mono/metadata/gc.c

   1 /*
   2  * metadata/gc.c: GC icalls.
   3  *
   4  * Author: Paolo Molaro <lupus@ximian.com>
   5  *
   6  * (C) 2002 Ximian, Inc.
   7  */
   8
   9 #include <config.h>
  10 #include <glib.h>
  11 #include <string.h>
  12
  13 #include <mono/metadata/gc-internal.h>
  14 #include <mono/metadata/threads.h>
  15 #include <mono/metadata/tabledefs.h>
  16 #include <mono/metadata/exception.h>
  17 #define GC_I_HIDE_POINTERS
  18 #include <mono/os/gc_wrapper.h>
  19
  20 #ifndef HIDE_POINTER
  21 #define HIDE_POINTER(v)         (v)
  22 #define REVEAL_POINTER(v)       (v)
  23 #endif
  24
  25 static int finalize_slot = -1;
  26
  27 static void object_register_finalizer (MonoObject *obj, void (*callback)(void *, void*));
  28
  29 /*
  30  * actually, we might want to queue the finalize requests in a separate thread,
  31  * but we need to be careful about the execution domain of the thread...
  32  */
  33 static void
  34 run_finalize (void *obj, void *data)
  35 {
  36         MonoObject *exc = NULL;
  37         MonoObject *o;
  38         o = (MonoObject*)((char*)obj + GPOINTER_TO_UINT (data));
  39
  40         if (finalize_slot < 0) {
  41                 int i;
  42                 for (i = 0; i < mono_defaults.object_class->vtable_size; ++i) {
  43                         MonoMethod *cm = mono_defaults.object_class->vtable [i];
  44
  45                         if (!strcmp (cm->name, "Finalize")) {
  46                                 finalize_slot = i;
  47                                 break;
  48                         }
  49                 }
  50         }
  51
  52         /* make sure the finalizer is not called again if the object is resurrected */
  53         object_register_finalizer (obj, NULL);
  54         /* speedup later... and use a timeout */
  55         /*g_print ("Finalize run on %p %s.%s\n", o, mono_object_class (o)->name_space, mono_object_class (o)->name);*/
  56         mono_domain_set (mono_object_domain (o));
  57
  58         mono_runtime_invoke (o->vtable->klass->vtable [finalize_slot], o, NULL, &exc);
  59
  60         if (exc) {
  61                 /* fixme: do something useful */
  62         }
  63 }
  64
  65 /*
  66  * Some of our objects may point to a different address than the address returned by GC_malloc()
  67  * (because of the GetHashCode hack), but we need to pass the real address to register_finalizer.
  68  * This also means that in the callback we need to adjust the pointer to get back the real
  69  * MonoObject*.
  70  * We also need to be consistent in the use of the GC_debug* variants of malloc and register_finalizer,
  71  * since that, too, can cause the underlying pointer to be offset.
  72  */
  73 static void
  74 object_register_finalizer (MonoObject *obj, void (*callback)(void *, void*))
  75 {
  76 #if HAVE_BOEHM_GC
  77         guint offset = 0;
  78
  79         g_assert (GC_base (obj) == (char*)obj - offset);
  80         GC_REGISTER_FINALIZER_NO_ORDER ((char*)obj - offset, callback, GUINT_TO_POINTER (offset), NULL, NULL);
  81 #endif
  82 }
  83
  84 void
  85 mono_object_register_finalizer (MonoObject *obj)
  86 {
  87         /*g_print ("Registered finalizer on %p %s.%s\n", obj, mono_object_class (obj)->name_space, mono_object_class (obj)->name);*/
  88         object_register_finalizer (obj, run_finalize);
  89 }
  90
  91 /*
  92  * to speedup, at class init time, check if a class or struct
  93  * have fields that need to be finalized and set a flag.
  94  */
  95 static void
  96 finalize_fields (MonoClass *class, char *data, gboolean instance, GHashTable *todo) {
  97         int i;
  98         MonoClassField *field;
  99         MonoObject *obj;
 100
 101         /*if (!instance)
 102                 g_print ("Finalize statics on on %s\n", class->name);*/
 103         if (instance && class->valuetype)
 104                 data -= sizeof (MonoObject);
 105         do {
 106                 for (i = 0; i < class->field.count; ++i) {
 107                         field = &class->fields [i];
 108                         if (instance) {
 109                                 if (field->type->attrs & FIELD_ATTRIBUTE_STATIC)
 110                                         continue;
 111                         } else {
 112                                 if (!(field->type->attrs & FIELD_ATTRIBUTE_STATIC))
 113                                         continue;
 114                         }
 115                         switch (field->type->type) {
 116                         case MONO_TYPE_OBJECT:
 117                         case MONO_TYPE_CLASS:
 118                                 obj = *((MonoObject**)(data + field->offset));
 119                                 if (obj) {
 120                                         if (mono_object_class (obj)->has_finalize) {
 121                                                 /* disable the registered finalizer */
 122                                                 object_register_finalizer (obj, NULL);
 123                                                 run_finalize (obj, NULL);
 124                                         } else {
 125                                                 /*
 126                                                  * if the type doesn't have a finalizer, we finalize
 127                                                  * the fields ourselves just like we do for structs.
