mono/metadata/sgen-fin-weak-hash.c

   1 /*
   2  * sgen-fin-weak-hash.c:
   3  *
   4  * Author:
   5  *      Paolo Molaro (lupus@ximian.com)
   6  *  Rodrigo Kumpera (kumpera@gmail.com)
   7  *
   8  * Copyright 2005-2011 Novell, Inc (http://www.novell.com)
   9  * Copyright 2011 Xamarin Inc (http://www.xamarin.com)
  10  * Copyright 2011 Xamarin, Inc.
  11  *
  12  * Permission is hereby granted, free of charge, to any person obtaining
  13  * a copy of this software and associated documentation files (the
  14  * "Software"), to deal in the Software without restriction, including
  15  * without limitation the rights to use, copy, modify, merge, publish,
  16  * distribute, sublicense, and/or sell copies of the Software, and to
  17  * permit persons to whom the Software is furnished to do so, subject to
  18  * the following conditions:
  19  *
  20  * The above copyright notice and this permission notice shall be
  21  * included in all copies or substantial portions of the Software.
  22  *
  23  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  27  * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  28  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  29  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  30  */
  31
  32 #include "config.h"
  33 #ifdef HAVE_SGEN_GC
  34
  35 #include "metadata/sgen-gc.h"
  36 #include "metadata/sgen-gray.h"
  37
  38 #define ptr_in_nursery sgen_ptr_in_nursery
  39
  40 typedef SgenGrayQueue GrayQueue;
  41
  42 int num_ready_finalizers = 0;
  43 static int no_finalize = 0;
  44
  45 #define DISLINK_OBJECT(l)       (REVEAL_POINTER (*(void**)(l)))
  46 #define DISLINK_TRACK(l)        ((~(gulong)(*(void**)(l))) & 1)
  47
  48 /*
  49  * The finalizable hash has the object as the key, the
  50  * disappearing_link hash, has the link address as key.
  51  *
  52  * Copyright 2011 Xamarin Inc.
  53  */
  54
  55 #define TAG_MASK ((mword)0x1)
  56
  57 static inline MonoObject*
  58 tagged_object_get_object (MonoObject *object)
  59 {
  60         return (MonoObject*)(((mword)object) & ~TAG_MASK);
  61 }
  62
  63 static inline int
  64 tagged_object_get_tag (MonoObject *object)
  65 {
  66         return ((mword)object) & TAG_MASK;
  67 }
  68
  69 static inline MonoObject*
  70 tagged_object_apply (void *object, int tag_bits)
  71 {
  72        return (MonoObject*)((mword)object | (mword)tag_bits);
  73 }
  74
  75 static int
  76 tagged_object_hash (MonoObject *o)
  77 {
  78         return mono_object_hash (tagged_object_get_object (o));
  79 }
  80
  81 static gboolean
  82 tagged_object_equals (MonoObject *a, MonoObject *b)
  83 {
  84         return tagged_object_get_object (a) == tagged_object_get_object (b);
  85 }
  86
  87 static SgenHashTable minor_finalizable_hash = SGEN_HASH_TABLE_INIT (INTERNAL_MEM_FIN_TABLE, INTERNAL_MEM_FINALIZE_ENTRY, 0, (GHashFunc)tagged_object_hash, (GEqualFunc)tagged_object_equals);
  88 static SgenHashTable major_finalizable_hash = SGEN_HASH_TABLE_INIT (INTERNAL_MEM_FIN_TABLE, INTERNAL_MEM_FINALIZE_ENTRY, 0, (GHashFunc)tagged_object_hash, (GEqualFunc)tagged_object_equals);
  89
  90 static SgenHashTable*
  91 get_finalize_entry_hash_table (int generation)
  92 {
  93         switch (generation) {
  94         case GENERATION_NURSERY: return &minor_finalizable_hash;
  95         case GENERATION_OLD: return &major_finalizable_hash;
  96         default: g_assert_not_reached ();
  97         }
  98 }
  99
 100 #define BRIDGE_OBJECT_MARKED 0x1
 101
 102 /* LOCKING: requires that the GC lock is held */
 103 void
 104 sgen_mark_bridge_object (MonoObject *obj)
 105 {
 106         SgenHashTable *hash_table = get_finalize_entry_hash_table (ptr_in_nursery (obj) ? GENERATION_NURSERY : GENERATION_OLD);
 107
 108         sgen_hash_table_set_key (hash_table, obj, tagged_object_apply (obj, BRIDGE_OBJECT_MARKED));
 109 }
 110
 111 /* LOCKING: requires that the GC lock is held */
 112 void
