2 * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
3 * Copyright (c) 1991-1996 by Xerox Corporation. All rights reserved.
5 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
6 * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
8 * Permission is hereby granted to use or copy this program
9 * for any purpose, provided the above notices are retained on all copies.
10 * Permission to modify the code and to distribute modified code is granted,
11 * provided the above notices are retained, and a notice that the code was
12 * modified is included with the above copyright notice.
14 /* Boehm, February 1, 1996 1:19 pm PST */
15 # define I_HIDE_POINTERS
19 /* Type of mark procedure used for marking from finalizable object. */
20 /* This procedure normally does not mark the object, only its */
22 typedef void finalization_mark_proc(/* ptr_t finalizable_obj_ptr */);
24 # define HASH3(addr,size,log_size) \
25 ((((word)(addr) >> 3) ^ ((word)(addr) >> (3+(log_size)))) \
27 #define HASH2(addr,log_size) HASH3(addr, 1 << log_size, log_size)
29 struct hash_chain_entry {
31 struct hash_chain_entry * next;
34 unsigned GC_finalization_failures = 0;
35 /* Number of finalization requests that failed for lack of memory. */
37 static struct disappearing_link {
38 struct hash_chain_entry prolog;
39 # define dl_hidden_link prolog.hidden_key
40 /* Field to be cleared. */
41 # define dl_next(x) (struct disappearing_link *)((x) -> prolog.next)
42 # define dl_set_next(x,y) (x) -> prolog.next = (struct hash_chain_entry *)(y)
44 word dl_hidden_obj; /* Pointer to object base */
47 static signed_word log_dl_table_size = -1;
49 /* current size of array pointed to by dl_head. */
50 /* -1 ==> size is 0. */
52 word GC_dl_entries = 0; /* Number of entries currently in disappearing */
55 static struct finalizable_object {
56 struct hash_chain_entry prolog;
57 # define fo_hidden_base prolog.hidden_key
58 /* Pointer to object base. */
59 /* No longer hidden once object */
60 /* is on finalize_now queue. */
61 # define fo_next(x) (struct finalizable_object *)((x) -> prolog.next)
62 # define fo_set_next(x,y) (x) -> prolog.next = (struct hash_chain_entry *)(y)
63 GC_finalization_proc fo_fn; /* Finalizer. */
65 word fo_object_size; /* In bytes. */
66 finalization_mark_proc * fo_mark_proc; /* Mark-through procedure */
69 struct finalizable_object * GC_finalize_now = 0;
70 /* LIst of objects that should be finalized now. */
72 static signed_word log_fo_table_size = -1;
74 word GC_fo_entries = 0;
77 void GC_push_finalizer_structures()
79 GC_push_all((ptr_t)(&dl_head), (ptr_t)(&dl_head) + sizeof(word));
80 GC_push_all((ptr_t)(&fo_head), (ptr_t)(&fo_head) + sizeof(word));
84 /* Double the size of a hash table. *size_ptr is the log of its current */
85 /* size. May be a noop. */
86 /* *table is a pointer to an array of hash headers. If we succeed, we */
87 /* update both *table and *log_size_ptr. */
88 /* Lock is held. Signals are disabled. */
89 void GC_grow_table(table, log_size_ptr)
90 struct hash_chain_entry ***table;
91 signed_word * log_size_ptr;
94 register struct hash_chain_entry *p;
95 int log_old_size = *log_size_ptr;
96 register int log_new_size = log_old_size + 1;
97 word old_size = ((log_old_size == -1)? 0: (1 << log_old_size));
98 register word new_size = 1 << log_new_size;
99 struct hash_chain_entry **new_table = (struct hash_chain_entry **)
100 GC_generic_malloc_inner_ignore_off_page(
101 (size_t)new_size * sizeof(struct hash_chain_entry *), NORMAL);
103 if (new_table == 0) {
105 ABORT("Insufficient space for initial table allocation");
110 for (i = 0; i < old_size; i++) {
