 */
int cell_link_sparts(struct cell *c, struct spart *sparts) {
258
259
260
261
#ifdef SWIFT_DEBUG_CHECKS
  if (c->nodeID == engine_rank)
    error("Linking foreign particles in a local cell!");

262
  if (c->stars.parts != NULL)
263
264
265
    error("Linking sparts into a cell that was already linked");
#endif

266
  c->stars.parts = sparts;
267
  c->stars.parts_rebuild = sparts;
268
269
270
271
272
273
274
275
276
277
278

  /* Fill the progeny recursively, depth-first. */
  if (c->split) {
    int offset = 0;
    for (int k = 0; k < 8; k++) {
      if (c->progeny[k] != NULL)
        offset += cell_link_sparts(c->progeny[k], &sparts[offset]);
    }
  }

  /* Return the total number of linked particles. */
279
  return c->stars.count;
280
281
}

282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
/**
 * @brief Link the cells recursively to the given #bpart array.
 *
 * @param c The #cell.
 * @param bparts The #bpart array.
 *
 * @return The number of particles linked.
 */
int cell_link_bparts(struct cell *c, struct bpart *bparts) {

#ifdef SWIFT_DEBUG_CHECKS
  if (c->nodeID == engine_rank)
    error("Linking foreign particles in a local cell!");

  if (c->black_holes.parts != NULL)
    error("Linking bparts into a cell that was already linked");
#endif

  c->black_holes.parts = bparts;

  /* Fill the progeny recursively, depth-first. */
  if (c->split) {
    int offset = 0;
    for (int k = 0; k < 8; k++) {
      if (c->progeny[k] != NULL)
        offset += cell_link_bparts(c->progeny[k], &bparts[offset]);
    }
  }

  /* Return the total number of linked particles. */
  return c->black_holes.count;
}

315
316
317
318
319
320
321
322
323
324
/**
 * @brief Recurse down foreign cells until reaching one with hydro
 * tasks; then trigger the linking of the #part array from that
 * level.
 *
 * @param c The #cell.
 * @param parts The #part array.
 *
 * @return The number of particles linked.
 */
325
int cell_link_foreign_parts(struct cell *c, struct part *parts) {
326
327
#ifdef WITH_MPI

328
329
330
331
332
333
#ifdef SWIFT_DEBUG_CHECKS
  if (c->nodeID == engine_rank)
    error("Linking foreign particles in a local cell!");
#endif

  /* Do we have a hydro task at this level? */
334
  if (cell_get_recv(c, task_subtype_xv) != NULL) {
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352

    /* Recursively attach the parts */
    const int counts = cell_link_parts(c, parts);
#ifdef SWIFT_DEBUG_CHECKS
    if (counts != c->hydro.count)
      error("Something is wrong with the foreign counts");
#endif
    return counts;
  }

  /* Go deeper to find the level where the tasks are */
  if (c->split) {
    int count = 0;
    for (int k = 0; k < 8; k++) {
      if (c->progeny[k] != NULL) {
        count += cell_link_foreign_parts(c->progeny[k], &parts[count]);
      }
    }
353
354
355
    return count;
  } else {
    return 0;
356
  }
357
358
359
360

#else
  error("Calling linking of foregin particles in non-MPI mode.");
#endif
361
362
}

363
364
365
366
367
368
369
370
371
372
/**
 * @brief Recurse down foreign cells until reaching one with gravity
 * tasks; then trigger the linking of the #gpart array from that
 * level.
 *
 * @param c The #cell.
 * @param gparts The #gpart array.
 *
 * @return The number of particles linked.
 */
373
int cell_link_foreign_gparts(struct cell *c, struct gpart *gparts) {
374
375
#ifdef WITH_MPI

376
377
378
379
380
#ifdef SWIFT_DEBUG_CHECKS
  if (c->nodeID == engine_rank)
    error("Linking foreign particles in a local cell!");
#endif

381
382
  /* Do we have a gravity task at this level? */
  if (cell_get_recv(c, task_subtype_gpart) != NULL) {
383

384
    /* Recursively attach the gparts */
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
    const int counts = cell_link_gparts(c, gparts);
#ifdef SWIFT_DEBUG_CHECKS
    if (counts != c->grav.count)
      error("Something is wrong with the foreign counts");
#endif
    return counts;
  }

  /* Go deeper to find the level where the tasks are */
  if (c->split) {
    int count = 0;
    for (int k = 0; k < 8; k++) {
      if (c->progeny[k] != NULL) {
        count += cell_link_foreign_gparts(c->progeny[k], &gparts[count]);
      }
    }
401
402
403
    return count;
  } else {
    return 0;
404
  }
405
406
407
408

#else
  error("Calling linking of foregin particles in non-MPI mode.");
#endif
409
410
}

411
412
413
414
415
416
417
418
/**
 * @brief Recursively count the number of #part in foreign cells that
 * are in cells with hydro-related tasks.
 *
 * @param c The #cell.
 *
 * @return The number of particles linked.
 */
419
int cell_count_parts_for_tasks(const struct cell *c) {
420
421
#ifdef WITH_MPI