 128                                                  * Disabled for now: how do we handle loops?
 129                                                  */
 130                                                 /*finalize_fields (mono_object_class (obj), obj, TRUE, todo);*/
 131                                         }
 132                                 }
 133                                 break;
 134                         case MONO_TYPE_VALUETYPE: {
 135                                 MonoClass *fclass = mono_class_from_mono_type (field->type);
 136                                 if (fclass->enumtype)
 137                                         continue;
 138                                 /*finalize_fields (fclass, data + field->offset, TRUE, todo);*/
 139                                 break;
 140                         }
 141                         case MONO_TYPE_ARRAY:
 142                         case MONO_TYPE_SZARRAY:
 143                                 /* FIXME: foreach item... */
 144                                 break;
 145                         }
 146                 }
 147                 if (!instance)
 148                         return;
 149                 class = class->parent;
 150         } while (class);
 151 }
 152
 153 static void
 154 finalize_static_data (MonoClass *class, MonoVTable *vtable, GHashTable *todo) {
 155
 156         if (class->enumtype || !vtable->data)
 157                 return;
 158         finalize_fields (class, vtable->data, FALSE, todo);
 159 }
 160
 161 void
 162 mono_domain_finalize (MonoDomain *domain) {
 163
 164         GHashTable *todo = g_hash_table_new (NULL, NULL);
 165 #if HAVE_BOEHM_GC
 166         GC_gcollect ();
 167 #endif
 168         mono_g_hash_table_foreach (domain->class_vtable_hash, (GHFunc)finalize_static_data, todo);
 169         /* FIXME: finalize objects in todo... */
 170         g_hash_table_destroy (todo);
 171 }
 172
 173 void
 174 ves_icall_System_GC_InternalCollect (int generation)
 175 {
 176         MONO_ARCH_SAVE_REGS;
 177
 178 #if HAVE_BOEHM_GC
 179         GC_gcollect ();
 180 #endif
 181 }
 182
 183 gint64
 184 ves_icall_System_GC_GetTotalMemory (MonoBoolean forceCollection)
 185 {
 186         MONO_ARCH_SAVE_REGS;
 187
 188 #if HAVE_BOEHM_GC
 189         if (forceCollection)
 190                 GC_gcollect ();
 191         return GC_get_heap_size ();
 192 #else
 193         return 0;
 194 #endif
 195 }
 196
 197 void
 198 ves_icall_System_GC_KeepAlive (MonoObject *obj)
 199 {
 200         MONO_ARCH_SAVE_REGS;
 201
 202         /*
 203          * Does nothing.
 204          */
 205 }
 206
 207 void
 208 ves_icall_System_GC_ReRegisterForFinalize (MonoObject *obj)
 209 {
 210         MONO_ARCH_SAVE_REGS;
 211
 212         object_register_finalizer (obj, run_finalize);
 213 }
 214
 215 void
 216 ves_icall_System_GC_SuppressFinalize (MonoObject *obj)
 217 {
 218         MONO_ARCH_SAVE_REGS;
 219
 220         object_register_finalizer (obj, NULL);
 221 }
 222
 223 void
 224 ves_icall_System_GC_WaitForPendingFinalizers (void)
 225 {
 226         MONO_ARCH_SAVE_REGS;
 227 }
 228
 229 static CRITICAL_SECTION handle_section;
 230 static guint32 next_handle = 0;
 231 static gpointer *gc_handles = NULL;
 232 static guint8 *gc_handle_types = NULL;
 233 static guint32 array_size = 0;
 234
 235 /*
 236  * The handle type is encoded in the lower two bits of the handle value:
 237  * 0 -> normal
 238  * 1 -> pinned
 239  * 2 -> weak
 240  */
 241
 242 typedef enum {
 243         HANDLE_WEAK,
 244         HANDLE_WEAK_TRACK,
 245         HANDLE_NORMAL,
 246         HANDLE_PINNED
 247 } HandleType;
 248
 249 /*
 250  * FIXME: make thread safe and reuse the array entries.
