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 static guint32
 162 internal_domain_finalize (gpointer data) {
 163         MonoDomain *domain=(MonoDomain *)data;
 164         GHashTable *todo = g_hash_table_new (NULL, NULL);
 165
 166         mono_new_thread_init (GetCurrentThreadId (), todo, NULL);
 167
 168 #if HAVE_BOEHM_GC
 169         GC_gcollect ();
 170 #endif
 171         mono_g_hash_table_foreach (domain->class_vtable_hash, (GHFunc)finalize_static_data, todo);
 172         /* FIXME: finalize objects in todo... */
 173         g_hash_table_destroy (todo);
 174
 175         return(0);
 176 }
 177
 178 void
 179 mono_domain_finalize (MonoDomain *domain)
 180 {
 181         HANDLE finalize_thread;
 182
 183         /* Need to run managed code in a subthread.
 184          * Mono_domain_finalize() is called from the main thread in
 185          * the jit and the embedded example, hence the thread creation
 186          * here.
 187          */
 188         finalize_thread=CreateThread (NULL, 0, internal_domain_finalize, domain, 0, NULL);
 189         if(finalize_thread==NULL) {
 190                 g_assert_not_reached ();
 191         }
 192         WaitForSingleObject (finalize_thread, INFINITE);
 193         CloseHandle (finalize_thread);
 194 }
 195
 196 void
 197 ves_icall_System_GC_InternalCollect (int generation)
 198 {
 199         MONO_ARCH_SAVE_REGS;
 200
 201 #if HAVE_BOEHM_GC
 202         GC_gcollect ();
 203 #endif
 204 }
 205
 206 gint64
 207 ves_icall_System_GC_GetTotalMemory (MonoBoolean forceCollection)
 208 {
 209         MONO_ARCH_SAVE_REGS;
 210
 211 #if HAVE_BOEHM_GC
 212         if (forceCollection)
 213                 GC_gcollect ();
 214         return GC_get_heap_size ();
 215 #else
 216         return 0;
 217 #endif
 218 }
 219
 220 void
 221 ves_icall_System_GC_KeepAlive (MonoObject *obj)
 222 {
 223         MONO_ARCH_SAVE_REGS;
 224
 225         /*
 226          * Does nothing.
 227          */
 228 }
 229
 230 void
 231 ves_icall_System_GC_ReRegisterForFinalize (MonoObject *obj)
 232 {
 233         MONO_ARCH_SAVE_REGS;
 234
 235         object_register_finalizer (obj, run_finalize);
 236 }
 237
 238 void
 239 ves_icall_System_GC_SuppressFinalize (MonoObject *obj)
 240 {
 241         MONO_ARCH_SAVE_REGS;
 242
 243         object_register_finalizer (obj, NULL);
 244 }
 245
 246 void
 247 ves_icall_System_GC_WaitForPendingFinalizers (void)
 248 {
 249         MONO_ARCH_SAVE_REGS;
 250 }
 251
 252 static CRITICAL_SECTION handle_section;
 253 static guint32 next_handle = 0;
 254 static gpointer *gc_handles = NULL;
 255 static guint8 *gc_handle_types = NULL;
 256 static guint32 array_size = 0;
 257
 258 /*
 259  * The handle type is encoded in the lower two bits of the handle value:
 260  * 0 -> normal
 261  * 1 -> pinned
 262  * 2 -> weak
 263  */
 264
 265 typedef enum {
 266         HANDLE_WEAK,
 267         HANDLE_WEAK_TRACK,
 268         HANDLE_NORMAL,
 269         HANDLE_PINNED
 270 } HandleType;
 271
 272 /*
 273  * FIXME: make thread safe and reuse the array entries.
