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 /* toggleref support */
 311 typedef struct {
 312         GC_PTR strong_ref;
 313         GC_hidden_pointer weak_ref;
 314 } GCToggleRef;
 315
 316 static int (*GC_toggleref_callback) (GC_PTR obj);
 317 static GCToggleRef *GC_toggleref_array;
 318 static int GC_toggleref_array_size;
 319 static int GC_toggleref_array_capacity;
 320
 321
 322 void
 323 GC_process_togglerefs (void)
 324 {
 325         int i, w;
 326         int toggle_ref_counts [3] = { 0, 0, 0 };
 327
 328         for (i = w = 0; i < GC_toggleref_array_size; ++i) {
 329                 int res;
 330                 GCToggleRef r = GC_toggleref_array [i];
 331
 332                 GC_PTR obj;
 333
 334                 if (r.strong_ref)
 335                         obj = r.strong_ref;
 336                 else if (r.weak_ref)
 337                         obj = REVEAL_POINTER (r.weak_ref);
 338                 else
 339                         continue;
 340
 341                 res = GC_toggleref_callback (obj);
 342                 ++toggle_ref_counts [res];
 343                 switch (res) {
 344                 case 0:
 345                         break;
 346                 case 1:
 347                         GC_toggleref_array [w].strong_ref = obj;
 348                         GC_toggleref_array [w].weak_ref = (GC_hidden_pointer)NULL;
 349                         ++w;
 350                         break;
 351                 case 2:
 352                         GC_toggleref_array [w].strong_ref = NULL;
 353                         GC_toggleref_array [w].weak_ref = HIDE_POINTER (obj);
 354                         ++w;
 355                         break;
 356                 default:
 357                         ABORT("Invalid callback result");
 358                 }
 359         }
 360
 361         for (i = w; i < GC_toggleref_array_size; ++i) {
 362                 GC_toggleref_array [w].strong_ref = NULL;
 363                 GC_toggleref_array [w].weak_ref = (GC_hidden_pointer)NULL;
 364         }
 365
 366         GC_toggleref_array_size = w;
 367 }
 368
 369
 370 static void push_and_mark_object (GC_PTR p)
 371 {
 372     hdr * hhdr = HDR(p);
 373
 374     PUSH_OBJ((word *)p, hhdr, GC_mark_stack_top,
 375              &(GC_mark_stack[GC_mark_stack_size]));
 376
 377         while (!GC_mark_stack_empty()) MARK_FROM_MARK_STACK();
 378         GC_set_mark_bit (p);
 379         if (GC_mark_state != MS_NONE)
 380         while (!GC_mark_some((ptr_t)0)) {}
 381 }
 382
 383 static void GC_mark_togglerefs ()
 384 {
 385         int i;
 386         if (!GC_toggleref_array)
 387                 return;
 388
 389         GC_set_mark_bit ((GC_PTR)GC_toggleref_array);
 390         for (i = 0; i < GC_toggleref_array_size; ++i) {
 391                 if (GC_toggleref_array [i].strong_ref) {
 392                         GC_PTR object = GC_toggleref_array [i].strong_ref;
 393
 394                         push_and_mark_object (object);
 395                 }
 396         }
 397 }
 398
 399 static void GC_clear_togglerefs ()
 400 {
 401         int i;
 402         for (i = 0; i < GC_toggleref_array_size; ++i) {
 403                 if (GC_toggleref_array [i].weak_ref) {
 404                         GC_PTR object = REVEAL_POINTER (GC_toggleref_array [i].weak_ref);
 405
 406                         if (!GC_is_marked (object)) {
 407                                 GC_toggleref_array [i].weak_ref = (GC_hidden_pointer)NULL; /* We defer compaction to only happen on the callback step. */
 408                         } else {
 409                                 /*No need to copy, boehm is non-moving */
 410                         }
 411                 }
 412         }
 413 }
 414
 415
 416
 417 void GC_toggleref_register_callback(int (*proccess_toggleref) (GC_PTR obj))
 418 {
 419         GC_toggleref_callback = proccess_toggleref;
 420 }
 421
 422 static void
