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 "private/gc_pmark.h"
  18
  19 # ifdef FINALIZE_ON_DEMAND
  20     int GC_finalize_on_demand = 1;
  21 # else
  22     int GC_finalize_on_demand = 0;
  23 # endif
  24
  25 # ifdef JAVA_FINALIZATION
  26     int GC_java_finalization = 1;
  27 # else
  28     int GC_java_finalization = 0;
  29 # endif
  30
  31 /* Type of mark procedure used for marking from finalizable object.     */
  32 /* This procedure normally does not mark the object, only its           */
  33 /* descendents.                                                         */
  34 typedef void finalization_mark_proc(/* ptr_t finalizable_obj_ptr */);
  35
  36 # define HASH3(addr,size,log_size) \
  37     ((((word)(addr) >> 3) ^ ((word)(addr) >> (3+(log_size)))) \
  38     & ((size) - 1))
  39 #define HASH2(addr,log_size) HASH3(addr, 1 << log_size, log_size)
  40
  41 struct hash_chain_entry {
  42     word hidden_key;
  43     struct hash_chain_entry * next;
  44 };
  45
  46 unsigned GC_finalization_failures = 0;
  47         /* Number of finalization requests that failed for lack of memory. */
  48
  49 static struct disappearing_link {
  50     struct hash_chain_entry prolog;
  51 #   define dl_hidden_link prolog.hidden_key
  52                                 /* Field to be cleared.         */
  53 #   define dl_next(x) (struct disappearing_link *)((x) -> prolog.next)
  54 #   define dl_set_next(x,y) (x) -> prolog.next = (struct hash_chain_entry *)(y)
  55
  56     word dl_hidden_obj;         /* Pointer to object base       */
  57 } **dl_head = 0;
  58
  59 static signed_word log_dl_table_size = -1;
  60                         /* Binary log of                                */
  61                         /* current size of array pointed to by dl_head. */
  62                         /* -1 ==> size is 0.                            */
  63
  64 word GC_dl_entries = 0; /* Number of entries currently in disappearing  */
  65                         /* link table.                                  */
  66
  67 static struct finalizable_object {
  68     struct hash_chain_entry prolog;
  69 #   define fo_hidden_base prolog.hidden_key
  70                                 /* Pointer to object base.      */
  71                                 /* No longer hidden once object */
  72                                 /* is on finalize_now queue.    */
  73 #   define fo_next(x) (struct finalizable_object *)((x) -> prolog.next)
  74 #   define fo_set_next(x,y) (x) -> prolog.next = (struct hash_chain_entry *)(y)
  75     GC_finalization_proc fo_fn; /* Finalizer.                   */
  76     ptr_t fo_client_data;
  77     word fo_object_size;        /* In bytes.                    */
  78     finalization_mark_proc * fo_mark_proc;      /* Mark-through procedure */
  79 } **fo_head = 0;
  80
  81 struct finalizable_object * GC_finalize_now = 0;
  82         /* LIst of objects that should be finalized now.        */
  83
  84 static signed_word log_fo_table_size = -1;
  85
  86 word GC_fo_entries = 0;
  87
  88 void GC_push_finalizer_structures GC_PROTO((void))
  89 {
  90     GC_push_all((ptr_t)(&dl_head), (ptr_t)(&dl_head) + sizeof(word));
  91     GC_push_all((ptr_t)(&fo_head), (ptr_t)(&fo_head) + sizeof(word));
  92     GC_push_all((ptr_t)(&GC_finalize_now),
  93                 (ptr_t)(&GC_finalize_now) + sizeof(word));
  94 }
  95
  96 /* Double the size of a hash table. *size_ptr is the log of its current */
  97 /* size.  May be a noop.                                                */
  98 /* *table is a pointer to an array of hash headers.  If we succeed, we  */
  99 /* update both *table and *log_size_ptr.                                */
 100 /* Lock is held.  Signals are disabled.                                 */
 101 void GC_grow_table(table, log_size_ptr)