422
423
424
425
426
427
#ifdef SWIFT_DEBUG_CHECKS
  if (c->nodeID == engine_rank)
    error("Counting foreign particles in a local cell!");
#endif

  /* Do we have a hydro task at this level? */
428
  if (cell_get_recv(c, task_subtype_xv) != NULL) {
429
430
431
432
433
434
435
436
437
438
    return c->hydro.count;
  }

  if (c->split) {
    int count = 0;
    for (int k = 0; k < 8; ++k) {
      if (c->progeny[k] != NULL) {
        count += cell_count_parts_for_tasks(c->progeny[k]);
      }
    }
439
440
441
    return count;
  } else {
    return 0;
442
  }
443
444
445
446

#else
  error("Calling linking of foregin particles in non-MPI mode.");
#endif
447
448
}

449
450
451
452
453
454
455
456
/**
 * @brief Recursively count the number of #gpart in foreign cells that
 * are in cells with gravity-related tasks.
 *
 * @param c The #cell.
 *
 * @return The number of particles linked.
 */
457
int cell_count_gparts_for_tasks(const struct cell *c) {
458
459
#ifdef WITH_MPI

460
461
462
463
464
#ifdef SWIFT_DEBUG_CHECKS
  if (c->nodeID == engine_rank)
    error("Counting foreign particles in a local cell!");
#endif

465
466
  /* Do we have a gravity task at this level? */
  if (cell_get_recv(c, task_subtype_gpart) != NULL) {
467
468
469
470
471
472
473
474
475
476
    return c->grav.count;
  }

  if (c->split) {
    int count = 0;
    for (int k = 0; k < 8; ++k) {
      if (c->progeny[k] != NULL) {
        count += cell_count_gparts_for_tasks(c->progeny[k]);
      }
    }
477
478
479
    return count;
  } else {
    return 0;
480
  }
481
482
483
484

#else
  error("Calling linking of foregin particles in non-MPI mode.");
#endif
485
486
}

487
488
489
490
491
492
/**
 * @brief Pack the data of the given cell and all it's sub-cells.
 *
 * @param c The #cell.
 * @param pc Pointer to an array of packed cells in which the
 *      cells will be packed.
493
494
 * @param with_gravity Are we running with gravity and hence need
 *      to exchange multipoles?
495
496
497
 *
 * @return The number of packed cells.
 */
498
int cell_pack(struct cell *restrict c, struct pcell *restrict pc,
Matthieu Schaller's avatar
Matthieu Schaller committed
499
              const int with_gravity) {
500
501
#ifdef WITH_MPI

502
  /* Start by packing the data of the current cell. */
503
  pc->hydro.h_max = c->hydro.h_max;
504
  pc->stars.h_max = c->stars.h_max;
505
  pc->black_holes.h_max = c->black_holes.h_max;
506
507
508
509
  pc->hydro.ti_end_min = c->hydro.ti_end_min;
  pc->hydro.ti_end_max = c->hydro.ti_end_max;
  pc->grav.ti_end_min = c->grav.ti_end_min;
  pc->grav.ti_end_max = c->grav.ti_end_max;
510
  pc->stars.ti_end_min = c->stars.ti_end_min;
511
  pc->stars.ti_end_max = c->stars.ti_end_max;
512
513
  pc->black_holes.ti_end_min = c->black_holes.ti_end_min;
  pc->black_holes.ti_end_max = c->black_holes.ti_end_max;
514
515
  pc->hydro.ti_old_part = c->hydro.ti_old_part;
  pc->grav.ti_old_part = c->grav.ti_old_part;
516
  pc->grav.ti_old_multipole = c->grav.ti_old_multipole;
517
  pc->stars.ti_old_part = c->stars.ti_old_part;
518
  pc->hydro.count = c->hydro.count;
519
520
  pc->grav.count = c->grav.count;
  pc->stars.count = c->stars.count;
521
  pc->black_holes.count = c->black_holes.count;
522
  pc->maxdepth = c->maxdepth;
523

524
  /* Copy the Multipole related information */
Matthieu Schaller's avatar
Matthieu Schaller committed
525
  if (with_gravity) {
526
    const struct gravity_tensors *mp = c->grav.multipole;
527

528
529
530
531
532
533
534
535
536
    pc->grav.m_pole = mp->m_pole;
    pc->grav.CoM[0] = mp->CoM[0];
    pc->grav.CoM[1] = mp->CoM[1];
    pc->grav.CoM[2] = mp->CoM[2];
    pc->grav.CoM_rebuild[0] = mp->CoM_rebuild[0];
    pc->grav.CoM_rebuild[1] = mp->CoM_rebuild[1];
    pc->grav.CoM_rebuild[2] = mp->CoM_rebuild[2];
    pc->grav.r_max = mp->r_max;
    pc->grav.r_max_rebuild = mp->r_max_rebuild;
537
538
  }

