2 * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
3 * Copyright (c) 1991-1996 by Xerox Corporation. All rights reserved.
4 * Copyright (c) 1996-1999 by Silicon Graphics. All rights reserved.
5 * Copyright (C) 2007 Free Software Foundation, Inc
7 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
8 * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
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.
17 #include "private/gc_pmark.h"
19 #ifndef GC_NO_FINALIZATION
21 /* Type of mark procedure used for marking from finalizable object. */
22 /* This procedure normally does not mark the object, only its */
24 typedef void (* finalization_mark_proc)(ptr_t /* finalizable_obj_ptr */);
26 #define HASH3(addr,size,log_size) \
27 ((((word)(addr) >> 3) ^ ((word)(addr) >> (3 + (log_size)))) \
29 #define HASH2(addr,log_size) HASH3(addr, (word)1 << (log_size), log_size)
31 struct hash_chain_entry {
33 struct hash_chain_entry * next;
36 struct disappearing_link {
37 struct hash_chain_entry prolog;
38 # define dl_hidden_link prolog.hidden_key
39 /* Field to be cleared. */
40 # define dl_next(x) (struct disappearing_link *)((x) -> prolog.next)
41 # define dl_set_next(x, y) \
42 (void)((x)->prolog.next = (struct hash_chain_entry *)(y))
43 word dl_hidden_obj; /* Pointer to object base */
47 struct disappearing_link **head;
52 STATIC struct dl_hashtbl_s GC_dl_hashtbl = {
53 /* head */ NULL, /* log_size */ -1, /* entries */ 0 };
54 #ifndef GC_LONG_REFS_NOT_NEEDED
55 STATIC struct dl_hashtbl_s GC_ll_hashtbl = { NULL, -1, 0 };
58 struct finalizable_object {
59 struct hash_chain_entry prolog;
60 # define fo_hidden_base prolog.hidden_key
61 /* Pointer to object base. */
62 /* No longer hidden once object */
63 /* is on finalize_now queue. */
64 # define fo_next(x) (struct finalizable_object *)((x) -> prolog.next)
65 # define fo_set_next(x,y) ((x)->prolog.next = (struct hash_chain_entry *)(y))
66 GC_finalization_proc fo_fn; /* Finalizer. */
68 word fo_object_size; /* In bytes. */
69 finalization_mark_proc fo_mark_proc; /* Mark-through procedure */
72 static signed_word log_fo_table_size = -1;
75 struct finalizable_object **fo_head;
76 /* List of objects that should be finalized now: */
77 struct finalizable_object *finalize_now;
78 } GC_fnlz_roots = { NULL, NULL };
80 GC_API void GC_CALL GC_push_finalizer_structures(void)
82 GC_ASSERT((word)&GC_dl_hashtbl.head % sizeof(word) == 0);
83 GC_ASSERT((word)&GC_fnlz_roots % sizeof(word) == 0);
84 # ifndef GC_LONG_REFS_NOT_NEEDED
85 GC_ASSERT((word)&GC_ll_hashtbl.head % sizeof(word) == 0);
86 GC_PUSH_ALL_SYM(GC_ll_hashtbl.head);
88 GC_PUSH_ALL_SYM(GC_dl_hashtbl.head);
89 GC_PUSH_ALL_SYM(GC_fnlz_roots);
92 /* Double the size of a hash table. *size_ptr is the log of its current */
93 /* size. May be a no-op. */
94 /* *table is a pointer to an array of hash headers. If we succeed, we */
95 /* update both *table and *log_size_ptr. Lock is held. */
96 STATIC void GC_grow_table(struct hash_chain_entry ***table,
97 signed_word *log_size_ptr)
100 register struct hash_chain_entry *p;
101 signed_word log_old_size = *log_size_ptr;
102 signed_word log_new_size = log_old_size + 1;
103 word old_size = log_old_size == -1 ? 0 : (word)1 << log_old_size;
104 word new_size = (word)1 << log_new_size;
105 /* FIXME: Power of 2 size often gets rounded up to one more page. */
106 struct hash_chain_entry **new_table;
108 GC_ASSERT(I_HOLD_LOCK());
109 new_table = (struct hash_chain_entry **)
110 GC_INTERNAL_MALLOC_IGNORE_OFF_PAGE(
111 (size_t)new_size * sizeof(struct hash_chain_entry *),
113 if (new_table == 0) {
115 ABORT("Insufficient space for initial table allocation");
120 for (i = 0; i < old_size; i++) {
123 ptr_t real_key = GC_REVEAL_POINTER(p -> hidden_key);
124 struct hash_chain_entry *next = p -> next;
125 size_t new_hash = HASH3(real_key, new_size, log_new_size);
127 p -> next = new_table[new_hash];
128 new_table[new_hash] = p;
132 *log_size_ptr = log_new_size;
136 GC_API int GC_CALL GC_register_disappearing_link(void * * link)
140 base = (ptr_t)GC_base(link);
142 ABORT("Bad arg to GC_register_disappearing_link");
143 return(GC_general_register_disappearing_link(link, base));
146 STATIC int GC_register_disappearing_link_inner(
147 struct dl_hashtbl_s *dl_hashtbl, void **link,
148 const void *obj, const char *tbl_log_name)
150 struct disappearing_link *curr_dl;
152 struct disappearing_link * new_dl;
