libgc/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 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 };
  58
  59 struct dl_hashtbl_s {
  60     struct disappearing_link **head;
  61     signed_word log_size;
  62     word entries;
  63 };
  64
  65 /* Forward decls. */
  66 static int GC_register_disappearing_link_inner(struct dl_hashtbl_s *dl_hashtbl, GC_PTR * link, GC_PTR obj);
  67 static int GC_unregister_disappearing_link_inner(struct dl_hashtbl_s *dl_hashtbl, GC_PTR * link);
  68
  69 static struct dl_hashtbl_s GC_dl_hashtbl = {
  70     /* head */ NULL, /* log_size */ -1, /* entries */ 0 };
  71
  72 static struct dl_hashtbl_s GC_ll_hashtbl = { NULL, -1, 0 };
  73
  74
  75 static struct finalizable_object {
  76     struct hash_chain_entry prolog;
  77 #   define fo_hidden_base prolog.hidden_key
  78                                 /* Pointer to object base.      */
  79                                 /* No longer hidden once object */
  80                                 /* is on finalize_now queue.    */
  81 #   define fo_next(x) (struct finalizable_object *)((x) -> prolog.next)
  82 #   define fo_set_next(x,y) (x) -> prolog.next = (struct hash_chain_entry *)(y)
  83     GC_finalization_proc fo_fn; /* Finalizer.                   */
  84     ptr_t fo_client_data;
  85     word fo_object_size;        /* In bytes.                    */
  86     finalization_mark_proc * fo_mark_proc;      /* Mark-through procedure */
  87 } **fo_head = 0;
  88
  89 struct finalizable_object * GC_finalize_now = 0;
  90         /* LIst of objects that should be finalized now.        */
  91
  92 static signed_word log_fo_table_size = -1;
  93
  94 word GC_fo_entries = 0;
  95
  96 void GC_push_finalizer_structures GC_PROTO((void))
  97 {
  98     GC_push_all((ptr_t)(&GC_ll_hashtbl.head),
  99                 (ptr_t)(&GC_ll_hashtbl.head) + sizeof(word));
 100     GC_push_all((ptr_t)(&GC_dl_hashtbl.head),
 101                 (ptr_t)(&GC_dl_hashtbl.head) + sizeof(word));
 102     GC_push_all((ptr_t)(&fo_head), (ptr_t)(&fo_head) + sizeof(word));
 103     GC_push_all((ptr_t)(&GC_finalize_now),
 104                 (ptr_t)(&GC_finalize_now) + sizeof(word));
 105 }
 106
 107 /* Double the size of a hash table. *size_ptr is the log of its current */
 108 /* size.  May be a noop.                                                */
 109 /* *table is a pointer to an array of hash headers.  If we succeed, we  */
 110 /* update both *table and *log_size_ptr.                                */
 111 /* Lock is held.  Signals are disabled.                                 */
 112 void GC_grow_table(table, log_size_ptr)
 113 struct hash_chain_entry ***table;
 114 signed_word * log_size_ptr;
 115 {
 116     register word i;
 117     register struct hash_chain_entry *p;
 118     int log_old_size = *log_size_ptr;
 119     register int log_new_size = log_old_size + 1;
 120     word old_size = ((log_old_size == -1)? 0: (1 << log_old_size));
 121     register word new_size = 1 << log_new_size;
 122     struct hash_chain_entry **new_table = (struct hash_chain_entry **)
 123         GC_INTERNAL_MALLOC_IGNORE_OFF_PAGE(
 124                 (size_t)new_size * sizeof(struct hash_chain_entry *), NORMAL);
 125
 126     if (new_table == 0) {
 127         if (table == 0) {
 128             ABORT("Insufficient space for initial table allocation");
 129         } else {
 130             return;
 131         }
 132     }
 133     for (i = 0; i < old_size; i++) {
 134       p = (*table)[i];
 135       while (p != 0) {
 136         register ptr_t real_key = (ptr_t)REVEAL_POINTER(p -> hidden_key);
 137         register struct hash_chain_entry *next = p -> next;
 138         register int new_hash = HASH3(real_key, new_size, log_new_size);
 139
 140         p -> next = new_table[new_hash];
 141         new_table[new_hash] = p;
 142         p = next;
 143       }
 144     }
 145     *log_size_ptr = log_new_size;
 146     *table = new_table;
 147 }
 148
 149 # if defined(__STDC__) || defined(__cplusplus)
 150     int GC_register_disappearing_link(GC_PTR * link)
 151 # else
 152     int GC_register_disappearing_link(link)
 153     GC_PTR * link;
 154 # endif
 155 {
 156     ptr_t base;
 157
 158     base = (ptr_t)GC_base((GC_PTR)link);
 159     if (base == 0)
 160         ABORT("Bad arg to GC_register_disappearing_link");
 161     return(GC_general_register_disappearing_link(link, base));
