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 #include "utils/mono-time.h"
  52 #include "utils/mono-compiler.h"
  53
  54 MonoGCBridgeCallbacks bridge_callbacks;
  55 static SgenBridgeProcessor bridge_processor;
  56 static SgenBridgeProcessor compare_to_bridge_processor;
  57
  58 gboolean bridge_processing_in_progress = FALSE;
  59
  60 void
  61 mono_gc_wait_for_bridge_processing (void)
  62 {
  63         if (!bridge_processing_in_progress)
  64                 return;
  65
  66         mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_GC, "GC_BRIDGE waiting for bridge processing to finish");
  67
  68         sgen_gc_lock ();
  69         sgen_gc_unlock ();
  70 }
  71
  72
  73 void
  74 mono_gc_register_bridge_callbacks (MonoGCBridgeCallbacks *callbacks)
  75 {
  76         if (callbacks->bridge_version != SGEN_BRIDGE_VERSION)
  77                 g_error ("Invalid bridge callback version. Expected %d but got %d\n", SGEN_BRIDGE_VERSION, callbacks->bridge_version);
  78
  79         bridge_callbacks = *callbacks;
  80
  81         if (!bridge_processor.reset_data)
  82                 sgen_old_bridge_init (&bridge_processor);
  83 }
  84
  85 static gboolean
  86 init_bridge_processor (SgenBridgeProcessor *processor, const char *name)
  87 {
  88         if (!strcmp ("old", name)) {
  89                 memset (processor, 0, sizeof (SgenBridgeProcessor));
  90                 sgen_old_bridge_init (processor);
  91         } else if (!strcmp ("new", name)) {
  92                 memset (processor, 0, sizeof (SgenBridgeProcessor));
  93                 sgen_new_bridge_init (processor);
  94         } else if (!strcmp ("tarjan", name)) {
  95                 memset (processor, 0, sizeof (SgenBridgeProcessor));
  96                 sgen_tarjan_bridge_init (processor);
  97         } else {
  98                 return FALSE;
  99         }
 100         return TRUE;
 101 }
 102
 103 void
 104 sgen_set_bridge_implementation (const char *name)
 105 {
 106         if (!init_bridge_processor (&bridge_processor, name))
 107                 g_warning ("Invalid value for bridge implementation, valid values are: 'new' and 'old'.");
 108 }
 109
 110 gboolean
 111 sgen_is_bridge_object (MonoObject *obj)
 112 {
 113         if ((obj->vtable->gc_bits & SGEN_GC_BIT_BRIDGE_OBJECT) != SGEN_GC_BIT_BRIDGE_OBJECT)
 114                 return FALSE;
 115         return bridge_callbacks.is_bridge_object (obj);
 116 }
 117
 118 gboolean
 119 sgen_need_bridge_processing (void)
 120 {
 121         return bridge_callbacks.cross_references != NULL;
 122 }
 123
 124 static gboolean
 125 compare_bridge_processors (void)
 126 {
 127         return compare_to_bridge_processor.reset_data != NULL;
 128 }
 129
 130 /* Dispatch wrappers */
 131 void
 132 sgen_bridge_reset_data (void)
 133 {
 134         bridge_processor.reset_data ();
 135         if (compare_bridge_processors ())
 136                 compare_to_bridge_processor.reset_data ();
 137 }
 138
 139 void
 140 sgen_bridge_processing_stw_step (void)
 141 {
 142         /*
 143          * bridge_processing_in_progress must be set with the world
 144          * stopped.  If not there would be race conditions.