 274  */
 275 MonoObject *
 276 ves_icall_System_GCHandle_GetTarget (guint32 handle)
 277 {
 278         MonoObject *obj;
 279         gint32 type;
 280
 281         MONO_ARCH_SAVE_REGS;
 282
 283         if (gc_handles) {
 284                 type = handle & 0x3;
 285                 EnterCriticalSection (&handle_section);
 286                 g_assert (type == gc_handle_types [handle >> 2]);
 287                 obj = gc_handles [handle >> 2];
 288                 LeaveCriticalSection (&handle_section);
 289                 if (!obj)
 290                         return NULL;
 291
 292                 if ((type == HANDLE_WEAK) || (type == HANDLE_WEAK_TRACK))
 293                         return REVEAL_POINTER (obj);
 294                 else
 295                         return obj;
 296         }
 297         return NULL;
 298 }
 299
 300 guint32
 301 ves_icall_System_GCHandle_GetTargetHandle (MonoObject *obj, guint32 handle, gint32 type)
 302 {
 303         gpointer val = obj;
 304         guint32 h, idx;
 305
 306         MONO_ARCH_SAVE_REGS;
 307
 308         EnterCriticalSection (&handle_section);
 309         idx = next_handle++;
 310         if (idx >= array_size) {
 311 #if HAVE_BOEHM_GC
 312                 gpointer *new_array;
 313                 guint8 *new_type_array;
 314                 if (!array_size)
 315                         array_size = 16;
 316                 new_array = GC_MALLOC (sizeof (gpointer) * (array_size * 2));
 317                 new_type_array = GC_MALLOC (sizeof (guint8) * (array_size * 2));
 318                 if (gc_handles) {
 319                         int i;
 320                         memcpy (new_array, gc_handles, sizeof (gpointer) * array_size);
 321                         memcpy (new_type_array, gc_handle_types, sizeof (guint8) * array_size);
 322                         /* need to re-register links for weak refs. test if GC_realloc needs the same */
 323                         for (i = 0; i < array_size; ++i) {
 324 #if 0 /* This breaks the threaded finalizer, by causing segfaults deep
 325        * inside libgc.  I assume it will also break without the
 326        * threaded finalizer, just that the stress test (bug 31333)
 327        * deadlocks too early without it.  Reverting to the previous
 328        * version here stops the segfault.
 329        */
 330                                 if ((gc_handle_types[i] == HANDLE_WEAK) || (gc_handle_types[i] == HANDLE_WEAK_TRACK)) { /* all and only disguised pointers have it set */
 331 #else
 332                                 if (((gulong)new_array [i]) & 0x1) {
 333 #endif
 334                                         if (gc_handles [i] != (gpointer)-1)
 335                                                 GC_unregister_disappearing_link (&(gc_handles [i]));
 336                                         if (new_array [i] != (gpointer)-1)
 337                                                 GC_GENERAL_REGISTER_DISAPPEARING_LINK (&(new_array [i]), REVEAL_POINTER (new_array [i]));
 338                                 }
 339                         }
 340                 }
 341                 array_size *= 2;
 342                 gc_handles = new_array;
 343                 gc_handle_types = new_type_array;
 344 #else
 345                 mono_raise_exception (mono_get_exception_execution_engine ("No GCHandle support built-in"));
 346 #endif
 347         }
 348
 349         /* resuse the type from the old target */
 350         if (type == -1)
 351                 type =  handle & 0x3;
 352         h = (idx << 2) | type;
 353         switch (type) {
 354         case HANDLE_WEAK:
 355         case HANDLE_WEAK_TRACK:
 356                 val = (gpointer)HIDE_POINTER (val);
 357                 gc_handles [idx] = val;
 358                 gc_handle_types [idx] = type;
 359 #if HAVE_BOEHM_GC
 360                 if (gc_handles [idx] != (gpointer)-1)
 361                         GC_GENERAL_REGISTER_DISAPPEARING_LINK (&(gc_handles [idx]), obj);
 362 #else
 363                 mono_raise_exception (mono_get_exception_execution_engine ("No weakref support"));
 364 #endif
 365                 break;
 366         default:
 367                 gc_handles [idx] = val;
 368                 gc_handle_types [idx] = type;
 369                 break;
 370         }
 371         LeaveCriticalSection (&handle_section);