 162 }
 163
 164 # if defined(__STDC__) || defined(__cplusplus)
 165     int GC_general_register_disappearing_link(GC_PTR * link,
 166                                               GC_PTR obj)
 167 # else
 168     int GC_general_register_disappearing_link(link, obj)
 169     GC_PTR * link;
 170     GC_PTR obj;
 171 # endif
 172 {
 173     return GC_register_disappearing_link_inner(&GC_dl_hashtbl, link, obj);
 174 }
 175
 176 # if defined(__STDC__) || defined(__cplusplus)
 177     static int GC_register_disappearing_link_inner(struct dl_hashtbl_s *dl_hashtbl, GC_PTR * link,
 178                                               GC_PTR obj)
 179 # else
 180     static int GC_register_disappearing_link_inner(dl_hashtbl, link, obj)
 181         struct dl_hashtbl_s *dl_hashtbl
 182     GC_PTR * link;
 183     GC_PTR obj;
 184 # endif
 185 {
 186     struct disappearing_link *curr_dl;
 187     int index;
 188     struct disappearing_link * new_dl;
 189     DCL_LOCK_STATE;
 190
 191     if ((word)link & (ALIGNMENT-1))
 192         ABORT("Bad arg to GC_general_register_disappearing_link");
 193 #   ifdef THREADS
 194         DISABLE_SIGNALS();
 195         LOCK();
 196 #   endif
 197     if (dl_hashtbl -> log_size == -1
 198         || dl_hashtbl -> entries > ((word)1 << dl_hashtbl -> log_size)) {
 199 #       ifndef THREADS
 200             DISABLE_SIGNALS();
 201 #       endif
 202         GC_grow_table((struct hash_chain_entry ***)(&dl_hashtbl -> head),
 203                       &dl_hashtbl -> log_size);
 204 #       ifdef CONDPRINT
 205           if (GC_print_stats) {
 206             GC_printf1("Grew dl table to %lu entries\n",
 207                         (unsigned long)(1 << dl_hashtbl -> log_size));
 208           }
 209 #       endif
 210 #       ifndef THREADS
 211             ENABLE_SIGNALS();
 212 #       endif
 213     }
 214     index = HASH2(link, dl_hashtbl -> log_size);
 215     curr_dl = dl_hashtbl -> head[index];
 216     for (curr_dl = dl_hashtbl -> head[index]; curr_dl != 0; curr_dl = dl_next(curr_dl)) {
 217         if (curr_dl -> dl_hidden_link == HIDE_POINTER(link)) {
 218             curr_dl -> dl_hidden_obj = HIDE_POINTER(obj);
 219 #           ifdef THREADS
 220                 UNLOCK();
 221                 ENABLE_SIGNALS();
 222 #           endif
 223             return(1);
 224         }
 225     }
 226     new_dl = (struct disappearing_link *)
 227         GC_INTERNAL_MALLOC(sizeof(struct disappearing_link),NORMAL);
 228     if (0 == new_dl) {
 229 #     ifdef THREADS
 230         UNLOCK();
 231         ENABLE_SIGNALS();
 232 #     endif
 233       new_dl = (struct disappearing_link *)
 234               GC_oom_fn(sizeof(struct disappearing_link));
 235       if (0 == new_dl) {
 236         GC_finalization_failures++;
 237         return(0);
 238       }
 239       /* It's not likely we'll make it here, but ... */
 240 #     ifdef THREADS
 241         DISABLE_SIGNALS();
 242         LOCK();
 243 #     endif
 244     }
 245     new_dl -> dl_hidden_obj = HIDE_POINTER(obj);
 246     new_dl -> dl_hidden_link = HIDE_POINTER(link);
 247     dl_set_next(new_dl, dl_hashtbl -> head[index]);
 248     dl_hashtbl -> head[index] = new_dl;
 249     dl_hashtbl -> entries++;
 250 #   ifdef THREADS
 251         UNLOCK();
 252         ENABLE_SIGNALS();
 253 #   endif
 254     return(0);
 255 }
 256
 257 # if defined(__STDC__) || defined(__cplusplus)
 258     int GC_unregister_disappearing_link(GC_PTR * link)
 259 # else
 260     int GC_unregister_disappearing_link(link)
 261     GC_PTR * link;
 262 # endif
 263 {
 264         return GC_unregister_disappearing_link_inner(&GC_dl_hashtbl, link);
 265 }
 266
 267 # if defined(__STDC__) || defined(__cplusplus)
 268     static int GC_unregister_disappearing_link_inner(struct dl_hashtbl_s *dl_hashtbl, GC_PTR * link)
 269 # else
 270     static int GC_unregister_disappearing_link_inner(dl_hashtbl, link)
 271         struct dl_hashtbl_s *dl_hashtbl;
 272     GC_PTR * link;
 273 # endif
 274 {
 275     struct disappearing_link *curr_dl, *prev_dl;
 276     int index;
 277     DCL_LOCK_STATE;
 278
 279     DISABLE_SIGNALS();
 280     LOCK();
 281     index = HASH2(link, dl_hashtbl->log_size);
 282     if (((unsigned long)link & (ALIGNMENT-1))) goto out;
 283     prev_dl = 0; curr_dl = dl_hashtbl -> head[index];
 284     while (curr_dl != 0) {