156 GC_ASSERT(obj != NULL && GC_base_C(obj) == obj);
157 if (dl_hashtbl -> log_size == -1
158 || dl_hashtbl -> entries > ((word)1 << dl_hashtbl -> log_size)) {
159 GC_grow_table((struct hash_chain_entry ***)&dl_hashtbl -> head,
160 &dl_hashtbl -> log_size);
161 GC_COND_LOG_PRINTF("Grew %s table to %u entries\n", tbl_log_name,
162 1 << (unsigned)dl_hashtbl -> log_size);
164 index = HASH2(link, dl_hashtbl -> log_size);
165 for (curr_dl = dl_hashtbl -> head[index]; curr_dl != 0;
166 curr_dl = dl_next(curr_dl)) {
167 if (curr_dl -> dl_hidden_link == GC_HIDE_POINTER(link)) {
168 curr_dl -> dl_hidden_obj = GC_HIDE_POINTER(obj);
173 new_dl = (struct disappearing_link *)
174 GC_INTERNAL_MALLOC(sizeof(struct disappearing_link),NORMAL);
176 GC_oom_func oom_fn = GC_oom_fn;
178 new_dl = (struct disappearing_link *)
179 (*oom_fn)(sizeof(struct disappearing_link));
183 /* It's not likely we'll make it here, but ... */
185 /* Recalculate index since the table may grow. */
186 index = HASH2(link, dl_hashtbl -> log_size);
187 /* Check again that our disappearing link not in the table. */
188 for (curr_dl = dl_hashtbl -> head[index]; curr_dl != 0;
189 curr_dl = dl_next(curr_dl)) {
190 if (curr_dl -> dl_hidden_link == GC_HIDE_POINTER(link)) {
191 curr_dl -> dl_hidden_obj = GC_HIDE_POINTER(obj);
193 # ifndef DBG_HDRS_ALL
194 /* Free unused new_dl returned by GC_oom_fn() */
195 GC_free((void *)new_dl);
201 new_dl -> dl_hidden_obj = GC_HIDE_POINTER(obj);
202 new_dl -> dl_hidden_link = GC_HIDE_POINTER(link);
203 dl_set_next(new_dl, dl_hashtbl -> head[index]);
204 dl_hashtbl -> head[index] = new_dl;
205 dl_hashtbl -> entries++;
210 GC_API int GC_CALL GC_general_register_disappearing_link(void * * link,
213 if (((word)link & (ALIGNMENT-1)) != 0 || !NONNULL_ARG_NOT_NULL(link))
214 ABORT("Bad arg to GC_general_register_disappearing_link");
215 return GC_register_disappearing_link_inner(&GC_dl_hashtbl, link, obj,
220 # define FREE_DL_ENTRY(curr_dl) dl_set_next(curr_dl, NULL)
222 # define FREE_DL_ENTRY(curr_dl) GC_free(curr_dl)
225 /* Unregisters given link and returns the link entry to free. */
226 /* Assume the lock is held. */
227 GC_INLINE struct disappearing_link *GC_unregister_disappearing_link_inner(
228 struct dl_hashtbl_s *dl_hashtbl, void **link)
230 struct disappearing_link *curr_dl;
231 struct disappearing_link *prev_dl = NULL;
232 size_t index = HASH2(link, dl_hashtbl->log_size);
234 for (curr_dl = dl_hashtbl -> head[index]; curr_dl;
235 curr_dl = dl_next(curr_dl)) {
236 if (curr_dl -> dl_hidden_link == GC_HIDE_POINTER(link)) {
237 /* Remove found entry from the table. */
238 if (NULL == prev_dl) {
239 dl_hashtbl -> head[index] = dl_next(curr_dl);
241 dl_set_next(prev_dl, dl_next(curr_dl));
243 dl_hashtbl -> entries--;
251 GC_API int GC_CALL GC_unregister_disappearing_link(void * * link)
253 struct disappearing_link *curr_dl;
256 if (((word)link & (ALIGNMENT-1)) != 0) return(0); /* Nothing to do. */
259 curr_dl = GC_unregister_disappearing_link_inner(&GC_dl_hashtbl, link);
261 if (NULL == curr_dl) return 0;
262 FREE_DL_ENTRY(curr_dl);
266 /* Toggle-ref support. */
267 #ifndef GC_TOGGLE_REFS_NOT_NEEDED
269 /* Lowest bit is used to distinguish between choices. */
271 GC_hidden_pointer weak_ref;
274 STATIC GC_toggleref_func GC_toggleref_callback = 0;
275 STATIC GCToggleRef *GC_toggleref_arr = NULL;
276 STATIC int GC_toggleref_array_size = 0;
277 STATIC int GC_toggleref_array_capacity = 0;
279 GC_INNER void GC_process_togglerefs(void)
284 GC_ASSERT(I_HOLD_LOCK());
285 for (i = 0; i < GC_toggleref_array_size; ++i) {
286 GCToggleRef r = GC_toggleref_arr[i];
287 void *obj = r.strong_ref;
289 if (((word)obj & 1) != 0) {
290 obj = GC_REVEAL_POINTER(r.weak_ref);
295 switch (GC_toggleref_callback(obj)) {
296 case GC_TOGGLE_REF_DROP:
298 case GC_TOGGLE_REF_STRONG:
299 GC_toggleref_arr[new_size++].strong_ref = obj;
301 case GC_TOGGLE_REF_WEAK:
302 GC_toggleref_arr[new_size++].weak_ref = GC_HIDE_POINTER(obj);
305 ABORT("Bad toggle-ref status returned by callback");
309 if (new_size < GC_toggleref_array_size) {
310 BZERO(&GC_toggleref_arr[new_size],
311 (GC_toggleref_array_size - new_size) * sizeof(GCToggleRef));
312 GC_toggleref_array_size = new_size;
316 STATIC void GC_normal_finalize_mark_proc(ptr_t);
318 static void push_and_mark_object(void *p)
320 GC_normal_finalize_mark_proc(p);
321 while (!GC_mark_stack_empty()) {
322 MARK_FROM_MARK_STACK();
