boehm-gc/finalize.c

   1 /*
   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
   6  * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
   7  * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
   8  *
   9  * Permission is hereby granted to use or copy this program
  10  * for any purpose,  provided the above notices are retained on all copies.
  11  * Permission to modify the code and to distribute modified code is granted,
  12  * provided the above notices are retained, and a notice that the code was
  13  * modified is included with the above copyright notice.
  14  */
  15 /* Boehm, February 1, 1996 1:19 pm PST */
  16 # define I_HIDE_POINTERS
  17 # include "gc_priv.h"
  18 # include "gc_mark.h"
  19
  20 # ifdef FINALIZE_ON_DEMAND
  21     int GC_finalize_on_demand = 1;
  22 # else
  23     int GC_finalize_on_demand = 0;
  24 # endif
  25
  26 # ifdef JAVA_FINALIZATION
  27     int GC_java_finalization = 1;
  28 # else
  29     int GC_java_finalization = 0;
  30 # endif
  31
  32 /* Type of mark procedure used for marking from finalizable object.     */
  33 /* This procedure normally does not mark the object, only its           */
  34 /* descendents.                                                         */
  35 typedef void finalization_mark_proc(/* ptr_t finalizable_obj_ptr */);
  36
  37 # define HASH3(addr,size,log_size) \
  38     ((((word)(addr) >> 3) ^ ((word)(addr) >> (3+(log_size)))) \
  39     & ((size) - 1))
  40 #define HASH2(addr,log_size) HASH3(addr, 1 << log_size, log_size)
  41
  42 struct hash_chain_entry {
  43     word hidden_key;
  44     struct hash_chain_entry * next;
  45 };
  46
  47 unsigned GC_finalization_failures = 0;
  48         /* Number of finalization requests that failed for lack of memory. */
  49
  50 static struct disappearing_link {
  51     struct hash_chain_entry prolog;
  52 #   define dl_hidden_link prolog.hidden_key
  53                                 /* Field to be cleared.         */
  54 #   define dl_next(x) (struct disappearing_link *)((x) -> prolog.next)
  55 #   define dl_set_next(x,y) (x) -> prolog.next = (struct hash_chain_entry *)(y)
  56
  57     word dl_hidden_obj;         /* Pointer to object base       */
  58 } **dl_head = 0;
  59
  60 static signed_word log_dl_table_size = -1;
  61                         /* Binary log of                                */
  62                         /* current size of array pointed to by dl_head. */
  63                         /* -1 ==> size is 0.                            */
  64
  65 word GC_dl_entries = 0; /* Number of entries currently in disappearing  */
  66                         /* link table.                                  */
  67
  68 static struct finalizable_object {
  69     struct hash_chain_entry prolog;
  70 #   define fo_hidden_base prolog.hidden_key
  71                                 /* Pointer to object base.      */
  72                                 /* No longer hidden once object */
  73                                 /* is on finalize_now queue.    */
  74 #   define fo_next(x) (struct finalizable_object *)((x) -> prolog.next)
  75 #   define fo_set_next(x,y) (x) -> prolog.next = (struct hash_chain_entry *)(y)
  76     GC_finalization_proc fo_fn; /* Finalizer.                   */
  77     ptr_t fo_client_data;
  78     word fo_object_size;        /* In bytes.                    */
  79     finalization_mark_proc * fo_mark_proc;      /* Mark-through procedure */
  80 } **fo_head = 0;
  81
  82 struct finalizable_object * GC_finalize_now = 0;
  83         /* LIst of objects that should be finalized now.        */
  84
  85 static signed_word log_fo_table_size = -1;
  86
  87 word GC_fo_entries = 0;
  88
  89 # ifdef SRC_M3