 102 struct hash_chain_entry ***table;
 103 signed_word * log_size_ptr;
 104 {
 105     register word i;
 106     register struct hash_chain_entry *p;
 107     int log_old_size = *log_size_ptr;
 108     register int log_new_size = log_old_size + 1;
 109     word old_size = ((log_old_size == -1)? 0: (1 << log_old_size));
 110     register word new_size = 1 << log_new_size;
 111     struct hash_chain_entry **new_table = (struct hash_chain_entry **)
 112         GC_INTERNAL_MALLOC_IGNORE_OFF_PAGE(
 113                 (size_t)new_size * sizeof(struct hash_chain_entry *), NORMAL);
 114
 115     if (new_table == 0) {
 116         if (table == 0) {
 117             ABORT("Insufficient space for initial table allocation");
 118         } else {
 119             return;
 120         }
 121     }
 122     for (i = 0; i < old_size; i++) {
 123       p = (*table)[i];
 124       while (p != 0) {
 125         register ptr_t real_key = (ptr_t)REVEAL_POINTER(p -> hidden_key);
 126         register struct hash_chain_entry *next = p -> next;
 127         register int new_hash = HASH3(real_key, new_size, log_new_size);
 128
 129         p -> next = new_table[new_hash];
 130         new_table[new_hash] = p;
 131         p = next;
 132       }
 133     }
 134     *log_size_ptr = log_new_size;
 135     *table = new_table;
 136 }
 137
 138 # if defined(__STDC__) || defined(__cplusplus)
 139     int GC_register_disappearing_link(GC_PTR * link)
 140 # else
 141     int GC_register_disappearing_link(link)
 142     GC_PTR * link;
 143 # endif
 144 {
 145     ptr_t base;
 146
 147     base = (ptr_t)GC_base((GC_PTR)link);
 148     if (base == 0)
 149         ABORT("Bad arg to GC_register_disappearing_link");
 150     return(GC_general_register_disappearing_link(link, base));
 151 }
 152
 153 # if defined(__STDC__) || defined(__cplusplus)
 154     int GC_general_register_disappearing_link(GC_PTR * link,
 155                                               GC_PTR obj)
 156 # else
 157     int GC_general_register_disappearing_link(link, obj)
 158     GC_PTR * link;
 159     GC_PTR obj;
 160 # endif
 161
 162 {
 163     struct disappearing_link *curr_dl;
 164     int index;
 165     struct disappearing_link * new_dl;
 166     DCL_LOCK_STATE;
 167
 168     if ((word)link & (ALIGNMENT-1))
 169         ABORT("Bad arg to GC_general_register_disappearing_link");
 170 #   ifdef THREADS
 171         DISABLE_SIGNALS();
 172         LOCK();
 173 #   endif
 174     if (log_dl_table_size == -1
 175         || GC_dl_entries > ((word)1 << log_dl_table_size)) {
 176 #       ifndef THREADS
 177             DISABLE_SIGNALS();
 178 #       endif
 179         GC_grow_table((struct hash_chain_entry ***)(&dl_head),
 180                       &log_dl_table_size);
 181 #       ifdef CONDPRINT
 182           if (GC_print_stats) {
 183             GC_printf1("Grew dl table to %lu entries\n",
 184                         (unsigned long)(1 << log_dl_table_size));
 185           }
 186 #       endif
 187 #       ifndef THREADS
 188             ENABLE_SIGNALS();
 189 #       endif
 190     }
 191     index = HASH2(link, log_dl_table_size);
 192     curr_dl = dl_head[index];
 193     for (curr_dl = dl_head[index]; curr_dl != 0; curr_dl = dl_next(curr_dl)) {
 194         if (curr_dl -> dl_hidden_link == HIDE_POINTER(link)) {
 195             curr_dl -> dl_hidden_obj = HIDE_POINTER(obj);
 196 #           ifdef THREADS
 197                 UNLOCK();
 198                 ENABLE_SIGNALS();
 199 #           endif
 200             return(1);
 201         }
 202     }
 203     new_dl = (struct disappearing_link *)
 204         GC_INTERNAL_MALLOC(sizeof(struct disappearing_link),NORMAL);
 205     if (0 == new_dl) {
 206 #     ifdef THREADS
 207         UNLOCK();
 208         ENABLE_SIGNALS();
 209 #     endif
 210       new_dl = GC_oom_fn(sizeof(struct disappearing_link));