325 if (GC_mark_state != MS_NONE) {
326 while (!GC_mark_some(0)) {
332 STATIC void GC_mark_togglerefs(void)
335 if (NULL == GC_toggleref_arr)
338 /* TODO: Hide GC_toggleref_arr to avoid its marking from roots. */
339 GC_set_mark_bit(GC_toggleref_arr);
340 for (i = 0; i < GC_toggleref_array_size; ++i) {
341 void *obj = GC_toggleref_arr[i].strong_ref;
342 if (obj != NULL && ((word)obj & 1) == 0) {
343 push_and_mark_object(obj);
348 STATIC void GC_clear_togglerefs(void)
351 for (i = 0; i < GC_toggleref_array_size; ++i) {
352 if ((GC_toggleref_arr[i].weak_ref & 1) != 0) {
353 if (!GC_is_marked(GC_REVEAL_POINTER(GC_toggleref_arr[i].weak_ref))) {
354 GC_toggleref_arr[i].weak_ref = 0;
356 /* No need to copy, BDWGC is a non-moving collector. */
362 GC_API void GC_CALL GC_set_toggleref_func(GC_toggleref_func fn)
367 GC_toggleref_callback = fn;
371 GC_API GC_toggleref_func GC_CALL GC_get_toggleref_func(void)
373 GC_toggleref_func fn;
377 fn = GC_toggleref_callback;
382 static GC_bool ensure_toggleref_capacity(int capacity_inc)
384 GC_ASSERT(capacity_inc >= 0);
385 if (NULL == GC_toggleref_arr) {
386 GC_toggleref_array_capacity = 32; /* initial capacity */
387 GC_toggleref_arr = GC_INTERNAL_MALLOC_IGNORE_OFF_PAGE(
388 GC_toggleref_array_capacity * sizeof(GCToggleRef),
390 if (NULL == GC_toggleref_arr)
393 if ((unsigned)GC_toggleref_array_size + (unsigned)capacity_inc
394 >= (unsigned)GC_toggleref_array_capacity) {
395 GCToggleRef *new_array;
396 while ((unsigned)GC_toggleref_array_capacity
397 < (unsigned)GC_toggleref_array_size + (unsigned)capacity_inc) {
398 GC_toggleref_array_capacity *= 2;
399 if (GC_toggleref_array_capacity < 0) /* overflow */
403 new_array = GC_INTERNAL_MALLOC_IGNORE_OFF_PAGE(
404 GC_toggleref_array_capacity * sizeof(GCToggleRef),
406 if (NULL == new_array)
408 BCOPY(GC_toggleref_arr, new_array,
409 GC_toggleref_array_size * sizeof(GCToggleRef));
410 GC_INTERNAL_FREE(GC_toggleref_arr);
411 GC_toggleref_arr = new_array;
416 GC_API int GC_CALL GC_toggleref_add(void *obj, int is_strong_ref)
418 int res = GC_SUCCESS;
421 GC_ASSERT(obj != NULL);
423 if (GC_toggleref_callback != 0) {
424 if (!ensure_toggleref_capacity(1)) {
427 GC_toggleref_arr[GC_toggleref_array_size++].strong_ref =
428 is_strong_ref ? obj : (void *)GC_HIDE_POINTER(obj);
434 #endif /* !GC_TOGGLE_REFS_NOT_NEEDED */
436 /* Finalizer callback support. */
437 STATIC GC_await_finalize_proc GC_object_finalized_proc = 0;
439 GC_API void GC_CALL GC_set_await_finalize_proc(GC_await_finalize_proc fn)
444 GC_object_finalized_proc = fn;
448 GC_API GC_await_finalize_proc GC_CALL GC_get_await_finalize_proc(void)
450 GC_await_finalize_proc fn;
454 fn = GC_object_finalized_proc;
459 #ifndef GC_LONG_REFS_NOT_NEEDED
460 GC_API int GC_CALL GC_register_long_link(void * * link, const void * obj)
462 if (((word)link & (ALIGNMENT-1)) != 0 || !NONNULL_ARG_NOT_NULL(link))
463 ABORT("Bad arg to GC_register_long_link");
464 return GC_register_disappearing_link_inner(&GC_ll_hashtbl, link, obj,
468 GC_API int GC_CALL GC_unregister_long_link(void * * link)
470 struct disappearing_link *curr_dl;
473 if (((word)link & (ALIGNMENT-1)) != 0) return(0); /* Nothing to do. */
476 curr_dl = GC_unregister_disappearing_link_inner(&GC_ll_hashtbl, link);
478 if (NULL == curr_dl) return 0;
479 FREE_DL_ENTRY(curr_dl);
482 #endif /* !GC_LONG_REFS_NOT_NEEDED */
484 #ifndef GC_MOVE_DISAPPEARING_LINK_NOT_NEEDED
485 /* Moves a link. Assume the lock is held. */
486 STATIC int GC_move_disappearing_link_inner(
487 struct dl_hashtbl_s *dl_hashtbl,
488 void **link, void **new_link)
490 struct disappearing_link *curr_dl, *prev_dl, *new_dl;
491 size_t curr_index, new_index;
492 word curr_hidden_link;
493 word new_hidden_link;
495 /* Find current link. */
496 curr_index = HASH2(link, dl_hashtbl -> log_size);
497 curr_hidden_link = GC_HIDE_POINTER(link);
499 for (curr_dl = dl_hashtbl -> head[curr_index]; curr_dl;
500 curr_dl = dl_next(curr_dl)) {
501 if (curr_dl -> dl_hidden_link == curr_hidden_link)
506 if (NULL == curr_dl) {
510 if (link == new_link) {
511 return GC_SUCCESS; /* Nothing to do. */
514 /* link found; now check new_link not present. */
515 new_index = HASH2(new_link, dl_hashtbl -> log_size);
516 new_hidden_link = GC_HIDE_POINTER(new_link);
517 for (new_dl = dl_hashtbl -> head[new_index]; new_dl;
518 new_dl = dl_next(new_dl)) {
519 if (new_dl -> dl_hidden_link == new_hidden_link) {