 113 sgen_collect_bridge_objects (CopyOrMarkObjectFunc copy_func, char *start, char *end, int generation, GrayQueue *queue)
 114 {
 115         SgenHashTable *hash_table = get_finalize_entry_hash_table (generation);
 116         MonoObject *object;
 117         gpointer dummy;
 118         char *copy;
 119
 120         if (no_finalize)
 121                 return;
 122
 123         SGEN_HASH_TABLE_FOREACH (hash_table, object, dummy) {
 124                 int tag = tagged_object_get_tag (object);
 125                 object = tagged_object_get_object (object);
 126
 127                 /* Bridge code told us to ignore this one */
 128                 if (tag == BRIDGE_OBJECT_MARKED)
 129                         continue;
 130
 131                 /* Object is a bridge object and major heap says it's dead  */
 132                 if (!((char*)object >= start && (char*)object < end && !major_collector.is_object_live ((char*)object)))
 133                         continue;
 134
 135                 /* Nursery says the object is dead. */
 136                 if (!sgen_gc_is_object_ready_for_finalization (object))
 137                         continue;
 138
 139                 if (!sgen_is_bridge_object (object))
 140                         continue;
 141
 142                 copy = (char*)object;
 143                 copy_func ((void**)&copy, queue);
 144
 145                 sgen_bridge_register_finalized_object ((MonoObject*)copy);
 146
 147                 if (hash_table == &minor_finalizable_hash && !ptr_in_nursery (copy)) {
 148                         /* remove from the list */
 149                         SGEN_HASH_TABLE_FOREACH_REMOVE (TRUE);
 150
 151                         /* insert it into the major hash */
 152                         sgen_hash_table_replace (&major_finalizable_hash, tagged_object_apply (copy, tag), NULL, NULL);
 153
 154                         DEBUG (5, fprintf (gc_debug_file, "Promoting finalization of object %p (%s) (was at %p) to major table\n", copy, sgen_safe_name (copy), object));
 155
 156                         continue;
 157                 } else {
 158                         /* update pointer */
 159                         DEBUG (5, fprintf (gc_debug_file, "Updating object for finalization: %p (%s) (was at %p)\n", copy, sgen_safe_name (copy), object));
 160                         SGEN_HASH_TABLE_FOREACH_SET_KEY (tagged_object_apply (copy, tag));
 161                 }
 162         } SGEN_HASH_TABLE_FOREACH_END;
 163 }
 164
 165
 166 /* LOCKING: requires that the GC lock is held */
 167 void
 168 sgen_finalize_in_range (CopyOrMarkObjectFunc copy_func, char *start, char *end, int generation, GrayQueue *queue)
 169 {
 170         SgenHashTable *hash_table = get_finalize_entry_hash_table (generation);
 171         MonoObject *object;
 172         gpointer dummy;
 173
 174         if (no_finalize)
 175                 return;
 176         SGEN_HASH_TABLE_FOREACH (hash_table, object, dummy) {
 177                 int tag = tagged_object_get_tag (object);
 178                 object = tagged_object_get_object (object);
 179                 if ((char*)object >= start && (char*)object < end && !major_collector.is_object_live ((char*)object)) {
 180                         gboolean is_fin_ready = sgen_gc_is_object_ready_for_finalization (object);
 181                         MonoObject *copy = object;
 182                         copy_func ((void**)&copy, queue);
 183                         if (is_fin_ready) {
 184                                 /* remove and put in fin_ready_list */
 185                                 SGEN_HASH_TABLE_FOREACH_REMOVE (TRUE);
 186                                 num_ready_finalizers++;
 187                                 sgen_queue_finalization_entry (copy);
 188                                 /* Make it survive */
 189                                 DEBUG (5, fprintf (gc_debug_file, "Queueing object for finalization: %p (%s) (was at %p) (%d/%d)\n", copy, sgen_safe_name (copy), object, num_ready_finalizers, sgen_hash_table_num_entries (hash_table)));
