mono/metadata/sgen-bridge.c

   1 /*
   2  * sgen-bridge.c: Simple generational GC.
   3  *
   4  * Copyright 2011 Novell, Inc (http://www.novell.com)
   5  * Copyright 2011 Xamarin Inc (http://www.xamarin.com)
   6  *
   7  * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
   8  * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
   9  *
  10  * Permission is hereby granted to use or copy this program
  11  * for any purpose,  provided the above notices are retained on all copies.
  12  * Permission to modify the code and to distribute modified code is granted,
  13  * provided the above notices are retained, and a notice that the code was
  14  * modified is included with the above copyright notice.
  15  *
  16  *
  17  * Copyright 2001-2003 Ximian, Inc
  18  * Copyright 2003-2010 Novell, Inc.
  19  *
  20  * Permission is hereby granted, free of charge, to any person obtaining
  21  * a copy of this software and associated documentation files (the
  22  * "Software"), to deal in the Software without restriction, including
  23  * without limitation the rights to use, copy, modify, merge, publish,
  24  * distribute, sublicense, and/or sell copies of the Software, and to
  25  * permit persons to whom the Software is furnished to do so, subject to
  26  * the following conditions:
  27  *
  28  * The above copyright notice and this permission notice shall be
  29  * included in all copies or substantial portions of the Software.
  30  *
  31  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  32  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  33  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  34  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  35  * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  36  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  37  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  38  */
  39
  40 #include "config.h"
  41
  42 #ifdef HAVE_SGEN_GC
  43
  44 #include <stdlib.h>
  45
  46 #include "sgen-gc.h"
  47 #include "sgen-bridge.h"
  48 #include "sgen-hash-table.h"
  49 #include "sgen-qsort.h"
  50 #include "utils/mono-logger-internal.h"
  51
  52 MonoGCBridgeCallbacks bridge_callbacks;
  53 static SgenBridgeProcessor bridge_processor;
  54 static SgenBridgeProcessor compare_to_bridge_processor;
  55
  56 gboolean bridge_processing_in_progress = FALSE;
  57
  58 void
  59 mono_gc_wait_for_bridge_processing (void)
  60 {
  61         if (!bridge_processing_in_progress)
  62                 return;
  63
  64         mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_GC, "GC_BRIDGE waiting for bridge processing to finish");
  65
  66         sgen_gc_lock ();
  67         sgen_gc_unlock ();
  68 }
  69
  70
  71 void
  72 mono_gc_register_bridge_callbacks (MonoGCBridgeCallbacks *callbacks)
  73 {
  74         if (callbacks->bridge_version != SGEN_BRIDGE_VERSION)
  75                 g_error ("Invalid bridge callback version. Expected %d but got %d\n", SGEN_BRIDGE_VERSION, callbacks->bridge_version);
  76
  77         bridge_callbacks = *callbacks;
  78
  79         if (!bridge_processor.reset_data)
  80                 sgen_old_bridge_init (&bridge_processor);
  81 }
  82
  83 static gboolean
  84 init_bridge_processor (SgenBridgeProcessor *processor, const char *name)
  85 {
  86         if (!strcmp ("old", name)) {
  87                 memset (processor, 0, sizeof (SgenBridgeProcessor));
  88                 sgen_old_bridge_init (processor);
  89         } else if (!strcmp ("new", name)) {
  90                 memset (processor, 0, sizeof (SgenBridgeProcessor));
  91                 sgen_new_bridge_init (processor);
  92         } else if (!strcmp ("tarjan", name)) {
  93                 memset (processor, 0, sizeof (SgenBridgeProcessor));
  94                 sgen_tarjan_bridge_init (processor);
  95         } else {
  96                 return FALSE;
  97         }
  98         return TRUE;
  99 }
 100
 101 void
 102 sgen_set_bridge_implementation (const char *name)
 103 {
 104         if (!init_bridge_processor (&bridge_processor, name))
 105                 g_warning ("Invalid value for bridge implementation, valid values are: 'new' and 'old'.");
 106 }
 107
 108 gboolean
 109 sgen_is_bridge_object (GCObject *obj)
 110 {
 111         if ((obj->vtable->gc_bits & SGEN_GC_BIT_BRIDGE_OBJECT) != SGEN_GC_BIT_BRIDGE_OBJECT)
 112                 return FALSE;
 113         return bridge_callbacks.is_bridge_object (obj);
 114 }
 115
 116 gboolean
 117 sgen_need_bridge_processing (void)
 118 {
 119         return bridge_callbacks.cross_references != NULL;
 120 }
 121
 122 static gboolean
 123 compare_bridge_processors (void)
 124 {
 125         return compare_to_bridge_processor.reset_data != NULL;
 126 }
 127
 128 /* Dispatch wrappers */
 129 void
 130 sgen_bridge_reset_data (void)
 131 {
 132         bridge_processor.reset_data ();
 133         if (compare_bridge_processors ())
 134                 compare_to_bridge_processor.reset_data ();
 135 }
 136
 137 void
 138 sgen_bridge_processing_stw_step (void)
 139 {
 140         /*
 141          * bridge_processing_in_progress must be set with the world
 142          * stopped.  If not there would be race conditions.