 372         return h;
 373 }
 374
 375 void
 376 ves_icall_System_GCHandle_FreeHandle (guint32 handle)
 377 {
 378         int idx = handle >> 2;
 379         int type = handle & 0x3;
 380
 381         MONO_ARCH_SAVE_REGS;
 382
 383         EnterCriticalSection (&handle_section);
 384
 385 #ifdef HAVE_BOEHM_GC
 386         g_assert (type == gc_handle_types [idx]);
 387         if ((type == HANDLE_WEAK) || (type == HANDLE_WEAK_TRACK)) {
 388                 if (gc_handles [idx] != (gpointer)-1)
 389                         GC_unregister_disappearing_link (&(gc_handles [idx]));
 390         }
 391 #else
 392         mono_raise_exception (mono_get_exception_execution_engine ("No GCHandle support"));
 393 #endif
 394
 395         gc_handles [idx] = (gpointer)-1;
 396         gc_handle_types [idx] = (guint8)-1;
 397         LeaveCriticalSection (&handle_section);
 398 }
 399
 400 gpointer
 401 ves_icall_System_GCHandle_GetAddrOfPinnedObject (guint32 handle)
 402 {
 403         MonoObject *obj;
 404         int type = handle & 0x3;
 405
 406         MONO_ARCH_SAVE_REGS;
 407
 408         if (gc_handles) {
 409                 EnterCriticalSection (&handle_section);
 410                 obj = gc_handles [handle >> 2];
 411                 g_assert (gc_handle_types [handle >> 2] == type);
 412                 LeaveCriticalSection (&handle_section);
 413                 if ((type == HANDLE_WEAK) || (type == HANDLE_WEAK_TRACK)) {
 414                         obj = REVEAL_POINTER (obj);
 415                         if (obj == (MonoObject *) -1)
 416                                 return NULL;
 417                 }
 418                 return obj;
 419         }
 420         return NULL;
 421 }
 422
 423 #if HAVE_BOEHM_GC
 424
 425 static HANDLE finalizer_event;
 426 static volatile gboolean finished=FALSE;
 427
 428 static void finalize_notify (void)
 429 {
 430 #ifdef DEBUG
 431         g_message (G_GNUC_PRETTY_FUNCTION ": prodding finalizer");
 432 #endif
 433
 434         SetEvent (finalizer_event);
 435 }
 436
 437 static guint32 finalizer_thread (gpointer unused)
 438 {
 439         guint32 stack_start;
 440
 441         mono_new_thread_init (GetCurrentThreadId (), &stack_start, NULL);
 442
 443         while(!finished) {
 444                 /* Wait to be notified that there's at least one
 445                  * finaliser to run
 446                  */
 447                 WaitForSingleObject (finalizer_event, INFINITE);
 448
 449 #ifdef DEBUG
 450                 g_message (G_GNUC_PRETTY_FUNCTION ": invoking finalizers");
 451 #endif
 452
 453                 GC_invoke_finalizers ();
 454         }
 455
 456         return(0);
 457 }
 458
 459 /*
 460  * Enable or disable the separate finalizer thread.
 461  * It's currently disabled because it still requires some
 462  * work in the rest of the runtime.
 463  */
 464 #define ENABLE_FINALIZER_THREAD
 465
 466 void mono_gc_init (void)
 467 {
 468         HANDLE gc_thread;
 469
 470         InitializeCriticalSection (&handle_section);
 471
 472 #ifdef ENABLE_FINALIZER_THREAD
 473
 474         if (getenv ("GC_DONT_GC"))
 475                 return;
 476
 477         finalizer_event = CreateEvent (NULL, FALSE, FALSE, NULL);
 478         if (finalizer_event == NULL) {
 479                 g_assert_not_reached ();
 480         }
 481
 482         GC_finalize_on_demand = 1;
 483         GC_finalizer_notifier = finalize_notify;
 484
 485         /* Don't use mono_thread_create here, because we don't want
 486          * the runtime to wait for this thread to exit when it's
 487          * cleaning up.
 488          */
 489         gc_thread = CreateThread (NULL, 0, finalizer_thread, NULL, 0, NULL);
 490         if (gc_thread == NULL) {
 491                 g_assert_not_reached ();
 492         }
 493 #endif
 494 }
 495
 496 void mono_gc_cleanup (void)
 497 {
 498 #ifdef DEBUG
 499         g_message (G_GNUC_PRETTY_FUNCTION ": cleaning up finalizer");
 500 #endif
 501
 502 #ifdef ENABLE_FINALIZER_THREAD
 503         finished = TRUE;
 504         finalize_notify ();
 505 #endif
 506 }
 507
 508 #else
 509
 510 /* no Boehm GC support. */
 511 void mono_gc_init (void)
 512 {
 513         InitializeCriticalSection (&handle_section);
 514 }
 515
 516 void mono_gc_cleanup (void)
 517 {
 518 }
 519
 520 #endif
 521