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 (new_dl != 0) {
 206         new_dl -> dl_hidden_obj = HIDE_POINTER(obj);
 207         new_dl -> dl_hidden_link = HIDE_POINTER(link);
 208         dl_set_next(new_dl, dl_head[index]);
 209         dl_head[index] = new_dl;
 210         GC_dl_entries++;
 211     } else {
 212         GC_finalization_failures++;
 213     }
 214 #   ifdef THREADS
 215         UNLOCK();
 216         ENABLE_SIGNALS();
 217 #   endif
 218     return(0);
 219 }
 220
 221 # if defined(__STDC__) || defined(__cplusplus)
 222     int GC_unregister_disappearing_link(GC_PTR * link)
 223 # else
 224     int GC_unregister_disappearing_link(link)
 225     GC_PTR * link;
 226 # endif
 227 {
 228     struct disappearing_link *curr_dl, *prev_dl;
 229     int index;
 230     DCL_LOCK_STATE;
 231
 232     DISABLE_SIGNALS();
 233     LOCK();
 234     index = HASH2(link, log_dl_table_size);
 235     if (((unsigned long)link & (ALIGNMENT-1))) goto out;
 236     prev_dl = 0; curr_dl = dl_head[index];
 237     while (curr_dl != 0) {
 238         if (curr_dl -> dl_hidden_link == HIDE_POINTER(link)) {
 239             if (prev_dl == 0) {
 240                 dl_head[index] = dl_next(curr_dl);
 241             } else {
 242                 dl_set_next(prev_dl, dl_next(curr_dl));
 243             }
 244             GC_dl_entries--;
 245             UNLOCK();
 246             ENABLE_SIGNALS();
 247 #           ifdef DBG_HDRS_ALL
 248               dl_next(curr_dl) = 0;
 249 #           else
 250               GC_free((GC_PTR)curr_dl);
 251 #           endif
 252             return(1);
 253         }
 254         prev_dl = curr_dl;
 255         curr_dl = dl_next(curr_dl);
 256     }
 257 out:
 258     UNLOCK();
 259     ENABLE_SIGNALS();
 260     return(0);
 261 }
 262
 263 /* Possible finalization_marker procedures.  Note that mark stack       */
 264 /* overflow is handled by the caller, and is not a disaster.            */
 265 GC_API void GC_normal_finalize_mark_proc(p)
 266 ptr_t p;
 267 {
 268     hdr * hhdr = HDR(p);
 269
 270     PUSH_OBJ((word *)p, hhdr, GC_mark_stack_top,
 271              &(GC_mark_stack[GC_mark_stack_size]));
 272 }
 273
 274 /* This only pays very partial attention to the mark descriptor.        */
 275 /* It does the right thing for normal and atomic objects, and treats    */
 276 /* most others as normal.                                               */
 277 GC_API void GC_ignore_self_finalize_mark_proc(p)
 278 ptr_t p;
 279 {
 280     hdr * hhdr = HDR(p);
 281     word descr = hhdr -> hb_descr;
 282     ptr_t q, r;
 283     ptr_t scan_limit;
 284     ptr_t target_limit = p + WORDS_TO_BYTES(hhdr -> hb_sz) - 1;
 285
 286     if ((descr & GC_DS_TAGS) == GC_DS_LENGTH) {
 287        scan_limit = p + descr - sizeof(word);
 288     } else {
 289        scan_limit = target_limit + 1 - sizeof(word);
 290     }
 291     for (q = p; q <= scan_limit; q += ALIGNMENT) {
 292         r = *(ptr_t *)q;
 293         if (r < p || r > target_limit) {
 294             GC_PUSH_ONE_HEAP((word)r, q);
 295         }
 296     }
 297 }
 298
 299 /*ARGSUSED*/
 300 GC_API void GC_null_finalize_mark_proc(p)
 301 ptr_t p;
 302 {
 303 }
 304
 305
 306
 307 /* Register a finalization function.  See gc.h for details.     */
 308 /* in the nonthreads case, we try to avoid disabling signals,   */
 309 /* since it can be expensive.  Threads packages typically       */
 310 /* make it cheaper.                                             */
 311 /* The last parameter is a procedure that determines            */
 312 /* marking for finalization ordering.  Any objects marked       */
 313 /* by that procedure will be guaranteed to not have been        */
 314 /* finalized when this finalizer is invoked.                    */