  90 void GC_push_finalizer_structures()
  91 {
  92     GC_push_all((ptr_t)(&dl_head), (ptr_t)(&dl_head) + sizeof(word));
  93     GC_push_all((ptr_t)(&fo_head), (ptr_t)(&fo_head) + sizeof(word));
  94 }
  95 # endif
  96
  97 /* Double the size of a hash table. *size_ptr is the log of its current */
  98 /* size.  May be a noop.                                                */
  99 /* *table is a pointer to an array of hash headers.  If we succeed, we  */
 100 /* update both *table and *log_size_ptr.                                */
 101 /* Lock is held.  Signals are disabled.                                 */
 102 void GC_grow_table(table, log_size_ptr)
 103 struct hash_chain_entry ***table;
 104 signed_word * log_size_ptr;
 105 {
 106     register word i;
 107     register struct hash_chain_entry *p;
 108     int log_old_size = *log_size_ptr;
 109     register int log_new_size = log_old_size + 1;
 110     word old_size = ((log_old_size == -1)? 0: (1 << log_old_size));
 111     register word new_size = 1 << log_new_size;
 112     struct hash_chain_entry **new_table = (struct hash_chain_entry **)
 113         GC_generic_malloc_inner_ignore_off_page(
 114                 (size_t)new_size * sizeof(struct hash_chain_entry *), NORMAL);
 115
 116     if (new_table == 0) {
 117         if (table == 0) {
 118             ABORT("Insufficient space for initial table allocation");
 119         } else {
 120             return;
 121         }
 122     }
 123     for (i = 0; i < old_size; i++) {
 124       p = (*table)[i];
 125       while (p != 0) {
 126         register ptr_t real_key = (ptr_t)REVEAL_POINTER(p -> hidden_key);
 127         register struct hash_chain_entry *next = p -> next;
 128         register int new_hash = HASH3(real_key, new_size, log_new_size);
 129
 130         p -> next = new_table[new_hash];
 131         new_table[new_hash] = p;
 132         p = next;
 133       }
 134     }
 135     *log_size_ptr = log_new_size;
 136     *table = new_table;
 137 }
 138
 139 # if defined(__STDC__) || defined(__cplusplus)
 140     int GC_register_disappearing_link(GC_PTR * link)
 141 # else
 142     int GC_register_disappearing_link(link)
 143     GC_PTR * link;
 144 # endif
 145 {
 146     ptr_t base;
 147
 148     base = (ptr_t)GC_base((GC_PTR)link);
 149     if (base == 0)
 150         ABORT("Bad arg to GC_register_disappearing_link");
 151     return(GC_general_register_disappearing_link(link, base));
 152 }
 153
 154 # if defined(__STDC__) || defined(__cplusplus)
 155     int GC_general_register_disappearing_link(GC_PTR * link,
 156                                               GC_PTR obj)
 157 # else
 158     int GC_general_register_disappearing_link(link, obj)
 159     GC_PTR * link;
 160     GC_PTR obj;
 161 # endif
 162
 163 {
 164     struct disappearing_link *curr_dl;
 165     int index;
 166     struct disappearing_link * new_dl;
 167     DCL_LOCK_STATE;
 168
 169     if ((word)link & (ALIGNMENT-1))
 170         ABORT("Bad arg to GC_general_register_disappearing_link");
 171 #   ifdef THREADS
 172         DISABLE_SIGNALS();
 173         LOCK();
 174 #   endif
 175     if (log_dl_table_size == -1
 176         || GC_dl_entries > ((word)1 << log_dl_table_size)) {
 177 #       ifndef THREADS
 178             DISABLE_SIGNALS();
 179 #       endif
 180         GC_grow_table((struct hash_chain_entry ***)(&dl_head),
 181                       &log_dl_table_size);
 182 #       ifdef PRINTSTATS
 183             GC_printf1("Grew dl table to %lu entries\n",
 184                         (unsigned long)(1 << log_dl_table_size));
 185 #       endif
 186 #       ifndef THREADS
 187             ENABLE_SIGNALS();
 188 #       endif
 189     }
 190     index = HASH2(link, log_dl_table_size);
