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 /* Finalizer proc support */
 370 static void (*GC_object_finalized_proc) (GC_PTR obj);
 371
 372 void
 373 GC_set_finalizer_notify_proc (void (*proc) (GC_PTR obj))
 374 {
 375         GC_object_finalized_proc = proc;
 376 }
 377
 378
 379 static void push_and_mark_object (GC_PTR p)
 380 {
 381     hdr * hhdr = HDR(p);
 382
 383     PUSH_OBJ((word *)p, hhdr, GC_mark_stack_top,
 384              &(GC_mark_stack[GC_mark_stack_size]));
 385
 386         while (!GC_mark_stack_empty()) MARK_FROM_MARK_STACK();
 387         GC_set_mark_bit (p);
 388         if (GC_mark_state != MS_NONE)
 389         while (!GC_mark_some((ptr_t)0)) {}
 390 }
 391
 392 static void GC_mark_togglerefs ()
 393 {
 394         int i;
 395         if (!GC_toggleref_array)
 396                 return;
 397
 398         GC_set_mark_bit ((GC_PTR)GC_toggleref_array);
 399         for (i = 0; i < GC_toggleref_array_size; ++i) {
 400                 if (GC_toggleref_array [i].strong_ref) {
 401                         GC_PTR object = GC_toggleref_array [i].strong_ref;
 402
 403                         push_and_mark_object (object);
 404                 }
 405         }
 406 }
 407
 408 static void GC_clear_togglerefs ()
 409 {
 410         int i;
 411         for (i = 0; i < GC_toggleref_array_size; ++i) {
 412                 if (GC_toggleref_array [i].weak_ref) {
 413                         GC_PTR object = REVEAL_POINTER (GC_toggleref_array [i].weak_ref);
 414
 415                         if (!GC_is_marked (object)) {
 416                                 GC_toggleref_array [i].weak_ref = (GC_hidden_pointer)NULL; /* We defer compaction to only happen on the callback step. */
 417                         } else {
 418                                 /*No need to copy, boehm is non-moving */
 419                         }
 420                 }
 421         }
 422 }
 423
 424
 425
 426 void GC_toggleref_register_callback(int (*proccess_toggleref) (GC_PTR obj))
 427 {
 428         GC_toggleref_callback = proccess_toggleref;
 429 }
 430
 431 static void
 432 ensure_toggleref_capacity (int capacity)
 433 {
 434         if (!GC_toggleref_array) {
 435                 GC_toggleref_array_capacity = 32;
 436                 GC_toggleref_array = (GCToggleRef *) GC_INTERNAL_MALLOC_IGNORE_OFF_PAGE (GC_toggleref_array_capacity * sizeof (GCToggleRef), NORMAL);
 437         }
 438         if (GC_toggleref_array_size + capacity >= GC_toggleref_array_capacity) {
 439                 GCToggleRef *tmp;
 440                 int old_capacity = GC_toggleref_array_capacity;
 441                 while (GC_toggleref_array_capacity < GC_toggleref_array_size + capacity)
 442                         GC_toggleref_array_capacity *= 2;
 443
 444                 tmp = (GCToggleRef *) GC_INTERNAL_MALLOC_IGNORE_OFF_PAGE (GC_toggleref_array_capacity * sizeof (GCToggleRef), NORMAL);
 445                 memcpy (tmp, GC_toggleref_array, GC_toggleref_array_size * sizeof (GCToggleRef));
 446                 GC_INTERNAL_FREE (GC_toggleref_array);
 447                 GC_toggleref_array = tmp;
 448         }
 449 }
 450
 451 void
 452 GC_toggleref_add (GC_PTR object, int strong_ref)
 453 {
 454     DCL_LOCK_STATE;
 455 # ifdef THREADS
 456         DISABLE_SIGNALS();
 457         LOCK();
 458 # endif
 459
 460         if (!GC_toggleref_callback)
 461                 goto end;
 462
 463         ensure_toggleref_capacity (1);
 464         GC_toggleref_array [GC_toggleref_array_size].strong_ref = strong_ref ? object : NULL;
 465         GC_toggleref_array [GC_toggleref_array_size].weak_ref = strong_ref ? (GC_hidden_pointer)NULL : HIDE_POINTER (object);
 466         ++GC_toggleref_array_size;
 467
 468 end:
 469 # ifdef THREADS
 470         UNLOCK();
 471         ENABLE_SIGNALS();
 472 # endif
 473 }
 474
 475
 476
 477 # if defined(__STDC__) || defined(__cplusplus)
 478     int GC_register_long_link(GC_PTR * link, GC_PTR obj)
 479 # else
 480     int GC_register_long_link(link, obj)