 143          */
 144         bridge_processing_in_progress = TRUE;
 145
 146         bridge_processor.processing_stw_step ();
 147         if (compare_bridge_processors ())
 148                 compare_to_bridge_processor.processing_stw_step ();
 149 }
 150
 151 static mono_bool
 152 is_bridge_object_alive (GCObject *obj, void *data)
 153 {
 154         SgenHashTable *table = data;
 155         unsigned char *value = sgen_hash_table_lookup (table, obj);
 156         if (!value)
 157                 return TRUE;
 158         return *value;
 159 }
 160
 161 static void
 162 null_weak_links_to_dead_objects (SgenBridgeProcessor *processor, int generation)
 163 {
 164         int i, j;
 165         int num_sccs = processor->num_sccs;
 166         MonoGCBridgeSCC **api_sccs = processor->api_sccs;
 167         SgenHashTable alive_hash = SGEN_HASH_TABLE_INIT (INTERNAL_MEM_BRIDGE_ALIVE_HASH_TABLE, INTERNAL_MEM_BRIDGE_ALIVE_HASH_TABLE_ENTRY, 1, mono_aligned_addr_hash, NULL);
 168
 169         for (i = 0; i < num_sccs; ++i) {
 170                 unsigned char alive = api_sccs [i]->is_alive ? 1 : 0;
 171                 for (j = 0; j < api_sccs [i]->num_objs; ++j) {
 172                         /* Build hash table for nulling weak links. */
 173                         sgen_hash_table_replace (&alive_hash, api_sccs [i]->objs [j], &alive, NULL);
 174
 175                         /* Release for finalization those objects we no longer care. */
 176                         if (!api_sccs [i]->is_alive)
 177                                 sgen_mark_bridge_object (api_sccs [i]->objs [j]);
 178                 }
 179         }
 180
 181         /* Null weak links to dead objects. */
 182         sgen_null_links_with_predicate (GENERATION_NURSERY, is_bridge_object_alive, &alive_hash);
 183         if (generation == GENERATION_OLD)
 184                 sgen_null_links_with_predicate (GENERATION_OLD, is_bridge_object_alive, &alive_hash);
 185
 186         sgen_hash_table_clean (&alive_hash);
 187 }
 188
 189 static void
 190 free_callback_data (SgenBridgeProcessor *processor)
 191 {
 192         int i;
 193         int num_sccs = processor->num_sccs;
 194         int num_xrefs = processor->num_xrefs;
 195         MonoGCBridgeSCC **api_sccs = processor->api_sccs;
 196         MonoGCBridgeXRef *api_xrefs = processor->api_xrefs;
 197
 198         for (i = 0; i < num_sccs; ++i) {
 199                 sgen_free_internal_dynamic (api_sccs [i],
 200                                 sizeof (MonoGCBridgeSCC) + sizeof (MonoObject*) * api_sccs [i]->num_objs,
 201                                 INTERNAL_MEM_BRIDGE_DATA);
 202         }
 203         sgen_free_internal_dynamic (api_sccs, sizeof (MonoGCBridgeSCC*) * num_sccs, INTERNAL_MEM_BRIDGE_DATA);
 204
 205         sgen_free_internal_dynamic (api_xrefs, sizeof (MonoGCBridgeXRef) * num_xrefs, INTERNAL_MEM_BRIDGE_DATA);
 206
 207         processor->num_sccs = 0;
 208         processor->api_sccs = NULL;
 209         processor->num_xrefs = 0;
 210         processor->api_xrefs = NULL;
 211 }
 212
 213 void
 214 sgen_bridge_processing_finish (int generation)
 215 {
 216         bridge_processor.processing_build_callback_data (generation);
 217         if (compare_bridge_processors ())
 218                 compare_to_bridge_processor.processing_build_callback_data (generation);
 219
 220         if (bridge_processor.num_sccs == 0) {
 221                 g_assert (bridge_processor.num_xrefs == 0);
 222                 goto after_callback;
 223         }
 224
 225         bridge_callbacks.cross_references (bridge_processor.num_sccs, bridge_processor.api_sccs,
 226                         bridge_processor.num_xrefs, bridge_processor.api_xrefs);
 227
 228         if (compare_bridge_processors ())
 229                 sgen_compare_bridge_processor_results (&bridge_processor, &compare_to_bridge_processor);
 230
 231         null_weak_links_to_dead_objects (&bridge_processor, generation);
 232
 233         free_callback_data (&bridge_processor);
 234         if (compare_bridge_processors ())
 235                 free_callback_data (&compare_to_bridge_processor);