 190                                 continue;
 191                         } else {
 192                                 if (hash_table == &minor_finalizable_hash && !ptr_in_nursery (copy)) {
 193                                         /* remove from the list */
 194                                         SGEN_HASH_TABLE_FOREACH_REMOVE (TRUE);
 195
 196                                         /* insert it into the major hash */
 197                                         sgen_hash_table_replace (&major_finalizable_hash, tagged_object_apply (copy, tag), NULL, NULL);
 198
 199                                         DEBUG (5, fprintf (gc_debug_file, "Promoting finalization of object %p (%s) (was at %p) to major table\n", copy, sgen_safe_name (copy), object));
 200
 201                                         continue;
 202                                 } else {
 203                                         /* update pointer */
 204                                         DEBUG (5, fprintf (gc_debug_file, "Updating object for finalization: %p (%s) (was at %p)\n", copy, sgen_safe_name (copy), object));
 205                                         SGEN_HASH_TABLE_FOREACH_SET_KEY (tagged_object_apply (copy, tag));
 206                                 }
 207                         }
 208                 }
 209         } SGEN_HASH_TABLE_FOREACH_END;
 210 }
 211
 212 /* LOCKING: requires that the GC lock is held */
 213 static void
 214 register_for_finalization (MonoObject *obj, void *user_data, int generation)
 215 {
 216         SgenHashTable *hash_table = get_finalize_entry_hash_table (generation);
 217
 218         if (no_finalize)
 219                 return;
 220
 221         g_assert (user_data == NULL || user_data == mono_gc_run_finalize);
 222
 223         if (user_data) {
 224                 if (sgen_hash_table_replace (hash_table, obj, NULL, NULL))
 225                         DEBUG (5, fprintf (gc_debug_file, "Added finalizer for object: %p (%s) (%d) to %s table\n", obj, obj->vtable->klass->name, hash_table->num_entries, sgen_generation_name (generation)));
 226         } else {
 227                 if (sgen_hash_table_remove (hash_table, obj, NULL))
 228                         DEBUG (5, fprintf (gc_debug_file, "Removed finalizer for object: %p (%s) (%d)\n", obj, obj->vtable->klass->name, hash_table->num_entries));
 229         }
 230 }
 231
 232 #define STAGE_ENTRY_FREE        0
 233 #define STAGE_ENTRY_BUSY        1
 234 #define STAGE_ENTRY_USED        2
 235
 236 typedef struct {
 237         gint32 state;
 238         MonoObject *obj;
 239         void *user_data;
 240 } StageEntry;
 241
 242 #define NUM_FIN_STAGE_ENTRIES   1024
 243
 244 static volatile gint32 next_fin_stage_entry = 0;
 245 static StageEntry fin_stage_entries [NUM_FIN_STAGE_ENTRIES];
 246
 247 /* LOCKING: requires that the GC lock is held */
 248 static void
 249 process_stage_entries (int num_entries, volatile gint32 *next_entry, StageEntry *entries, void (*process_func) (MonoObject*, void*))
 250 {
 251         int i;
 252         int num_registered = 0;
 253         int num_busy = 0;
 254
 255         for (i = 0; i < num_entries; ++i) {
 256                 gint32 state = entries [i].state;
 257
 258                 if (state == STAGE_ENTRY_BUSY)
 259                         ++num_busy;
 260
 261                 if (state != STAGE_ENTRY_USED ||
 262                                 InterlockedCompareExchange (&entries [i].state, STAGE_ENTRY_BUSY, STAGE_ENTRY_USED) != STAGE_ENTRY_USED) {
 263                         continue;
 264                 }
 265
 266                 process_func (entries [i].obj, entries [i].user_data);
 267
 268                 entries [i].obj = NULL;
 269                 entries [i].user_data = NULL;
 270
 271                 mono_memory_write_barrier ();
 272
 273                 entries [i].state = STAGE_ENTRY_FREE;
 274