 423 ensure_toggleref_capacity (int capacity)
 424 {
 425         if (!GC_toggleref_array) {
 426                 GC_toggleref_array_capacity = 32;
 427                 GC_toggleref_array = (GCToggleRef *) GC_INTERNAL_MALLOC_IGNORE_OFF_PAGE (GC_toggleref_array_capacity * sizeof (GCToggleRef), NORMAL);
 428         }
 429         if (GC_toggleref_array_size + capacity >= GC_toggleref_array_capacity) {
 430                 GCToggleRef *tmp;
 431                 int old_capacity = GC_toggleref_array_capacity;
 432                 while (GC_toggleref_array_capacity < GC_toggleref_array_size + capacity)
 433                         GC_toggleref_array_capacity *= 2;
 434
 435                 tmp = (GCToggleRef *) GC_INTERNAL_MALLOC_IGNORE_OFF_PAGE (GC_toggleref_array_capacity * sizeof (GCToggleRef), NORMAL);
 436                 memcpy (tmp, GC_toggleref_array, GC_toggleref_array_size * sizeof (GCToggleRef));
 437                 GC_INTERNAL_FREE (GC_toggleref_array);
 438                 GC_toggleref_array = tmp;
 439         }
 440 }
 441
 442 void
 443 GC_toggleref_add (GC_PTR object, int strong_ref)
 444 {
 445     DCL_LOCK_STATE;
 446 # ifdef THREADS
 447         DISABLE_SIGNALS();
 448         LOCK();
 449 # endif
 450
 451         if (!GC_toggleref_callback)
 452                 goto end;
 453
 454         ensure_toggleref_capacity (1);
 455         GC_toggleref_array [GC_toggleref_array_size].strong_ref = strong_ref ? object : NULL;
 456         GC_toggleref_array [GC_toggleref_array_size].weak_ref = strong_ref ? (GC_hidden_pointer)NULL : HIDE_POINTER (object);
 457         ++GC_toggleref_array_size;
 458
 459 end:
 460 # ifdef THREADS
 461         UNLOCK();
 462         ENABLE_SIGNALS();
 463 # endif
 464 }
 465
 466
 467
 468 # if defined(__STDC__) || defined(__cplusplus)
 469     int GC_register_long_link(GC_PTR * link, GC_PTR obj)
 470 # else
 471     int GC_register_long_link(link, obj)
 472     GC_PTR * link;
 473         GC_PTR obj;
 474 # endif
 475 {
 476     return GC_register_disappearing_link_inner(&GC_ll_hashtbl, link, obj);
 477 }
 478
 479 # if defined(__STDC__) || defined(__cplusplus)
 480     int GC_unregister_long_link(GC_PTR * link)
 481 # else
 482     int GC_unregister_long_link(link)
 483     GC_PTR * link;
 484 # endif
 485 {
 486         return GC_unregister_disappearing_link_inner(&GC_ll_hashtbl, link);
 487 }
 488
 489 /* Possible finalization_marker procedures.  Note that mark stack       */
 490 /* overflow is handled by the caller, and is not a disaster.            */
 491 GC_API void GC_normal_finalize_mark_proc(p)
 492 ptr_t p;
 493 {
 494     hdr * hhdr = HDR(p);
 495
 496     PUSH_OBJ((word *)p, hhdr, GC_mark_stack_top,
 497              &(GC_mark_stack[GC_mark_stack_size]));
 498 }
 499
 500 /* This only pays very partial attention to the mark descriptor.        */
 501 /* It does the right thing for normal and atomic objects, and treats    */
 502 /* most others as normal.                                               */
 503 GC_API void GC_ignore_self_finalize_mark_proc(p)
 504 ptr_t p;
 505 {
 506     hdr * hhdr = HDR(p);
 507     word descr = hhdr -> hb_descr;
 508     ptr_t q, r;
 509     ptr_t scan_limit;
 510     ptr_t target_limit = p + WORDS_TO_BYTES(hhdr -> hb_sz) - 1;
 511
 512     if ((descr & GC_DS_TAGS) == GC_DS_LENGTH) {
 513        scan_limit = p + descr - sizeof(word);
 514     } else {
 515        scan_limit = target_limit + 1 - sizeof(word);
 516     }
 517     for (q = p; q <= scan_limit; q += ALIGNMENT) {
 518         r = *(ptr_t *)q;
 519         if (r < p || r > target_limit) {
 520             GC_PUSH_ONE_HEAP((word)r, q);
 521         }
 522     }
 523 }
 524
 525 /*ARGSUSED*/
 526 GC_API void GC_null_finalize_mark_proc(p)
 527 ptr_t p;
 528 {
 529 }
 530
 531
 532
 533 /* Register a finalization function.  See gc.h for details.     */
 534 /* in the nonthreads case, we try to avoid disabling signals,   */