 285         if (curr_dl -> dl_hidden_link == HIDE_POINTER(link)) {
 286             if (prev_dl == 0) {
 287                 dl_hashtbl -> head[index] = dl_next(curr_dl);
 288             } else {
 289                 dl_set_next(prev_dl, dl_next(curr_dl));
 290             }
 291             dl_hashtbl -> entries--;
 292             UNLOCK();
 293             ENABLE_SIGNALS();
 294 #           ifdef DBG_HDRS_ALL
 295               dl_set_next(curr_dl, 0);
 296 #           else
 297               GC_free((GC_PTR)curr_dl);
 298 #           endif
 299             return(1);
 300         }
 301         prev_dl = curr_dl;
 302         curr_dl = dl_next(curr_dl);
 303     }
 304 out:
 305     UNLOCK();
 306     ENABLE_SIGNALS();
 307     return(0);
 308 }
 309
 310
 311 # if defined(__STDC__) || defined(__cplusplus)
 312     int GC_register_long_link(GC_PTR * link, GC_PTR obj)
 313 # else
 314     int GC_register_long_link(link, obj)
 315     GC_PTR * link;
 316         GC_PTR obj;
 317 # endif
 318 {
 319     return GC_register_disappearing_link_inner(&GC_ll_hashtbl, link, obj);
 320 }
 321
 322 # if defined(__STDC__) || defined(__cplusplus)
 323     int GC_unregister_long_link(GC_PTR * link)
 324 # else
 325     int GC_unregister_long_link(link)
 326     GC_PTR * link;
 327 # endif
 328 {
 329         return GC_unregister_disappearing_link_inner(&GC_ll_hashtbl, link);
 330 }
 331
 332 /* Possible finalization_marker procedures.  Note that mark stack       */
 333 /* overflow is handled by the caller, and is not a disaster.            */
 334 GC_API void GC_normal_finalize_mark_proc(p)
 335 ptr_t p;
 336 {
 337     hdr * hhdr = HDR(p);
 338
 339     PUSH_OBJ((word *)p, hhdr, GC_mark_stack_top,
 340              &(GC_mark_stack[GC_mark_stack_size]));
 341 }
 342
 343 /* This only pays very partial attention to the mark descriptor.        */
 344 /* It does the right thing for normal and atomic objects, and treats    */
 345 /* most others as normal.                                               */
 346 GC_API void GC_ignore_self_finalize_mark_proc(p)
 347 ptr_t p;
 348 {
 349     hdr * hhdr = HDR(p);
 350     word descr = hhdr -> hb_descr;
 351     ptr_t q, r;
 352     ptr_t scan_limit;
 353     ptr_t target_limit = p + WORDS_TO_BYTES(hhdr -> hb_sz) - 1;
 354
 355     if ((descr & GC_DS_TAGS) == GC_DS_LENGTH) {
 356        scan_limit = p + descr - sizeof(word);
 357     } else {
 358        scan_limit = target_limit + 1 - sizeof(word);
 359     }
 360     for (q = p; q <= scan_limit; q += ALIGNMENT) {
 361         r = *(ptr_t *)q;
 362         if (r < p || r > target_limit) {
 363             GC_PUSH_ONE_HEAP((word)r, q);
 364         }
 365     }
 366 }
 367
 368 /*ARGSUSED*/
 369 GC_API void GC_null_finalize_mark_proc(p)
 370 ptr_t p;
 371 {
 372 }
 373
 374
 375
 376 /* Register a finalization function.  See gc.h for details.     */
 377 /* in the nonthreads case, we try to avoid disabling signals,   */
 378 /* since it can be expensive.  Threads packages typically       */
 379 /* make it cheaper.                                             */
 380 /* The last parameter is a procedure that determines            */
 381 /* marking for finalization ordering.  Any objects marked       */
 382 /* by that procedure will be guaranteed to not have been        */
 383 /* finalized when this finalizer is invoked.                    */
 384 GC_API void GC_register_finalizer_inner(obj, fn, cd, ofn, ocd, mp)
 385 GC_PTR obj;
 386 GC_finalization_proc fn;
 387 GC_PTR cd;
 388 GC_finalization_proc * ofn;
 389 GC_PTR * ocd;
 390 finalization_mark_proc * mp;
 391 {
 392     ptr_t base;
 393     struct finalizable_object * curr_fo, * prev_fo;
 394     int index;
 395     struct finalizable_object *new_fo;
 396     hdr *hhdr;
 397     DCL_LOCK_STATE;
 398
 399 #   ifdef THREADS
 400         DISABLE_SIGNALS();
 401         LOCK();
 402 #   endif
 403     if (log_fo_table_size == -1
 404         || GC_fo_entries > ((word)1 << log_fo_table_size)) {
 405 #       ifndef THREADS
 406             DISABLE_SIGNALS();
 407 #       endif
 408         GC_grow_table((struct hash_chain_entry ***)(&fo_head),
 409                       &log_fo_table_size);
 410 #       ifdef CONDPRINT
 411           if (GC_print_stats) {
 412             GC_printf1("Grew fo table to %lu entries\n",
 413                         (unsigned long)(1 << log_fo_table_size));
 414           }
 415 #       endif