 251  */
 252 MonoObject *
 253 ves_icall_System_GCHandle_GetTarget (guint32 handle)
 254 {
 255         MonoObject *obj;
 256         gint32 type;
 257
 258         MONO_ARCH_SAVE_REGS;
 259
 260         if (gc_handles) {
 261                 type = handle & 0x3;
 262                 EnterCriticalSection (&handle_section);
 263                 g_assert (type == gc_handle_types [handle >> 2]);
 264                 obj = gc_handles [handle >> 2];
 265                 LeaveCriticalSection (&handle_section);
 266                 if (!obj)
 267                         return NULL;
 268
 269                 if ((type == HANDLE_WEAK) || (type == HANDLE_WEAK_TRACK))
 270                         return REVEAL_POINTER (obj);
 271                 else
 272                         return obj;
 273         }
 274         return NULL;
 275 }
 276
 277 guint32
 278 ves_icall_System_GCHandle_GetTargetHandle (MonoObject *obj, guint32 handle, gint32 type)
 279 {
 280         gpointer val = obj;
 281         guint32 h, idx;
 282
 283         MONO_ARCH_SAVE_REGS;
 284
 285         EnterCriticalSection (&handle_section);
 286         idx = next_handle++;
 287         if (idx >= array_size) {
 288 #if HAVE_BOEHM_GC
 289                 gpointer *new_array;
 290                 guint8 *new_type_array;
 291                 if (!array_size)
 292                         array_size = 16;
 293                 new_array = GC_MALLOC (sizeof (gpointer) * (array_size * 2));
 294                 new_type_array = GC_MALLOC (sizeof (guint8) * (array_size * 2));
 295                 if (gc_handles) {
 296                         int i;
 297                         memcpy (new_array, gc_handles, sizeof (gpointer) * array_size);
 298                         memcpy (new_type_array, gc_handle_types, sizeof (guint8) * array_size);
 299                         /* need to re-register links for weak refs. test if GC_realloc needs the same */
 300                         for (i = 0; i < array_size; ++i) {
 301 #if 0 /* This breaks the threaded finalizer, by causing segfaults deep
 302        * inside libgc.  I assume it will also break without the
 303        * threaded finalizer, just that the stress test (bug 31333)
 304        * deadlocks too early without it.  Reverting to the previous
 305        * version here stops the segfault.
 306        */
 307                                 if ((gc_handle_types[i] == HANDLE_WEAK) || (gc_handle_types[i] == HANDLE_WEAK_TRACK)) { /* all and only disguised pointers have it set */
 308 #else
 309                                 if (((gulong)new_array [i]) & 0x1) {
 310 #endif
 311                                         if (gc_handles [i] != (gpointer)-1)
 312                                                 GC_unregister_disappearing_link (&(gc_handles [i]));
 313                                         if (new_array [i] != (gpointer)-1)
 314                                                 GC_GENERAL_REGISTER_DISAPPEARING_LINK (&(new_array [i]), REVEAL_POINTER (new_array [i]));
 315                                 }
 316                         }
 317                 }
 318                 array_size *= 2;
 319                 gc_handles = new_array;
 320                 gc_handle_types = new_type_array;
 321 #else
 322                 mono_raise_exception (mono_get_exception_execution_engine ("No GCHandle support built-in"));
 323 #endif
 324         }
 325
 326         /* resuse the type from the old target */
 327         if (type == -1)
 328                 type =  handle & 0x3;
 329         h = (idx << 2) | type;
 330         switch (type) {
 331         case HANDLE_WEAK:
 332         case HANDLE_WEAK_TRACK:
 333                 val = (gpointer)HIDE_POINTER (val);
 334                 gc_handles [idx] = val;
 335                 gc_handle_types [idx] = type;
 336 #if HAVE_BOEHM_GC
 337                 if (gc_handles [idx] != (gpointer)-1)
 338                         GC_GENERAL_REGISTER_DISAPPEARING_LINK (&(gc_handles [idx]), obj);
 339 #else
 340                 mono_raise_exception (mono_get_exception_execution_engine ("No weakref support"));
 341 #endif
 342                 break;
 343         default:
 344                 gc_handles [idx] = val;
 345                 gc_handle_types [idx] = type;
 346                 break;
 347         }