 535 /* since it can be expensive.  Threads packages typically       */
 536 /* make it cheaper.                                             */
 537 /* The last parameter is a procedure that determines            */
 538 /* marking for finalization ordering.  Any objects marked       */
 539 /* by that procedure will be guaranteed to not have been        */
 540 /* finalized when this finalizer is invoked.                    */
 541 GC_API void GC_register_finalizer_inner(obj, fn, cd, ofn, ocd, mp)
 542 GC_PTR obj;
 543 GC_finalization_proc fn;
 544 GC_PTR cd;
 545 GC_finalization_proc * ofn;
 546 GC_PTR * ocd;
 547 finalization_mark_proc * mp;
 548 {
 549     ptr_t base;
 550     struct finalizable_object * curr_fo, * prev_fo;
 551     int index;
 552     struct finalizable_object *new_fo;
 553     hdr *hhdr;
 554     DCL_LOCK_STATE;
 555
 556 #   ifdef THREADS
 557         DISABLE_SIGNALS();
 558         LOCK();
 559 #   endif
 560     if (log_fo_table_size == -1
 561         || GC_fo_entries > ((word)1 << log_fo_table_size)) {
 562 #       ifndef THREADS
 563             DISABLE_SIGNALS();
 564 #       endif
 565         GC_grow_table((struct hash_chain_entry ***)(&fo_head),
 566                       &log_fo_table_size);
 567 #       ifdef CONDPRINT
 568           if (GC_print_stats) {
 569             GC_printf1("Grew fo table to %lu entries\n",
 570                         (unsigned long)(1 << log_fo_table_size));
 571           }
 572 #       endif
 573 #       ifndef THREADS
 574             ENABLE_SIGNALS();
 575 #       endif
 576     }
 577     /* in the THREADS case signals are disabled and we hold allocation  */
 578     /* lock; otherwise neither is true.  Proceed carefully.             */
 579     base = (ptr_t)obj;
 580     index = HASH2(base, log_fo_table_size);
 581     prev_fo = 0; curr_fo = fo_head[index];
 582     while (curr_fo != 0) {
 583         if (curr_fo -> fo_hidden_base == HIDE_POINTER(base)) {
 584             /* Interruption by a signal in the middle of this   */
 585             /* should be safe.  The client may see only *ocd    */
 586             /* updated, but we'll declare that to be his        */
 587             /* problem.                                         */
 588             if (ocd) *ocd = (GC_PTR) curr_fo -> fo_client_data;
 589             if (ofn) *ofn = curr_fo -> fo_fn;
 590             /* Delete the structure for base. */
 591                 if (prev_fo == 0) {
 592                   fo_head[index] = fo_next(curr_fo);
 593                 } else {
 594                   fo_set_next(prev_fo, fo_next(curr_fo));
 595                 }
 596             if (fn == 0) {
 597                 GC_fo_entries--;
 598                   /* May not happen if we get a signal.  But a high     */
 599                   /* estimate will only make the table larger than      */
 600                   /* necessary.                                         */
 601 #               if !defined(THREADS) && !defined(DBG_HDRS_ALL)
 602                   GC_free((GC_PTR)curr_fo);
 603 #               endif
 604             } else {
 605                 curr_fo -> fo_fn = fn;
 606                 curr_fo -> fo_client_data = (ptr_t)cd;
 607                 curr_fo -> fo_mark_proc = mp;
 608                 /* Reinsert it.  We deleted it first to maintain        */
 609                 /* consistency in the event of a signal.                */
 610                 if (prev_fo == 0) {
 611                   fo_head[index] = curr_fo;
 612                 } else {
 613                   fo_set_next(prev_fo, curr_fo);
 614                 }
 615             }
 616 #           ifdef THREADS
 617                 UNLOCK();
 618                 ENABLE_SIGNALS();
 619 #           endif
 620             return;
 621         }
 622         prev_fo = curr_fo;
 623         curr_fo = fo_next(curr_fo);
 624     }
 625     if (ofn) *ofn = 0;