539
540
541
#ifdef SWIFT_DEBUG_CHECKS
  pc->cellID = c->cellID;
#endif
542
543

  /* Fill in the progeny, depth-first recursion. */
Pedro Gonnet's avatar
Pedro Gonnet committed
544
545
  int count = 1;
  for (int k = 0; k < 8; k++)
546
547
    if (c->progeny[k] != NULL) {
      pc->progeny[k] = count;
548
      count += cell_pack(c->progeny[k], &pc[count], with_gravity);
549
    } else {
550
      pc->progeny[k] = -1;
551
    }
552
553

  /* Return the number of packed cells used. */
554
  c->mpi.pcell_size = count;
555
  return count;
556
557
558
559
560

#else
  error("SWIFT was not compiled with MPI support.");
  return 0;
#endif
561
562
}

563
564
565
566
567
568
569
570
571
572
573
574
/**
 * @brief Pack the tag of the given cell and all it's sub-cells.
 *
 * @param c The #cell.
 * @param tags Pointer to an array of packed tags.
 *
 * @return The number of packed tags.
 */
int cell_pack_tags(const struct cell *c, int *tags) {
#ifdef WITH_MPI

  /* Start by packing the data of the current cell. */
575
  tags[0] = c->mpi.tag;
576
577
578
579
580
581
582
583

  /* Fill in the progeny, depth-first recursion. */
  int count = 1;
  for (int k = 0; k < 8; k++)
    if (c->progeny[k] != NULL)
      count += cell_pack_tags(c->progeny[k], &tags[count]);

#ifdef SWIFT_DEBUG_CHECKS
584
  if (c->mpi.pcell_size != count) error("Inconsistent tag and pcell count!");
585
586
587
588
589
590
591
592
593
594
595
#endif  // SWIFT_DEBUG_CHECKS

  /* Return the number of packed tags used. */
  return count;

#else
  error("SWIFT was not compiled with MPI support.");
  return 0;
#endif
}

596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
void cell_pack_part_swallow(const struct cell *c,
                            struct black_holes_part_data *data) {

  const size_t count = c->hydro.count;
  const struct part *parts = c->hydro.parts;

  for (size_t i = 0; i < count; ++i) {
    data[i] = parts[i].black_holes_data;
  }
}

void cell_unpack_part_swallow(struct cell *c,
                              const struct black_holes_part_data *data) {

  const size_t count = c->hydro.count;
  struct part *parts = c->hydro.parts;

  for (size_t i = 0; i < count; ++i) {
    parts[i].black_holes_data = data[i];
  }
}

618
619
620
621
622
623
624
void cell_pack_bpart_swallow(const struct cell *c,
                             struct black_holes_bpart_data *data) {

  const size_t count = c->black_holes.count;
  const struct bpart *bparts = c->black_holes.parts;

  for (size_t i = 0; i < count; ++i) {
625
    data[i] = bparts[i].merger_data;
626
627
628
629
630
631
632
633
634
635
636
637
638
639
  }
}

void cell_unpack_bpart_swallow(struct cell *c,
                               const struct black_holes_bpart_data *data) {

  const size_t count = c->black_holes.count;
  struct bpart *bparts = c->black_holes.parts;

  for (size_t i = 0; i < count; ++i) {
    bparts[i].merger_data = data[i];
  }
}

640
641
642
643
644
645
/**
 * @brief Unpack the data of a given cell and its sub-cells.
 *
 * @param pc An array of packed #pcell.
 * @param c The #cell in which to unpack the #pcell.
 * @param s The #space in which the cells are created.
646
647
 * @param with_gravity Are we running with gravity and hence need
 *      to exchange multipoles?
648
649
650
 *
 * @return The number of cells created.
 */
Matthieu Schaller's avatar
Matthieu Schaller committed
651
int cell_unpack(struct pcell *restrict pc, struct cell *restrict c,
652
                struct space *restrict s, const int with_gravity) {
653
654
655
#ifdef WITH_MPI

  /* Unpack the current pcell. */
656
  c->hydro.h_max = pc->hydro.h_max;
657
  c->stars.h_max = pc->stars.h_max;
658
  c->black_holes.h_max = pc->black_holes.h_max;
659
660
661
662
  c->hydro.ti_end_min = pc->hydro.ti_end_min;
  c->hydro.ti_end_max = pc->hydro.ti_end_max;
  c->grav.ti_end_min = pc->grav.ti_end_min;
  c->grav.ti_end_max = pc->grav.ti_end_max;
663
  c->stars.ti_end_min = pc->stars.ti_end_min;
664
  c->stars.ti_end_max = pc->stars.ti_end_max;
665
666
  c->black_holes.ti_end_min = pc->black_holes.ti_end_min;
  c->black_holes.ti_end_max = pc->black_holes.ti_end_max;
667
668
  c->hydro.ti_old_part = pc->hydro.ti_old_part;
  c->grav.ti_old_part = pc->grav.ti_old_part;
669
  c->grav.ti_old_multipole = pc->grav.ti_old_multipole;
670
  c->stars.ti_old_part = pc->stars.ti_old_part;
671
  c->black_holes.ti_old_part = pc->black_holes.ti_old_part;
672
  c->hydro.count = pc->hydro.count;
673
674
  c->grav.count = pc->grav.count;
  c->stars.count = pc->stars.count;
675
  c->black_holes.count = pc->black_holes.count;
676
677
  c->maxdepth = pc->maxdepth;