 275                 ++num_registered;
 276         }
 277
 278         *next_entry = 0;
 279
 280         /* g_print ("stage busy %d reg %d\n", num_busy, num_registered); */
 281 }
 282
 283 static gboolean
 284 add_stage_entry (int num_entries, volatile gint32 *next_entry, StageEntry *entries, MonoObject *obj, void *user_data)
 285 {
 286         gint32 index;
 287
 288         do {
 289                 do {
 290                         index = *next_entry;
 291                         if (index >= num_entries)
 292                                 return FALSE;
 293                 } while (InterlockedCompareExchange (next_entry, index + 1, index) != index);
 294
 295                 /*
 296                  * We don't need a write barrier here.  *next_entry is just a
 297                  * help for finding an index, its value is irrelevant for
 298                  * correctness.
 299                  */
 300         } while (entries [index].state != STAGE_ENTRY_FREE ||
 301                         InterlockedCompareExchange (&entries [index].state, STAGE_ENTRY_BUSY, STAGE_ENTRY_FREE) != STAGE_ENTRY_FREE);
 302
 303         entries [index].obj = obj;
 304         entries [index].user_data = user_data;
 305
 306         mono_memory_write_barrier ();
 307
 308         entries [index].state = STAGE_ENTRY_USED;
 309
 310         return TRUE;
 311 }
 312
 313 /* LOCKING: requires that the GC lock is held */
 314 static void
 315 process_fin_stage_entry (MonoObject *obj, void *user_data)
 316 {
 317         if (ptr_in_nursery (obj))
 318                 register_for_finalization (obj, user_data, GENERATION_NURSERY);
 319         else
 320                 register_for_finalization (obj, user_data, GENERATION_OLD);
 321 }
 322
 323 /* LOCKING: requires that the GC lock is held */
 324 void
 325 sgen_process_fin_stage_entries (void)
 326 {
 327         process_stage_entries (NUM_FIN_STAGE_ENTRIES, &next_fin_stage_entry, fin_stage_entries, process_fin_stage_entry);
 328 }
 329
 330 void
 331 mono_gc_register_for_finalization (MonoObject *obj, void *user_data)
 332 {
 333         while (!add_stage_entry (NUM_FIN_STAGE_ENTRIES, &next_fin_stage_entry, fin_stage_entries, obj, user_data)) {
 334                 LOCK_GC;
 335                 sgen_process_fin_stage_entries ();
 336                 UNLOCK_GC;
 337         }
 338 }
 339
 340 /* LOCKING: requires that the GC lock is held */
 341 static int
 342 finalizers_for_domain (MonoDomain *domain, MonoObject **out_array, int out_size,
 343         SgenHashTable *hash_table)
 344 {
 345         MonoObject *object;
 346         gpointer dummy;
 347         int count;
 348
 349         if (no_finalize || !out_size || !out_array)
 350                 return 0;
 351         count = 0;
 352         SGEN_HASH_TABLE_FOREACH (hash_table, object, dummy) {
 353                 object = tagged_object_get_object (object);
 354
 355                 if (mono_object_domain (object) == domain) {
 356                         /* remove and put in out_array */
 357                         SGEN_HASH_TABLE_FOREACH_REMOVE (TRUE);
 358                         out_array [count ++] = object;
 359                         DEBUG (5, fprintf (gc_debug_file, "Collecting object for finalization: %p (%s) (%d/%d)\n", object, sgen_safe_name (object), num_ready_finalizers, sgen_hash_table_num_entries (hash_table)));
 360                         if (count == out_size)
 361                                 return count;
 362                         continue;
 363                 }
 364         } SGEN_HASH_TABLE_FOREACH_END;
 365         return count;
 366 }
 367
 368 /**
 369  * mono_gc_finalizers_for_domain:
 370  * @domain: the unloading appdomain
 371  * @out_array: output array
 372  * @out_size: size of output array
 373  *
 374  * Store inside @out_array up to @out_size objects that belong to the unloading
 375  * appdomain @domain. Returns the number of stored items. Can be called repeteadly
 376  * until it returns 0.