 191     curr_dl = dl_head[index];
 192     for (curr_dl = dl_head[index]; curr_dl != 0; curr_dl = dl_next(curr_dl)) {
 193         if (curr_dl -> dl_hidden_link == HIDE_POINTER(link)) {
 194             curr_dl -> dl_hidden_obj = HIDE_POINTER(obj);
 195 #           ifdef THREADS
 196                 UNLOCK();
 197                 ENABLE_SIGNALS();
 198 #           endif
 199             return(1);
 200         }
 201     }
 202 #   ifdef THREADS
 203       new_dl = (struct disappearing_link *)
 204         GC_generic_malloc_inner(sizeof(struct disappearing_link),NORMAL);
 205 #   else
 206       new_dl = (struct disappearing_link *)
 207         GC_malloc(sizeof(struct disappearing_link));
 208 #   endif
 209     if (new_dl != 0) {
 210         new_dl -> dl_hidden_obj = HIDE_POINTER(obj);
 211         new_dl -> dl_hidden_link = HIDE_POINTER(link);
 212         dl_set_next(new_dl, dl_head[index]);
 213         dl_head[index] = new_dl;
 214         GC_dl_entries++;
 215     } else {
 216         GC_finalization_failures++;
 217     }
 218 #   ifdef THREADS
 219         UNLOCK();
 220         ENABLE_SIGNALS();
 221 #   endif
 222     return(0);
 223 }
 224
 225 # if defined(__STDC__) || defined(__cplusplus)
 226     int GC_unregister_disappearing_link(GC_PTR * link)
 227 # else
 228     int GC_unregister_disappearing_link(link)
 229     GC_PTR * link;
 230 # endif
 231 {
 232     struct disappearing_link *curr_dl, *prev_dl;
 233     int index;
 234     DCL_LOCK_STATE;
 235
 236     DISABLE_SIGNALS();
 237     LOCK();
 238     index = HASH2(link, log_dl_table_size);
 239     if (((unsigned long)link & (ALIGNMENT-1))) goto out;
 240     prev_dl = 0; curr_dl = dl_head[index];
 241     while (curr_dl != 0) {
 242         if (curr_dl -> dl_hidden_link == HIDE_POINTER(link)) {
 243             if (prev_dl == 0) {
 244                 dl_head[index] = dl_next(curr_dl);
 245             } else {
 246                 dl_set_next(prev_dl, dl_next(curr_dl));
 247             }
 248             GC_dl_entries--;
 249             UNLOCK();
 250             ENABLE_SIGNALS();
 251             GC_free((GC_PTR)curr_dl);
 252             return(1);
 253         }
 254         prev_dl = curr_dl;
 255         curr_dl = dl_next(curr_dl);
 256     }
 257 out:
 258     UNLOCK();
 259     ENABLE_SIGNALS();
 260     return(0);
 261 }
 262
 263 /* Possible finalization_marker procedures.  Note that mark stack       */
 264 /* overflow is handled by the caller, and is not a disaster.            */
 265 GC_API void GC_normal_finalize_mark_proc(p)
 266 ptr_t p;
 267 {
 268     hdr * hhdr = HDR(p);
 269
 270     PUSH_OBJ((word *)p, hhdr, GC_mark_stack_top,
 271              &(GC_mark_stack[GC_mark_stack_size]));
 272 }
 273
 274 /* This only pays very partial attention to the mark descriptor.        */
 275 /* It does the right thing for normal and atomic objects, and treats    */
 276 /* most others as normal.                                               */
 277 GC_API void GC_ignore_self_finalize_mark_proc(p)
 278 ptr_t p;
 279 {
 280     hdr * hhdr = HDR(p);
 281     word descr = hhdr -> hb_descr;
 282     ptr_t q, r;
 283     ptr_t scan_limit;
 284     ptr_t target_limit = p + WORDS_TO_BYTES(hhdr -> hb_sz) - 1;
 285
 286     if ((descr & DS_TAGS) == DS_LENGTH) {
 287        scan_limit = p + descr - sizeof(word);
 288     } else {
 289        scan_limit = target_limit + 1 - sizeof(word);
 290     }
 291     for (q = p; q <= scan_limit; q += ALIGNMENT) {
 292         r = *(ptr_t *)q;
 293         if (r < p || r > target_limit) {
 294             GC_PUSH_ONE_HEAP((word)r, q);
 295         }
 296     }
 297 }
 298
 299 /*ARGSUSED*/
 300 GC_API void GC_null_finalize_mark_proc(p)