 211       if (0 == new_dl) {
 212         GC_finalization_failures++;
 213         return(0);
 214       }
 215       /* It's not likely we'll make it here, but ... */
 216 #     ifdef THREADS
 217         DISABLE_SIGNALS();
 218         LOCK();
 219 #     endif
 220     }
 221     new_dl -> dl_hidden_obj = HIDE_POINTER(obj);
 222     new_dl -> dl_hidden_link = HIDE_POINTER(link);
 223     dl_set_next(new_dl, dl_head[index]);
 224     dl_head[index] = new_dl;
 225     GC_dl_entries++;
 226 #   ifdef THREADS
 227         UNLOCK();
 228         ENABLE_SIGNALS();
 229 #   endif
 230     return(0);
 231 }
 232
 233 # if defined(__STDC__) || defined(__cplusplus)
 234     int GC_unregister_disappearing_link(GC_PTR * link)
 235 # else
 236     int GC_unregister_disappearing_link(link)
 237     GC_PTR * link;
 238 # endif
 239 {
 240     struct disappearing_link *curr_dl, *prev_dl;
 241     int index;
 242     DCL_LOCK_STATE;
 243
 244     DISABLE_SIGNALS();
 245     LOCK();
 246     index = HASH2(link, log_dl_table_size);
 247     if (((unsigned long)link & (ALIGNMENT-1))) goto out;
 248     prev_dl = 0; curr_dl = dl_head[index];
 249     while (curr_dl != 0) {
 250         if (curr_dl -> dl_hidden_link == HIDE_POINTER(link)) {
 251             if (prev_dl == 0) {
 252                 dl_head[index] = dl_next(curr_dl);
 253             } else {
 254                 dl_set_next(prev_dl, dl_next(curr_dl));
 255             }
 256             GC_dl_entries--;
 257             UNLOCK();
 258             ENABLE_SIGNALS();
 259 #           ifdef DBG_HDRS_ALL
 260               dl_set_next(curr_dl, 0);
 261 #           else
 262               GC_free((GC_PTR)curr_dl);
 263 #           endif
 264             return(1);
 265         }
 266         prev_dl = curr_dl;
 267         curr_dl = dl_next(curr_dl);
 268     }
 269 out:
 270     UNLOCK();
 271     ENABLE_SIGNALS();
 272     return(0);
 273 }
 274
 275 /* Possible finalization_marker procedures.  Note that mark stack       */
 276 /* overflow is handled by the caller, and is not a disaster.            */
 277 GC_API void GC_normal_finalize_mark_proc(p)
 278 ptr_t p;
 279 {
 280     hdr * hhdr = HDR(p);
 281
 282     PUSH_OBJ((word *)p, hhdr, GC_mark_stack_top,
 283              &(GC_mark_stack[GC_mark_stack_size]));
 284 }
 285
 286 /* This only pays very partial attention to the mark descriptor.        */
 287 /* It does the right thing for normal and atomic objects, and treats    */
 288 /* most others as normal.                                               */
 289 GC_API void GC_ignore_self_finalize_mark_proc(p)
 290 ptr_t p;
 291 {
 292     hdr * hhdr = HDR(p);
 293     word descr = hhdr -> hb_descr;
 294     ptr_t q, r;
 295     ptr_t scan_limit;
 296     ptr_t target_limit = p + WORDS_TO_BYTES(hhdr -> hb_sz) - 1;
 297
 298     if ((descr & GC_DS_TAGS) == GC_DS_LENGTH) {
 299        scan_limit = p + descr - sizeof(word);
 300     } else {
 301        scan_limit = target_limit + 1 - sizeof(word);
 302     }
 303     for (q = p; q <= scan_limit; q += ALIGNMENT) {
 304         r = *(ptr_t *)q;
 305         if (r < p || r > target_limit) {
 306             GC_PUSH_ONE_HEAP((word)r, q);
 307         }
 308     }
 309 }
 310
 311 /*ARGSUSED*/
 312 GC_API void GC_null_finalize_mark_proc(p)
 313 ptr_t p;
 314 {
 315 }
 316
 317
 318
 319 /* Register a finalization function.  See gc.h for details.     */
 320 /* in the nonthreads case, we try to avoid disabling signals,   */
 321 /* since it can be expensive.  Threads packages typically       */
 322 /* make it cheaper.                                             */
 323 /* The last parameter is a procedure that determines            */
 324 /* marking for finalization ordering.  Any objects marked       */
 325 /* by that procedure will be guaranteed to not have been        */
 326 /* finalized when this finalizer is invoked.                    */