520 /* Target already registered; bail. */
525 /* Remove from old, add to new, update link. */
526 if (NULL == prev_dl) {
527 dl_hashtbl -> head[curr_index] = dl_next(curr_dl);
529 dl_set_next(prev_dl, dl_next(curr_dl));
531 curr_dl -> dl_hidden_link = new_hidden_link;
532 dl_set_next(curr_dl, dl_hashtbl -> head[new_index]);
533 dl_hashtbl -> head[new_index] = curr_dl;
537 GC_API int GC_CALL GC_move_disappearing_link(void **link, void **new_link)
542 if (((word)new_link & (ALIGNMENT-1)) != 0
543 || !NONNULL_ARG_NOT_NULL(new_link))
544 ABORT("Bad new_link arg to GC_move_disappearing_link");
545 if (((word)link & (ALIGNMENT-1)) != 0)
546 return GC_NOT_FOUND; /* Nothing to do. */
549 result = GC_move_disappearing_link_inner(&GC_dl_hashtbl, link, new_link);
554 # ifndef GC_LONG_REFS_NOT_NEEDED
555 GC_API int GC_CALL GC_move_long_link(void **link, void **new_link)
560 if (((word)new_link & (ALIGNMENT-1)) != 0
561 || !NONNULL_ARG_NOT_NULL(new_link))
562 ABORT("Bad new_link arg to GC_move_long_link");
563 if (((word)link & (ALIGNMENT-1)) != 0)
564 return GC_NOT_FOUND; /* Nothing to do. */
567 result = GC_move_disappearing_link_inner(&GC_ll_hashtbl, link, new_link);
571 # endif /* !GC_LONG_REFS_NOT_NEEDED */
572 #endif /* !GC_MOVE_DISAPPEARING_LINK_NOT_NEEDED */
574 /* Possible finalization_marker procedures. Note that mark stack */
575 /* overflow is handled by the caller, and is not a disaster. */
576 STATIC void GC_normal_finalize_mark_proc(ptr_t p)
580 PUSH_OBJ(p, hhdr, GC_mark_stack_top,
581 &(GC_mark_stack[GC_mark_stack_size]));
584 /* This only pays very partial attention to the mark descriptor. */
585 /* It does the right thing for normal and atomic objects, and treats */
586 /* most others as normal. */
587 STATIC void GC_ignore_self_finalize_mark_proc(ptr_t p)
590 word descr = hhdr -> hb_descr;
594 ptr_t target_limit = p + hhdr -> hb_sz - 1;
596 if ((descr & GC_DS_TAGS) == GC_DS_LENGTH) {
597 scan_limit = p + descr - sizeof(word);
599 scan_limit = target_limit + 1 - sizeof(word);
601 for (q = p; (word)q <= (word)scan_limit; q += ALIGNMENT) {
603 if (r < (word)p || r > (word)target_limit) {
604 GC_PUSH_ONE_HEAP(r, q, GC_mark_stack_top);
609 STATIC void GC_null_finalize_mark_proc(ptr_t p GC_ATTR_UNUSED) {}
611 /* Possible finalization_marker procedures. Note that mark stack */
612 /* overflow is handled by the caller, and is not a disaster. */
614 /* GC_unreachable_finalize_mark_proc is an alias for normal marking, */
615 /* but it is explicitly tested for, and triggers different */
616 /* behavior. Objects registered in this way are not finalized */
617 /* if they are reachable by other finalizable objects, even if those */
618 /* other objects specify no ordering. */
619 STATIC void GC_unreachable_finalize_mark_proc(ptr_t p)
621 GC_normal_finalize_mark_proc(p);
624 /* Register a finalization function. See gc.h for details. */
625 /* The last parameter is a procedure that determines */
626 /* marking for finalization ordering. Any objects marked */
627 /* by that procedure will be guaranteed to not have been */
628 /* finalized when this finalizer is invoked. */
629 STATIC void GC_register_finalizer_inner(void * obj,
630 GC_finalization_proc fn, void *cd,
631 GC_finalization_proc *ofn, void **ocd,
632 finalization_mark_proc mp)
635 struct finalizable_object * curr_fo, * prev_fo;
637 struct finalizable_object *new_fo = 0;
638 hdr *hhdr = NULL; /* initialized to prevent warning. */
643 if (log_fo_table_size == -1
644 || GC_fo_entries > ((word)1 << log_fo_table_size)) {
645 GC_grow_table((struct hash_chain_entry ***)&GC_fnlz_roots.fo_head,
647 GC_COND_LOG_PRINTF("Grew fo table to %u entries\n",
648 1 << (unsigned)log_fo_table_size);
650 /* in the THREADS case we hold allocation lock. */
653 index = HASH2(base, log_fo_table_size);
655 curr_fo = GC_fnlz_roots.fo_head[index];
656 while (curr_fo != 0) {
657 GC_ASSERT(GC_size(curr_fo) >= sizeof(struct finalizable_object));
658 if (curr_fo -> fo_hidden_base == GC_HIDE_POINTER(base)) {
659 /* Interruption by a signal in the middle of this */
660 /* should be safe. The client may see only *ocd */
661 /* updated, but we'll declare that to be his problem. */
662 if (ocd) *ocd = (void *) (curr_fo -> fo_client_data);
663 if (ofn) *ofn = curr_fo -> fo_fn;
664 /* Delete the structure for base. */
666 GC_fnlz_roots.fo_head[index] = fo_next(curr_fo);
668 fo_set_next(prev_fo, fo_next(curr_fo));