 301 ptr_t p;
 302 {
 303 }
 304
 305
 306
 307 /* Register a finalization function.  See gc.h for details.     */
 308 /* in the nonthreads case, we try to avoid disabling signals,   */
 309 /* since it can be expensive.  Threads packages typically       */
 310 /* make it cheaper.                                             */
 311 /* The last parameter is a procedure that determines            */
 312 /* marking for finalization ordering.  Any objects marked       */
 313 /* by that procedure will be guaranteed to not have been        */
 314 /* finalized when this finalizer is invoked.                    */
 315 GC_API void GC_register_finalizer_inner(obj, fn, cd, ofn, ocd, mp)
 316 GC_PTR obj;
 317 GC_finalization_proc fn;
 318 GC_PTR cd;
 319 GC_finalization_proc * ofn;
 320 GC_PTR * ocd;
 321 finalization_mark_proc * mp;
 322 {
 323     ptr_t base;
 324     struct finalizable_object * curr_fo, * prev_fo;
 325     int index;
 326     struct finalizable_object *new_fo;
 327     hdr *hhdr;
 328     DCL_LOCK_STATE;
 329
 330 #   ifdef THREADS
 331         DISABLE_SIGNALS();
 332         LOCK();
 333 #   endif
 334     if (log_fo_table_size == -1
 335         || GC_fo_entries > ((word)1 << log_fo_table_size)) {
 336 #       ifndef THREADS
 337             DISABLE_SIGNALS();
 338 #       endif
 339         GC_grow_table((struct hash_chain_entry ***)(&fo_head),
 340                       &log_fo_table_size);
 341 #       ifdef PRINTSTATS
 342             GC_printf1("Grew fo table to %lu entries\n",
 343                         (unsigned long)(1 << log_fo_table_size));
 344 #       endif
 345 #       ifndef THREADS
 346             ENABLE_SIGNALS();
 347 #       endif
 348     }
 349     /* in the THREADS case signals are disabled and we hold allocation  */
 350     /* lock; otherwise neither is true.  Proceed carefully.             */
 351     base = (ptr_t)obj;
 352     index = HASH2(base, log_fo_table_size);
 353     prev_fo = 0; curr_fo = fo_head[index];
 354     while (curr_fo != 0) {
 355         if (curr_fo -> fo_hidden_base == HIDE_POINTER(base)) {
 356             /* Interruption by a signal in the middle of this   */
 357             /* should be safe.  The client may see only *ocd    */
 358             /* updated, but we'll declare that to be his        */
 359             /* problem.                                         */
 360             if (ocd) *ocd = (GC_PTR) curr_fo -> fo_client_data;
 361             if (ofn) *ofn = curr_fo -> fo_fn;
 362             /* Delete the structure for base. */
 363                 if (prev_fo == 0) {
 364                   fo_head[index] = fo_next(curr_fo);
 365                 } else {
 366                   fo_set_next(prev_fo, fo_next(curr_fo));
 367                 }
 368             if (fn == 0) {
 369                 GC_fo_entries--;
 370                   /* May not happen if we get a signal.  But a high     */
 371                   /* estimate will only make the table larger than      */
 372                   /* necessary.                                         */
 373 #               ifndef THREADS
 374                   GC_free((GC_PTR)curr_fo);
 375 #               endif
 376             } else {
 377                 curr_fo -> fo_fn = fn;
 378                 curr_fo -> fo_client_data = (ptr_t)cd;
 379                 curr_fo -> fo_mark_proc = mp;
 380                 /* Reinsert it.  We deleted it first to maintain        */
 381                 /* consistency in the event of a signal.                */
 382                 if (prev_fo == 0) {
 383                   fo_head[index] = curr_fo;
 384                 } else {
 385                   fo_set_next(prev_fo, curr_fo);
 386                 }