 481     GC_PTR * link;
 482         GC_PTR obj;
 483 # endif
 484 {
 485     return GC_register_disappearing_link_inner(&GC_ll_hashtbl, link, obj);
 486 }
 487
 488 # if defined(__STDC__) || defined(__cplusplus)
 489     int GC_unregister_long_link(GC_PTR * link)
 490 # else
 491     int GC_unregister_long_link(link)
 492     GC_PTR * link;
 493 # endif
 494 {
 495         return GC_unregister_disappearing_link_inner(&GC_ll_hashtbl, link);
 496 }
 497
 498 /* Possible finalization_marker procedures.  Note that mark stack       */
 499 /* overflow is handled by the caller, and is not a disaster.            */
 500 GC_API void GC_normal_finalize_mark_proc(p)
 501 ptr_t p;
 502 {
 503     hdr * hhdr = HDR(p);
 504
 505     PUSH_OBJ((word *)p, hhdr, GC_mark_stack_top,
 506              &(GC_mark_stack[GC_mark_stack_size]));
 507 }
 508
 509 /* This only pays very partial attention to the mark descriptor.        */
 510 /* It does the right thing for normal and atomic objects, and treats    */
 511 /* most others as normal.                                               */
 512 GC_API void GC_ignore_self_finalize_mark_proc(p)
 513 ptr_t p;
 514 {
 515     hdr * hhdr = HDR(p);
 516     word descr = hhdr -> hb_descr;
 517     ptr_t q, r;
 518     ptr_t scan_limit;
 519     ptr_t target_limit = p + WORDS_TO_BYTES(hhdr -> hb_sz) - 1;
 520
 521     if ((descr & GC_DS_TAGS) == GC_DS_LENGTH) {
 522        scan_limit = p + descr - sizeof(word);
 523     } else {
 524        scan_limit = target_limit + 1 - sizeof(word);
 525     }
 526     for (q = p; q <= scan_limit; q += ALIGNMENT) {
 527         r = *(ptr_t *)q;
 528         if (r < p || r > target_limit) {
 529             GC_PUSH_ONE_HEAP((word)r, q);
 530         }
 531     }
 532 }
 533
 534 /*ARGSUSED*/
 535 GC_API void GC_null_finalize_mark_proc(p)
 536 ptr_t p;
 537 {
 538 }
 539
 540
 541
 542 /* Register a finalization function.  See gc.h for details.     */
 543 /* in the nonthreads case, we try to avoid disabling signals,   */
 544 /* since it can be expensive.  Threads packages typically       */
 545 /* make it cheaper.                                             */
 546 /* The last parameter is a procedure that determines            */
 547 /* marking for finalization ordering.  Any objects marked       */
 548 /* by that procedure will be guaranteed to not have been        */
 549 /* finalized when this finalizer is invoked.                    */
 550 GC_API void GC_register_finalizer_inner(obj, fn, cd, ofn, ocd, mp)
 551 GC_PTR obj;
 552 GC_finalization_proc fn;
 553 GC_PTR cd;
 554 GC_finalization_proc * ofn;
 555 GC_PTR * ocd;
 556 finalization_mark_proc * mp;
 557 {
 558     ptr_t base;
 559     struct finalizable_object * curr_fo, * prev_fo;
 560     int index;
 561     struct finalizable_object *new_fo;
 562     hdr *hhdr;
 563     DCL_LOCK_STATE;
 564
 565 #   ifdef THREADS
 566         DISABLE_SIGNALS();
 567         LOCK();
 568 #   endif
 569     if (log_fo_table_size == -1
 570         || GC_fo_entries > ((word)1 << log_fo_table_size)) {
 571 #       ifndef THREADS
 572             DISABLE_SIGNALS();
 573 #       endif
 574         GC_grow_table((struct hash_chain_entry ***)(&fo_head),
 575                       &log_fo_table_size);
 576 #       ifdef CONDPRINT
 577           if (GC_print_stats) {
 578             GC_printf1("Grew fo table to %lu entries\n",
 579                         (unsigned long)(1 << log_fo_table_size));
 580           }
 581 #       endif
 582 #       ifndef THREADS
 583             ENABLE_SIGNALS();
 584 #       endif
 585     }
 586     /* in the THREADS case signals are disabled and we hold allocation  */
 587     /* lock; otherwise neither is true.  Proceed carefully.             */
 588     base = (ptr_t)obj;
 589     index = HASH2(base, log_fo_table_size);
 590     prev_fo = 0; curr_fo = fo_head[index];
 591     while (curr_fo != 0) {
 592         if (curr_fo -> fo_hidden_base == HIDE_POINTER(base)) {
 593             /* Interruption by a signal in the middle of this   */