 626     if (ocd) *ocd = 0;
 627     if (fn == 0) {
 628 #       ifdef THREADS
 629             UNLOCK();
 630             ENABLE_SIGNALS();
 631 #       endif
 632         return;
 633     }
 634     GET_HDR(base, hhdr);
 635     if (0 == hhdr) {
 636       /* We won't collect it, hence finalizer wouldn't be run. */
 637 #     ifdef THREADS
 638           UNLOCK();
 639           ENABLE_SIGNALS();
 640 #     endif
 641       return;
 642     }
 643     new_fo = (struct finalizable_object *)
 644         GC_INTERNAL_MALLOC(sizeof(struct finalizable_object),NORMAL);
 645     if (0 == new_fo) {
 646 #     ifdef THREADS
 647         UNLOCK();
 648         ENABLE_SIGNALS();
 649 #     endif
 650       new_fo = (struct finalizable_object *)
 651               GC_oom_fn(sizeof(struct finalizable_object));
 652       if (0 == new_fo) {
 653         GC_finalization_failures++;
 654         return;
 655       }
 656       /* It's not likely we'll make it here, but ... */
 657 #     ifdef THREADS
 658         DISABLE_SIGNALS();
 659         LOCK();
 660 #     endif
 661     }
 662     new_fo -> fo_hidden_base = (word)HIDE_POINTER(base);
 663     new_fo -> fo_fn = fn;
 664     new_fo -> fo_client_data = (ptr_t)cd;
 665     new_fo -> fo_object_size = hhdr -> hb_sz;
 666     new_fo -> fo_mark_proc = mp;
 667     fo_set_next(new_fo, fo_head[index]);
 668     GC_fo_entries++;
 669     fo_head[index] = new_fo;
 670 #   ifdef THREADS
 671         UNLOCK();
 672         ENABLE_SIGNALS();
 673 #   endif
 674 }
 675
 676 # if defined(__STDC__)
 677     void GC_register_finalizer(void * obj,
 678                                GC_finalization_proc fn, void * cd,
 679                                GC_finalization_proc *ofn, void ** ocd)
 680 # else
 681     void GC_register_finalizer(obj, fn, cd, ofn, ocd)
 682     GC_PTR obj;
 683     GC_finalization_proc fn;
 684     GC_PTR cd;
 685     GC_finalization_proc * ofn;
 686     GC_PTR * ocd;
 687 # endif
 688 {
 689     GC_register_finalizer_inner(obj, fn, cd, ofn,
 690                                 ocd, GC_normal_finalize_mark_proc);
 691 }
 692
 693 # if defined(__STDC__)
 694     void GC_register_finalizer_ignore_self(void * obj,
 695                                GC_finalization_proc fn, void * cd,
 696                                GC_finalization_proc *ofn, void ** ocd)
 697 # else
 698     void GC_register_finalizer_ignore_self(obj, fn, cd, ofn, ocd)
 699     GC_PTR obj;
 700     GC_finalization_proc fn;
 701     GC_PTR cd;
 702     GC_finalization_proc * ofn;
 703     GC_PTR * ocd;
 704 # endif
 705 {
 706     GC_register_finalizer_inner(obj, fn, cd, ofn,
 707                                 ocd, GC_ignore_self_finalize_mark_proc);
 708 }
 709
 710 # if defined(__STDC__)
 711     void GC_register_finalizer_no_order(void * obj,
 712                                GC_finalization_proc fn, void * cd,
 713                                GC_finalization_proc *ofn, void ** ocd)
 714 # else
 715     void GC_register_finalizer_no_order(obj, fn, cd, ofn, ocd)
 716     GC_PTR obj;
 717     GC_finalization_proc fn;
 718     GC_PTR cd;
 719     GC_finalization_proc * ofn;
 720     GC_PTR * ocd;
 721 # endif
 722 {
 723     GC_register_finalizer_inner(obj, fn, cd, ofn,
 724                                 ocd, GC_null_finalize_mark_proc);
 725 }
 726
 727 #ifndef NO_DEBUGGING
 728
 729 static void GC_dump_finalization_links(struct dl_hashtbl_s *dl_hashtbl)
 730 {
 731   struct disappearing_link *curr_dl;
 732   ptr_t real_ptr, real_link;
 733   size_t dl_size = dl_hashtbl->log_size == -1 ? 0 :
 734                               1 << dl_hashtbl->log_size;
 735   int i;
 736
 737   for (i = 0; i < dl_size; i++) {
 738     for (curr_dl = dl_hashtbl -> head[i]; curr_dl != 0;
 739          curr_dl = dl_next(curr_dl)) {
 740       real_ptr = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_obj);
 741       real_link = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link);