113 register ptr_t real_key = (ptr_t)REVEAL_POINTER(p -> hidden_key);
114 register struct hash_chain_entry *next = p -> next;
115 register int new_hash = HASH3(real_key, new_size, log_new_size);
117 p -> next = new_table[new_hash];
118 new_table[new_hash] = p;
122 *log_size_ptr = log_new_size;
126 # if defined(__STDC__) || defined(__cplusplus)
127 int GC_register_disappearing_link(GC_PTR * link)
129 int GC_register_disappearing_link(link)
135 base = (ptr_t)GC_base((GC_PTR)link);
137 ABORT("Bad arg to GC_register_disappearing_link");
138 return(GC_general_register_disappearing_link(link, base));
141 # if defined(__STDC__) || defined(__cplusplus)
142 int GC_general_register_disappearing_link(GC_PTR * link,
145 int GC_general_register_disappearing_link(link, obj)
151 struct disappearing_link *curr_dl;
153 struct disappearing_link * new_dl;
156 if ((word)link & (ALIGNMENT-1))
157 ABORT("Bad arg to GC_general_register_disappearing_link");
162 if (log_dl_table_size == -1
163 || GC_dl_entries > ((word)1 << log_dl_table_size)) {
167 GC_grow_table((struct hash_chain_entry ***)(&dl_head),
170 GC_printf1("Grew dl table to %lu entries\n",
171 (unsigned long)(1 << log_dl_table_size));
177 index = HASH2(link, log_dl_table_size);
178 curr_dl = dl_head[index];
179 for (curr_dl = dl_head[index]; curr_dl != 0; curr_dl = dl_next(curr_dl)) {
180 if (curr_dl -> dl_hidden_link == HIDE_POINTER(link)) {
181 curr_dl -> dl_hidden_obj = HIDE_POINTER(obj);
190 new_dl = (struct disappearing_link *)
191 GC_generic_malloc_inner(sizeof(struct disappearing_link),NORMAL);
193 new_dl = (struct disappearing_link *)
194 GC_malloc(sizeof(struct disappearing_link));
197 new_dl -> dl_hidden_obj = HIDE_POINTER(obj);
198 new_dl -> dl_hidden_link = HIDE_POINTER(link);
199 dl_set_next(new_dl, dl_head[index]);
200 dl_head[index] = new_dl;
203 GC_finalization_failures++;
212 # if defined(__STDC__) || defined(__cplusplus)
213 int GC_unregister_disappearing_link(GC_PTR * link)
215 int GC_unregister_disappearing_link(link)
219 struct disappearing_link *curr_dl, *prev_dl;
225 index = HASH2(link, log_dl_table_size);
226 if (((unsigned long)link & (ALIGNMENT-1))) goto out;
227 prev_dl = 0; curr_dl = dl_head[index];
228 while (curr_dl != 0) {
229 if (curr_dl -> dl_hidden_link == HIDE_POINTER(link)) {
231 dl_head[index] = dl_next(curr_dl);
233 dl_set_next(prev_dl, dl_next(curr_dl));
238 GC_free((GC_PTR)curr_dl);
242 curr_dl = dl_next(curr_dl);
250 /* Possible finalization_marker procedures. Note that mark stack */
251 /* overflow is handled by the caller, and is not a disaster. */
252 void GC_normal_finalize_mark_proc(p)
257 PUSH_OBJ((word *)p, hhdr, GC_mark_stack_top,
258 &(GC_mark_stack[GC_mark_stack_size]));
261 /* This only pays very partial attention to the mark descriptor. */
262 /* It does the right thing for normal and atomic objects, and treats */
263 /* most others as normal. */
264 void GC_ignore_self_finalize_mark_proc(p)
268 word descr = hhdr -> hb_descr;
271 ptr_t target_limit = p + WORDS_TO_BYTES(hhdr -> hb_sz) - 1;
273 if ((descr & DS_TAGS) == DS_LENGTH) {
274 scan_limit = p + descr - sizeof(word);
276 scan_limit = target_limit + 1 - sizeof(word);
278 for (q = p; q <= scan_limit; q += ALIGNMENT) {
280 if (r < p || r > target_limit) {
281 GC_PUSH_ONE_HEAP((word)r);
287 void GC_null_finalize_mark_proc(p)
294 /* Register a finalization function. See gc.h for details. */
295 /* in the nonthreads case, we try to avoid disabling signals, */
296 /* since it can be expensive. Threads packages typically */
297 /* make it cheaper. */
298 void GC_register_finalizer_inner(obj, fn, cd, ofn, ocd, mp)
300 GC_finalization_proc fn;