 594             /* should be safe.  The client may see only *ocd    */
 595             /* updated, but we'll declare that to be his        */
 596             /* problem.                                         */
 597             if (ocd) *ocd = (GC_PTR) curr_fo -> fo_client_data;
 598             if (ofn) *ofn = curr_fo -> fo_fn;
 599             /* Delete the structure for base. */
 600                 if (prev_fo == 0) {
 601                   fo_head[index] = fo_next(curr_fo);
 602                 } else {
 603                   fo_set_next(prev_fo, fo_next(curr_fo));
 604                 }
 605             if (fn == 0) {
 606                 GC_fo_entries--;
 607                   /* May not happen if we get a signal.  But a high     */
 608                   /* estimate will only make the table larger than      */
 609                   /* necessary.                                         */
 610 #               if !defined(THREADS) && !defined(DBG_HDRS_ALL)
 611                   GC_free((GC_PTR)curr_fo);
 612 #               endif
 613             } else {
 614                 curr_fo -> fo_fn = fn;
 615                 curr_fo -> fo_client_data = (ptr_t)cd;
 616                 curr_fo -> fo_mark_proc = mp;
 617                 /* Reinsert it.  We deleted it first to maintain        */
 618                 /* consistency in the event of a signal.                */
 619                 if (prev_fo == 0) {
 620                   fo_head[index] = curr_fo;
 621                 } else {
 622                   fo_set_next(prev_fo, curr_fo);
 623                 }
 624             }
 625 #           ifdef THREADS
 626                 UNLOCK();
 627                 ENABLE_SIGNALS();
 628 #           endif
 629             return;
 630         }
 631         prev_fo = curr_fo;
 632         curr_fo = fo_next(curr_fo);
 633     }
 634     if (ofn) *ofn = 0;
 635     if (ocd) *ocd = 0;
 636     if (fn == 0) {
 637 #       ifdef THREADS
 638             UNLOCK();
 639             ENABLE_SIGNALS();
 640 #       endif
 641         return;
 642     }
 643     GET_HDR(base, hhdr);
 644     if (0 == hhdr) {
 645       /* We won't collect it, hence finalizer wouldn't be run. */
 646 #     ifdef THREADS
 647           UNLOCK();
 648           ENABLE_SIGNALS();
 649 #     endif
 650       return;
 651     }
 652     new_fo = (struct finalizable_object *)
 653         GC_INTERNAL_MALLOC(sizeof(struct finalizable_object),NORMAL);
 654     if (0 == new_fo) {
 655 #     ifdef THREADS
 656         UNLOCK();
 657         ENABLE_SIGNALS();
 658 #     endif
 659       new_fo = (struct finalizable_object *)
 660               GC_oom_fn(sizeof(struct finalizable_object));
 661       if (0 == new_fo) {
 662         GC_finalization_failures++;
 663         return;
 664       }
 665       /* It's not likely we'll make it here, but ... */
 666 #     ifdef THREADS
 667         DISABLE_SIGNALS();
 668         LOCK();
 669 #     endif
 670     }
 671     new_fo -> fo_hidden_base = (word)HIDE_POINTER(base);
 672     new_fo -> fo_fn = fn;
 673     new_fo -> fo_client_data = (ptr_t)cd;
 674     new_fo -> fo_object_size = hhdr -> hb_sz;
 675     new_fo -> fo_mark_proc = mp;
 676     fo_set_next(new_fo, fo_head[index]);
 677     GC_fo_entries++;
 678     fo_head[index] = new_fo;
 679 #   ifdef THREADS
 680         UNLOCK();
 681         ENABLE_SIGNALS();
 682 #   endif
 683 }
 684
 685 # if defined(__STDC__)
 686     void GC_register_finalizer(void * obj,
 687                                GC_finalization_proc fn, void * cd,
 688                                GC_finalization_proc *ofn, void ** ocd)
 689 # else
 690     void GC_register_finalizer(obj, fn, cd, ofn, ocd)
 691     GC_PTR obj;
 692     GC_finalization_proc fn;
 693     GC_PTR cd;
 694     GC_finalization_proc * ofn;
 695     GC_PTR * ocd;
 696 # endif
 697 {
 698     GC_register_finalizer_inner(obj, fn, cd, ofn,
 699                                 ocd, GC_normal_finalize_mark_proc);
 700 }
 701