 315 GC_API void GC_register_finalizer_inner(obj, fn, cd, ofn, ocd, mp)
 316 GC_PTR obj;
 317 GC_finalization_proc fn;
 318 GC_PTR cd;
 319 GC_finalization_proc * ofn;
 320 GC_PTR * ocd;
 321 finalization_mark_proc * mp;
 322 {
 323     ptr_t base;
 324     struct finalizable_object * curr_fo, * prev_fo;
 325     int index;
 326     struct finalizable_object *new_fo;
 327     hdr *hhdr;
 328     DCL_LOCK_STATE;
 329
 330 #   ifdef THREADS
 331         DISABLE_SIGNALS();
 332         LOCK();
 333 #   endif
 334     if (log_fo_table_size == -1
 335         || GC_fo_entries > ((word)1 << log_fo_table_size)) {
 336 #       ifndef THREADS
 337             DISABLE_SIGNALS();
 338 #       endif
 339         GC_grow_table((struct hash_chain_entry ***)(&fo_head),
 340                       &log_fo_table_size);
 341 #       ifdef CONDPRINT
 342           if (GC_print_stats) {
 343             GC_printf1("Grew fo table to %lu entries\n",
 344                         (unsigned long)(1 << log_fo_table_size));
 345           }
 346 #       endif
 347 #       ifndef THREADS
 348             ENABLE_SIGNALS();
 349 #       endif
 350     }
 351     /* in the THREADS case signals are disabled and we hold allocation  */
 352     /* lock; otherwise neither is true.  Proceed carefully.             */
 353     base = (ptr_t)obj;
 354     index = HASH2(base, log_fo_table_size);
 355     prev_fo = 0; curr_fo = fo_head[index];
 356     while (curr_fo != 0) {
 357         if (curr_fo -> fo_hidden_base == HIDE_POINTER(base)) {
 358             /* Interruption by a signal in the middle of this   */
 359             /* should be safe.  The client may see only *ocd    */
 360             /* updated, but we'll declare that to be his        */
 361             /* problem.                                         */
 362             if (ocd) *ocd = (GC_PTR) curr_fo -> fo_client_data;
 363             if (ofn) *ofn = curr_fo -> fo_fn;
 364             /* Delete the structure for base. */
 365                 if (prev_fo == 0) {
 366                   fo_head[index] = fo_next(curr_fo);
 367                 } else {
 368                   fo_set_next(prev_fo, fo_next(curr_fo));
 369                 }
 370             if (fn == 0) {
 371                 GC_fo_entries--;
 372                   /* May not happen if we get a signal.  But a high     */
 373                   /* estimate will only make the table larger than      */
 374                   /* necessary.                                         */
 375 #               if !defined(THREADS) && !defined(DBG_HDRS_ALL)
 376                   GC_free((GC_PTR)curr_fo);
 377 #               endif
 378             } else {
 379                 curr_fo -> fo_fn = fn;
 380                 curr_fo -> fo_client_data = (ptr_t)cd;
 381                 curr_fo -> fo_mark_proc = mp;
 382                 /* Reinsert it.  We deleted it first to maintain        */
 383                 /* consistency in the event of a signal.                */
 384                 if (prev_fo == 0) {
 385                   fo_head[index] = curr_fo;
 386                 } else {
 387                   fo_set_next(prev_fo, curr_fo);
 388                 }
 389             }
 390 #           ifdef THREADS
 391                 UNLOCK();
 392                 ENABLE_SIGNALS();
 393 #           endif
 394             return;
 395         }
 396         prev_fo = curr_fo;
 397         curr_fo = fo_next(curr_fo);
 398     }
 399     if (ofn) *ofn = 0;
 400     if (ocd) *ocd = 0;
 401     if (fn == 0) {
 402 #       ifdef THREADS
 403             UNLOCK();
 404             ENABLE_SIGNALS();
 405 #       endif
 406         return;
 407     }
 408     GET_HDR(base, hhdr);
 409     if (0 == hhdr) {
 410       /* We won't collect it, hence finalizer wouldn't be run. */
 411 #     ifdef THREADS