302 GC_finalization_proc * ofn;
304 finalization_mark_proc * mp;
307 struct finalizable_object * curr_fo, * prev_fo;
309 struct finalizable_object *new_fo;
316 if (log_fo_table_size == -1
317 || GC_fo_entries > ((word)1 << log_fo_table_size)) {
321 GC_grow_table((struct hash_chain_entry ***)(&fo_head),
324 GC_printf1("Grew fo table to %lu entries\n",
325 (unsigned long)(1 << log_fo_table_size));
331 /* in the THREADS case signals are disabled and we hold allocation */
332 /* lock; otherwise neither is true. Proceed carefully. */
334 index = HASH2(base, log_fo_table_size);
335 prev_fo = 0; curr_fo = fo_head[index];
336 while (curr_fo != 0) {
337 if (curr_fo -> fo_hidden_base == HIDE_POINTER(base)) {
338 /* Interruption by a signal in the middle of this */
339 /* should be safe. The client may see only *ocd */
340 /* updated, but we'll declare that to be his */
342 if (ocd) *ocd = (GC_PTR) curr_fo -> fo_client_data;
343 if (ofn) *ofn = curr_fo -> fo_fn;
344 /* Delete the structure for base. */
346 fo_head[index] = fo_next(curr_fo);
348 fo_set_next(prev_fo, fo_next(curr_fo));
352 /* May not happen if we get a signal. But a high */
353 /* estimate will only make the table larger than */
356 GC_free((GC_PTR)curr_fo);
359 curr_fo -> fo_fn = fn;
360 curr_fo -> fo_client_data = (ptr_t)cd;
361 curr_fo -> fo_mark_proc = mp;
362 /* Reinsert it. We deleted it first to maintain */
363 /* consistency in the event of a signal. */
365 fo_head[index] = curr_fo;
367 fo_set_next(prev_fo, curr_fo);
377 curr_fo = fo_next(curr_fo);
389 new_fo = (struct finalizable_object *)
390 GC_generic_malloc_inner(sizeof(struct finalizable_object),NORMAL);
392 new_fo = (struct finalizable_object *)
393 GC_malloc(sizeof(struct finalizable_object));
396 new_fo -> fo_hidden_base = (word)HIDE_POINTER(base);
397 new_fo -> fo_fn = fn;
398 new_fo -> fo_client_data = (ptr_t)cd;
399 new_fo -> fo_object_size = GC_size(base);
400 new_fo -> fo_mark_proc = mp;
401 fo_set_next(new_fo, fo_head[index]);
403 fo_head[index] = new_fo;
405 GC_finalization_failures++;
413 # if defined(__STDC__)
414 void GC_register_finalizer(void * obj,
415 GC_finalization_proc fn, void * cd,
416 GC_finalization_proc *ofn, void ** ocd)
418 void GC_register_finalizer(obj, fn, cd, ofn, ocd)
420 GC_finalization_proc fn;
422 GC_finalization_proc * ofn;
426 GC_register_finalizer_inner(obj, fn, cd, ofn,
427 ocd, GC_normal_finalize_mark_proc);
430 # if defined(__STDC__)
431 void GC_register_finalizer_ignore_self(void * obj,
432 GC_finalization_proc fn, void * cd,
433 GC_finalization_proc *ofn, void ** ocd)
435 void GC_register_finalizer_ignore_self(obj, fn, cd, ofn, ocd)
437 GC_finalization_proc fn;
439 GC_finalization_proc * ofn;
443 GC_register_finalizer_inner(obj, fn, cd, ofn,
444 ocd, GC_ignore_self_finalize_mark_proc);
447 # if defined(__STDC__)
448 void GC_register_finalizer_no_order(void * obj,
449 GC_finalization_proc fn, void * cd,
450 GC_finalization_proc *ofn, void ** ocd)
452 void GC_register_finalizer_no_order(obj, fn, cd, ofn, ocd)
454 GC_finalization_proc fn;
456 GC_finalization_proc * ofn;
460 GC_register_finalizer_inner(obj, fn, cd, ofn,
461 ocd, GC_null_finalize_mark_proc);
465 /* Called with world stopped. Cause disappearing links to disappear, */
466 /* and invoke finalizers. */
469 struct disappearing_link * curr_dl, * prev_dl, * next_dl;
470 struct finalizable_object * curr_fo, * prev_fo, * next_fo;
471 ptr_t real_ptr, real_link;
473 int dl_size = (log_dl_table_size == -1 ) ? 0 : (1 << log_dl_table_size);
474 int fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);
476 /* Make disappearing links disappear */
477 for (i = 0; i < dl_size; i++) {