 327 GC_API void GC_register_finalizer_inner(obj, fn, cd, ofn, ocd, mp)
 328 GC_PTR obj;
 329 GC_finalization_proc fn;
 330 GC_PTR cd;
 331 GC_finalization_proc * ofn;
 332 GC_PTR * ocd;
 333 finalization_mark_proc * mp;
 334 {
 335     ptr_t base;
 336     struct finalizable_object * curr_fo, * prev_fo;
 337     int index;
 338     struct finalizable_object *new_fo;
 339     hdr *hhdr;
 340     DCL_LOCK_STATE;
 341
 342 #   ifdef THREADS
 343         DISABLE_SIGNALS();
 344         LOCK();
 345 #   endif
 346     if (log_fo_table_size == -1
 347         || GC_fo_entries > ((word)1 << log_fo_table_size)) {
 348 #       ifndef THREADS
 349             DISABLE_SIGNALS();
 350 #       endif
 351         GC_grow_table((struct hash_chain_entry ***)(&fo_head),
 352                       &log_fo_table_size);
 353 #       ifdef CONDPRINT
 354           if (GC_print_stats) {
 355             GC_printf1("Grew fo table to %lu entries\n",
 356                         (unsigned long)(1 << log_fo_table_size));
 357           }
 358 #       endif
 359 #       ifndef THREADS
 360             ENABLE_SIGNALS();
 361 #       endif
 362     }
 363     /* in the THREADS case signals are disabled and we hold allocation  */
 364     /* lock; otherwise neither is true.  Proceed carefully.             */
 365     base = (ptr_t)obj;
 366     index = HASH2(base, log_fo_table_size);
 367     prev_fo = 0; curr_fo = fo_head[index];
 368     while (curr_fo != 0) {
 369         if (curr_fo -> fo_hidden_base == HIDE_POINTER(base)) {
 370             /* Interruption by a signal in the middle of this   */
 371             /* should be safe.  The client may see only *ocd    */
 372             /* updated, but we'll declare that to be his        */
 373             /* problem.                                         */
 374             if (ocd) *ocd = (GC_PTR) curr_fo -> fo_client_data;
 375             if (ofn) *ofn = curr_fo -> fo_fn;
 376             /* Delete the structure for base. */
 377                 if (prev_fo == 0) {
 378                   fo_head[index] = fo_next(curr_fo);
 379                 } else {
 380                   fo_set_next(prev_fo, fo_next(curr_fo));
 381                 }
 382             if (fn == 0) {
 383                 GC_fo_entries--;
 384                   /* May not happen if we get a signal.  But a high     */
 385                   /* estimate will only make the table larger than      */
 386                   /* necessary.                                         */
 387 #               if !defined(THREADS) && !defined(DBG_HDRS_ALL)
 388                   GC_free((GC_PTR)curr_fo);
 389 #               endif
 390             } else {
 391                 curr_fo -> fo_fn = fn;
 392                 curr_fo -> fo_client_data = (ptr_t)cd;
 393                 curr_fo -> fo_mark_proc = mp;
 394                 /* Reinsert it.  We deleted it first to maintain        */
 395                 /* consistency in the event of a signal.                */
 396                 if (prev_fo == 0) {
 397                   fo_head[index] = curr_fo;
 398                 } else {
 399                   fo_set_next(prev_fo, curr_fo);
 400                 }
 401             }
 402 #           ifdef THREADS
 403                 UNLOCK();
 404                 ENABLE_SIGNALS();
 405 #           endif
 406             return;
 407         }
 408         prev_fo = curr_fo;
 409         curr_fo = fo_next(curr_fo);
 410     }
 411     if (ofn) *ofn = 0;
 412     if (ocd) *ocd = 0;
 413     if (fn == 0) {
 414 #       ifdef THREADS
 415             UNLOCK();
 416             ENABLE_SIGNALS();
 417 #       endif
 418         return;
 419     }
 420     GET_HDR(base, hhdr);
 421     if (0 == hhdr) {
 422       /* We won't collect it, hence finalizer wouldn't be run. */
 423 #     ifdef THREADS