 387             }
 388 #           ifdef THREADS
 389                 UNLOCK();
 390                 ENABLE_SIGNALS();
 391 #           endif
 392             return;
 393         }
 394         prev_fo = curr_fo;
 395         curr_fo = fo_next(curr_fo);
 396     }
 397     if (ofn) *ofn = 0;
 398     if (ocd) *ocd = 0;
 399     if (fn == 0) {
 400 #       ifdef THREADS
 401             UNLOCK();
 402             ENABLE_SIGNALS();
 403 #       endif
 404         return;
 405     }
 406     GET_HDR(base, hhdr);
 407     if (0 == hhdr) {
 408       /* We won't collect it, hence finalizer wouldn't be run. */
 409       /* This is changed for gcj, but it will be in version 6.0 of the  */
 410       /* standard collector distribution.  It costs virtually nothing   */
 411       /* here, but it's expensive to check in the hash synchronization  */
 412       /* code, where it matters.                -HB                     */
 413 #     ifdef THREADS
 414           UNLOCK();
 415           ENABLE_SIGNALS();
 416 #     endif
 417       return;
 418     }
 419 #   ifdef THREADS
 420       new_fo = (struct finalizable_object *)
 421         GC_generic_malloc_inner(sizeof(struct finalizable_object),NORMAL);
 422 #   else
 423       new_fo = (struct finalizable_object *)
 424         GC_malloc(sizeof(struct finalizable_object));
 425 #   endif
 426     if (new_fo != 0) {
 427         new_fo -> fo_hidden_base = (word)HIDE_POINTER(base);
 428         new_fo -> fo_fn = fn;
 429         new_fo -> fo_client_data = (ptr_t)cd;
 430         new_fo -> fo_object_size = hhdr -> hb_sz;
 431         new_fo -> fo_mark_proc = mp;
 432         fo_set_next(new_fo, fo_head[index]);
 433         GC_fo_entries++;
 434         fo_head[index] = new_fo;
 435     } else {
 436         GC_finalization_failures++;
 437     }
 438 #   ifdef THREADS
 439         UNLOCK();
 440         ENABLE_SIGNALS();
 441 #   endif
 442 }
 443
 444 # if defined(__STDC__)
 445     void GC_register_finalizer(void * obj,
 446                                GC_finalization_proc fn, void * cd,
 447                                GC_finalization_proc *ofn, void ** ocd)
 448 # else
 449     void GC_register_finalizer(obj, fn, cd, ofn, ocd)
 450     GC_PTR obj;
 451     GC_finalization_proc fn;
 452     GC_PTR cd;
 453     GC_finalization_proc * ofn;
 454     GC_PTR * ocd;
 455 # endif
 456 {
 457     GC_register_finalizer_inner(obj, fn, cd, ofn,
 458                                 ocd, GC_normal_finalize_mark_proc);
 459 }
 460
 461 # if defined(__STDC__)
 462     void GC_register_finalizer_ignore_self(void * obj,
 463                                GC_finalization_proc fn, void * cd,
 464                                GC_finalization_proc *ofn, void ** ocd)
 465 # else
 466     void GC_register_finalizer_ignore_self(obj, fn, cd, ofn, ocd)
 467     GC_PTR obj;
 468     GC_finalization_proc fn;
 469     GC_PTR cd;
 470     GC_finalization_proc * ofn;
 471     GC_PTR * ocd;
 472 # endif
 473 {
 474     GC_register_finalizer_inner(obj, fn, cd, ofn,
 475                                 ocd, GC_ignore_self_finalize_mark_proc);
 476 }
 477
 478 # if defined(__STDC__)
 479     void GC_register_finalizer_no_order(void * obj,
 480                                GC_finalization_proc fn, void * cd,
 481                                GC_finalization_proc *ofn, void ** ocd)
 482 # else
 483     void GC_register_finalizer_no_order(obj, fn, cd, ofn, ocd)
 484     GC_PTR obj;
 485     GC_finalization_proc fn;
 486     GC_PTR cd;
 487     GC_finalization_proc * ofn;
 488     GC_PTR * ocd;
 489 # endif
 490 {
 491     GC_register_finalizer_inner(obj, fn, cd, ofn,
 492                                 ocd, GC_null_finalize_mark_proc);
 493 }
 494