 236
 237  after_callback:
 238         bridge_processor.processing_after_callback (generation);
 239         if (compare_bridge_processors ())
 240                 compare_to_bridge_processor.processing_after_callback (generation);
 241
 242         bridge_processing_in_progress = FALSE;
 243 }
 244
 245 MonoGCBridgeObjectKind
 246 sgen_bridge_class_kind (MonoClass *class)
 247 {
 248         return bridge_processor.class_kind (class);
 249 }
 250
 251 void
 252 sgen_bridge_register_finalized_object (GCObject *obj)
 253 {
 254         bridge_processor.register_finalized_object (obj);
 255         if (compare_bridge_processors ())
 256                 compare_to_bridge_processor.register_finalized_object (obj);
 257 }
 258
 259 void
 260 sgen_bridge_describe_pointer (GCObject *obj)
 261 {
 262         if (bridge_processor.describe_pointer)
 263                 bridge_processor.describe_pointer (obj);
 264 }
 265
 266 static void
 267 set_dump_prefix (const char *prefix)
 268 {
 269         if (!bridge_processor.set_dump_prefix) {
 270                 fprintf (stderr, "Warning: Bridge implementation does not support dumping - ignoring.\n");
 271                 return;
 272         }
 273
 274         bridge_processor.set_dump_prefix (prefix);
 275 }
 276
 277 /* Test support code */
 278 static const char *bridge_class;
 279
 280 static MonoGCBridgeObjectKind
 281 bridge_test_bridge_class_kind (MonoClass *class)
 282 {
 283         if (!strcmp (bridge_class, class->name))
 284                 return GC_BRIDGE_TRANSPARENT_BRIDGE_CLASS;
 285         return GC_BRIDGE_TRANSPARENT_CLASS;
 286 }
 287
 288 static gboolean
 289 bridge_test_is_bridge_object (MonoObject *object)
 290 {
 291         return TRUE;
 292 }
 293
 294 static void
 295 bridge_test_cross_reference (int num_sccs, MonoGCBridgeSCC **sccs, int num_xrefs, MonoGCBridgeXRef *xrefs)
 296 {
 297         int i;
 298         for (i = 0; i < num_sccs; ++i) {
 299                 int j;
 300         //      g_print ("--- SCC %d\n", i);
 301                 for (j = 0; j < sccs [i]->num_objs; ++j) {
 302         //              g_print ("  %s\n", sgen_safe_name (sccs [i]->objs [j]));
 303                         if (i & 1) /*retain half of the bridged objects */
 304                                 sccs [i]->is_alive = TRUE;
 305                 }
 306         }
 307         for (i = 0; i < num_xrefs; ++i) {
 308                 g_assert (xrefs [i].src_scc_index >= 0 && xrefs [i].src_scc_index < num_sccs);
 309                 g_assert (xrefs [i].dst_scc_index >= 0 && xrefs [i].dst_scc_index < num_sccs);
 310         //      g_print ("%d -> %d\n", xrefs [i].src_scc_index, xrefs [i].dst_scc_index);
 311         }
 312 }
 313
 314 static MonoClassField *mono_bridge_test_field;
 315
 316 enum {
 317         BRIDGE_DEAD,
 318         BRIDGE_ROOT,
 319         BRIDGE_SAME_SCC,
 320         BRIDGE_XREF,
 321 };
 322
 323 static gboolean
 324 test_scc (MonoGCBridgeSCC *scc, int i)
 325 {
 326         int status = BRIDGE_DEAD;
 327         mono_field_get_value (scc->objs [i], mono_bridge_test_field, &status);
 328         return status > 0;
 329 }
 330
 331 static void
 332 mark_scc (MonoGCBridgeSCC *scc, int value)
 333 {
 334         int i;
 335         for (i = 0; i < scc->num_objs; ++i) {
 336                 if (!test_scc (scc, i)) {
 337                         int status = value;
 338                         mono_field_set_value (scc->objs [i], mono_bridge_test_field, &status);
 339                 }
 340         }
 341 }
 342
 343 static void
 344 bridge_test_cross_reference2 (int num_sccs, MonoGCBridgeSCC **sccs, int num_xrefs, MonoGCBridgeXRef *xrefs)
 345 {
 346         int i;
 347         gboolean modified;
 348
 349         if (!mono_bridge_test_field) {
 350                 mono_bridge_test_field = mono_class_get_field_from_name (mono_object_get_class (sccs[0]->objs [0]), "__test");
 351                 g_assert (mono_bridge_test_field);
 352         }
 353
 354         /*We mark all objects in a scc with live objects as reachable by scc*/