 416 #       ifndef THREADS
 417             ENABLE_SIGNALS();
 418 #       endif
 419     }
 420     /* in the THREADS case signals are disabled and we hold allocation  */
 421     /* lock; otherwise neither is true.  Proceed carefully.             */
 422     base = (ptr_t)obj;
 423     index = HASH2(base, log_fo_table_size);
 424     prev_fo = 0; curr_fo = fo_head[index];
 425     while (curr_fo != 0) {
 426         if (curr_fo -> fo_hidden_base == HIDE_POINTER(base)) {
 427             /* Interruption by a signal in the middle of this   */
 428             /* should be safe.  The client may see only *ocd    */
 429             /* updated, but we'll declare that to be his        */
 430             /* problem.                                         */
 431             if (ocd) *ocd = (GC_PTR) curr_fo -> fo_client_data;
 432             if (ofn) *ofn = curr_fo -> fo_fn;
 433             /* Delete the structure for base. */
 434                 if (prev_fo == 0) {
 435                   fo_head[index] = fo_next(curr_fo);
 436                 } else {
 437                   fo_set_next(prev_fo, fo_next(curr_fo));
 438                 }
 439             if (fn == 0) {
 440                 GC_fo_entries--;
 441                   /* May not happen if we get a signal.  But a high     */
 442                   /* estimate will only make the table larger than      */
 443                   /* necessary.                                         */
 444 #               if !defined(THREADS) && !defined(DBG_HDRS_ALL)
 445                   GC_free((GC_PTR)curr_fo);
 446 #               endif
 447             } else {
 448                 curr_fo -> fo_fn = fn;
 449                 curr_fo -> fo_client_data = (ptr_t)cd;
 450                 curr_fo -> fo_mark_proc = mp;
 451                 /* Reinsert it.  We deleted it first to maintain        */
 452                 /* consistency in the event of a signal.                */
 453                 if (prev_fo == 0) {
 454                   fo_head[index] = curr_fo;
 455                 } else {
 456                   fo_set_next(prev_fo, curr_fo);
 457                 }
 458             }
 459 #           ifdef THREADS
 460                 UNLOCK();
 461                 ENABLE_SIGNALS();
 462 #           endif
 463             return;
 464         }
 465         prev_fo = curr_fo;
 466         curr_fo = fo_next(curr_fo);
 467     }
 468     if (ofn) *ofn = 0;
 469     if (ocd) *ocd = 0;
 470     if (fn == 0) {
 471 #       ifdef THREADS
 472             UNLOCK();
 473             ENABLE_SIGNALS();
 474 #       endif
 475         return;
 476     }
 477     GET_HDR(base, hhdr);
 478     if (0 == hhdr) {
 479       /* We won't collect it, hence finalizer wouldn't be run. */
 480 #     ifdef THREADS
 481           UNLOCK();
 482           ENABLE_SIGNALS();
 483 #     endif
 484       return;
 485     }
 486     new_fo = (struct finalizable_object *)
 487         GC_INTERNAL_MALLOC(sizeof(struct finalizable_object),NORMAL);
 488     if (0 == new_fo) {
 489 #     ifdef THREADS
 490         UNLOCK();
 491         ENABLE_SIGNALS();
 492 #     endif
 493       new_fo = (struct finalizable_object *)
 494               GC_oom_fn(sizeof(struct finalizable_object));
 495       if (0 == new_fo) {
 496         GC_finalization_failures++;
 497         return;
 498       }
 499       /* It's not likely we'll make it here, but ... */
 500 #     ifdef THREADS
 501         DISABLE_SIGNALS();
 502         LOCK();
 503 #     endif
 504     }
 505     new_fo -> fo_hidden_base = (word)HIDE_POINTER(base);
 506     new_fo -> fo_fn = fn;
 507     new_fo -> fo_client_data = (ptr_t)cd;
 508     new_fo -> fo_object_size = hhdr -> hb_sz;
 509     new_fo -> fo_mark_proc = mp;
 510     fo_set_next(new_fo, fo_head[index]);
 511     GC_fo_entries++;
 512     fo_head[index] = new_fo;
 513 #   ifdef THREADS
 514         UNLOCK();
 515         ENABLE_SIGNALS();
 516 #   endif
 517 }
 518
 519 # if defined(__STDC__)
 520     void GC_register_finalizer(void * obj,
 521                                GC_finalization_proc fn, void * cd,
 522                                GC_finalization_proc *ofn, void ** ocd)
 523 # else
 524     void GC_register_finalizer(obj, fn, cd, ofn, ocd)
 525     GC_PTR obj;
 526     GC_finalization_proc fn;
 527     GC_PTR cd;
 528     GC_finalization_proc * ofn;
 529     GC_PTR * ocd;
 530 # endif