 412           UNLOCK();
 413           ENABLE_SIGNALS();
 414 #     endif
 415       return;
 416     }
 417     new_fo = (struct finalizable_object *)
 418         GC_INTERNAL_MALLOC(sizeof(struct finalizable_object),NORMAL);
 419     if (new_fo != 0) {
 420         new_fo -> fo_hidden_base = (word)HIDE_POINTER(base);
 421         new_fo -> fo_fn = fn;
 422         new_fo -> fo_client_data = (ptr_t)cd;
 423         new_fo -> fo_object_size = hhdr -> hb_sz;
 424         new_fo -> fo_mark_proc = mp;
 425         fo_set_next(new_fo, fo_head[index]);
 426         GC_fo_entries++;
 427         fo_head[index] = new_fo;
 428     } else {
 429         GC_finalization_failures++;
 430     }
 431 #   ifdef THREADS
 432         UNLOCK();
 433         ENABLE_SIGNALS();
 434 #   endif
 435 }
 436
 437 # if defined(__STDC__)
 438     void GC_register_finalizer(void * obj,
 439                                GC_finalization_proc fn, void * cd,
 440                                GC_finalization_proc *ofn, void ** ocd)
 441 # else
 442     void GC_register_finalizer(obj, fn, cd, ofn, ocd)
 443     GC_PTR obj;
 444     GC_finalization_proc fn;
 445     GC_PTR cd;
 446     GC_finalization_proc * ofn;
 447     GC_PTR * ocd;
 448 # endif
 449 {
 450     GC_register_finalizer_inner(obj, fn, cd, ofn,
 451                                 ocd, GC_normal_finalize_mark_proc);
 452 }
 453
 454 # if defined(__STDC__)
 455     void GC_register_finalizer_ignore_self(void * obj,
 456                                GC_finalization_proc fn, void * cd,
 457                                GC_finalization_proc *ofn, void ** ocd)
 458 # else
 459     void GC_register_finalizer_ignore_self(obj, fn, cd, ofn, ocd)
 460     GC_PTR obj;
 461     GC_finalization_proc fn;
 462     GC_PTR cd;
 463     GC_finalization_proc * ofn;
 464     GC_PTR * ocd;
 465 # endif
 466 {
 467     GC_register_finalizer_inner(obj, fn, cd, ofn,
 468                                 ocd, GC_ignore_self_finalize_mark_proc);
 469 }
 470
 471 # if defined(__STDC__)
 472     void GC_register_finalizer_no_order(void * obj,
 473                                GC_finalization_proc fn, void * cd,
 474                                GC_finalization_proc *ofn, void ** ocd)
 475 # else
 476     void GC_register_finalizer_no_order(obj, fn, cd, ofn, ocd)
 477     GC_PTR obj;
 478     GC_finalization_proc fn;
 479     GC_PTR cd;
 480     GC_finalization_proc * ofn;
 481     GC_PTR * ocd;
 482 # endif
 483 {
 484     GC_register_finalizer_inner(obj, fn, cd, ofn,
 485                                 ocd, GC_null_finalize_mark_proc);
 486 }
 487
 488 #ifndef NO_DEBUGGING
 489 void GC_dump_finalization()
 490 {
 491     struct disappearing_link * curr_dl;
 492     struct finalizable_object * curr_fo;
 493     ptr_t real_ptr, real_link;
 494     int dl_size = (log_dl_table_size == -1 ) ? 0 : (1 << log_dl_table_size);
 495     int fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);
 496     int i;
 497
 498     GC_printf0("Disappearing links:\n");
 499     for (i = 0; i < dl_size; i++) {
 500       for (curr_dl = dl_head[i]; curr_dl != 0; curr_dl = dl_next(curr_dl)) {
 501         real_ptr = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_obj);
 502         real_link = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link);
 503         GC_printf2("Object: 0x%lx, Link:0x%lx\n", real_ptr, real_link);
 504       }
 505     }
 506     GC_printf0("Finalizers:\n");
 507     for (i = 0; i < fo_size; i++) {
 508       for (curr_fo = fo_head[i]; curr_fo != 0; curr_fo = fo_next(curr_fo)) {
 509         real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 510         GC_printf1("Finalizable object: 0x%lx\n", real_ptr);
 511       }
 512     }
 513 }
 514 #endif
 515
 516 /* Called with world stopped.  Cause disappearing links to disappear,   */