 377  * The items are removed from the finalizer data structure, so the caller is supposed
 378  * to finalize them.
 379  * @out_array should be on the stack to allow the GC to know the objects are still alive.
 380  */
 381 int
 382 mono_gc_finalizers_for_domain (MonoDomain *domain, MonoObject **out_array, int out_size)
 383 {
 384         int result;
 385
 386         LOCK_GC;
 387         sgen_process_fin_stage_entries ();
 388         result = finalizers_for_domain (domain, out_array, out_size, &minor_finalizable_hash);
 389         if (result < out_size) {
 390                 result += finalizers_for_domain (domain, out_array + result, out_size - result,
 391                         &major_finalizable_hash);
 392         }
 393         UNLOCK_GC;
 394
 395         return result;
 396 }
 397
 398 static SgenHashTable minor_disappearing_link_hash = SGEN_HASH_TABLE_INIT (INTERNAL_MEM_DISLINK_TABLE, INTERNAL_MEM_DISLINK, 0, mono_aligned_addr_hash, NULL);
 399 static SgenHashTable major_disappearing_link_hash = SGEN_HASH_TABLE_INIT (INTERNAL_MEM_DISLINK_TABLE, INTERNAL_MEM_DISLINK, 0, mono_aligned_addr_hash, NULL);
 400
 401 static SgenHashTable*
 402 get_dislink_hash_table (int generation)
 403 {
 404         switch (generation) {
 405         case GENERATION_NURSERY: return &minor_disappearing_link_hash;
 406         case GENERATION_OLD: return &major_disappearing_link_hash;
 407         default: g_assert_not_reached ();
 408         }
 409 }
 410
 411 /* LOCKING: assumes the GC lock is held */
 412 static void
 413 add_or_remove_disappearing_link (MonoObject *obj, void **link, int generation)
 414 {
 415         SgenHashTable *hash_table = get_dislink_hash_table (generation);
 416
 417         if (!obj) {
 418                 if (sgen_hash_table_remove (hash_table, link, NULL)) {
 419                         DEBUG (5, fprintf (gc_debug_file, "Removed dislink %p (%d) from %s table\n",
 420                                         link, hash_table->num_entries, sgen_generation_name (generation)));
 421                 }
 422                 return;
 423         }
 424
 425         sgen_hash_table_replace (hash_table, link, NULL, NULL);
 426         DEBUG (5, fprintf (gc_debug_file, "Added dislink for object: %p (%s) at %p to %s table\n",
 427                         obj, obj->vtable->klass->name, link, sgen_generation_name (generation)));
 428 }
 429
 430 /* LOCKING: requires that the GC lock is held */
 431 void
 432 sgen_null_link_in_range (CopyOrMarkObjectFunc copy_func, char *start, char *end, int generation, gboolean before_finalization, GrayQueue *queue)
 433 {
 434         void **link;
 435         gpointer dummy;
 436         SgenHashTable *hash = get_dislink_hash_table (generation);
 437
 438         SGEN_HASH_TABLE_FOREACH (hash, link, dummy) {
 439                 char *object;
 440                 gboolean track = DISLINK_TRACK (link);
 441
 442                 /*
 443                  * Tracked references are processed after
 444                  * finalization handling whereas standard weak
 445                  * references are processed before.  If an
 446                  * object is still not marked after finalization
 447                  * handling it means that it either doesn't have
 448                  * a finalizer or the finalizer has already run,
 449                  * so we must null a tracking reference.