 355         for (i = 0; i < num_sccs; ++i) {
 356                 int j;
 357                 gboolean live = FALSE;
 358                 for (j = 0; j < sccs [i]->num_objs; ++j) {
 359                         if (test_scc (sccs [i], j)) {
 360                                 live = TRUE;
 361                                 break;
 362                         }
 363                 }
 364                 if (!live)
 365                         continue;
 366                 for (j = 0; j < sccs [i]->num_objs; ++j) {
 367                         if (!test_scc (sccs [i], j)) {
 368                                 int status = BRIDGE_SAME_SCC;
 369                                 mono_field_set_value (sccs [i]->objs [j], mono_bridge_test_field, &status);
 370                         }
 371                 }
 372         }
 373
 374         /*Now we mark the transitive closure of reachable objects from the xrefs*/
 375         modified = TRUE;
 376         while (modified) {
 377                 modified = FALSE;
 378                 /* Mark all objects that are brought to life due to xrefs*/
 379                 for (i = 0; i < num_xrefs; ++i) {
 380                         MonoGCBridgeXRef ref = xrefs [i];
 381                         if (test_scc (sccs [ref.src_scc_index], 0) && !test_scc (sccs [ref.dst_scc_index], 0)) {
 382                                 modified = TRUE;
 383                                 mark_scc (sccs [ref.dst_scc_index], BRIDGE_XREF);
 384                         }
 385                 }
 386         }
 387
 388         /* keep everything in memory, all we want to do is test persistence */
 389         for (i = 0; i < num_sccs; ++i)
 390                 sccs [i]->is_alive = TRUE;
 391 }
 392
 393 static void
 394 register_test_bridge_callbacks (const char *bridge_class_name)
 395 {
 396         MonoGCBridgeCallbacks callbacks;
 397         callbacks.bridge_version = SGEN_BRIDGE_VERSION;
 398         callbacks.bridge_class_kind = bridge_test_bridge_class_kind;
 399         callbacks.is_bridge_object = bridge_test_is_bridge_object;
 400         callbacks.cross_references = bridge_class_name[0] == '2' ? bridge_test_cross_reference2 : bridge_test_cross_reference;
 401         mono_gc_register_bridge_callbacks (&callbacks);
 402         bridge_class = bridge_class_name + (bridge_class_name[0] == '2' ? 1 : 0);
 403 }
 404
 405 gboolean
 406 sgen_bridge_handle_gc_debug (const char *opt)
 407 {
 408         if (g_str_has_prefix (opt, "bridge=")) {
 409                 opt = strchr (opt, '=') + 1;
 410                 register_test_bridge_callbacks (g_strdup (opt));
 411         } else if (!strcmp (opt, "enable-bridge-accounting")) {
 412                 bridge_processor.enable_accounting ();
 413         } else if (g_str_has_prefix (opt, "bridge-dump=")) {
 414                 char *prefix = strchr (opt, '=') + 1;
 415                 set_dump_prefix (prefix);
 416         } else if (g_str_has_prefix (opt, "bridge-compare-to=")) {
 417                 const char *name = strchr (opt, '=') + 1;
 418                 if (init_bridge_processor (&compare_to_bridge_processor, name)) {
 419                         if (compare_to_bridge_processor.reset_data == bridge_processor.reset_data) {
 420                                 g_warning ("Cannot compare bridge implementation to itself - ignoring.");
 421                                 memset (&compare_to_bridge_processor, 0, sizeof (SgenBridgeProcessor));
 422                         }
 423                 } else {
 424                         g_warning ("Invalid bridge implementation to compare against - ignoring.");
 425                 }
 426         } else {
 427                 return FALSE;
 428         }
 429         return TRUE;
 430 }
 431
 432 void
 433 sgen_bridge_print_gc_debug_usage (void)
 434 {
 435         fprintf (stderr, "  bridge=<class-name>\n");
 436         fprintf (stderr, "  enable-bridge-accounting\n");
 437         fprintf (stderr, "  bridge-dump=<filename-prefix>\n");
 438         fprintf (stderr, "  bridge-compare-to=<implementation>\n");
 439 }
 440
 441 #endif