 424           UNLOCK();
 425           ENABLE_SIGNALS();
 426 #     endif
 427       return;
 428     }
 429     new_fo = (struct finalizable_object *)
 430         GC_INTERNAL_MALLOC(sizeof(struct finalizable_object),NORMAL);
 431     if (0 == new_fo) {
 432 #     ifdef THREADS
 433         UNLOCK();
 434         ENABLE_SIGNALS();
 435 #     endif
 436       new_fo = GC_oom_fn(sizeof(struct finalizable_object));
 437       if (0 == new_fo) {
 438         GC_finalization_failures++;
 439         return;
 440       }
 441       /* It's not likely we'll make it here, but ... */
 442 #     ifdef THREADS
 443         DISABLE_SIGNALS();
 444         LOCK();
 445 #     endif
 446     }
 447     new_fo -> fo_hidden_base = (word)HIDE_POINTER(base);
 448     new_fo -> fo_fn = fn;
 449     new_fo -> fo_client_data = (ptr_t)cd;
 450     new_fo -> fo_object_size = hhdr -> hb_sz;
 451     new_fo -> fo_mark_proc = mp;
 452     fo_set_next(new_fo, fo_head[index]);
 453     GC_fo_entries++;
 454     fo_head[index] = new_fo;
 455 #   ifdef THREADS
 456         UNLOCK();
 457         ENABLE_SIGNALS();
 458 #   endif
 459 }
 460
 461 # if defined(__STDC__)
 462     void GC_register_finalizer(void * obj,
 463                                GC_finalization_proc fn, void * cd,
 464                                GC_finalization_proc *ofn, void ** ocd)
 465 # else
 466     void GC_register_finalizer(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_normal_finalize_mark_proc);
 476 }
 477
 478 # if defined(__STDC__)
 479     void GC_register_finalizer_ignore_self(void * obj,
 480                                GC_finalization_proc fn, void * cd,
 481                                GC_finalization_proc *ofn, void ** ocd)
 482 # else
 483     void GC_register_finalizer_ignore_self(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_ignore_self_finalize_mark_proc);
 493 }
 494
 495 # if defined(__STDC__)
 496     void GC_register_finalizer_no_order(void * obj,
 497                                GC_finalization_proc fn, void * cd,
 498                                GC_finalization_proc *ofn, void ** ocd)
 499 # else
 500     void GC_register_finalizer_no_order(obj, fn, cd, ofn, ocd)
 501     GC_PTR obj;
 502     GC_finalization_proc fn;
 503     GC_PTR cd;
 504     GC_finalization_proc * ofn;
 505     GC_PTR * ocd;
 506 # endif
 507 {
 508     GC_register_finalizer_inner(obj, fn, cd, ofn,
 509                                 ocd, GC_null_finalize_mark_proc);
 510 }
 511
 512 #ifndef NO_DEBUGGING
 513 void GC_dump_finalization()
 514 {
 515     struct disappearing_link * curr_dl;
 516     struct finalizable_object * curr_fo;
 517     ptr_t real_ptr, real_link;
 518     int dl_size = (log_dl_table_size == -1 ) ? 0 : (1 << log_dl_table_size);
 519     int fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);
 520     int i;
 521
 522     GC_printf0("Disappearing links:\n");
 523     for (i = 0; i < dl_size; i++) {
 524       for (curr_dl = dl_head[i]; curr_dl != 0; curr_dl = dl_next(curr_dl)) {
 525         real_ptr = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_obj);
 526         real_link = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link);
 527         GC_printf2("Object: 0x%lx, Link:0x%lx\n", real_ptr, real_link);
 528       }
 529     }
 530     GC_printf0("Finalizers:\n");
 531     for (i = 0; i < fo_size; i++) {
 532       for (curr_fo = fo_head[i]; curr_fo != 0; curr_fo = fo_next(curr_fo)) {
 533         real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 534         GC_printf1("Finalizable object: 0x%lx\n", real_ptr);
 535       }
 536     }
 537 }
 538 #endif
 539
 540 /* Called with world stopped.  Cause disappearing links to disappear,   */
 541 /* and invoke finalizers.                                               */
 542 void GC_finalize()
 543 {
 544     struct disappearing_link * curr_dl, * prev_dl, * next_dl;