 145          */
 146         bridge_processing_in_progress = TRUE;
 147
 148         bridge_processor.processing_stw_step ();
 149         if (compare_bridge_processors ())
 150                 compare_to_bridge_processor.processing_stw_step ();
 151 }
 152
 153 static mono_bool
 154 is_bridge_object_alive (MonoObject *obj, void *data)
 155 {
 156         SgenHashTable *table = data;
 157         unsigned char *value = sgen_hash_table_lookup (table, obj);
 158         if (!value)
 159                 return TRUE;
 160         return *value;
 161 }
 162
 163 static void
 164 null_weak_links_to_dead_objects (SgenBridgeProcessor *processor, int generation)
 165 {
 166         int i, j;
 167         int num_sccs = processor->num_sccs;
 168         MonoGCBridgeSCC **api_sccs = processor->api_sccs;
 169         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);
 170
 171         for (i = 0; i < num_sccs; ++i) {
 172                 unsigned char alive = api_sccs [i]->is_alive ? 1 : 0;
 173                 for (j = 0; j < api_sccs [i]->num_objs; ++j) {
 174                         /* Build hash table for nulling weak links. */
 175                         sgen_hash_table_replace (&alive_hash, api_sccs [i]->objs [j], &alive, NULL);
 176
 177                         /* Release for finalization those objects we no longer care. */
 178                         if (!api_sccs [i]->is_alive)
 179                                 sgen_mark_bridge_object (api_sccs [i]->objs [j]);
 180                 }
 181         }
 182
 183         /* Null weak links to dead objects. */
 184         sgen_null_links_with_predicate (GENERATION_NURSERY, is_bridge_object_alive, &alive_hash);
 185         if (generation == GENERATION_OLD)
 186                 sgen_null_links_with_predicate (GENERATION_OLD, is_bridge_object_alive, &alive_hash);
 187
 188         sgen_hash_table_clean (&alive_hash);
 189 }
 190
 191 static void
 192 free_callback_data (SgenBridgeProcessor *processor)
 193 {
 194         int i;
 195         int num_sccs = processor->num_sccs;
 196         int num_xrefs = processor->num_xrefs;
 197         MonoGCBridgeSCC **api_sccs = processor->api_sccs;
 198         MonoGCBridgeXRef *api_xrefs = processor->api_xrefs;
 199
 200         for (i = 0; i < num_sccs; ++i) {
 201                 sgen_free_internal_dynamic (api_sccs [i],
 202                                 sizeof (MonoGCBridgeSCC) + sizeof (MonoObject*) * api_sccs [i]->num_objs,
 203                                 INTERNAL_MEM_BRIDGE_DATA);
 204         }
 205         sgen_free_internal_dynamic (api_sccs, sizeof (MonoGCBridgeSCC*) * num_sccs, INTERNAL_MEM_BRIDGE_DATA);
 206
 207         sgen_free_internal_dynamic (api_xrefs, sizeof (MonoGCBridgeXRef) * num_xrefs, INTERNAL_MEM_BRIDGE_DATA);
 208
 209         processor->num_sccs = 0;
 210         processor->api_sccs = NULL;
 211         processor->num_xrefs = 0;
 212         processor->api_xrefs = NULL;
 213 }
 214
 215 void
 216 sgen_bridge_processing_finish (int generation)
 217 {
 218         bridge_processor.processing_build_callback_data (generation);
 219         if (compare_bridge_processors ())
 220                 compare_to_bridge_processor.processing_build_callback_data (generation);
 221
 222         if (bridge_processor.num_sccs == 0) {
 223                 g_assert (bridge_processor.num_xrefs == 0);
 224                 goto after_callback;
 225         }
 226
 227         bridge_callbacks.cross_references (bridge_processor.num_sccs, bridge_processor.api_sccs,
 228                         bridge_processor.num_xrefs, bridge_processor.api_xrefs);
 229
 230         if (compare_bridge_processors ())
 231                 sgen_compare_bridge_processor_results (&bridge_processor, &compare_to_bridge_processor);
 232
 233         null_weak_links_to_dead_objects (&bridge_processor, generation);
 234
 235         free_callback_data (&bridge_processor);
 236         if (compare_bridge_processors ())
 237                 free_callback_data (&compare_to_bridge_processor);
 238
 239  after_callback:
 240         bridge_processor.processing_after_callback (generation);
 241         if (compare_bridge_processors ())
 242                 compare_to_bridge_processor.processing_after_callback (generation);
 243
 244         bridge_processing_in_progress = FALSE;
 245 }
 246
 247 MonoGCBridgeObjectKind
 248 sgen_bridge_class_kind (MonoClass *class)
 249 {
 250         return bridge_processor.class_kind (class);
 251 }
 252
 253 void
 254 sgen_bridge_register_finalized_object (MonoObject *obj)
 255 {
 256         bridge_processor.register_finalized_object (obj);
 257         if (compare_bridge_processors ())
 258                 compare_to_bridge_processor.register_finalized_object (obj);
 259 }
 260
 261 void
 262 sgen_bridge_describe_pointer (MonoObject *obj)
 263 {
 264         if (bridge_processor.describe_pointer)
 265                 bridge_processor.describe_pointer (obj);
 266 }
 267
 268 static void
 269 set_dump_prefix (const char *prefix)
 270 {
 271         if (!bridge_processor.set_dump_prefix) {
 272                 fprintf (stderr, "Warning: Bridge implementation does not support dumping - ignoring.\n");
 273                 return;
 274         }
 275
 276         bridge_processor.set_dump_prefix (prefix);
 277 }
 278
 279 /* Test support code */
 280 static const char *bridge_class;
 281
 282 static MonoGCBridgeObjectKind
 283 bridge_test_bridge_class_kind (MonoClass *class)
 284 {
 285         if (!strcmp (bridge_class, class->name))
 286                 return GC_BRIDGE_TRANSPARENT_BRIDGE_CLASS;
 287         return GC_BRIDGE_TRANSPARENT_CLASS;
 288 }
 289
 290 static gboolean
 291 bridge_test_is_bridge_object (MonoObject *object)
 292 {
 293         return TRUE;
 294 }
 295
 296 static void
 297 bridge_test_cross_reference (int num_sccs, MonoGCBridgeSCC **sccs, int num_xrefs, MonoGCBridgeXRef *xrefs)
 298 {
 299         int i;
 300         for (i = 0; i < num_sccs; ++i) {
 301                 int j;
 302         //      g_print ("--- SCC %d\n", i);
 303                 for (j = 0; j < sccs [i]->num_objs; ++j) {
 304         //              g_print ("  %s\n", sgen_safe_name (sccs [i]->objs [j]));
 305                         if (i & 1) /*retain half of the bridged objects */
 306                                 sccs [i]->is_alive = TRUE;
 307                 }
 308         }
 309         for (i = 0; i < num_xrefs; ++i) {
 310                 g_assert (xrefs [i].src_scc_index >= 0 && xrefs [i].src_scc_index < num_sccs);
 311                 g_assert (xrefs [i].dst_scc_index >= 0 && xrefs [i].dst_scc_index < num_sccs);
 312         //      g_print ("%d -> %d\n", xrefs [i].src_scc_index, xrefs [i].dst_scc_index);
 313         }
 314 }
 315
 316 static MonoClassField *mono_bridge_test_field;
 317
 318 enum {
 319         BRIDGE_DEAD,
 320         BRIDGE_ROOT,
 321         BRIDGE_SAME_SCC,
 322         BRIDGE_XREF,
 323 };
 324
 325 static gboolean
 326 test_scc (MonoGCBridgeSCC *scc, int i)
 327 {
 328         int status = BRIDGE_DEAD;
 329         mono_field_get_value (scc->objs [i], mono_bridge_test_field, &status);
 330         return status > 0;
 331 }
 332
 333 static void
 334 mark_scc (MonoGCBridgeSCC *scc, int value)
 335 {
 336         int i;
 337         for (i = 0; i < scc->num_objs; ++i) {
 338                 if (!test_scc (scc, i)) {
 339                         int status = value;
 340                         mono_field_set_value (scc->objs [i], mono_bridge_test_field, &status);
 341                 }
 342         }
 343 }
 344
 345 static void
 346 bridge_test_cross_reference2 (int num_sccs, MonoGCBridgeSCC **sccs, int num_xrefs, MonoGCBridgeXRef *xrefs)
 347 {
 348         int i;
 349         gboolean modified;
 350
 351         if (!mono_bridge_test_field) {
 352                 mono_bridge_test_field = mono_class_get_field_from_name (mono_object_get_class (sccs[0]->objs [0]), "__test");
 353                 g_assert (mono_bridge_test_field);
 354         }
 355
 356         /*We mark all objects in a scc with live objects as reachable by scc*/
 357         for (i = 0; i < num_sccs; ++i) {