 742       GC_printf2("Object: %lx, link: %lx\n", real_ptr, real_link);
 743     }
 744   }
 745 }
 746
 747 void GC_dump_finalization()
 748 {
 749     struct finalizable_object * curr_fo;
 750     ptr_t real_ptr;
 751     int fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);
 752     int i;
 753
 754     GC_printf0("Disappearing (short) links:\n");
 755     GC_dump_finalization_links(&GC_dl_hashtbl);
 756     GC_printf0("Disappearing long links:\n");
 757     GC_dump_finalization_links(&GC_ll_hashtbl);
 758
 759     GC_printf0("Finalizers:\n");
 760     for (i = 0; i < fo_size; i++) {
 761       for (curr_fo = fo_head[i]; curr_fo != 0; curr_fo = fo_next(curr_fo)) {
 762         real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 763         GC_printf1("Finalizable object: 0x%lx\n", real_ptr);
 764       }
 765     }
 766 }
 767 #endif
 768
 769 static void GC_make_disappearing_links_disappear(struct dl_hashtbl_s *dl_hashtbl)
 770 {
 771     struct disappearing_link * curr_dl, * prev_dl, * next_dl;
 772     ptr_t real_ptr, real_link;
 773     register int i;
 774     int dl_size = (dl_hashtbl -> log_size == -1 ) ? 0 : (1 << dl_hashtbl -> log_size);
 775
 776     for (i = 0; i < dl_size; i++) {
 777       curr_dl = dl_hashtbl -> head[i];
 778       prev_dl = 0;
 779       while (curr_dl != 0) {
 780         real_ptr = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_obj);
 781         real_link = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link);
 782         if (!GC_is_marked(real_ptr)) {
 783             *(word *)real_link = 0;
 784             next_dl = dl_next(curr_dl);
 785             if (prev_dl == 0) {
 786                 dl_hashtbl -> head[i] = next_dl;
 787             } else {
 788                 dl_set_next(prev_dl, next_dl);
 789             }
 790             GC_clear_mark_bit((ptr_t)curr_dl);
 791             dl_hashtbl -> entries--;
 792             curr_dl = next_dl;
 793         } else {
 794             prev_dl = curr_dl;
 795             curr_dl = dl_next(curr_dl);
 796         }
 797       }
 798     }
 799 }
 800
 801 static void GC_remove_dangling_disappearing_links(struct dl_hashtbl_s *dl_hashtbl)
 802 {
 803     struct disappearing_link * curr_dl, * prev_dl, * next_dl;
 804     ptr_t real_ptr, real_link;
 805     register int i;
 806     int dl_size = (dl_hashtbl -> log_size == -1 ) ? 0 : (1 << dl_hashtbl -> log_size);
 807
 808     for (i = 0; i < dl_size; i++) {
 809       curr_dl = dl_hashtbl -> head[i];
 810       prev_dl = 0;
 811       while (curr_dl != 0) {
 812         real_link = GC_base((ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link));
 813         if (real_link != 0 && !GC_is_marked(real_link)) {
 814             next_dl = dl_next(curr_dl);
 815             if (prev_dl == 0) {
 816                 dl_hashtbl -> head[i] = next_dl;
 817             } else {
 818                 dl_set_next(prev_dl, next_dl);
 819             }
 820             GC_clear_mark_bit((ptr_t)curr_dl);
 821             dl_hashtbl -> entries--;
 822             curr_dl = next_dl;
 823         } else {
 824             prev_dl = curr_dl;
 825             curr_dl = dl_next(curr_dl);
 826         }
 827       }
 828     }
 829 }
 830
 831 /* Called with world stopped.  Cause disappearing links to disappear,   */
 832 /* and invoke finalizers.                                               */
 833 void GC_finalize()
 834 {
 835     struct finalizable_object * curr_fo, * prev_fo, * next_fo;
 836     ptr_t real_ptr;
 837     register int i;
 838     int fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);
 839
 840         GC_mark_togglerefs();
 841
 842   /* Make non-tracking disappearing links disappear */
 843         GC_make_disappearing_links_disappear(&GC_dl_hashtbl);
 844
 845   /* Mark all objects reachable via chains of 1 or more pointers        */