 450                  */
 451                 if (track != before_finalization) {
 452                         object = DISLINK_OBJECT (link);
 453
 454                         if (object >= start && object < end && !major_collector.is_object_live (object)) {
 455                                 if (sgen_gc_is_object_ready_for_finalization (object)) {
 456                                         *link = NULL;
 457                                         DEBUG (5, fprintf (gc_debug_file, "Dislink nullified at %p to GCed object %p\n", link, object));
 458                                         SGEN_HASH_TABLE_FOREACH_REMOVE (TRUE);
 459                                         continue;
 460                                 } else {
 461                                         char *copy = object;
 462                                         copy_func ((void**)&copy, queue);
 463
 464                                         /* Update pointer if it's moved.  If the object
 465                                          * has been moved out of the nursery, we need to
 466                                          * remove the link from the minor hash table to
 467                                          * the major one.
 468                                          *
 469                                          * FIXME: what if an object is moved earlier?
 470                                          */
 471
 472                                         if (hash == &minor_disappearing_link_hash && !ptr_in_nursery (copy)) {
 473                                                 SGEN_HASH_TABLE_FOREACH_REMOVE (TRUE);
 474
 475                                                 g_assert (copy);
 476                                                 *link = HIDE_POINTER (copy, track);
 477                                                 add_or_remove_disappearing_link ((MonoObject*)copy, link, GENERATION_OLD);
 478
 479                                                 DEBUG (5, fprintf (gc_debug_file, "Upgraded dislink at %p to major because object %p moved to %p\n", link, object, copy));
 480
 481                                                 continue;
 482                                         } else {
 483                                                 *link = HIDE_POINTER (copy, track);
 484                                                 DEBUG (5, fprintf (gc_debug_file, "Updated dislink at %p to %p\n", link, DISLINK_OBJECT (link)));
 485                                         }
 486                                 }
 487                         }
 488                 }
 489         } SGEN_HASH_TABLE_FOREACH_END;
 490 }
 491
 492 /* LOCKING: requires that the GC lock is held */
 493 void
 494 sgen_null_links_for_domain (MonoDomain *domain, int generation)
 495 {
 496         void **link;
 497         gpointer dummy;
 498         SgenHashTable *hash = get_dislink_hash_table (generation);
 499         SGEN_HASH_TABLE_FOREACH (hash, link, dummy) {
 500                 char *object = DISLINK_OBJECT (link);
 501                 if (object && !((MonoObject*)object)->vtable) {
 502                         gboolean free = TRUE;
 503
 504                         if (*link) {
 505                                 *link = NULL;
 506                                 free = FALSE;
 507                                 /*
 508                                  * This can happen if finalizers are not ran, i.e. Environment.Exit ()
 509                                  * is called from finalizer like in finalizer-abort.cs.