 517 /* and invoke finalizers.                                               */
 518 void GC_finalize()
 519 {
 520     struct disappearing_link * curr_dl, * prev_dl, * next_dl;
 521     struct finalizable_object * curr_fo, * prev_fo, * next_fo;
 522     ptr_t real_ptr, real_link;
 523     register int i;
 524     int dl_size = (log_dl_table_size == -1 ) ? 0 : (1 << log_dl_table_size);
 525     int fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);
 526
 527   /* Make disappearing links disappear */
 528     for (i = 0; i < dl_size; i++) {
 529       curr_dl = dl_head[i];
 530       prev_dl = 0;
 531       while (curr_dl != 0) {
 532         real_ptr = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_obj);
 533         real_link = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link);
 534         if (!GC_is_marked(real_ptr)) {
 535             *(word *)real_link = 0;
 536             next_dl = dl_next(curr_dl);
 537             if (prev_dl == 0) {
 538                 dl_head[i] = next_dl;
 539             } else {
 540                 dl_set_next(prev_dl, next_dl);
 541             }
 542             GC_clear_mark_bit((ptr_t)curr_dl);
 543             GC_dl_entries--;
 544             curr_dl = next_dl;
 545         } else {
 546             prev_dl = curr_dl;
 547             curr_dl = dl_next(curr_dl);
 548         }
 549       }
 550     }
 551   /* Mark all objects reachable via chains of 1 or more pointers        */
 552   /* from finalizable objects.                                          */
 553     GC_ASSERT(GC_mark_state == MS_NONE);
 554     for (i = 0; i < fo_size; i++) {
 555       for (curr_fo = fo_head[i]; curr_fo != 0; curr_fo = fo_next(curr_fo)) {
 556         real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 557         if (!GC_is_marked(real_ptr)) {
 558             GC_MARKED_FOR_FINALIZATION(real_ptr);
 559             GC_MARK_FO(real_ptr, curr_fo -> fo_mark_proc);
 560             if (GC_is_marked(real_ptr)) {
 561                 WARN("Finalization cycle involving %lx\n", real_ptr);
 562             }
 563         }
 564       }
 565     }
 566   /* Enqueue for finalization all objects that are still                */
 567   /* unreachable.                                                       */
 568     GC_words_finalized = 0;
 569     for (i = 0; i < fo_size; i++) {
 570       curr_fo = fo_head[i];
 571       prev_fo = 0;
 572       while (curr_fo != 0) {
 573         real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 574         if (!GC_is_marked(real_ptr)) {
 575             if (!GC_java_finalization) {
 576               GC_set_mark_bit(real_ptr);
 577             }
 578             /* Delete from hash table */
 579               next_fo = fo_next(curr_fo);
 580               if (prev_fo == 0) {
 581                 fo_head[i] = next_fo;
 582               } else {
 583                 fo_set_next(prev_fo, next_fo);
 584               }
 585               GC_fo_entries--;
 586             /* Add to list of objects awaiting finalization.    */
 587               fo_set_next(curr_fo, GC_finalize_now);
 588               GC_finalize_now = curr_fo;
 589               /* unhide object pointer so any future collections will   */
 590               /* see it.                                                */
 591               curr_fo -> fo_hidden_base =
 592                         (word) REVEAL_POINTER(curr_fo -> fo_hidden_base);
 593               GC_words_finalized +=
 594                         ALIGNED_WORDS(curr_fo -> fo_object_size)
 595                         + ALIGNED_WORDS(sizeof(struct finalizable_object));
 596             GC_ASSERT(GC_is_marked((ptr_t)curr_fo));
 597             curr_fo = next_fo;
 598         } else {
 599             prev_fo = curr_fo;