 846   /* from finalizable objects.                                          */
 847     GC_ASSERT(GC_mark_state == MS_NONE);
 848     for (i = 0; i < fo_size; i++) {
 849       for (curr_fo = fo_head[i]; curr_fo != 0; curr_fo = fo_next(curr_fo)) {
 850         real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 851         if (!GC_is_marked(real_ptr)) {
 852             GC_MARKED_FOR_FINALIZATION(real_ptr);
 853             GC_MARK_FO(real_ptr, curr_fo -> fo_mark_proc);
 854             if (GC_is_marked(real_ptr)) {
 855                 WARN("Finalization cycle involving %lx\n", real_ptr);
 856             }
 857         }
 858       }
 859     }
 860   /* Enqueue for finalization all objects that are still                */
 861   /* unreachable.                                                       */
 862     GC_words_finalized = 0;
 863     for (i = 0; i < fo_size; i++) {
 864       curr_fo = fo_head[i];
 865       prev_fo = 0;
 866       while (curr_fo != 0) {
 867         real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 868         if (!GC_is_marked(real_ptr)) {
 869             if (!GC_java_finalization) {
 870               GC_set_mark_bit(real_ptr);
 871             }
 872             /* Delete from hash table */
 873               next_fo = fo_next(curr_fo);
 874               if (prev_fo == 0) {
 875                 fo_head[i] = next_fo;
 876               } else {
 877                 fo_set_next(prev_fo, next_fo);
 878               }
 879               GC_fo_entries--;
 880             /* Add to list of objects awaiting finalization.    */
 881               fo_set_next(curr_fo, GC_finalize_now);
 882               GC_finalize_now = curr_fo;
 883               /* unhide object pointer so any future collections will   */
 884               /* see it.                                                */
 885               curr_fo -> fo_hidden_base =
 886                         (word) REVEAL_POINTER(curr_fo -> fo_hidden_base);
 887               GC_words_finalized +=
 888                         ALIGNED_WORDS(curr_fo -> fo_object_size)
 889                         + ALIGNED_WORDS(sizeof(struct finalizable_object));
 890             GC_ASSERT(GC_is_marked(GC_base((ptr_t)curr_fo)));
 891             curr_fo = next_fo;
 892         } else {
 893             prev_fo = curr_fo;
 894             curr_fo = fo_next(curr_fo);
 895         }
 896       }
 897     }
 898
 899   if (GC_java_finalization) {
 900     /* make sure we mark everything reachable from objects finalized
 901        using the no_order mark_proc */
 902       for (curr_fo = GC_finalize_now;
 903          curr_fo != NULL; curr_fo = fo_next(curr_fo)) {
 904         real_ptr = (ptr_t)curr_fo -> fo_hidden_base;
 905         if (!GC_is_marked(real_ptr)) {
 906             if (curr_fo -> fo_mark_proc == GC_null_finalize_mark_proc) {
 907                 GC_MARK_FO(real_ptr, GC_normal_finalize_mark_proc);
 908             }
 909             GC_set_mark_bit(real_ptr);
 910         }
 911       }
 912   }
 913
 914   /* Remove dangling disappearing links. */
 915   GC_remove_dangling_disappearing_links(&GC_dl_hashtbl);
 916
 917         GC_clear_togglerefs ();
 918
 919   /* Make long links disappear and remove dangling ones. */
 920   GC_make_disappearing_links_disappear(&GC_ll_hashtbl);
 921   GC_remove_dangling_disappearing_links(&GC_ll_hashtbl);
 922 }
 923
 924 #ifndef JAVA_FINALIZATION_NOT_NEEDED
 925
 926 /* Enqueue all remaining finalizers to be run - Assumes lock is
 927  * held, and signals are disabled */
 928 void GC_enqueue_all_finalizers()
 929 {
 930     struct finalizable_object * curr_fo, * prev_fo, * next_fo;
 931     ptr_t real_ptr;
 932     register int i;
 933     int fo_size;
 934
 935     fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);
 936     GC_words_finalized = 0;
 937     for (i = 0; i < fo_size; i++) {
 938         curr_fo = fo_head[i];
 939         prev_fo = 0;