 348         LeaveCriticalSection (&handle_section);
 349         return h;
 350 }
 351
 352 void
 353 ves_icall_System_GCHandle_FreeHandle (guint32 handle)
 354 {
 355         int idx = handle >> 2;
 356         int type = handle & 0x3;
 357
 358         MONO_ARCH_SAVE_REGS;
 359
 360         EnterCriticalSection (&handle_section);
 361
 362 #ifdef HAVE_BOEHM_GC
 363         g_assert (type == gc_handle_types [idx]);
 364         if ((type == HANDLE_WEAK) || (type == HANDLE_WEAK_TRACK)) {
 365                 if (gc_handles [idx] != (gpointer)-1)
 366                         GC_unregister_disappearing_link (&(gc_handles [idx]));
 367         }
 368 #else
 369         mono_raise_exception (mono_get_exception_execution_engine ("No GCHandle support"));
 370 #endif
 371
 372         gc_handles [idx] = (gpointer)-1;
 373         gc_handle_types [idx] = (guint8)-1;
 374         LeaveCriticalSection (&handle_section);
 375 }
 376
 377 gpointer
 378 ves_icall_System_GCHandle_GetAddrOfPinnedObject (guint32 handle)
 379 {
 380         MonoObject *obj;
 381         int type = handle & 0x3;
 382
 383         MONO_ARCH_SAVE_REGS;
 384
 385         if (gc_handles) {
 386                 EnterCriticalSection (&handle_section);
 387                 obj = gc_handles [handle >> 2];
 388                 g_assert (gc_handle_types [handle >> 2] == type);
 389                 LeaveCriticalSection (&handle_section);
 390                 if ((type == HANDLE_WEAK) || (type == HANDLE_WEAK_TRACK)) {
 391                         obj = REVEAL_POINTER (obj);
 392                         if (obj == (MonoObject *) -1)
 393                                 return NULL;
 394                 }
 395                 return obj;
 396         }
 397         return NULL;
 398 }
 399
 400 #if HAVE_BOEHM_GC
 401
 402 static HANDLE finalizer_event;
 403 static volatile gboolean finished=FALSE;
 404
 405 static void finalize_notify (void)
 406 {
 407 #ifdef DEBUG
 408         g_message (G_GNUC_PRETTY_FUNCTION ": prodding finalizer");
 409 #endif
 410
 411         SetEvent (finalizer_event);
 412 }
 413
 414 static guint32 finalizer_thread (gpointer unused)
 415 {
 416         guint32 stack_start;
 417
 418         mono_new_thread_init (NULL, &stack_start, NULL);
 419
 420         while(!finished) {
 421                 /* Wait to be notified that there's at least one
 422                  * finaliser to run
 423                  */
 424                 WaitForSingleObject (finalizer_event, INFINITE);
 425
 426 #ifdef DEBUG
 427                 g_message (G_GNUC_PRETTY_FUNCTION ": invoking finalizers");
 428 #endif
 429
 430                 GC_invoke_finalizers ();
 431         }
 432
 433         return(0);
 434 }
 435
 436 /*
 437  * Enable or disable the separate finalizer thread.
 438  * It's currently disabled because it still requires some
 439  * work in the rest of the runtime.
 440  */
 441 #undef ENABLE_FINALIZER_THREAD
 442
 443 void mono_gc_init (void)
 444 {
 445         HANDLE gc_thread;
 446
 447         InitializeCriticalSection (&handle_section);
 448
 449 #ifdef ENABLE_FINALIZER_THREAD
 450
 451         if (getenv ("GC_DONT_GC"))
 452                 return;
 453
 454         finalizer_event = CreateEvent (NULL, FALSE, FALSE, NULL);
 455         if (finalizer_event == NULL) {
 456                 g_assert_not_reached ();
 457         }
 458
 459         GC_finalize_on_demand = 1;
 460         GC_finalizer_notifier = finalize_notify;
 461
 462         /* Don't use mono_thread_create here, because we don't want
 463          * the runtime to wait for this thread to exit when it's
 464          * cleaning up.
 465          */
 466         gc_thread = CreateThread (NULL, 0, finalizer_thread, NULL, 0, NULL);
 467         if (gc_thread == NULL) {
 468                 g_assert_not_reached ();
 469         }
 470 #endif
 471 }
 472
 473 void mono_gc_cleanup (void)
 474 {
 475 #ifdef DEBUG
 476         g_message (G_GNUC_PRETTY_FUNCTION ": cleaning up finalizer");
 477 #endif
 478
 479 #ifdef ENABLE_FINALIZER_THREAD
 480         finished = TRUE;
 481         finalize_notify ();
 482 #endif
 483 }
 484
 485 #else
 486
 487 /* no Boehm GC support. */
 488 void mono_gc_init (void)
 489 {
 490         InitializeCriticalSection (&handle_section);
 491 }
 492
 493 void mono_gc_cleanup (void)
 494 {
 495 }
 496
 497 #endif
 498