 531 {
 532     GC_register_finalizer_inner(obj, fn, cd, ofn,
 533                                 ocd, GC_normal_finalize_mark_proc);
 534 }
 535
 536 # if defined(__STDC__)
 537     void GC_register_finalizer_ignore_self(void * obj,
 538                                GC_finalization_proc fn, void * cd,
 539                                GC_finalization_proc *ofn, void ** ocd)
 540 # else
 541     void GC_register_finalizer_ignore_self(obj, fn, cd, ofn, ocd)
 542     GC_PTR obj;
 543     GC_finalization_proc fn;
 544     GC_PTR cd;
 545     GC_finalization_proc * ofn;
 546     GC_PTR * ocd;
 547 # endif
 548 {
 549     GC_register_finalizer_inner(obj, fn, cd, ofn,
 550                                 ocd, GC_ignore_self_finalize_mark_proc);
 551 }
 552
 553 # if defined(__STDC__)
 554     void GC_register_finalizer_no_order(void * obj,
 555                                GC_finalization_proc fn, void * cd,
 556                                GC_finalization_proc *ofn, void ** ocd)
 557 # else
 558     void GC_register_finalizer_no_order(obj, fn, cd, ofn, ocd)
 559     GC_PTR obj;
 560     GC_finalization_proc fn;
 561     GC_PTR cd;
 562     GC_finalization_proc * ofn;
 563     GC_PTR * ocd;
 564 # endif
 565 {
 566     GC_register_finalizer_inner(obj, fn, cd, ofn,
 567                                 ocd, GC_null_finalize_mark_proc);
 568 }
 569
 570 #ifndef NO_DEBUGGING
 571
 572 static void GC_dump_finalization_links(struct dl_hashtbl_s *dl_hashtbl)
 573 {
 574   struct disappearing_link *curr_dl;
 575   ptr_t real_ptr, real_link;
 576   size_t dl_size = dl_hashtbl->log_size == -1 ? 0 :
 577                               1 << dl_hashtbl->log_size;
 578   int i;
 579
 580   for (i = 0; i < dl_size; i++) {
 581     for (curr_dl = dl_hashtbl -> head[i]; curr_dl != 0;
 582          curr_dl = dl_next(curr_dl)) {
 583       real_ptr = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_obj);
 584       real_link = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link);
 585       GC_printf2("Object: %lx, link: %lx\n", real_ptr, real_link);
 586     }
 587   }
 588 }
 589
 590 void GC_dump_finalization()
 591 {
 592     struct finalizable_object * curr_fo;
 593     ptr_t real_ptr;
 594     int fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);
 595     int i;
 596
 597     GC_printf0("Disappearing (short) links:\n");
 598     GC_dump_finalization_links(&GC_dl_hashtbl);
 599     GC_printf0("Disappearing long links:\n");
 600     GC_dump_finalization_links(&GC_ll_hashtbl);
 601
 602     GC_printf0("Finalizers:\n");
 603     for (i = 0; i < fo_size; i++) {
 604       for (curr_fo = fo_head[i]; curr_fo != 0; curr_fo = fo_next(curr_fo)) {
 605         real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 606         GC_printf1("Finalizable object: 0x%lx\n", real_ptr);
 607       }
 608     }
 609 }
 610 #endif
 611
 612 static void GC_make_disappearing_links_disappear(struct dl_hashtbl_s *dl_hashtbl)
 613 {
 614     struct disappearing_link * curr_dl, * prev_dl, * next_dl;
 615     ptr_t real_ptr, real_link;
 616     register int i;
 617     int dl_size = (dl_hashtbl -> log_size == -1 ) ? 0 : (1 << dl_hashtbl -> log_size);
 618
 619     for (i = 0; i < dl_size; i++) {
 620       curr_dl = dl_hashtbl -> head[i];
 621       prev_dl = 0;
 622       while (curr_dl != 0) {
 623         real_ptr = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_obj);
 624         real_link = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link);
 625         if (!GC_is_marked(real_ptr)) {
 626             *(word *)real_link = 0;
 627             next_dl = dl_next(curr_dl);
 628             if (prev_dl == 0) {
 629                 dl_hashtbl -> head[i] = next_dl;
 630             } else {
 631                 dl_set_next(prev_dl, next_dl);
 632             }
 633             GC_clear_mark_bit((ptr_t)curr_dl);
 634             dl_hashtbl -> entries--;
 635             curr_dl = next_dl;
 636         } else {
 637             prev_dl = curr_dl;
 638             curr_dl = dl_next(curr_dl);
 639         }
 640       }
 641     }
 642 }
 643
 644 static void GC_remove_dangling_disappearing_links(struct dl_hashtbl_s *dl_hashtbl)
 645 {
 646     struct disappearing_link * curr_dl, * prev_dl, * next_dl;
 647     ptr_t real_ptr, real_link;
 648     register int i;
 649     int dl_size = (dl_hashtbl -> log_size == -1 ) ? 0 : (1 << dl_hashtbl -> log_size);