 545     struct finalizable_object * curr_fo, * prev_fo, * next_fo;
 546     ptr_t real_ptr, real_link;
 547     register int i;
 548     int dl_size = (log_dl_table_size == -1 ) ? 0 : (1 << log_dl_table_size);
 549     int fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);
 550
 551   /* Make disappearing links disappear */
 552     for (i = 0; i < dl_size; i++) {
 553       curr_dl = dl_head[i];
 554       prev_dl = 0;
 555       while (curr_dl != 0) {
 556         real_ptr = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_obj);
 557         real_link = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link);
 558         if (!GC_is_marked(real_ptr)) {
 559             *(word *)real_link = 0;
 560             next_dl = dl_next(curr_dl);
 561             if (prev_dl == 0) {
 562                 dl_head[i] = next_dl;
 563             } else {
 564                 dl_set_next(prev_dl, next_dl);
 565             }
 566             GC_clear_mark_bit((ptr_t)curr_dl);
 567             GC_dl_entries--;
 568             curr_dl = next_dl;
 569         } else {
 570             prev_dl = curr_dl;
 571             curr_dl = dl_next(curr_dl);
 572         }
 573       }
 574     }
 575   /* Mark all objects reachable via chains of 1 or more pointers        */
 576   /* from finalizable objects.                                          */
 577     GC_ASSERT(GC_mark_state == MS_NONE);
 578     for (i = 0; i < fo_size; i++) {
 579       for (curr_fo = fo_head[i]; curr_fo != 0; curr_fo = fo_next(curr_fo)) {
 580         real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 581         if (!GC_is_marked(real_ptr)) {
 582             GC_MARKED_FOR_FINALIZATION(real_ptr);
 583             GC_MARK_FO(real_ptr, curr_fo -> fo_mark_proc);
 584             if (GC_is_marked(real_ptr)) {
 585                 WARN("Finalization cycle involving %lx\n", real_ptr);
 586             }
 587         }
 588       }
 589     }
 590   /* Enqueue for finalization all objects that are still                */
 591   /* unreachable.                                                       */
 592     GC_words_finalized = 0;
 593     for (i = 0; i < fo_size; i++) {
 594       curr_fo = fo_head[i];
 595       prev_fo = 0;
 596       while (curr_fo != 0) {
 597         real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 598         if (!GC_is_marked(real_ptr)) {
 599             if (!GC_java_finalization) {
 600               GC_set_mark_bit(real_ptr);
 601             }
 602             /* Delete from hash table */
 603               next_fo = fo_next(curr_fo);
 604               if (prev_fo == 0) {
 605                 fo_head[i] = next_fo;
 606               } else {
 607                 fo_set_next(prev_fo, next_fo);
 608               }
 609               GC_fo_entries--;
 610             /* Add to list of objects awaiting finalization.    */
 611               fo_set_next(curr_fo, GC_finalize_now);
 612               GC_finalize_now = curr_fo;
 613               /* unhide object pointer so any future collections will   */
 614               /* see it.                                                */
 615               curr_fo -> fo_hidden_base =
 616                         (word) REVEAL_POINTER(curr_fo -> fo_hidden_base);
 617               GC_words_finalized +=
 618                         ALIGNED_WORDS(curr_fo -> fo_object_size)
 619                         + ALIGNED_WORDS(sizeof(struct finalizable_object));
 620             GC_ASSERT(GC_is_marked(GC_base((ptr_t)curr_fo)));
 621             curr_fo = next_fo;
 622         } else {
 623             prev_fo = curr_fo;
 624             curr_fo = fo_next(curr_fo);
 625         }
 626       }
 627     }
 628
 629   if (GC_java_finalization) {
 630     /* make sure we mark everything reachable from objects finalized
 631        using the no_order mark_proc */