 702 # if defined(__STDC__)
 703     void GC_register_finalizer_ignore_self(void * obj,
 704                                GC_finalization_proc fn, void * cd,
 705                                GC_finalization_proc *ofn, void ** ocd)
 706 # else
 707     void GC_register_finalizer_ignore_self(obj, fn, cd, ofn, ocd)
 708     GC_PTR obj;
 709     GC_finalization_proc fn;
 710     GC_PTR cd;
 711     GC_finalization_proc * ofn;
 712     GC_PTR * ocd;
 713 # endif
 714 {
 715     GC_register_finalizer_inner(obj, fn, cd, ofn,
 716                                 ocd, GC_ignore_self_finalize_mark_proc);
 717 }
 718
 719 # if defined(__STDC__)
 720     void GC_register_finalizer_no_order(void * obj,
 721                                GC_finalization_proc fn, void * cd,
 722                                GC_finalization_proc *ofn, void ** ocd)
 723 # else
 724     void GC_register_finalizer_no_order(obj, fn, cd, ofn, ocd)
 725     GC_PTR obj;
 726     GC_finalization_proc fn;
 727     GC_PTR cd;
 728     GC_finalization_proc * ofn;
 729     GC_PTR * ocd;
 730 # endif
 731 {
 732     GC_register_finalizer_inner(obj, fn, cd, ofn,
 733                                 ocd, GC_null_finalize_mark_proc);
 734 }
 735
 736 #ifndef NO_DEBUGGING
 737
 738 static void GC_dump_finalization_links(struct dl_hashtbl_s *dl_hashtbl)
 739 {
 740   struct disappearing_link *curr_dl;
 741   ptr_t real_ptr, real_link;
 742   size_t dl_size = dl_hashtbl->log_size == -1 ? 0 :
 743                               1 << dl_hashtbl->log_size;
 744   int i;
 745
 746   for (i = 0; i < dl_size; i++) {
 747     for (curr_dl = dl_hashtbl -> head[i]; curr_dl != 0;
 748          curr_dl = dl_next(curr_dl)) {
 749       real_ptr = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_obj);
 750       real_link = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link);
 751       GC_printf2("Object: %lx, link: %lx\n", real_ptr, real_link);
 752     }
 753   }
 754 }
 755
 756 void GC_dump_finalization()
 757 {
 758     struct finalizable_object * curr_fo;
 759     ptr_t real_ptr;
 760     int fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);
 761     int i;
 762
 763     GC_printf0("Disappearing (short) links:\n");
 764     GC_dump_finalization_links(&GC_dl_hashtbl);
 765     GC_printf0("Disappearing long links:\n");
 766     GC_dump_finalization_links(&GC_ll_hashtbl);
 767
 768     GC_printf0("Finalizers:\n");
 769     for (i = 0; i < fo_size; i++) {
 770       for (curr_fo = fo_head[i]; curr_fo != 0; curr_fo = fo_next(curr_fo)) {
 771         real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 772         GC_printf1("Finalizable object: 0x%lx\n", real_ptr);
 773       }
 774     }
 775 }
 776 #endif
 777
 778 static void GC_make_disappearing_links_disappear(struct dl_hashtbl_s *dl_hashtbl)
 779 {
 780     struct disappearing_link * curr_dl, * prev_dl, * next_dl;
 781     ptr_t real_ptr, real_link;
 782     register int i;
 783     int dl_size = (dl_hashtbl -> log_size == -1 ) ? 0 : (1 << dl_hashtbl -> log_size);
 784
 785     for (i = 0; i < dl_size; i++) {
 786       curr_dl = dl_hashtbl -> head[i];
 787       prev_dl = 0;
 788       while (curr_dl != 0) {
 789         real_ptr = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_obj);
 790         real_link = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link);
 791         if (!GC_is_marked(real_ptr)) {
 792             *(word *)real_link = 0;
 793             next_dl = dl_next(curr_dl);
 794             if (prev_dl == 0) {
 795                 dl_hashtbl -> head[i] = next_dl;
 796             } else {
 797                 dl_set_next(prev_dl, next_dl);
 798             }
 799             GC_clear_mark_bit((ptr_t)curr_dl);
 800             dl_hashtbl -> entries--;
 801             curr_dl = next_dl;
 802         } else {
 803             prev_dl = curr_dl;
 804             curr_dl = dl_next(curr_dl);
 805         }
 806       }
 807     }
 808 }
 809
 810 static void GC_remove_dangling_disappearing_links(struct dl_hashtbl_s *dl_hashtbl)