478 curr_dl = dl_head[i];
480 while (curr_dl != 0) {
481 real_ptr = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_obj);
482 real_link = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link);
483 if (!GC_is_marked(real_ptr)) {
484 *(word *)real_link = 0;
485 next_dl = dl_next(curr_dl);
487 dl_head[i] = next_dl;
489 dl_set_next(prev_dl, next_dl);
491 GC_clear_mark_bit((ptr_t)curr_dl);
496 curr_dl = dl_next(curr_dl);
500 /* Mark all objects reachable via chains of 1 or more pointers */
501 /* from finalizable objects. */
503 if (GC_mark_state != MS_NONE) ABORT("Bad mark state");
505 for (i = 0; i < fo_size; i++) {
506 for (curr_fo = fo_head[i]; curr_fo != 0; curr_fo = fo_next(curr_fo)) {
507 real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
508 if (!GC_is_marked(real_ptr)) {
509 (*(curr_fo -> fo_mark_proc))(real_ptr);
510 while (!GC_mark_stack_empty()) GC_mark_from_mark_stack();
511 if (GC_mark_state != MS_NONE) {
512 /* Mark stack overflowed. Very unlikely. */
514 if (GC_mark_state != MS_INVALID) ABORT("Bad mark state");
515 GC_printf0("Mark stack overflowed in finalization!!\n");
517 /* Make mark bits consistent again. Forget about */
518 /* finalizing this object for now. */
519 GC_set_mark_bit(real_ptr);
520 while (!GC_mark_some());
522 if (GC_is_marked(real_ptr)) {
523 WARN("Finalization cycle involving %lx\n", real_ptr);
529 /* Enqueue for finalization all objects that are still */
531 GC_words_finalized = 0;
532 for (i = 0; i < fo_size; i++) {
533 curr_fo = fo_head[i];
535 while (curr_fo != 0) {
536 real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
537 if (!GC_is_marked(real_ptr)) {
538 GC_set_mark_bit(real_ptr);
539 /* Delete from hash table */
540 next_fo = fo_next(curr_fo);
542 fo_head[i] = next_fo;
544 fo_set_next(prev_fo, next_fo);
547 /* Add to list of objects awaiting finalization. */
548 fo_set_next(curr_fo, GC_finalize_now);
549 GC_finalize_now = curr_fo;
550 /* unhide object pointer so any future collections will */
552 curr_fo -> fo_hidden_base =
553 (word) REVEAL_POINTER(curr_fo -> fo_hidden_base);
554 GC_words_finalized +=
555 ALIGNED_WORDS(curr_fo -> fo_object_size)
556 + ALIGNED_WORDS(sizeof(struct finalizable_object));
558 if (!GC_is_marked((ptr_t)curr_fo)) {
559 ABORT("GC_finalize: found accessible unmarked object\n");
565 curr_fo = fo_next(curr_fo);
569 /* Remove dangling disappearing links. */
570 for (i = 0; i < dl_size; i++) {
571 curr_dl = dl_head[i];
573 while (curr_dl != 0) {
574 real_link = GC_base((ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link));
575 if (real_link != 0 && !GC_is_marked(real_link)) {
576 next_dl = dl_next(curr_dl);
578 dl_head[i] = next_dl;
580 dl_set_next(prev_dl, next_dl);
582 GC_clear_mark_bit((ptr_t)curr_dl);
587 curr_dl = dl_next(curr_dl);
593 /* Invoke finalizers for all objects that are ready to be finalized. */
594 /* Should be called without allocation lock. */
595 void GC_invoke_finalizers()
597 register struct finalizable_object * curr_fo;
600 while (GC_finalize_now != 0) {
605 curr_fo = GC_finalize_now;
607 if (curr_fo != 0) GC_finalize_now = fo_next(curr_fo);
610 if (curr_fo == 0) break;
612 GC_finalize_now = fo_next(curr_fo);
614 fo_set_next(curr_fo, 0);
615 (*(curr_fo -> fo_fn))((ptr_t)(curr_fo -> fo_hidden_base),
616 curr_fo -> fo_client_data);
617 curr_fo -> fo_client_data = 0;
619 /* This is probably a bad idea. It throws off accounting if */
620 /* nearly all objects are finalizable. O.w. it shouldn't */
622 GC_free((GC_PTR)curr_fo);
628 GC_PTR GC_call_with_alloc_lock(GC_fn_type fn,
631 GC_PTR GC_call_with_alloc_lock(fn, client_data)
643 result = (*fn)(client_data);