 632       for (curr_fo = GC_finalize_now;
 633          curr_fo != NULL; curr_fo = fo_next(curr_fo)) {
 634         real_ptr = (ptr_t)curr_fo -> fo_hidden_base;
 635         if (!GC_is_marked(real_ptr)) {
 636             if (curr_fo -> fo_mark_proc == GC_null_finalize_mark_proc) {
 637                 GC_MARK_FO(real_ptr, GC_normal_finalize_mark_proc);
 638             }
 639             GC_set_mark_bit(real_ptr);
 640         }
 641       }
 642   }
 643
 644   /* Remove dangling disappearing links. */
 645     for (i = 0; i < dl_size; i++) {
 646       curr_dl = dl_head[i];
 647       prev_dl = 0;
 648       while (curr_dl != 0) {
 649         real_link = GC_base((ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link));
 650         if (real_link != 0 && !GC_is_marked(real_link)) {
 651             next_dl = dl_next(curr_dl);
 652             if (prev_dl == 0) {
 653                 dl_head[i] = next_dl;
 654             } else {
 655                 dl_set_next(prev_dl, next_dl);
 656             }
 657             GC_clear_mark_bit((ptr_t)curr_dl);
 658             GC_dl_entries--;
 659             curr_dl = next_dl;
 660         } else {
 661             prev_dl = curr_dl;
 662             curr_dl = dl_next(curr_dl);
 663         }
 664       }
 665     }
 666 }
 667
 668 #ifndef JAVA_FINALIZATION_NOT_NEEDED
 669
 670 /* Enqueue all remaining finalizers to be run - Assumes lock is
 671  * held, and signals are disabled */
 672 void GC_enqueue_all_finalizers()
 673 {
 674     struct finalizable_object * curr_fo, * prev_fo, * next_fo;
 675     ptr_t real_ptr;
 676     register int i;
 677     int fo_size;
 678
 679     fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);
 680     GC_words_finalized = 0;
 681     for (i = 0; i < fo_size; i++) {
 682         curr_fo = fo_head[i];
 683         prev_fo = 0;
 684       while (curr_fo != 0) {
 685           real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 686           GC_MARK_FO(real_ptr, GC_normal_finalize_mark_proc);
 687           GC_set_mark_bit(real_ptr);
 688
 689           /* Delete from hash table */
 690           next_fo = fo_next(curr_fo);
 691           if (prev_fo == 0) {
 692               fo_head[i] = next_fo;
 693           } else {
 694               fo_set_next(prev_fo, next_fo);
 695           }
 696           GC_fo_entries--;
 697
 698           /* Add to list of objects awaiting finalization.      */
 699           fo_set_next(curr_fo, GC_finalize_now);
 700           GC_finalize_now = curr_fo;
 701
 702           /* unhide object pointer so any future collections will       */
 703           /* see it.                                            */
 704           curr_fo -> fo_hidden_base =
 705                         (word) REVEAL_POINTER(curr_fo -> fo_hidden_base);
 706
 707           GC_words_finalized +=
 708                 ALIGNED_WORDS(curr_fo -> fo_object_size)
 709                         + ALIGNED_WORDS(sizeof(struct finalizable_object));
 710           curr_fo = next_fo;
 711         }
 712     }
 713
 714     return;
 715 }
 716
 717 /* Invoke all remaining finalizers that haven't yet been run.
 718  * This is needed for strict compliance with the Java standard,
 719  * which can make the runtime guarantee that all finalizers are run.
 720  * Unfortunately, the Java standard implies we have to keep running
 721  * finalizers until there are no more left, a potential infinite loop.
 722  * YUCK.
 723  * Note that this is even more dangerous than the usual Java
 724  * finalizers, in that objects reachable from static variables
 725  * may have been finalized when these finalizers are run.
 726  * Finalizers run at this point must be prepared to deal with a
 727  * mostly broken world.
 728  * This routine is externally callable, so is called without
 729  * the allocation lock.