 510                                  */
 511                                 DEBUG (5, fprintf (gc_debug_file, "Disappearing link %p not freed", link));
 512                         }
 513
 514                         SGEN_HASH_TABLE_FOREACH_REMOVE (free);
 515
 516                         continue;
 517                 }
 518         } SGEN_HASH_TABLE_FOREACH_END;
 519 }
 520
 521 /* LOCKING: requires that the GC lock is held */
 522 void
 523 sgen_null_links_with_predicate (int generation, WeakLinkAlivePredicateFunc predicate, void *data)
 524 {
 525         void **link;
 526         gpointer dummy;
 527         SgenHashTable *hash = get_dislink_hash_table (generation);
 528         fprintf (stderr, "**** nulling links with predicate\n");
 529         SGEN_HASH_TABLE_FOREACH (hash, link, dummy) {
 530                 char *object = DISLINK_OBJECT (link);
 531                 mono_bool is_alive = predicate ((MonoObject*)object, data);
 532
 533                 if (is_alive)
 534                         fprintf (stderr, "ALIVE %p %s\n", object, sgen_safe_name (object));
 535                 else
 536                         fprintf (stderr, "DEAD %p %s\n", object, sgen_safe_name (object));
 537
 538                 if (!is_alive) {
 539                         *link = NULL;
 540                         DEBUG (5, fprintf (gc_debug_file, "Dislink nullified by predicate at %p to GCed object %p\n", link, object));
 541                         SGEN_HASH_TABLE_FOREACH_REMOVE (TRUE);
 542                         continue;
 543                 }
 544         } SGEN_HASH_TABLE_FOREACH_END;
 545 }
 546
 547 void
 548 sgen_remove_finalizers_for_domain (MonoDomain *domain, int generation)
 549 {
 550         SgenHashTable *hash_table = get_finalize_entry_hash_table (generation);
 551         MonoObject *object;
 552         gpointer dummy;
 553
 554         SGEN_HASH_TABLE_FOREACH (hash_table, object, dummy) {
 555                 object = tagged_object_get_object (object);
 556
 557                 if (mono_object_domain (object) == domain) {
 558                         DEBUG (5, fprintf (gc_debug_file, "Unregistering finalizer for object: %p (%s)\n", object, sgen_safe_name (object)));
 559
 560                         SGEN_HASH_TABLE_FOREACH_REMOVE (TRUE);
 561                         continue;
 562                 }
 563         } SGEN_HASH_TABLE_FOREACH_END;
 564 }
 565
 566 /* LOCKING: requires that the GC lock is held */
 567 static void
 568 process_dislink_stage_entry (MonoObject *obj, void *_link)
 569 {
 570         void **link = _link;
 571
 572         add_or_remove_disappearing_link (NULL, link, GENERATION_NURSERY);
 573         add_or_remove_disappearing_link (NULL, link, GENERATION_OLD);
 574         if (obj) {
 575                 if (ptr_in_nursery (obj))
 576                         add_or_remove_disappearing_link (obj, link, GENERATION_NURSERY);
 577                 else
 578                         add_or_remove_disappearing_link (obj, link, GENERATION_OLD);
 579         }
 580 }
 581
 582 #define NUM_DISLINK_STAGE_ENTRIES       1024
 583
 584 static volatile gint32 next_dislink_stage_entry = 0;
 585 static StageEntry dislink_stage_entries [NUM_DISLINK_STAGE_ENTRIES];
 586
 587 /* LOCKING: requires that the GC lock is held */
 588 void
 589 sgen_process_dislink_stage_entries (void)
 590 {
 591         process_stage_entries (NUM_DISLINK_STAGE_ENTRIES, &next_dislink_stage_entry, dislink_stage_entries, process_dislink_stage_entry);
 592 }
 593
 594 void
 595 sgen_register_disappearing_link (MonoObject *obj, void **link, gboolean track, gboolean in_gc)
 596 {
 597         if (obj)
 598                 *link = HIDE_POINTER (obj, track);
 599         else
 600                 *link = NULL;
 601
 602 #if 1
 603         if (in_gc) {
 604                 process_dislink_stage_entry (obj, link);
 605         } else {
 606                 while (!add_stage_entry (NUM_DISLINK_STAGE_ENTRIES, &next_dislink_stage_entry, dislink_stage_entries, obj, link)) {
 607                         LOCK_GC;
 608                         sgen_process_dislink_stage_entries ();
 609                         UNLOCK_GC;
 610                 }
 611         }
 612 #else
 613         if (!in_gc)
 614                 LOCK_GC;
 615         process_dislink_stage_entry (obj, link);
 616         if (!in_gc)
 617                 UNLOCK_GC;
 618 #endif
 619 }
 620
 621 #endif /* HAVE_SGEN_GC */