 650
 651     for (i = 0; i < dl_size; i++) {
 652       curr_dl = dl_hashtbl -> head[i];
 653       prev_dl = 0;
 654       while (curr_dl != 0) {
 655         real_link = GC_base((ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link));
 656         if (real_link != 0 && !GC_is_marked(real_link)) {
 657             next_dl = dl_next(curr_dl);
 658             if (prev_dl == 0) {
 659                 dl_hashtbl -> head[i] = next_dl;
 660             } else {
 661                 dl_set_next(prev_dl, next_dl);
 662             }
 663             GC_clear_mark_bit((ptr_t)curr_dl);
 664             dl_hashtbl -> entries--;
 665             curr_dl = next_dl;
 666         } else {
 667             prev_dl = curr_dl;
 668             curr_dl = dl_next(curr_dl);
 669         }
 670       }
 671     }
 672 }
 673
 674 /* Called with world stopped.  Cause disappearing links to disappear,   */
 675 /* and invoke finalizers.                                               */
 676 void GC_finalize()
 677 {
 678     struct finalizable_object * curr_fo, * prev_fo, * next_fo;
 679     ptr_t real_ptr;
 680     register int i;
 681     int fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);
 682
 683   /* Make non-tracking disappearing links disappear */
 684         GC_make_disappearing_links_disappear(&GC_dl_hashtbl);
 685
 686   /* Mark all objects reachable via chains of 1 or more pointers        */
 687   /* from finalizable objects.                                          */
 688     GC_ASSERT(GC_mark_state == MS_NONE);
 689     for (i = 0; i < fo_size; i++) {
 690       for (curr_fo = fo_head[i]; curr_fo != 0; curr_fo = fo_next(curr_fo)) {
 691         real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 692         if (!GC_is_marked(real_ptr)) {
 693             GC_MARKED_FOR_FINALIZATION(real_ptr);
 694             GC_MARK_FO(real_ptr, curr_fo -> fo_mark_proc);
 695             if (GC_is_marked(real_ptr)) {
 696                 WARN("Finalization cycle involving %lx\n", real_ptr);
 697             }
 698         }
 699       }
 700     }
 701   /* Enqueue for finalization all objects that are still                */
 702   /* unreachable.                                                       */
 703     GC_words_finalized = 0;
 704     for (i = 0; i < fo_size; i++) {
 705       curr_fo = fo_head[i];
 706       prev_fo = 0;
 707       while (curr_fo != 0) {
 708         real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 709         if (!GC_is_marked(real_ptr)) {
 710             if (!GC_java_finalization) {
 711               GC_set_mark_bit(real_ptr);
 712             }
 713             /* Delete from hash table */
 714               next_fo = fo_next(curr_fo);
 715               if (prev_fo == 0) {
 716                 fo_head[i] = next_fo;
 717               } else {
 718                 fo_set_next(prev_fo, next_fo);
 719               }
 720               GC_fo_entries--;
 721             /* Add to list of objects awaiting finalization.    */
 722               fo_set_next(curr_fo, GC_finalize_now);
 723               GC_finalize_now = curr_fo;
 724               /* unhide object pointer so any future collections will   */
 725               /* see it.                                                */
 726               curr_fo -> fo_hidden_base =
 727                         (word) REVEAL_POINTER(curr_fo -> fo_hidden_base);
 728               GC_words_finalized +=
 729                         ALIGNED_WORDS(curr_fo -> fo_object_size)
 730                         + ALIGNED_WORDS(sizeof(struct finalizable_object));
 731             GC_ASSERT(GC_is_marked(GC_base((ptr_t)curr_fo)));
 732             curr_fo = next_fo;
 733         } else {
 734             prev_fo = curr_fo;
 735             curr_fo = fo_next(curr_fo);
 736         }
 737       }
 738     }
 739
 740   if (GC_java_finalization) {
 741     /* make sure we mark everything reachable from objects finalized
 742        using the no_order mark_proc */
 743       for (curr_fo = GC_finalize_now;
 744          curr_fo != NULL; curr_fo = fo_next(curr_fo)) {
 745         real_ptr = (ptr_t)curr_fo -> fo_hidden_base;
 746         if (!GC_is_marked(real_ptr)) {
 747             if (curr_fo -> fo_mark_proc == GC_null_finalize_mark_proc) {
 748                 GC_MARK_FO(real_ptr, GC_normal_finalize_mark_proc);
 749             }