 940       while (curr_fo != 0) {
 941           real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 942           GC_MARK_FO(real_ptr, GC_normal_finalize_mark_proc);
 943           GC_set_mark_bit(real_ptr);
 944
 945           /* Delete from hash table */
 946           next_fo = fo_next(curr_fo);
 947           if (prev_fo == 0) {
 948               fo_head[i] = next_fo;
 949           } else {
 950               fo_set_next(prev_fo, next_fo);
 951           }
 952           GC_fo_entries--;
 953
 954           /* Add to list of objects awaiting finalization.      */
 955           fo_set_next(curr_fo, GC_finalize_now);
 956           GC_finalize_now = curr_fo;
 957
 958           /* unhide object pointer so any future collections will       */
 959           /* see it.                                            */
 960           curr_fo -> fo_hidden_base =
 961                         (word) REVEAL_POINTER(curr_fo -> fo_hidden_base);
 962
 963           GC_words_finalized +=
 964                 ALIGNED_WORDS(curr_fo -> fo_object_size)
 965                         + ALIGNED_WORDS(sizeof(struct finalizable_object));
 966           curr_fo = next_fo;
 967         }
 968     }
 969
 970     return;
 971 }
 972
 973 /* Invoke all remaining finalizers that haven't yet been run.
 974  * This is needed for strict compliance with the Java standard,
 975  * which can make the runtime guarantee that all finalizers are run.
 976  * Unfortunately, the Java standard implies we have to keep running
 977  * finalizers until there are no more left, a potential infinite loop.
 978  * YUCK.
 979  * Note that this is even more dangerous than the usual Java
 980  * finalizers, in that objects reachable from static variables
 981  * may have been finalized when these finalizers are run.
 982  * Finalizers run at this point must be prepared to deal with a
 983  * mostly broken world.
 984  * This routine is externally callable, so is called without
 985  * the allocation lock.
 986  */
 987 GC_API void GC_finalize_all()
 988 {
 989     DCL_LOCK_STATE;
 990
 991     DISABLE_SIGNALS();
 992     LOCK();
 993     while (GC_fo_entries > 0) {
 994       GC_enqueue_all_finalizers();
 995       UNLOCK();
 996       ENABLE_SIGNALS();
 997       GC_INVOKE_FINALIZERS();
 998       DISABLE_SIGNALS();
 999       LOCK();
1000     }
1001     UNLOCK();
1002     ENABLE_SIGNALS();
1003 }
1004 #endif
1005
1006 /* Returns true if it is worth calling GC_invoke_finalizers. (Useful if */
1007 /* finalizers can only be called from some kind of `safe state' and     */
1008 /* getting into that safe state is expensive.)                          */
1009 int GC_should_invoke_finalizers GC_PROTO((void))
1010 {
1011     return GC_finalize_now != 0;
1012 }
1013
1014 /* Invoke finalizers for all objects that are ready to be finalized.    */
1015 /* Should be called without allocation lock.                            */
1016 int GC_invoke_finalizers()
1017 {
1018     struct finalizable_object * curr_fo;
1019     int count = 0;
1020     word mem_freed_before;
1021     DCL_LOCK_STATE;
1022
1023     while (GC_finalize_now != 0) {
1024 #       ifdef THREADS
1025             DISABLE_SIGNALS();
1026             LOCK();
1027 #       endif
1028         if (count == 0) {
1029             mem_freed_before = GC_mem_freed;
1030         }
1031         curr_fo = GC_finalize_now;
1032 #       ifdef THREADS
1033             if (curr_fo != 0) GC_finalize_now = fo_next(curr_fo);
1034             UNLOCK();
1035             ENABLE_SIGNALS();
1036             if (curr_fo == 0) break;
1037 #       else
1038             GC_finalize_now = fo_next(curr_fo);
1039 #       endif
1040         fo_set_next(curr_fo, 0);
1041         (*(curr_fo -> fo_fn))((ptr_t)(curr_fo -> fo_hidden_base),
1042                               curr_fo -> fo_client_data);
1043         curr_fo -> fo_client_data = 0;
1044         ++count;
1045 #       ifdef UNDEFINED