 811 {
 812     struct disappearing_link * curr_dl, * prev_dl, * next_dl;
 813     ptr_t real_ptr, real_link;
 814     register int i;
 815     int dl_size = (dl_hashtbl -> log_size == -1 ) ? 0 : (1 << dl_hashtbl -> log_size);
 816
 817     for (i = 0; i < dl_size; i++) {
 818       curr_dl = dl_hashtbl -> head[i];
 819       prev_dl = 0;
 820       while (curr_dl != 0) {
 821         real_link = GC_base((ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link));
 822         if (real_link != 0 && !GC_is_marked(real_link)) {
 823             next_dl = dl_next(curr_dl);
 824             if (prev_dl == 0) {
 825                 dl_hashtbl -> head[i] = next_dl;
 826             } else {
 827                 dl_set_next(prev_dl, next_dl);
 828             }
 829             GC_clear_mark_bit((ptr_t)curr_dl);
 830             dl_hashtbl -> entries--;
 831             curr_dl = next_dl;
 832         } else {
 833             prev_dl = curr_dl;
 834             curr_dl = dl_next(curr_dl);
 835         }
 836       }
 837     }
 838 }
 839
 840 /* Called with world stopped.  Cause disappearing links to disappear,   */
 841 /* and invoke finalizers.                                               */
 842 void GC_finalize()
 843 {
 844     struct finalizable_object * curr_fo, * prev_fo, * next_fo;
 845     ptr_t real_ptr;
 846     register int i;
 847     int fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);
 848
 849         GC_mark_togglerefs();
 850
 851   /* Make non-tracking disappearing links disappear */
 852         GC_make_disappearing_links_disappear(&GC_dl_hashtbl);
 853
 854   /* Mark all objects reachable via chains of 1 or more pointers        */
 855   /* from finalizable objects.                                          */
 856     GC_ASSERT(GC_mark_state == MS_NONE);
 857     for (i = 0; i < fo_size; i++) {
 858       for (curr_fo = fo_head[i]; curr_fo != 0; curr_fo = fo_next(curr_fo)) {
 859         real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 860         if (!GC_is_marked(real_ptr)) {
 861             GC_MARKED_FOR_FINALIZATION(real_ptr);
 862             GC_MARK_FO(real_ptr, curr_fo -> fo_mark_proc);
 863             if (GC_is_marked(real_ptr)) {
 864                 WARN("Finalization cycle involving %lx\n", real_ptr);
 865             }
 866         }
 867       }
 868     }
 869   /* Enqueue for finalization all objects that are still                */
 870   /* unreachable.                                                       */
 871     GC_words_finalized = 0;
 872     for (i = 0; i < fo_size; i++) {
 873       curr_fo = fo_head[i];
 874       prev_fo = 0;
 875       while (curr_fo != 0) {
 876         real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 877         if (!GC_is_marked(real_ptr)) {
 878             if (!GC_java_finalization) {
 879               GC_set_mark_bit(real_ptr);
 880             }
 881             /* Delete from hash table */
 882               next_fo = fo_next(curr_fo);
 883               if (prev_fo == 0) {
 884                 fo_head[i] = next_fo;
 885               } else {
 886                 fo_set_next(prev_fo, next_fo);
 887               }
 888               GC_fo_entries--;
 889
 890                           if (GC_object_finalized_proc)
 891                                   GC_object_finalized_proc (real_ptr);
 892
 893             /* Add to list of objects awaiting finalization.    */
 894               fo_set_next(curr_fo, GC_finalize_now);
 895               GC_finalize_now = curr_fo;
 896               /* unhide object pointer so any future collections will   */
 897               /* see it.                                                */
 898               curr_fo -> fo_hidden_base =
 899                         (word) REVEAL_POINTER(curr_fo -> fo_hidden_base);
 900               GC_words_finalized +=
 901                         ALIGNED_WORDS(curr_fo -> fo_object_size)
 902                         + ALIGNED_WORDS(sizeof(struct finalizable_object));