672 /* May not happen if we get a signal. But a high */
673 /* estimate will only make the table larger than */
675 # if !defined(THREADS) && !defined(DBG_HDRS_ALL)
676 GC_free((void *)curr_fo);
679 curr_fo -> fo_fn = fn;
680 curr_fo -> fo_client_data = (ptr_t)cd;
681 curr_fo -> fo_mark_proc = mp;
682 /* Reinsert it. We deleted it first to maintain */
683 /* consistency in the event of a signal. */
685 GC_fnlz_roots.fo_head[index] = curr_fo;
687 fo_set_next(prev_fo, curr_fo);
691 # ifndef DBG_HDRS_ALL
692 if (EXPECT(new_fo != 0, FALSE)) {
693 /* Free unused new_fo returned by GC_oom_fn() */
694 GC_free((void *)new_fo);
700 curr_fo = fo_next(curr_fo);
702 if (EXPECT(new_fo != 0, FALSE)) {
703 /* new_fo is returned by GC_oom_fn(), so fn != 0 and hhdr != 0. */
713 if (EXPECT(0 == hhdr, FALSE)) {
714 /* We won't collect it, hence finalizer wouldn't be run. */
720 new_fo = (struct finalizable_object *)
721 GC_INTERNAL_MALLOC(sizeof(struct finalizable_object),NORMAL);
722 if (EXPECT(new_fo != 0, TRUE))
726 new_fo = (struct finalizable_object *)
727 (*oom_fn)(sizeof(struct finalizable_object));
729 /* No enough memory. *ocd and *ofn remains unchanged. */
732 /* It's not likely we'll make it here, but ... */
734 /* Recalculate index since the table may grow and */
735 /* check again that our finalizer is not in the table. */
737 GC_ASSERT(GC_size(new_fo) >= sizeof(struct finalizable_object));
740 new_fo -> fo_hidden_base = GC_HIDE_POINTER(base);
741 new_fo -> fo_fn = fn;
742 new_fo -> fo_client_data = (ptr_t)cd;
743 new_fo -> fo_object_size = hhdr -> hb_sz;
744 new_fo -> fo_mark_proc = mp;
745 fo_set_next(new_fo, GC_fnlz_roots.fo_head[index]);
747 GC_fnlz_roots.fo_head[index] = new_fo;
751 GC_API void GC_CALL GC_register_finalizer(void * obj,
752 GC_finalization_proc fn, void * cd,
753 GC_finalization_proc *ofn, void ** ocd)
755 GC_register_finalizer_inner(obj, fn, cd, ofn,
756 ocd, GC_normal_finalize_mark_proc);
759 GC_API void GC_CALL GC_register_finalizer_ignore_self(void * obj,
760 GC_finalization_proc fn, void * cd,
761 GC_finalization_proc *ofn, void ** ocd)
763 GC_register_finalizer_inner(obj, fn, cd, ofn,
764 ocd, GC_ignore_self_finalize_mark_proc);
767 GC_API void GC_CALL GC_register_finalizer_no_order(void * obj,
768 GC_finalization_proc fn, void * cd,
769 GC_finalization_proc *ofn, void ** ocd)
771 GC_register_finalizer_inner(obj, fn, cd, ofn,
772 ocd, GC_null_finalize_mark_proc);
775 static GC_bool need_unreachable_finalization = FALSE;
776 /* Avoid the work if this isn't used. */
778 GC_API void GC_CALL GC_register_finalizer_unreachable(void * obj,
779 GC_finalization_proc fn, void * cd,
780 GC_finalization_proc *ofn, void ** ocd)
782 need_unreachable_finalization = TRUE;
783 GC_ASSERT(GC_java_finalization);
784 GC_register_finalizer_inner(obj, fn, cd, ofn,
785 ocd, GC_unreachable_finalize_mark_proc);
789 STATIC void GC_dump_finalization_links(
790 const struct dl_hashtbl_s *dl_hashtbl)
792 struct disappearing_link *curr_dl;
793 ptr_t real_ptr, real_link;
794 size_t dl_size = dl_hashtbl->log_size == -1 ? 0 :
795 (size_t)1 << dl_hashtbl->log_size;
798 for (i = 0; i < dl_size; i++) {
799 for (curr_dl = dl_hashtbl -> head[i]; curr_dl != 0;
800 curr_dl = dl_next(curr_dl)) {
801 real_ptr = GC_REVEAL_POINTER(curr_dl -> dl_hidden_obj);
802 real_link = GC_REVEAL_POINTER(curr_dl -> dl_hidden_link);
803 GC_printf("Object: %p, link: %p\n", real_ptr, real_link);
808 void GC_dump_finalization(void)
810 struct finalizable_object * curr_fo;
811 size_t fo_size = log_fo_table_size == -1 ? 0 :
812 (size_t)1 << log_fo_table_size;
816 GC_printf("Disappearing (short) links:\n");
817 GC_dump_finalization_links(&GC_dl_hashtbl);
818 # ifndef GC_LONG_REFS_NOT_NEEDED
819 GC_printf("Disappearing long links:\n");
820 GC_dump_finalization_links(&GC_ll_hashtbl);
822 GC_printf("Finalizers:\n");
823 for (i = 0; i < fo_size; i++) {
824 for (curr_fo = GC_fnlz_roots.fo_head[i];
825 curr_fo != NULL; curr_fo = fo_next(curr_fo)) {
826 real_ptr = GC_REVEAL_POINTER(curr_fo -> fo_hidden_base);
827 GC_printf("Finalizable object: %p\n", real_ptr);
831 #endif /* !NO_DEBUGGING */
834 STATIC word GC_old_dl_entries = 0; /* for stats printing */
835 # ifndef GC_LONG_REFS_NOT_NEEDED
836 STATIC word GC_old_ll_entries = 0;
838 #endif /* !SMALL_CONFIG */
841 /* Global variables to minimize the level of recursion when a client */
842 /* finalizer allocates memory. */