 600             curr_fo = fo_next(curr_fo);
 601         }
 602       }
 603     }
 604
 605   if (GC_java_finalization) {
 606     /* make sure we mark everything reachable from objects finalized
 607        using the no_order mark_proc */
 608       for (curr_fo = GC_finalize_now;
 609          curr_fo != NULL; curr_fo = fo_next(curr_fo)) {
 610         real_ptr = (ptr_t)curr_fo -> fo_hidden_base;
 611         if (!GC_is_marked(real_ptr)) {
 612             if (curr_fo -> fo_mark_proc == GC_null_finalize_mark_proc) {
 613                 GC_MARK_FO(real_ptr, GC_normal_finalize_mark_proc);
 614             }
 615             GC_set_mark_bit(real_ptr);
 616         }
 617       }
 618   }
 619
 620   /* Remove dangling disappearing links. */
 621     for (i = 0; i < dl_size; i++) {
 622       curr_dl = dl_head[i];
 623       prev_dl = 0;
 624       while (curr_dl != 0) {
 625         real_link = GC_base((ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link));
 626         if (real_link != 0 && !GC_is_marked(real_link)) {
 627             next_dl = dl_next(curr_dl);
 628             if (prev_dl == 0) {
 629                 dl_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             GC_dl_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 #ifndef JAVA_FINALIZATION_NOT_NEEDED
 645
 646 /* Enqueue all remaining finalizers to be run - Assumes lock is
 647  * held, and signals are disabled */
 648 void GC_enqueue_all_finalizers()
 649 {
 650     struct finalizable_object * curr_fo, * prev_fo, * next_fo;
 651     ptr_t real_ptr;
 652     register int i;
 653     int fo_size;
 654
 655     fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);
 656     GC_words_finalized = 0;
 657     for (i = 0; i < fo_size; i++) {
 658         curr_fo = fo_head[i];
 659         prev_fo = 0;
 660       while (curr_fo != 0) {
 661           real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 662           GC_MARK_FO(real_ptr, GC_normal_finalize_mark_proc);
 663           GC_set_mark_bit(real_ptr);
 664
 665           /* Delete from hash table */
 666           next_fo = fo_next(curr_fo);
 667           if (prev_fo == 0) {
 668               fo_head[i] = next_fo;
 669           } else {
 670               fo_set_next(prev_fo, next_fo);
 671           }
 672           GC_fo_entries--;
 673
 674           /* Add to list of objects awaiting finalization.      */
 675           fo_set_next(curr_fo, GC_finalize_now);
 676           GC_finalize_now = curr_fo;
 677
 678           /* unhide object pointer so any future collections will       */
 679           /* see it.                                            */
 680           curr_fo -> fo_hidden_base =
 681                         (word) REVEAL_POINTER(curr_fo -> fo_hidden_base);
 682
 683           GC_words_finalized +=
 684                 ALIGNED_WORDS(curr_fo -> fo_object_size)
 685                         + ALIGNED_WORDS(sizeof(struct finalizable_object));
 686           curr_fo = next_fo;
 687         }
 688     }
 689
 690     return;
 691 }
 692
 693 /* Invoke all remaining finalizers that haven't yet been run.
 694  * This is needed for strict compliance with the Java standard,
 695  * which can make the runtime guarantee that all finalizers are run.
 696  * Unfortunately, the Java standard implies we have to keep running
 697  * finalizers until there are no more left, a potential infinite loop.
 698  * YUCK.
 699  * Note that this is even more dangerous than the usual Java
 700  * finalizers, in that objects reachable from static variables
 701  * may have been finalized when these finalizers are run.
 702  * Finalizers run at this point must be prepared to deal with a
 703  * mostly broken world.
 704  * This routine is externally callable, so is called without
 705  * the allocation lock.