 495 /* Called with world stopped.  Cause disappearing links to disappear,   */
 496 /* and invoke finalizers.                                               */
 497 void GC_finalize()
 498 {
 499     struct disappearing_link * curr_dl, * prev_dl, * next_dl;
 500     struct finalizable_object * curr_fo, * prev_fo, * next_fo;
 501     ptr_t real_ptr, real_link;
 502     register int i;
 503     int dl_size = (log_dl_table_size == -1 ) ? 0 : (1 << log_dl_table_size);
 504     int fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);
 505
 506   /* Make disappearing links disappear */
 507     for (i = 0; i < dl_size; i++) {
 508       curr_dl = dl_head[i];
 509       prev_dl = 0;
 510       while (curr_dl != 0) {
 511         real_ptr = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_obj);
 512         real_link = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link);
 513         if (!GC_is_marked(real_ptr)) {
 514             *(word *)real_link = 0;
 515             next_dl = dl_next(curr_dl);
 516             if (prev_dl == 0) {
 517                 dl_head[i] = next_dl;
 518             } else {
 519                 dl_set_next(prev_dl, next_dl);
 520             }
 521             GC_clear_mark_bit((ptr_t)curr_dl);
 522             GC_dl_entries--;
 523             curr_dl = next_dl;
 524         } else {
 525             prev_dl = curr_dl;
 526             curr_dl = dl_next(curr_dl);
 527         }
 528       }
 529     }
 530   /* Mark all objects reachable via chains of 1 or more pointers        */
 531   /* from finalizable objects.                                          */
 532 #   ifdef PRINTSTATS
 533         if (GC_mark_state != MS_NONE) ABORT("Bad mark state");
 534 #   endif
 535     for (i = 0; i < fo_size; i++) {
 536       for (curr_fo = fo_head[i]; curr_fo != 0; curr_fo = fo_next(curr_fo)) {
 537         real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 538         if (!GC_is_marked(real_ptr)) {
 539             GC_MARKED_FOR_FINALIZATION(real_ptr);
 540             GC_MARK_FO(real_ptr, curr_fo -> fo_mark_proc);
 541             if (GC_is_marked(real_ptr)) {
 542                 WARN("Finalization cycle involving %lx\n", real_ptr);
 543             }
 544         }
 545       }
 546     }
 547   /* Enqueue for finalization all objects that are still                */
 548   /* unreachable.                                                       */
 549     GC_words_finalized = 0;
 550     for (i = 0; i < fo_size; i++) {
 551       curr_fo = fo_head[i];
 552       prev_fo = 0;
 553       while (curr_fo != 0) {
 554         real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 555         if (!GC_is_marked(real_ptr)) {
 556             if (!GC_java_finalization) {
 557               GC_set_mark_bit(real_ptr);
 558             }
 559             /* Delete from hash table */
 560               next_fo = fo_next(curr_fo);
 561               if (prev_fo == 0) {
 562                 fo_head[i] = next_fo;
 563               } else {
 564                 fo_set_next(prev_fo, next_fo);
 565               }
 566               GC_fo_entries--;
 567             /* Add to list of objects awaiting finalization.    */
 568               fo_set_next(curr_fo, GC_finalize_now);
 569               GC_finalize_now = curr_fo;
 570               /* unhide object pointer so any future collections will   */
 571               /* see it.                                                */
 572               curr_fo -> fo_hidden_base =
 573                         (word) REVEAL_POINTER(curr_fo -> fo_hidden_base);
 574               GC_words_finalized +=
 575                         ALIGNED_WORDS(curr_fo -> fo_object_size)
 576                         + ALIGNED_WORDS(sizeof(struct finalizable_object));