843 STATIC int GC_finalizer_nested = 0;
844 /* Only the lowest byte is used, the rest is */
845 /* padding for proper global data alignment */
846 /* required for some compilers (like Watcom). */
847 STATIC unsigned GC_finalizer_skipped = 0;
849 /* Checks and updates the level of finalizers recursion. */
850 /* Returns NULL if GC_invoke_finalizers() should not be called by the */
851 /* collector (to minimize the risk of a deep finalizers recursion), */
852 /* otherwise returns a pointer to GC_finalizer_nested. */
853 STATIC unsigned char *GC_check_finalizer_nested(void)
855 unsigned nesting_level = *(unsigned char *)&GC_finalizer_nested;
857 /* We are inside another GC_invoke_finalizers(). */
858 /* Skip some implicitly-called GC_invoke_finalizers() */
859 /* depending on the nesting (recursion) level. */
860 if (++GC_finalizer_skipped < (1U << nesting_level)) return NULL;
861 GC_finalizer_skipped = 0;
863 *(char *)&GC_finalizer_nested = (char)(nesting_level + 1);
864 return (unsigned char *)&GC_finalizer_nested;
868 #define ITERATE_DL_HASHTBL_BEGIN(dl_hashtbl, curr_dl, prev_dl) \
871 size_t dl_size = dl_hashtbl->log_size == -1 ? 0 : \
872 (size_t)1 << dl_hashtbl->log_size; \
873 for (i = 0; i < dl_size; i++) { \
874 curr_dl = dl_hashtbl -> head[i]; \
878 #define ITERATE_DL_HASHTBL_END(curr_dl, prev_dl) \
880 curr_dl = dl_next(curr_dl); \
885 #define DELETE_DL_HASHTBL_ENTRY(dl_hashtbl, curr_dl, prev_dl, next_dl) \
887 next_dl = dl_next(curr_dl); \
888 if (NULL == prev_dl) { \
889 dl_hashtbl -> head[i] = next_dl; \
891 dl_set_next(prev_dl, next_dl); \
893 GC_clear_mark_bit(curr_dl); \
894 dl_hashtbl -> entries--; \
899 GC_INLINE void GC_make_disappearing_links_disappear(
900 struct dl_hashtbl_s* dl_hashtbl)
902 struct disappearing_link *curr, *prev, *next;
903 ptr_t real_ptr, real_link;
905 ITERATE_DL_HASHTBL_BEGIN(dl_hashtbl, curr, prev)
906 real_ptr = GC_REVEAL_POINTER(curr -> dl_hidden_obj);
907 real_link = GC_REVEAL_POINTER(curr -> dl_hidden_link);
908 if (!GC_is_marked(real_ptr)) {
909 *(word *)real_link = 0;
910 GC_clear_mark_bit(curr);
911 DELETE_DL_HASHTBL_ENTRY(dl_hashtbl, curr, prev, next);
913 ITERATE_DL_HASHTBL_END(curr, prev)
916 GC_INLINE void GC_remove_dangling_disappearing_links(
917 struct dl_hashtbl_s* dl_hashtbl)
919 struct disappearing_link *curr, *prev, *next;
922 ITERATE_DL_HASHTBL_BEGIN(dl_hashtbl, curr, prev)
923 real_link = GC_base(GC_REVEAL_POINTER(curr -> dl_hidden_link));
924 if (NULL != real_link && !GC_is_marked(real_link)) {
925 GC_clear_mark_bit(curr);
926 DELETE_DL_HASHTBL_ENTRY(dl_hashtbl, curr, prev, next);
928 ITERATE_DL_HASHTBL_END(curr, prev)
931 /* Called with held lock (but the world is running). */
932 /* Cause disappearing links to disappear and unreachable objects to be */
933 /* enqueued for finalization. */
934 GC_INNER void GC_finalize(void)
936 struct finalizable_object * curr_fo, * prev_fo, * next_fo;
939 size_t fo_size = log_fo_table_size == -1 ? 0 :
940 (size_t)1 << log_fo_table_size;
942 # ifndef SMALL_CONFIG
943 /* Save current GC_[dl/ll]_entries value for stats printing */
944 GC_old_dl_entries = GC_dl_hashtbl.entries;
945 # ifndef GC_LONG_REFS_NOT_NEEDED
946 GC_old_ll_entries = GC_ll_hashtbl.entries;
950 # ifndef GC_TOGGLE_REFS_NOT_NEEDED
951 GC_mark_togglerefs();
953 GC_make_disappearing_links_disappear(&GC_dl_hashtbl);
955 /* Mark all objects reachable via chains of 1 or more pointers */
956 /* from finalizable objects. */
957 GC_ASSERT(GC_mark_state == MS_NONE);
958 for (i = 0; i < fo_size; i++) {
959 for (curr_fo = GC_fnlz_roots.fo_head[i];
960 curr_fo != NULL; curr_fo = fo_next(curr_fo)) {
961 GC_ASSERT(GC_size(curr_fo) >= sizeof(struct finalizable_object));
962 real_ptr = GC_REVEAL_POINTER(curr_fo -> fo_hidden_base);
963 if (!GC_is_marked(real_ptr)) {
964 GC_MARKED_FOR_FINALIZATION(real_ptr);
965 GC_MARK_FO(real_ptr, curr_fo -> fo_mark_proc);
966 if (GC_is_marked(real_ptr)) {
967 WARN("Finalization cycle involving %p\n", real_ptr);
972 /* Enqueue for finalization all objects that are still */
974 GC_bytes_finalized = 0;
975 for (i = 0; i < fo_size; i++) {
976 curr_fo = GC_fnlz_roots.fo_head[i];
978 while (curr_fo != 0) {
979 real_ptr = GC_REVEAL_POINTER(curr_fo -> fo_hidden_base);
980 if (!GC_is_marked(real_ptr)) {
981 if (!GC_java_finalization) {
982 GC_set_mark_bit(real_ptr);
984 /* Delete from hash table */
985 next_fo = fo_next(curr_fo);
986 if (NULL == prev_fo) {