 730  */
 731 GC_API void GC_finalize_all()
 732 {
 733     DCL_LOCK_STATE;
 734
 735     DISABLE_SIGNALS();
 736     LOCK();
 737     while (GC_fo_entries > 0) {
 738       GC_enqueue_all_finalizers();
 739       UNLOCK();
 740       ENABLE_SIGNALS();
 741       GC_INVOKE_FINALIZERS();
 742       DISABLE_SIGNALS();
 743       LOCK();
 744     }
 745     UNLOCK();
 746     ENABLE_SIGNALS();
 747 }
 748 #endif
 749
 750 /* Returns true if it is worth calling GC_invoke_finalizers. (Useful if */
 751 /* finalizers can only be called from some kind of `safe state' and     */
 752 /* getting into that safe state is expensive.)                          */
 753 int GC_should_invoke_finalizers GC_PROTO((void))
 754 {
 755     return GC_finalize_now != 0;
 756 }
 757
 758 /* Invoke finalizers for all objects that are ready to be finalized.    */
 759 /* Should be called without allocation lock.                            */
 760 int GC_invoke_finalizers()
 761 {
 762     register struct finalizable_object * curr_fo;
 763     register int count = 0;
 764     DCL_LOCK_STATE;
 765
 766     while (GC_finalize_now != 0) {
 767 #       ifdef THREADS
 768             DISABLE_SIGNALS();
 769             LOCK();
 770 #       endif
 771         curr_fo = GC_finalize_now;
 772 #       ifdef THREADS
 773             if (curr_fo != 0) GC_finalize_now = fo_next(curr_fo);
 774             UNLOCK();
 775             ENABLE_SIGNALS();
 776             if (curr_fo == 0) break;
 777 #       else
 778             GC_finalize_now = fo_next(curr_fo);
 779 #       endif
 780         fo_set_next(curr_fo, 0);
 781         (*(curr_fo -> fo_fn))((ptr_t)(curr_fo -> fo_hidden_base),
 782                               curr_fo -> fo_client_data);
 783         curr_fo -> fo_client_data = 0;
 784         ++count;
 785 #       ifdef UNDEFINED
 786             /* This is probably a bad idea.  It throws off accounting if */
 787             /* nearly all objects are finalizable.  O.w. it shouldn't    */
 788             /* matter.                                                   */
 789             GC_free((GC_PTR)curr_fo);
 790 #       endif
 791     }
 792     return count;
 793 }
 794
 795 void (* GC_finalizer_notifier)() = (void (*) GC_PROTO((void)))0;
 796
 797 static GC_word last_finalizer_notification = 0;
 798
 799 void GC_notify_or_invoke_finalizers GC_PROTO((void))
 800 {
 801     if (GC_finalize_now == 0) return;
 802     if (!GC_finalize_on_demand) {
 803         (void) GC_invoke_finalizers();
 804         GC_ASSERT(GC_finalize_now == 0);
 805         return;
 806     }
 807     if (GC_finalizer_notifier != (void (*) GC_PROTO((void)))0
 808         && last_finalizer_notification != GC_gc_no) {
 809         last_finalizer_notification = GC_gc_no;
 810         GC_finalizer_notifier();
 811     }
 812 }
 813
 814 # ifdef __STDC__
 815     GC_PTR GC_call_with_alloc_lock(GC_fn_type fn,
 816                                          GC_PTR client_data)
 817 # else
 818     GC_PTR GC_call_with_alloc_lock(fn, client_data)
 819     GC_fn_type fn;
 820     GC_PTR client_data;
 821 # endif
 822 {
 823     GC_PTR result;
 824     DCL_LOCK_STATE;
 825
 826 #   ifdef THREADS
 827       DISABLE_SIGNALS();
 828       LOCK();
 829       SET_LOCK_HOLDER();
 830 #   endif
 831     result = (*fn)(client_data);
 832 #   ifdef THREADS
 833 #     ifndef GC_ASSERTIONS
 834         UNSET_LOCK_HOLDER();
 835 #     endif /* o.w. UNLOCK() does it implicitly */
 836       UNLOCK();
 837       ENABLE_SIGNALS();
 838 #   endif
 839     return(result);
 840 }
 841