 358                 int j;
 359                 gboolean live = FALSE;
 360                 for (j = 0; j < sccs [i]->num_objs; ++j) {
 361                         if (test_scc (sccs [i], j)) {
 362                                 live = TRUE;
 363                                 break;
 364                         }
 365                 }
 366                 if (!live)
 367                         continue;
 368                 for (j = 0; j < sccs [i]->num_objs; ++j) {
 369                         if (!test_scc (sccs [i], j)) {
 370                                 int status = BRIDGE_SAME_SCC;
 371                                 mono_field_set_value (sccs [i]->objs [j], mono_bridge_test_field, &status);
 372                         }
 373                 }
 374         }
 375
 376         /*Now we mark the transitive closure of reachable objects from the xrefs*/
 377         modified = TRUE;
 378         while (modified) {
 379                 modified = FALSE;
 380                 /* Mark all objects that are brought to life due to xrefs*/
 381                 for (i = 0; i < num_xrefs; ++i) {
 382                         MonoGCBridgeXRef ref = xrefs [i];
 383                         if (test_scc (sccs [ref.src_scc_index], 0) && !test_scc (sccs [ref.dst_scc_index], 0)) {
 384                                 modified = TRUE;
 385                                 mark_scc (sccs [ref.dst_scc_index], BRIDGE_XREF);
 386                         }
 387                 }
 388         }
 389
 390         /* keep everything in memory, all we want to do is test persistence */
 391         for (i = 0; i < num_sccs; ++i)
 392                 sccs [i]->is_alive = TRUE;
 393 }
 394
 395 static void
 396 register_test_bridge_callbacks (const char *bridge_class_name)
 397 {
 398         MonoGCBridgeCallbacks callbacks;
 399         callbacks.bridge_version = SGEN_BRIDGE_VERSION;
 400         callbacks.bridge_class_kind = bridge_test_bridge_class_kind;
 401         callbacks.is_bridge_object = bridge_test_is_bridge_object;
 402         callbacks.cross_references = bridge_class_name[0] == '2' ? bridge_test_cross_reference2 : bridge_test_cross_reference;
 403         mono_gc_register_bridge_callbacks (&callbacks);
 404         bridge_class = bridge_class_name + (bridge_class_name[0] == '2' ? 1 : 0);
 405 }
 406
 407 gboolean
 408 sgen_bridge_handle_gc_debug (const char *opt)
 409 {
 410         if (g_str_has_prefix (opt, "bridge=")) {
 411                 opt = strchr (opt, '=') + 1;
 412                 register_test_bridge_callbacks (g_strdup (opt));
 413         } else if (!strcmp (opt, "enable-bridge-accounting")) {
 414                 bridge_processor.enable_accounting ();
 415         } else if (g_str_has_prefix (opt, "bridge-dump=")) {
 416                 char *prefix = strchr (opt, '=') + 1;
 417                 set_dump_prefix (prefix);
 418         } else if (g_str_has_prefix (opt, "bridge-compare-to=")) {
 419                 const char *name = strchr (opt, '=') + 1;
 420                 if (init_bridge_processor (&compare_to_bridge_processor, name)) {
 421                         if (compare_to_bridge_processor.reset_data == bridge_processor.reset_data) {
 422                                 g_warning ("Cannot compare bridge implementation to itself - ignoring.");
 423                                 memset (&compare_to_bridge_processor, 0, sizeof (SgenBridgeProcessor));
 424                         }
 425                 } else {
 426                         g_warning ("Invalid bridge implementation to compare against - ignoring.");
 427                 }
 428         } else {
 429                 return FALSE;
 430         }
 431         return TRUE;
 432 }
 433
 434 void
 435 sgen_bridge_print_gc_debug_usage (void)
 436 {
 437         fprintf (stderr, "  bridge=<class-name>\n");
 438         fprintf (stderr, "  enable-bridge-accounting\n");
 439         fprintf (stderr, "  bridge-dump=<filename-prefix>\n");
 440         fprintf (stderr, "  bridge-compare-to=<implementation>\n");
 441 }
 442
 443 #endif