987 GC_fnlz_roots.fo_head[i] = next_fo;
989 fo_set_next(prev_fo, next_fo);
992 if (GC_object_finalized_proc)
993 GC_object_finalized_proc(real_ptr);
995 /* Add to list of objects awaiting finalization. */
996 fo_set_next(curr_fo, GC_fnlz_roots.finalize_now);
997 GC_fnlz_roots.finalize_now = curr_fo;
998 /* unhide object pointer so any future collections will */
1000 curr_fo -> fo_hidden_base =
1001 (word)GC_REVEAL_POINTER(curr_fo -> fo_hidden_base);
1002 GC_bytes_finalized +=
1003 curr_fo -> fo_object_size
1004 + sizeof(struct finalizable_object);
1005 GC_ASSERT(GC_is_marked(GC_base(curr_fo)));
1009 curr_fo = fo_next(curr_fo);
1014 if (GC_java_finalization) {
1015 /* make sure we mark everything reachable from objects finalized
1016 using the no_order mark_proc */
1017 for (curr_fo = GC_fnlz_roots.finalize_now;
1018 curr_fo != NULL; curr_fo = fo_next(curr_fo)) {
1019 real_ptr = (ptr_t)curr_fo -> fo_hidden_base;
1020 if (!GC_is_marked(real_ptr)) {
1021 if (curr_fo -> fo_mark_proc == GC_null_finalize_mark_proc) {
1022 GC_MARK_FO(real_ptr, GC_normal_finalize_mark_proc);
1024 if (curr_fo -> fo_mark_proc != GC_unreachable_finalize_mark_proc) {
1025 GC_set_mark_bit(real_ptr);
1030 /* now revive finalize-when-unreachable objects reachable from
1031 other finalizable objects */
1032 if (need_unreachable_finalization) {
1033 curr_fo = GC_fnlz_roots.finalize_now;
1035 while (curr_fo != NULL) {
1036 next_fo = fo_next(curr_fo);
1037 if (curr_fo -> fo_mark_proc == GC_unreachable_finalize_mark_proc) {
1038 real_ptr = (ptr_t)curr_fo -> fo_hidden_base;
1039 if (!GC_is_marked(real_ptr)) {
1040 GC_set_mark_bit(real_ptr);
1042 if (NULL == prev_fo) {
1043 GC_fnlz_roots.finalize_now = next_fo;
1045 fo_set_next(prev_fo, next_fo);
1047 curr_fo -> fo_hidden_base =
1048 GC_HIDE_POINTER(curr_fo -> fo_hidden_base);
1049 GC_bytes_finalized -=
1050 curr_fo->fo_object_size + sizeof(struct finalizable_object);
1052 i = HASH2(real_ptr, log_fo_table_size);
1053 fo_set_next(curr_fo, GC_fnlz_roots.fo_head[i]);
1055 GC_fnlz_roots.fo_head[i] = curr_fo;
1065 GC_remove_dangling_disappearing_links(&GC_dl_hashtbl);
1066 # ifndef GC_TOGGLE_REFS_NOT_NEEDED
1067 GC_clear_togglerefs();
1069 # ifndef GC_LONG_REFS_NOT_NEEDED
1070 GC_make_disappearing_links_disappear(&GC_ll_hashtbl);
1071 GC_remove_dangling_disappearing_links(&GC_ll_hashtbl);
1074 if (GC_fail_count) {
1075 /* Don't prevent running finalizers if there has been an allocation */
1076 /* failure recently. */
1078 GC_reset_finalizer_nested();
1080 GC_finalizer_nested = 0;
1085 #ifndef JAVA_FINALIZATION_NOT_NEEDED
1087 /* Enqueue all remaining finalizers to be run - Assumes lock is held. */
1088 STATIC void GC_enqueue_all_finalizers(void)
1090 struct finalizable_object * curr_fo, * prev_fo, * next_fo;
1095 fo_size = log_fo_table_size == -1 ? 0 : 1 << log_fo_table_size;
1096 GC_bytes_finalized = 0;
1097 for (i = 0; i < fo_size; i++) {
1098 curr_fo = GC_fnlz_roots.fo_head[i];
1100 while (curr_fo != NULL) {
1101 real_ptr = GC_REVEAL_POINTER(curr_fo -> fo_hidden_base);
1102 GC_MARK_FO(real_ptr, GC_normal_finalize_mark_proc);
1103 GC_set_mark_bit(real_ptr);
1105 /* Delete from hash table */
1106 next_fo = fo_next(curr_fo);
1108 GC_fnlz_roots.fo_head[i] = next_fo;
1110 fo_set_next(prev_fo, next_fo);
1114 /* Add to list of objects awaiting finalization. */
1115 fo_set_next(curr_fo, GC_fnlz_roots.finalize_now);
1116 GC_fnlz_roots.finalize_now = curr_fo;
1118 /* unhide object pointer so any future collections will */
1120 curr_fo -> fo_hidden_base =
1121 (word)GC_REVEAL_POINTER(curr_fo -> fo_hidden_base);
1122 GC_bytes_finalized +=
1123 curr_fo -> fo_object_size + sizeof(struct finalizable_object);
1129 /* Invoke all remaining finalizers that haven't yet been run.
1130 * This is needed for strict compliance with the Java standard,
1131 * which can make the runtime guarantee that all finalizers are run.
1132 * Unfortunately, the Java standard implies we have to keep running
1133 * finalizers until there are no more left, a potential infinite loop.
1135 * Note that this is even more dangerous than the usual Java
1136 * finalizers, in that objects reachable from static variables
1137 * may have been finalized when these finalizers are run.
1138 * Finalizers run at this point must be prepared to deal with a
1139 * mostly broken world.
1140 * This routine is externally callable, so is called without
1141 * the allocation lock.