1046             /* This is probably a bad idea.  It throws off accounting if */
1047             /* nearly all objects are finalizable.  O.w. it shouldn't    */
1048             /* matter.                                                   */
1049             GC_free((GC_PTR)curr_fo);
1050 #       endif
1051     }
1052     if (count != 0 && mem_freed_before != GC_mem_freed) {
1053         LOCK();
1054         GC_finalizer_mem_freed += (GC_mem_freed - mem_freed_before);
1055         UNLOCK();
1056     }
1057     return count;
1058 }
1059
1060 void (* GC_finalizer_notifier)() = (void (*) GC_PROTO((void)))0;
1061
1062 static GC_word last_finalizer_notification = 0;
1063
1064 void GC_notify_or_invoke_finalizers GC_PROTO((void))
1065 {
1066     /* This is a convenient place to generate backtraces if appropriate, */
1067     /* since that code is not callable with the allocation lock.         */
1068 #   if defined(KEEP_BACK_PTRS) || defined(MAKE_BACK_GRAPH)
1069       static word last_back_trace_gc_no = 1;    /* Skip first one. */
1070
1071       if (GC_gc_no > last_back_trace_gc_no) {
1072         word i;
1073
1074 #       ifdef KEEP_BACK_PTRS
1075           LOCK();
1076           /* Stops when GC_gc_no wraps; that's OK.      */
1077           last_back_trace_gc_no = (word)(-1);  /* disable others. */
1078           for (i = 0; i < GC_backtraces; ++i) {
1079               /* FIXME: This tolerates concurrent heap mutation,        */
1080               /* which may cause occasional mysterious results.         */
1081               /* We need to release the GC lock, since GC_print_callers */
1082               /* acquires it.  It probably shouldn't.                   */
1083               UNLOCK();
1084               GC_generate_random_backtrace_no_gc();
1085               LOCK();
1086           }
1087           last_back_trace_gc_no = GC_gc_no;
1088           UNLOCK();
1089 #       endif
1090 #       ifdef MAKE_BACK_GRAPH
1091           if (GC_print_back_height)
1092             GC_print_back_graph_stats();
1093 #       endif
1094       }
1095 #   endif
1096     if (GC_finalize_now == 0) return;
1097     if (!GC_finalize_on_demand) {
1098         (void) GC_invoke_finalizers();
1099 #       ifndef THREADS
1100           GC_ASSERT(GC_finalize_now == 0);
1101 #       endif   /* Otherwise GC can run concurrently and add more */
1102         return;
1103     }
1104     if (GC_finalizer_notifier != (void (*) GC_PROTO((void)))0
1105         && last_finalizer_notification != GC_gc_no) {
1106         last_finalizer_notification = GC_gc_no;
1107         GC_finalizer_notifier();
1108     }
1109 }
1110
1111 # ifdef __STDC__
1112     GC_PTR GC_call_with_alloc_lock(GC_fn_type fn,
1113                                          GC_PTR client_data)
1114 # else
1115     GC_PTR GC_call_with_alloc_lock(fn, client_data)
1116     GC_fn_type fn;
1117     GC_PTR client_data;
1118 # endif
1119 {
1120     GC_PTR result;
1121     DCL_LOCK_STATE;
1122
1123 #   ifdef THREADS
1124       DISABLE_SIGNALS();
1125       LOCK();
1126       SET_LOCK_HOLDER();
1127 #   endif
1128     result = (*fn)(client_data);
1129 #   ifdef THREADS
1130 #     ifndef GC_ASSERTIONS
1131         UNSET_LOCK_HOLDER();
1132 #     endif /* o.w. UNLOCK() does it implicitly */
1133       UNLOCK();
1134       ENABLE_SIGNALS();
1135 #   endif
1136     return(result);
1137 }
1138
1139 #if !defined(NO_DEBUGGING)
1140
1141 void GC_print_finalization_stats()
1142 {
1143     struct finalizable_object *fo = GC_finalize_now;
1144     size_t ready = 0;
1145
1146     GC_printf3("%lu finalization table entries; %lu/%lu short/long disappearing links alive\n",
1147                GC_fo_entries, (unsigned long)GC_dl_hashtbl.entries, (unsigned long)GC_ll_hashtbl.entries);
1148     for (; 0 != fo; fo = fo_next(fo)) ++ready;
1149     GC_printf1("%lu objects are eligible for immediate finalization\n", ready);
1150 }
1151
1152 #endif /* NO_DEBUGGING */