678
679
680
#ifdef SWIFT_DEBUG_CHECKS
  c->cellID = pc->cellID;
#endif
681

682
  /* Copy the Multipole related information */
Matthieu Schaller's avatar
Matthieu Schaller committed
683
  if (with_gravity) {
684
    struct gravity_tensors *mp = c->grav.multipole;
685

686
687
688
689
690
691
692
693
694
    mp->m_pole = pc->grav.m_pole;
    mp->CoM[0] = pc->grav.CoM[0];
    mp->CoM[1] = pc->grav.CoM[1];
    mp->CoM[2] = pc->grav.CoM[2];
    mp->CoM_rebuild[0] = pc->grav.CoM_rebuild[0];
    mp->CoM_rebuild[1] = pc->grav.CoM_rebuild[1];
    mp->CoM_rebuild[2] = pc->grav.CoM_rebuild[2];
    mp->r_max = pc->grav.r_max;
    mp->r_max_rebuild = pc->grav.r_max_rebuild;
695
  }
Matthieu Schaller's avatar
Matthieu Schaller committed
696

697
698
699
700
  /* Number of new cells created. */
  int count = 1;

  /* Fill the progeny recursively, depth-first. */
701
  c->split = 0;
702
703
704
705
  for (int k = 0; k < 8; k++)
    if (pc->progeny[k] >= 0) {
      struct cell *temp;
      space_getcells(s, 1, &temp);
706
      temp->hydro.count = 0;
707
708
      temp->grav.count = 0;
      temp->stars.count = 0;
709
710
711
712
713
714
715
716
717
718
719
720
      temp->loc[0] = c->loc[0];
      temp->loc[1] = c->loc[1];
      temp->loc[2] = c->loc[2];
      temp->width[0] = c->width[0] / 2;
      temp->width[1] = c->width[1] / 2;
      temp->width[2] = c->width[2] / 2;
      temp->dmin = c->dmin / 2;
      if (k & 4) temp->loc[0] += temp->width[0];
      if (k & 2) temp->loc[1] += temp->width[1];
      if (k & 1) temp->loc[2] += temp->width[2];
      temp->depth = c->depth + 1;
      temp->split = 0;
721
      temp->hydro.dx_max_part = 0.f;
722
      temp->hydro.dx_max_sort = 0.f;
Loic Hausammann's avatar
Loic Hausammann committed
723
      temp->stars.dx_max_part = 0.f;
Loic Hausammann's avatar
Loic Hausammann committed
724
      temp->stars.dx_max_sort = 0.f;
725
      temp->black_holes.dx_max_part = 0.f;
726
727
728
729
      temp->nodeID = c->nodeID;
      temp->parent = c;
      c->progeny[k] = temp;
      c->split = 1;
730
      count += cell_unpack(&pc[pc->progeny[k]], temp, s, with_gravity);
731
732
733
    }

  /* Return the total number of unpacked cells. */
734
  c->mpi.pcell_size = count;
735
736
737
738
739
740
741
742
  return count;

#else
  error("SWIFT was not compiled with MPI support.");
  return 0;
#endif
}

743
744
745
746
747
748
749
750
751
752
753
754
/**
 * @brief Unpack the tags of a given cell and its sub-cells.
 *
 * @param tags An array of tags.
 * @param c The #cell in which to unpack the tags.
 *
 * @return The number of tags created.
 */
int cell_unpack_tags(const int *tags, struct cell *restrict c) {
#ifdef WITH_MPI

  /* Unpack the current pcell. */
755
  c->mpi.tag = tags[0];
756
757
758
759
760
761
762
763
764
765
766

  /* Number of new cells created. */
  int count = 1;

  /* Fill the progeny recursively, depth-first. */
  for (int k = 0; k < 8; k++)
    if (c->progeny[k] != NULL) {
      count += cell_unpack_tags(&tags[count], c->progeny[k]);
    }

#ifdef SWIFT_DEBUG_CHECKS
767
  if (c->mpi.pcell_size != count) error("Inconsistent tag and pcell count!");
768
769
770
771
772
773
774
775
776
777
778
#endif  // SWIFT_DEBUG_CHECKS

  /* Return the total number of unpacked tags. */
  return count;

#else
  error("SWIFT was not compiled with MPI support.");
  return 0;
#endif
}

779
780
781
782
/**
 * @brief Pack the time information of the given cell and all it's sub-cells.
 *
 * @param c The #cell.
783
 * @param pcells (output) The end-of-timestep information we pack into
784
785
786
 *
 * @return The number of packed cells.
 */
787
788
int cell_pack_end_step_hydro(struct cell *restrict c,
                             struct pcell_step_hydro *restrict pcells) {
789
790
#ifdef WITH_MPI