 750             GC_set_mark_bit(real_ptr);
 751         }
 752       }
 753   }
 754
 755   /* Remove dangling disappearing links. */
 756   GC_remove_dangling_disappearing_links(&GC_dl_hashtbl);
 757
 758   /* Make long links disappear and remove dangling ones. */
 759   GC_make_disappearing_links_disappear(&GC_ll_hashtbl);
 760   GC_remove_dangling_disappearing_links(&GC_ll_hashtbl);
 761 }
 762
 763 #ifndef JAVA_FINALIZATION_NOT_NEEDED
 764
 765 /* Enqueue all remaining finalizers to be run - Assumes lock is
 766  * held, and signals are disabled */
 767 void GC_enqueue_all_finalizers()
 768 {
 769     struct finalizable_object * curr_fo, * prev_fo, * next_fo;
 770     ptr_t real_ptr;
 771     register int i;
 772     int fo_size;
 773
 774     fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);
 775     GC_words_finalized = 0;
 776     for (i = 0; i < fo_size; i++) {
 777         curr_fo = fo_head[i];
 778         prev_fo = 0;
 779       while (curr_fo != 0) {
 780           real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 781           GC_MARK_FO(real_ptr, GC_normal_finalize_mark_proc);
 782           GC_set_mark_bit(real_ptr);
 783
 784           /* Delete from hash table */
 785           next_fo = fo_next(curr_fo);
 786           if (prev_fo == 0) {
 787               fo_head[i] = next_fo;
 788           } else {
 789               fo_set_next(prev_fo, next_fo);
 790           }
 791           GC_fo_entries--;
 792
 793           /* Add to list of objects awaiting finalization.      */
 794           fo_set_next(curr_fo, GC_finalize_now);
 795           GC_finalize_now = curr_fo;
 796
 797           /* unhide object pointer so any future collections will       */
 798           /* see it.                                            */
 799           curr_fo -> fo_hidden_base =
 800                         (word) REVEAL_POINTER(curr_fo -> fo_hidden_base);
 801
 802           GC_words_finalized +=
 803                 ALIGNED_WORDS(curr_fo -> fo_object_size)
 804                         + ALIGNED_WORDS(sizeof(struct finalizable_object));
 805           curr_fo = next_fo;
 806         }
 807     }
 808
 809     return;
 810 }
 811
 812 /* Invoke all remaining finalizers that haven't yet been run.
 813  * This is needed for strict compliance with the Java standard,
 814  * which can make the runtime guarantee that all finalizers are run.
 815  * Unfortunately, the Java standard implies we have to keep running
 816  * finalizers until there are no more left, a potential infinite loop.
 817  * YUCK.
 818  * Note that this is even more dangerous than the usual Java
 819  * finalizers, in that objects reachable from static variables
 820  * may have been finalized when these finalizers are run.
 821  * Finalizers run at this point must be prepared to deal with a
 822  * mostly broken world.
 823  * This routine is externally callable, so is called without
 824  * the allocation lock.
 825  */
 826 GC_API void GC_finalize_all()
 827 {
 828     DCL_LOCK_STATE;
 829
 830     DISABLE_SIGNALS();
 831     LOCK();
 832     while (GC_fo_entries > 0) {
 833       GC_enqueue_all_finalizers();
 834       UNLOCK();
 835       ENABLE_SIGNALS();
 836       GC_INVOKE_FINALIZERS();
 837       DISABLE_SIGNALS();
 838       LOCK();
 839     }
 840     UNLOCK();
 841     ENABLE_SIGNALS();
 842 }
 843 #endif
 844
 845 /* Returns true if it is worth calling GC_invoke_finalizers. (Useful if */
 846 /* finalizers can only be called from some kind of `safe state' and     */
 847 /* getting into that safe state is expensive.)                          */
 848 int GC_should_invoke_finalizers GC_PROTO((void))
 849 {
 850     return GC_finalize_now != 0;
 851 }
 852
 853 /* Invoke finalizers for all objects that are ready to be finalized.    */
 854 /* Should be called without allocation lock.                            */
 855 int GC_invoke_finalizers()
 856 {
 857     struct finalizable_object * curr_fo;
 858     int count = 0;
 859     word mem_freed_before;
 860     DCL_LOCK_STATE;
 861
 862     while (GC_finalize_now != 0) {
 863 #       ifdef THREADS
 864             DISABLE_SIGNALS();
 865             LOCK();
 866 #       endif
 867         if (count == 0) {
 868             mem_freed_before = GC_mem_freed;
 869         }
 870         curr_fo = GC_finalize_now;
 871 #       ifdef THREADS
 872             if (curr_fo != 0) GC_finalize_now = fo_next(curr_fo);