 577 #           ifdef PRINTSTATS
 578               if (!GC_is_marked((ptr_t)curr_fo)) {
 579                 ABORT("GC_finalize: found accessible unmarked object\n");
 580               }
 581 #           endif
 582             curr_fo = next_fo;
 583         } else {
 584             prev_fo = curr_fo;
 585             curr_fo = fo_next(curr_fo);
 586         }
 587       }
 588     }
 589
 590   if (GC_java_finalization) {
 591     /* make sure we mark everything reachable from objects finalized
 592        using the no_order mark_proc */
 593       for (curr_fo = GC_finalize_now;
 594          curr_fo != NULL; curr_fo = fo_next(curr_fo)) {
 595         real_ptr = (ptr_t)curr_fo -> fo_hidden_base;
 596         if (!GC_is_marked(real_ptr)) {
 597             if (curr_fo -> fo_mark_proc == GC_null_finalize_mark_proc) {
 598                 GC_MARK_FO(real_ptr, GC_normal_finalize_mark_proc);
 599             }
 600             GC_set_mark_bit(real_ptr);
 601         }
 602       }
 603   }
 604
 605   /* Remove dangling disappearing links. */
 606     for (i = 0; i < dl_size; i++) {
 607       curr_dl = dl_head[i];
 608       prev_dl = 0;
 609       while (curr_dl != 0) {
 610         real_link = GC_base((ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link));
 611         if (real_link != 0 && !GC_is_marked(real_link)) {
 612             next_dl = dl_next(curr_dl);
 613             if (prev_dl == 0) {
 614                 dl_head[i] = next_dl;
 615             } else {
 616                 dl_set_next(prev_dl, next_dl);
 617             }
 618             GC_clear_mark_bit((ptr_t)curr_dl);
 619             GC_dl_entries--;
 620             curr_dl = next_dl;
 621         } else {
 622             prev_dl = curr_dl;
 623             curr_dl = dl_next(curr_dl);
 624         }
 625       }
 626     }
 627 }
 628
 629 #ifndef JAVA_FINALIZATION_NOT_NEEDED
 630
 631 /* Enqueue all remaining finalizers to be run - Assumes lock is
 632  * held, and signals are disabled */
 633 void GC_enqueue_all_finalizers()
 634 {
 635     struct finalizable_object * curr_fo, * prev_fo, * next_fo;
 636     ptr_t real_ptr;
 637     register int i;
 638     int fo_size;
 639
 640     fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);
 641     GC_words_finalized = 0;
 642     for (i = 0; i < fo_size; i++) {
 643         curr_fo = fo_head[i];
 644         prev_fo = 0;
 645       while (curr_fo != 0) {
 646           real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 647           GC_MARK_FO(real_ptr, GC_normal_finalize_mark_proc);
 648           GC_set_mark_bit(real_ptr);
 649
 650           /* Delete from hash table */
 651           next_fo = fo_next(curr_fo);
 652           if (prev_fo == 0) {
 653               fo_head[i] = next_fo;
 654           } else {
 655               fo_set_next(prev_fo, next_fo);
 656           }
 657           GC_fo_entries--;
 658
 659           /* Add to list of objects awaiting finalization.      */
 660           fo_set_next(curr_fo, GC_finalize_now);
 661           GC_finalize_now = curr_fo;
 662
 663           /* unhide object pointer so any future collections will       */
 664           /* see it.                                            */
 665           curr_fo -> fo_hidden_base =
 666                         (word) REVEAL_POINTER(curr_fo -> fo_hidden_base);
 667
 668           GC_words_finalized +=
 669                 ALIGNED_WORDS(curr_fo -> fo_object_size)
 670                         + ALIGNED_WORDS(sizeof(struct finalizable_object));
 671           curr_fo = next_fo;
 672         }
 673     }
 674
 675     return;
 676 }
 677
 678 /* Invoke all remaining finalizers that haven't yet been run.