 706  */
 707 GC_API void GC_finalize_all()
 708 {
 709     DCL_LOCK_STATE;
 710
 711     DISABLE_SIGNALS();
 712     LOCK();
 713     while (GC_fo_entries > 0) {
 714       GC_enqueue_all_finalizers();
 715       UNLOCK();
 716       ENABLE_SIGNALS();
 717       GC_INVOKE_FINALIZERS();
 718       DISABLE_SIGNALS();
 719       LOCK();
 720     }
 721     UNLOCK();
 722     ENABLE_SIGNALS();
 723 }
 724 #endif
 725
 726 /* Returns true if it is worth calling GC_invoke_finalizers. (Useful if */
 727 /* finalizers can only be called from some kind of `safe state' and     */
 728 /* getting into that safe state is expensive.)                          */
 729 int GC_should_invoke_finalizers GC_PROTO((void))
 730 {
 731     return GC_finalize_now != 0;
 732 }
 733
 734 /* Invoke finalizers for all objects that are ready to be finalized.    */
 735 /* Should be called without allocation lock.                            */
 736 int GC_invoke_finalizers()
 737 {
 738     register struct finalizable_object * curr_fo;
 739     register int count = 0;
 740     DCL_LOCK_STATE;
 741
 742     while (GC_finalize_now != 0) {
 743 #       ifdef THREADS
 744             DISABLE_SIGNALS();
 745             LOCK();
 746 #       endif
 747         curr_fo = GC_finalize_now;
 748 #       ifdef THREADS
 749             if (curr_fo != 0) GC_finalize_now = fo_next(curr_fo);
 750             UNLOCK();
 751             ENABLE_SIGNALS();
 752             if (curr_fo == 0) break;
 753 #       else
 754             GC_finalize_now = fo_next(curr_fo);
 755 #       endif
 756         fo_set_next(curr_fo, 0);
 757         (*(curr_fo -> fo_fn))((ptr_t)(curr_fo -> fo_hidden_base),
 758                               curr_fo -> fo_client_data);
 759         curr_fo -> fo_client_data = 0;
 760         ++count;
 761 #       ifdef UNDEFINED
 762             /* This is probably a bad idea.  It throws off accounting if */
 763             /* nearly all objects are finalizable.  O.w. it shouldn't    */
 764             /* matter.                                                   */
 765             GC_free((GC_PTR)curr_fo);
 766 #       endif
 767     }
 768     return count;
 769 }
 770
 771 void (* GC_finalizer_notifier)() = (void (*) GC_PROTO((void)))0;
 772
 773 static GC_word last_finalizer_notification = 0;
 774
 775 void GC_notify_or_invoke_finalizers GC_PROTO((void))
 776 {
 777     if (GC_finalize_now == 0) return;
 778     if (!GC_finalize_on_demand) {
 779         (void) GC_invoke_finalizers();
 780         GC_ASSERT(GC_finalize_now == 0);
 781         return;
 782     }
 783     if (GC_finalizer_notifier != (void (*) GC_PROTO((void)))0
 784         && last_finalizer_notification != GC_gc_no) {
 785         last_finalizer_notification = GC_gc_no;
 786         GC_finalizer_notifier();
 787     }
 788 }
 789
 790 # ifdef __STDC__
 791     GC_PTR GC_call_with_alloc_lock(GC_fn_type fn,
 792                                          GC_PTR client_data)
 793 # else
 794     GC_PTR GC_call_with_alloc_lock(fn, client_data)
 795     GC_fn_type fn;
 796     GC_PTR client_data;
 797 # endif
 798 {
 799     GC_PTR result;
 800     DCL_LOCK_STATE;
 801
 802 #   ifdef THREADS
 803       DISABLE_SIGNALS();
 804       LOCK();
 805       SET_LOCK_HOLDER();
 806 #   endif
 807     result = (*fn)(client_data);
 808 #   ifdef THREADS
 809 #     ifndef GC_ASSERTIONS
 810         UNSET_LOCK_HOLDER();
 811 #     endif /* o.w. UNLOCK() does it implicitly */
 812       UNLOCK();
 813       ENABLE_SIGNALS();
 814 #   endif
 815     return(result);
 816 }