791
  /* Pack this cell's data. */
792
793
794
  pcells[0].ti_end_min = c->hydro.ti_end_min;
  pcells[0].ti_end_max = c->hydro.ti_end_max;
  pcells[0].dx_max_part = c->hydro.dx_max_part;
795

796
797
798
799
  /* Fill in the progeny, depth-first recursion. */
  int count = 1;
  for (int k = 0; k < 8; k++)
    if (c->progeny[k] != NULL) {
800
      count += cell_pack_end_step_hydro(c->progeny[k], &pcells[count]);
801
802
803
804
    }

  /* Return the number of packed values. */
  return count;
805
806
807
808
809

#else
  error("SWIFT was not compiled with MPI support.");
  return 0;
#endif
810
811
}

812
813
814
815
/**
 * @brief Unpack the time information of a given cell and its sub-cells.
 *
 * @param c The #cell
816
 * @param pcells The end-of-timestep information to unpack
817
818
819
 *
 * @return The number of cells created.
 */
820
821
int cell_unpack_end_step_hydro(struct cell *restrict c,
                               struct pcell_step_hydro *restrict pcells) {
822
823
#ifdef WITH_MPI

824
  /* Unpack this cell's data. */
825
826
827
  c->hydro.ti_end_min = pcells[0].ti_end_min;
  c->hydro.ti_end_max = pcells[0].ti_end_max;
  c->hydro.dx_max_part = pcells[0].dx_max_part;
828

829
830
831
832
  /* Fill in the progeny, depth-first recursion. */
  int count = 1;
  for (int k = 0; k < 8; k++)
    if (c->progeny[k] != NULL) {
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
      count += cell_unpack_end_step_hydro(c->progeny[k], &pcells[count]);
    }

  /* Return the number of packed values. */
  return count;

#else
  error("SWIFT was not compiled with MPI support.");
  return 0;
#endif
}

/**
 * @brief Pack the time information of the given cell and all it's sub-cells.
 *
 * @param c The #cell.
 * @param pcells (output) The end-of-timestep information we pack into
 *
 * @return The number of packed cells.
 */
int cell_pack_end_step_grav(struct cell *restrict c,
                            struct pcell_step_grav *restrict pcells) {
#ifdef WITH_MPI

  /* Pack this cell's data. */
  pcells[0].ti_end_min = c->grav.ti_end_min;
  pcells[0].ti_end_max = c->grav.ti_end_max;

  /* Fill in the progeny, depth-first recursion. */
  int count = 1;
  for (int k = 0; k < 8; k++)
    if (c->progeny[k] != NULL) {
      count += cell_pack_end_step_grav(c->progeny[k], &pcells[count]);
    }

  /* Return the number of packed values. */
  return count;

#else
  error("SWIFT was not compiled with MPI support.");
  return 0;
#endif
}

/**
 * @brief Unpack the time information of a given cell and its sub-cells.
 *
 * @param c The #cell
 * @param pcells The end-of-timestep information to unpack
 *
 * @return The number of cells created.
 */
int cell_unpack_end_step_grav(struct cell *restrict c,
                              struct pcell_step_grav *restrict pcells) {
#ifdef WITH_MPI

  /* Unpack this cell's data. */
  c->grav.ti_end_min = pcells[0].ti_end_min;
  c->grav.ti_end_max = pcells[0].ti_end_max;

  /* Fill in the progeny, depth-first recursion. */
  int count = 1;
  for (int k = 0; k < 8; k++)
    if (c->progeny[k] != NULL) {
      count += cell_unpack_end_step_grav(c->progeny[k], &pcells[count]);
    }

  /* Return the number of packed values. */
  return count;

#else
  error("SWIFT was not compiled with MPI support.");
  return 0;
#endif
}

/**
 * @brief Pack the time information of the given cell and all it's sub-cells.
 *
 * @param c The #cell.
 * @param pcells (output) The end-of-timestep information we pack into
 *
 * @return The number of packed cells.
 */
int cell_pack_end_step_stars(struct cell *restrict c,
                             struct pcell_step_stars *restrict pcells) {
#ifdef WITH_MPI

  /* Pack this cell's data. */
  pcells[0].ti_end_min = c->stars.ti_end_min;
  pcells[0].ti_end_max = c->stars.ti_end_max;
  pcells[0].dx_max_part = c->stars.dx_max_part;

  /* Fill in the progeny, depth-first recursion. */
  int count = 1;
  for (int k = 0; k < 8; k++)
    if (c->progeny[k] != NULL) {
      count += cell_pack_end_step_stars(c->progeny[k], &pcells[count]);
    }

  /* Return the number of packed values. */
  return count;

#else
  error("SWIFT was not compiled with MPI support.");
  return 0;
#endif
}

/**
 * @brief Unpack the time information of a given cell and its sub-cells.
 *
 * @param c The #cell
 * @param pcells The end-of-timestep information to unpack
 *
 * @return The number of cells created.
 */
int cell_unpack_end_step_stars(struct cell *restrict c,
                               struct pcell_step_stars *restrict pcells) {
#ifdef WITH_MPI