 873             UNLOCK();
 874             ENABLE_SIGNALS();
 875             if (curr_fo == 0) break;
 876 #       else
 877             GC_finalize_now = fo_next(curr_fo);
 878 #       endif
 879         fo_set_next(curr_fo, 0);
 880         (*(curr_fo -> fo_fn))((ptr_t)(curr_fo -> fo_hidden_base),
 881                               curr_fo -> fo_client_data);
 882         curr_fo -> fo_client_data = 0;
 883         ++count;
 884 #       ifdef UNDEFINED
 885             /* This is probably a bad idea.  It throws off accounting if */
 886             /* nearly all objects are finalizable.  O.w. it shouldn't    */
 887             /* matter.                                                   */
 888             GC_free((GC_PTR)curr_fo);
 889 #       endif
 890     }
 891     if (count != 0 && mem_freed_before != GC_mem_freed) {
 892         LOCK();
 893         GC_finalizer_mem_freed += (GC_mem_freed - mem_freed_before);
 894         UNLOCK();
 895     }
 896     return count;
 897 }
 898
 899 void (* GC_finalizer_notifier)() = (void (*) GC_PROTO((void)))0;
 900
 901 static GC_word last_finalizer_notification = 0;
 902
 903 void GC_notify_or_invoke_finalizers GC_PROTO((void))
 904 {
 905     /* This is a convenient place to generate backtraces if appropriate, */
 906     /* since that code is not callable with the allocation lock.         */
 907 #   if defined(KEEP_BACK_PTRS) || defined(MAKE_BACK_GRAPH)
 908       static word last_back_trace_gc_no = 1;    /* Skip first one. */
 909
 910       if (GC_gc_no > last_back_trace_gc_no) {
 911         word i;
 912
 913 #       ifdef KEEP_BACK_PTRS
 914           LOCK();
 915           /* Stops when GC_gc_no wraps; that's OK.      */
 916           last_back_trace_gc_no = (word)(-1);  /* disable others. */
 917           for (i = 0; i < GC_backtraces; ++i) {
 918               /* FIXME: This tolerates concurrent heap mutation,        */
 919               /* which may cause occasional mysterious results.         */
 920               /* We need to release the GC lock, since GC_print_callers */
 921               /* acquires it.  It probably shouldn't.                   */
 922               UNLOCK();
 923               GC_generate_random_backtrace_no_gc();
 924               LOCK();
 925           }
 926           last_back_trace_gc_no = GC_gc_no;
 927           UNLOCK();
 928 #       endif
 929 #       ifdef MAKE_BACK_GRAPH
 930           if (GC_print_back_height)
 931             GC_print_back_graph_stats();
 932 #       endif
 933       }
 934 #   endif
 935     if (GC_finalize_now == 0) return;
 936     if (!GC_finalize_on_demand) {
 937         (void) GC_invoke_finalizers();
 938 #       ifndef THREADS
 939           GC_ASSERT(GC_finalize_now == 0);
 940 #       endif   /* Otherwise GC can run concurrently and add more */
 941         return;
 942     }
 943     if (GC_finalizer_notifier != (void (*) GC_PROTO((void)))0
 944         && last_finalizer_notification != GC_gc_no) {
 945         last_finalizer_notification = GC_gc_no;
 946         GC_finalizer_notifier();
 947     }
 948 }
 949
 950 # ifdef __STDC__
 951     GC_PTR GC_call_with_alloc_lock(GC_fn_type fn,
 952                                          GC_PTR client_data)
 953 # else
 954     GC_PTR GC_call_with_alloc_lock(fn, client_data)
 955     GC_fn_type fn;
 956     GC_PTR client_data;
 957 # endif
 958 {
 959     GC_PTR result;
 960     DCL_LOCK_STATE;
 961
 962 #   ifdef THREADS
 963       DISABLE_SIGNALS();
 964       LOCK();
 965       SET_LOCK_HOLDER();
 966 #   endif
 967     result = (*fn)(client_data);
 968 #   ifdef THREADS
 969 #     ifndef GC_ASSERTIONS
 970         UNSET_LOCK_HOLDER();
 971 #     endif /* o.w. UNLOCK() does it implicitly */
 972       UNLOCK();
 973       ENABLE_SIGNALS();
 974 #   endif
 975     return(result);
 976 }
 977
 978 #if !defined(NO_DEBUGGING)
 979
 980 void GC_print_finalization_stats()
 981 {
 982     struct finalizable_object *fo = GC_finalize_now;
 983     size_t ready = 0;
 984
 985     GC_printf3("%lu finalization table entries; %lu/%lu short/long disappearing links alive\n",
 986                GC_fo_entries, (unsigned long)GC_dl_hashtbl.entries, (unsigned long)GC_ll_hashtbl.entries);
 987     for (; 0 != fo; fo = fo_next(fo)) ++ready;
 988     GC_printf1("%lu objects are eligible for immediate finalization\n", ready);
 989 }
 990
 991 #endif /* NO_DEBUGGING */