 679  * This is needed for strict compliance with the Java standard,
 680  * which can make the runtime guarantee that all finalizers are run.
 681  * Unfortunately, the Java standard implies we have to keep running
 682  * finalizers until there are no more left, a potential infinite loop.
 683  * YUCK.
 684  * Note that this is even more dangerous than the usual Java
 685  * finalizers, in that objects reachable from static variables
 686  * may have been finalized when these finalizers are run.
 687  * Finalizers run at this point must be prepared to deal with a
 688  * mostly broken world.
 689  * This routine is externally callable, so is called without
 690  * the allocation lock.
 691  */
 692 GC_API void GC_finalize_all()
 693 {
 694     DCL_LOCK_STATE;
 695
 696     DISABLE_SIGNALS();
 697     LOCK();
 698     while (GC_fo_entries > 0) {
 699       GC_enqueue_all_finalizers();
 700       UNLOCK();
 701       ENABLE_SIGNALS();
 702       GC_INVOKE_FINALIZERS();
 703       DISABLE_SIGNALS();
 704       LOCK();
 705     }
 706     UNLOCK();
 707     ENABLE_SIGNALS();
 708 }
 709 #endif
 710
 711 /* Returns true if it is worth calling GC_invoke_finalizers. (Useful if */
 712 /* finalizers can only be called from some kind of `safe state' and     */
 713 /* getting into that safe state is expensive.)                          */
 714 int GC_should_invoke_finalizers GC_PROTO((void))
 715 {
 716     return GC_finalize_now != 0;
 717 }
 718
 719 /* Invoke finalizers for all objects that are ready to be finalized.    */
 720 /* Should be called without allocation lock.                            */
 721 int GC_invoke_finalizers()
 722 {
 723     register struct finalizable_object * curr_fo;
 724     register int count = 0;
 725     DCL_LOCK_STATE;
 726
 727     while (GC_finalize_now != 0) {
 728 #       ifdef THREADS
 729             DISABLE_SIGNALS();
 730             LOCK();
 731 #       endif
 732         curr_fo = GC_finalize_now;
 733 #       ifdef THREADS
 734             if (curr_fo != 0) GC_finalize_now = fo_next(curr_fo);
 735             UNLOCK();
 736             ENABLE_SIGNALS();
 737             if (curr_fo == 0) break;
 738 #       else
 739             GC_finalize_now = fo_next(curr_fo);
 740 #       endif
 741         fo_set_next(curr_fo, 0);
 742         (*(curr_fo -> fo_fn))((ptr_t)(curr_fo -> fo_hidden_base),
 743                               curr_fo -> fo_client_data);
 744         curr_fo -> fo_client_data = 0;
 745         ++count;
 746 #       ifdef UNDEFINED
 747             /* This is probably a bad idea.  It throws off accounting if */
 748             /* nearly all objects are finalizable.  O.w. it shouldn't    */
 749             /* matter.                                                   */
 750             GC_free((GC_PTR)curr_fo);
 751 #       endif
 752     }
 753     return count;
 754 }
 755
 756 # ifdef __STDC__
 757     GC_PTR GC_call_with_alloc_lock(GC_fn_type fn,
 758                                          GC_PTR client_data)
 759 # else
 760     GC_PTR GC_call_with_alloc_lock(fn, client_data)
 761     GC_fn_type fn;
 762     GC_PTR client_data;
 763 # endif
 764 {
 765     GC_PTR result;
 766     DCL_LOCK_STATE;
 767
 768 #   ifdef THREADS
 769       DISABLE_SIGNALS();
 770       LOCK();
 771       SET_LOCK_HOLDER();
 772 #   endif
 773     result = (*fn)(client_data);
 774 #   ifdef THREADS
 775       UNSET_LOCK_HOLDER();
 776       UNLOCK();
 777       ENABLE_SIGNALS();
 778 #   endif
 779     return(result);
 780 }