  /* Unpack this cell's data. */
  c->stars.ti_end_min = pcells[0].ti_end_min;
  c->stars.ti_end_max = pcells[0].ti_end_max;
  c->stars.dx_max_part = pcells[0].dx_max_part;

  /* Fill in the progeny, depth-first recursion. */
  int count = 1;
  for (int k = 0; k < 8; k++)
    if (c->progeny[k] != NULL) {
      count += cell_unpack_end_step_stars(c->progeny[k], &pcells[count]);
964
965
966
    }

  /* Return the number of packed values. */
967
  return count;
968
969
970
971
972

#else
  error("SWIFT was not compiled with MPI support.");
  return 0;
#endif
973
}
974

975
976
977
978
979
980
981
982
/**
 * @brief Pack the time information of the given cell and all it's sub-cells.
 *
 * @param c The #cell.
 * @param pcells (output) The end-of-timestep information we pack into
 *
 * @return The number of packed cells.
 */
983
984
int cell_pack_end_step_black_holes(
    struct cell *restrict c, struct pcell_step_black_holes *restrict pcells) {
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016

#ifdef WITH_MPI

  /* Pack this cell's data. */
  pcells[0].ti_end_min = c->black_holes.ti_end_min;
  pcells[0].ti_end_max = c->black_holes.ti_end_max;
  pcells[0].dx_max_part = c->black_holes.dx_max_part;

  /* Fill in the progeny, depth-first recursion. */
  int count = 1;
  for (int k = 0; k < 8; k++)
    if (c->progeny[k] != NULL) {
      count += cell_pack_end_step_black_holes(c->progeny[k], &pcells[count]);
    }

  /* Return the number of packed values. */
  return count;

#else
  error("SWIFT was not compiled with MPI support.");
  return 0;
#endif
}

/**
 * @brief Unpack the time information of a given cell and its sub-cells.
 *
 * @param c The #cell
 * @param pcells The end-of-timestep information to unpack
 *
 * @return The number of cells created.
 */
1017
1018
int cell_unpack_end_step_black_holes(
    struct cell *restrict c, struct pcell_step_black_holes *restrict pcells) {
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042

#ifdef WITH_MPI

  /* Unpack this cell's data. */
  c->black_holes.ti_end_min = pcells[0].ti_end_min;
  c->black_holes.ti_end_max = pcells[0].ti_end_max;
  c->black_holes.dx_max_part = pcells[0].dx_max_part;

  /* Fill in the progeny, depth-first recursion. */
  int count = 1;
  for (int k = 0; k < 8; k++)
    if (c->progeny[k] != NULL) {
      count += cell_unpack_end_step_black_holes(c->progeny[k], &pcells[count]);
    }

  /* Return the number of packed values. */
  return count;

#else
  error("SWIFT was not compiled with MPI support.");
  return 0;
#endif
}

1043
/**
Matthieu Schaller's avatar
Matthieu Schaller committed
1044
1045
 * @brief Pack the multipole information of the given cell and all it's
 * sub-cells.
1046
1047
1048
1049
1050
1051
1052
 *
 * @param c The #cell.
 * @param pcells (output) The multipole information we pack into
 *
 * @return The number of packed cells.
 */
int cell_pack_multipoles(struct cell *restrict c,
Matthieu Schaller's avatar
Matthieu Schaller committed
1053
                         struct gravity_tensors *restrict pcells) {
1054
1055
1056
#ifdef WITH_MPI

  /* Pack this cell's data. */
1057
  pcells[0] = *c->grav.multipole;
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083

  /* Fill in the progeny, depth-first recursion. */
  int count = 1;
  for (int k = 0; k < 8; k++)
    if (c->progeny[k] != NULL) {
      count += cell_pack_multipoles(c->progeny[k], &pcells[count]);
    }

  /* Return the number of packed values. */
  return count;

#else
  error("SWIFT was not compiled with MPI support.");
  return 0;
#endif
}

/**
 * @brief Unpack the multipole information of a given cell and its sub-cells.
 *
 * @param c The #cell
 * @param pcells The multipole information to unpack
 *
 * @return The number of cells created.
 */
int cell_unpack_multipoles(struct cell *restrict c,
Matthieu Schaller's avatar
Matthieu Schaller committed
1084
                           struct gravity_tensors *restrict pcells) {
1085
1086
1087
#ifdef WITH_MPI

  /* Unpack this cell's data. */
1088
  *c->grav.multipole = pcells[0];
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105

  /* Fill in the progeny, depth-first recursion. */
  int count = 1;
  for (int k = 0; k < 8; k++)
    if (c->progeny[k] != NULL) {
      count += cell_unpack_multipoles(c->progeny[k], &pcells[count]);
    }

  /* Return the number of packed values. */
  return count;