1143 GC_API void GC_CALL GC_finalize_all(void)
1148 while (GC_fo_entries > 0) {
1149 GC_enqueue_all_finalizers();
1151 GC_invoke_finalizers();
1152 /* Running the finalizers in this thread is arguably not a good */
1153 /* idea when we should be notifying another thread to run them. */
1154 /* But otherwise we don't have a great way to wait for them to */
1161 #endif /* !JAVA_FINALIZATION_NOT_NEEDED */
1163 /* Returns true if it is worth calling GC_invoke_finalizers. (Useful if */
1164 /* finalizers can only be called from some kind of "safe state" and */
1165 /* getting into that safe state is expensive.) */
1166 GC_API int GC_CALL GC_should_invoke_finalizers(void)
1168 return GC_fnlz_roots.finalize_now != NULL;
1171 /* Invoke finalizers for all objects that are ready to be finalized. */
1172 /* Should be called without allocation lock. */
1173 GC_API int GC_CALL GC_invoke_finalizers(void)
1175 struct finalizable_object * curr_fo;
1177 word bytes_freed_before = 0; /* initialized to prevent warning. */
1180 while (GC_fnlz_roots.finalize_now != NULL) {
1185 bytes_freed_before = GC_bytes_freed;
1186 /* Don't do this outside, since we need the lock. */
1188 curr_fo = GC_fnlz_roots.finalize_now;
1190 if (curr_fo != 0) GC_fnlz_roots.finalize_now = fo_next(curr_fo);
1192 if (curr_fo == 0) break;
1194 GC_fnlz_roots.finalize_now = fo_next(curr_fo);
1196 fo_set_next(curr_fo, 0);
1197 (*(curr_fo -> fo_fn))((ptr_t)(curr_fo -> fo_hidden_base),
1198 curr_fo -> fo_client_data);
1199 curr_fo -> fo_client_data = 0;
1202 /* This is probably a bad idea. It throws off accounting if */
1203 /* nearly all objects are finalizable. O.w. it shouldn't */
1205 GC_free((void *)curr_fo);
1208 /* bytes_freed_before is initialized whenever count != 0 */
1209 if (count != 0 && bytes_freed_before != GC_bytes_freed) {
1211 GC_finalizer_bytes_freed += (GC_bytes_freed - bytes_freed_before);
1217 static word last_finalizer_notification = 0;
1219 GC_INNER void GC_notify_or_invoke_finalizers(void)
1221 GC_finalizer_notifier_proc notifier_fn = 0;
1222 # if defined(KEEP_BACK_PTRS) || defined(MAKE_BACK_GRAPH)
1223 static word last_back_trace_gc_no = 1; /* Skip first one. */
1227 # if defined(THREADS) && !defined(KEEP_BACK_PTRS) \
1228 && !defined(MAKE_BACK_GRAPH)
1229 /* Quick check (while unlocked) for an empty finalization queue. */
1230 if (NULL == GC_fnlz_roots.finalize_now) return;
1234 /* This is a convenient place to generate backtraces if appropriate, */
1235 /* since that code is not callable with the allocation lock. */
1236 # if defined(KEEP_BACK_PTRS) || defined(MAKE_BACK_GRAPH)
1237 if (GC_gc_no > last_back_trace_gc_no) {
1238 # ifdef KEEP_BACK_PTRS
1240 /* Stops when GC_gc_no wraps; that's OK. */
1241 last_back_trace_gc_no = (word)(-1); /* disable others. */
1242 for (i = 0; i < GC_backtraces; ++i) {
1243 /* FIXME: This tolerates concurrent heap mutation, */
1244 /* which may cause occasional mysterious results. */
1245 /* We need to release the GC lock, since GC_print_callers */
1246 /* acquires it. It probably shouldn't. */
1248 GC_generate_random_backtrace_no_gc();
1251 last_back_trace_gc_no = GC_gc_no;
1253 # ifdef MAKE_BACK_GRAPH
1254 if (GC_print_back_height) {
1256 GC_print_back_graph_stats();
1262 if (NULL == GC_fnlz_roots.finalize_now) {
1267 if (!GC_finalize_on_demand) {
1268 unsigned char *pnested = GC_check_finalizer_nested();
1270 /* Skip GC_invoke_finalizers() if nested */
1271 if (pnested != NULL) {
1272 (void) GC_invoke_finalizers();
1273 *pnested = 0; /* Reset since no more finalizers. */
1275 GC_ASSERT(NULL == GC_fnlz_roots.finalize_now);
1276 # endif /* Otherwise GC can run concurrently and add more */
1281 /* These variables require synchronization to avoid data races. */
1282 if (last_finalizer_notification != GC_gc_no) {
1283 last_finalizer_notification = GC_gc_no;
1284 notifier_fn = GC_finalizer_notifier;
1287 if (notifier_fn != 0)
1288 (*notifier_fn)(); /* Invoke the notifier */
1291 #ifndef SMALL_CONFIG
1292 # ifndef GC_LONG_REFS_NOT_NEEDED
1293 # define IF_LONG_REFS_PRESENT_ELSE(x,y) (x)
1295 # define IF_LONG_REFS_PRESENT_ELSE(x,y) (y)
1298 GC_INNER void GC_print_finalization_stats(void)
1300 struct finalizable_object *fo;
1301 unsigned long ready = 0;
1303 GC_log_printf("%lu finalization entries;"
1304 " %lu/%lu short/long disappearing links alive\n",
1305 (unsigned long)GC_fo_entries,
1306 (unsigned long)GC_dl_hashtbl.entries,
1307 (unsigned long)IF_LONG_REFS_PRESENT_ELSE(
1308 GC_ll_hashtbl.entries, 0));
1310 for (fo = GC_fnlz_roots.finalize_now; fo != NULL; fo = fo_next(fo))
1312 GC_log_printf("%lu finalization-ready objects;"
1313 " %ld/%ld short/long links cleared\n",
1315 (long)GC_old_dl_entries - (long)GC_dl_hashtbl.entries,
1316 (long)IF_LONG_REFS_PRESENT_ELSE(
1317 GC_old_ll_entries - GC_ll_hashtbl.entries, 0));
1319 #endif /* !SMALL_CONFIG */
1321 #endif /* !GC_NO_FINALIZATION */