#else
  error("SWIFT was not compiled with MPI support.");
  return 0;
#endif
}

1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
/**
 * @brief Pack the counts for star formation of the given cell and all it's
 * sub-cells.
 *
 * @param c The #cell.
 * @param pcells (output) The multipole information we pack into
 *
 * @return The number of packed cells.
 */
int cell_pack_sf_counts(struct cell *restrict c,
                        struct pcell_sf *restrict pcells) {

#ifdef WITH_MPI

  /* Pack this cell's data. */
  pcells[0].stars.delta_from_rebuild = c->stars.parts - c->stars.parts_rebuild;
  pcells[0].stars.count = c->stars.count;
1123
  pcells[0].stars.dx_max_part = c->stars.dx_max_part;
1124

1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
#ifdef SWIFT_DEBUG_CHECKS
  if (c->stars.parts_rebuild == NULL)
    error("Star particles array at rebuild is NULL! c->depth=%d", c->depth);

  if (pcells[0].stars.delta_from_rebuild < 0)
    error("Stars part pointer moved in the wrong direction!");

  if (pcells[0].stars.delta_from_rebuild > 0 && c->depth == 0)
    error("Shifting the top-level pointer is not allowed!");
#endif

  /* Fill in the progeny, depth-first recursion. */
  int count = 1;
  for (int k = 0; k < 8; k++)
    if (c->progeny[k] != NULL) {
      count += cell_pack_sf_counts(c->progeny[k], &pcells[count]);
    }

  /* Return the number of packed values. */
  return count;

#else
  error("SWIFT was not compiled with MPI support.");
  return 0;
#endif
}

/**
 * @brief Unpack the counts for star formation of a given cell and its
 * sub-cells.
 *
 * @param c The #cell
 * @param pcells The multipole information to unpack
 *
 * @return The number of cells created.
 */
int cell_unpack_sf_counts(struct cell *restrict c,
                          struct pcell_sf *restrict pcells) {

#ifdef WITH_MPI

#ifdef SWIFT_DEBUG_CHECKS
  if (c->stars.parts_rebuild == NULL)
    error("Star particles array at rebuild is NULL!");
#endif

  /* Unpack this cell's data. */
  c->stars.count = pcells[0].stars.count;
  c->stars.parts = c->stars.parts_rebuild + pcells[0].stars.delta_from_rebuild;
1174
  c->stars.dx_max_part = pcells[0].stars.dx_max_part;
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191

  /* Fill in the progeny, depth-first recursion. */
  int count = 1;
  for (int k = 0; k < 8; k++)
    if (c->progeny[k] != NULL) {
      count += cell_unpack_sf_counts(c->progeny[k], &pcells[count]);
    }

  /* Return the number of packed values. */
  return count;

#else
  error("SWIFT was not compiled with MPI support.");
  return 0;
#endif
}

1192
/**
1193
 * @brief Lock a cell for access to its array of #part and hold its parents.
1194
1195
 *
 * @param c The #cell.
1196
 * @return 0 on success, 1 on failure
1197
 */
1198
1199
1200
1201
int cell_locktree(struct cell *c) {
  TIMER_TIC

  /* First of all, try to lock this cell. */
1202
  if (c->hydro.hold || lock_trylock(&c->hydro.lock) != 0) {
1203
1204
1205
1206
1207
    TIMER_TOC(timer_locktree);
    return 1;
  }

  /* Did somebody hold this cell in the meantime? */
1208
  if (c->hydro.hold) {
1209
    /* Unlock this cell. */
1210
    if (lock_unlock(&c->hydro.lock) != 0) error("Failed to unlock cell.");
1211
1212
1213
1214
1215
1216
1217

    /* Admit defeat. */
    TIMER_TOC(timer_locktree);
    return 1;
  }

  /* Climb up the tree and lock/hold/unlock. */
Pedro Gonnet's avatar
Pedro Gonnet committed
1218
  struct cell *finger;
1219
1220
  for (finger = c->parent; finger != NULL; finger = finger->parent) {
    /* Lock this cell. */
1221
    if (lock_trylock(&finger->hydro.lock) != 0) break;
1222
1223

    /* Increment the hold. */
1224
    atomic_inc(&finger->hydro.hold);
1225
1226

    /* Unlock the cell. */
1227
    if (lock_unlock(&finger->hydro.lock) != 0) error("Failed to unlock cell.");
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
  }

  /* If we reached the top of the tree, we're done. */
  if (finger == NULL) {
    TIMER_TOC(timer_locktree);
    return 0;
  }

  /* Otherwise, we hit a snag. */
  else {
    /* Undo the holds up to finger. */
Pedro Gonnet's avatar
Pedro Gonnet committed
1239
1240
    for (struct cell *finger2 = c->parent; finger2 != finger;
         finger2 = finger2->parent)
1241
      atomic_dec(&finger2->hydro.hold);
1242
1243

    /* Unlock this cell. */
1244
    if (lock_unlock(&c->hydro.lock) != 0) error("Failed to unlock cell.");
1245
1246
1247
1248
1249
1250
1251

    /* Admit defeat. */
    TIMER_TOC(timer_locktree);
    return 1;
  }
}

1252
1253
1254
1255
1256
1257
/**
 * @brief Lock a cell for access to its array of #gpart and hold its parents.
 *
 * @param c The #cell.
 * @return 0 on success, 1 on failure
 */
1258
1259
1260
1261
int cell_glocktree(struct cell *c) {
  TIMER_TIC

  /* First of all, try to lock this cell. */
1262
  if (c->grav.phold || lock_trylock(&c->grav.plock) != 0) {
1263
1264
1265
1266
1267
    TIMER_TOC(timer_locktree);
    return 1;
  }

  /* Did somebody hold this cell in the meantime? */
1268
  if (c->grav.phold) {
1269
    /* Unlock this cell. */
1270
    if (lock_unlock(&c->grav.plock) != 0) error("Failed to unlock cell.");
1271
1272
1273
1274
1275
1276
1277

    /* Admit defeat. */
    TIMER_TOC(timer_locktree);
    return 1;
  }

  /* Climb up the tree and lock/hold/unlock. */
Pedro Gonnet's avatar
Pedro Gonnet committed
1278
  struct cell *finger;
1279
1280
  for (finger = c->parent; finger != NULL; finger = finger->parent) {
    /* Lock this cell. */
1281
    if (lock_trylock(&finger->grav.plock) != 0) break;
1282
1283

    /* Increment the hold. */
1284
    atomic_inc(&finger->grav.phold);
1285
1286

    /* Unlock the cell. */
1287
    if (lock_unlock(&finger->grav.plock) != 0) error("Failed to unlock cell.");
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
  }

  /* If we reached the top of the tree, we're done. */
  if (finger == NULL) {
    TIMER_TOC(timer_locktree);
    return 0;
  }

  /* Otherwise, we hit a snag. */
  else {
    /* Undo the holds up to finger. */
Pedro Gonnet's avatar
Pedro Gonnet committed
1299
1300
    for (struct cell *finger2 = c->parent; finger2 != finger;
         finger2 = finger2->parent)
1301
      atomic_dec(&finger2->grav.phold);
1302
1303

    /* Unlock this cell. */
1304
    if (lock_unlock(&c->grav.plock) != 0) error("Failed to unlock cell.");
1305
1306
1307
1308
1309
1310

    /* Admit defeat. */
    TIMER_TOC(timer_locktree);
    return 1;
  }
}
1311

1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
/**
 * @brief Lock a cell for access to its #multipole and hold its parents.
 *
 * @param c The #cell.
 * @return 0 on success, 1 on failure
 */
int cell_mlocktree(struct cell *c) {
  TIMER_TIC

  /* First of all, try to lock this cell. */
1322
  if (c->grav.mhold || lock_trylock(&c->grav.mlock) != 0) {
1323
1324
1325
1326
1327
    TIMER_TOC(timer_locktree);
    return 1;
  }

  /* Did somebody hold this cell in the meantime? */
1328
  if (c->grav.mhold) {
1329
    /* Unlock this cell. */
1330
    if (lock_unlock(&c->grav.mlock) != 0) error("Failed to unlock cell.");
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340

    /* Admit defeat. */
    TIMER_TOC(timer_locktree);
    return 1;
  }

  /* Climb up the tree and lock/hold/unlock. */
  struct cell *finger;
  for (finger = c->parent; finger != NULL; finger = finger->parent) {
    /* Lock this cell. */
1341
    if (lock_trylock(&finger->grav.mlock) != 0) break;
1342
1343

    /* Increment the hold. */
1344
    atomic_inc(&finger->grav.mhold);
1345
1346

    /* Unlock the cell. */
1347
    if (lock_unlock(&finger->grav.mlock) != 0) error("Failed to unlock cell.");
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
  }

  /* If we reached the top of the tree, we're done. */
  if (finger == NULL) {
    TIMER_TOC(timer_locktree);
    return 0;
  }

  /* Otherwise, we hit a snag. */
  else {
    /* Undo the holds up to finger. */
    for (struct cell *finger2 = c->parent; finger2 != finger;
         finger2 = finger2->parent)
1361
      atomic_dec(&finger2->grav.mhold);
1362
1363

    /* Unlock this cell. */
1364
    if (lock_unlock(&c->grav.mlock) != 0) error("Failed to unlock cell.");
1365
1366
1367
1368
1369
1370
1371

    /* Admit defeat. */
    TIMER_TOC(timer_locktree);
    return 1;
  }
}

1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
/**
 * @brief Lock a cell for access to its array of #spart and hold its parents.
 *
 * @param c The #cell.
 * @return 0 on success, 1 on failure
 */
int cell_slocktree(struct cell *c) {
  TIMER_TIC

  /* First of all, try to lock this cell. */
1382
  if (c->stars.hold || lock_trylock(&c->stars.lock) != 0) {
1383
1384
1385
1386
1387
    TIMER_TOC(timer_locktree);
    return 1;
  }

  /* Did somebody hold this cell in the meantime? */