 903             GC_ASSERT(GC_is_marked(GC_base((ptr_t)curr_fo)));
 904             curr_fo = next_fo;
 905         } else {
 906             prev_fo = curr_fo;
 907             curr_fo = fo_next(curr_fo);
 908         }
 909       }
 910     }
 911
 912   if (GC_java_finalization) {
 913     /* make sure we mark everything reachable from objects finalized
 914        using the no_order mark_proc */
 915       for (curr_fo = GC_finalize_now;
 916          curr_fo != NULL; curr_fo = fo_next(curr_fo)) {
 917         real_ptr = (ptr_t)curr_fo -> fo_hidden_base;
 918         if (!GC_is_marked(real_ptr)) {
 919             if (curr_fo -> fo_mark_proc == GC_null_finalize_mark_proc) {
 920                 GC_MARK_FO(real_ptr, GC_normal_finalize_mark_proc);
 921             }
 922             GC_set_mark_bit(real_ptr);
 923         }
 924       }
 925   }
 926
 927   /* Remove dangling disappearing links. */
 928   GC_remove_dangling_disappearing_links(&GC_dl_hashtbl);
 929
 930         GC_clear_togglerefs ();
 931
 932   /* Make long links disappear and remove dangling ones. */
 933   GC_make_disappearing_links_disappear(&GC_ll_hashtbl);
 934   GC_remove_dangling_disappearing_links(&GC_ll_hashtbl);
 935 }
 936
 937 #ifndef JAVA_FINALIZATION_NOT_NEEDED
 938
 939 /* Enqueue all remaining finalizers to be run - Assumes lock is
 940  * held, and signals are disabled */
 941 void GC_enqueue_all_finalizers()
 942 {
 943     struct finalizable_object * curr_fo, * prev_fo, * next_fo;
 944     ptr_t real_ptr;
 945     register int i;
 946     int fo_size;
 947
 948     fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);
 949     GC_words_finalized = 0;
 950     for (i = 0; i < fo_size; i++) {
 951         curr_fo = fo_head[i];
 952         prev_fo = 0;
 953       while (curr_fo != 0) {
 954           real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 955           GC_MARK_FO(real_ptr, GC_normal_finalize_mark_proc);
 956           GC_set_mark_bit(real_ptr);
 957
 958           /* Delete from hash table */
 959           next_fo = fo_next(curr_fo);
 960           if (prev_fo == 0) {
 961               fo_head[i] = next_fo;
 962           } else {
 963               fo_set_next(prev_fo, next_fo);
 964           }
 965           GC_fo_entries--;
 966
 967           /* Add to list of objects awaiting finalization.      */
 968           fo_set_next(curr_fo, GC_finalize_now);
 969           GC_finalize_now = curr_fo;
 970
 971           /* unhide object pointer so any future collections will       */
 972           /* see it.                                            */
 973           curr_fo -> fo_hidden_base =
 974                         (word) REVEAL_POINTER(curr_fo -> fo_hidden_base);
 975
 976           GC_words_finalized +=
 977                 ALIGNED_WORDS(curr_fo -> fo_object_size)
 978                         + ALIGNED_WORDS(sizeof(struct finalizable_object));
 979           curr_fo = next_fo;
 980         }
 981     }
 982
 983     return;
 984 }
 985
 986 /* Invoke all remaining finalizers that haven't yet been run.
 987  * This is needed for strict compliance with the Java standard,
 988  * which can make the runtime guarantee that all finalizers are run.
 989  * Unfortunately, the Java standard implies we have to keep running
 990  * finalizers until there are no more left, a potential infinite loop.
 991  * YUCK.
 992  * Note that this is even more dangerous than the usual Java
 993  * finalizers, in that objects reachable from static variables
 994  * may have been finalized when these finalizers are run.
 995  * Finalizers run at this point must be prepared to deal with a
 996  * mostly broken world.
 997  * This routine is externally callable, so is called without
 998  * the allocation lock.
 999  */
1000 GC_API void GC_finalize_all()
1001 {
1002     DCL_LOCK_STATE;
1003
1004     DISABLE_SIGNALS();
1005     LOCK();
1006     while (GC_fo_entries > 0) {
1007       GC_enqueue_all_finalizers();
1008       UNLOCK();
1009       ENABLE_SIGNALS();
1010       GC_INVOKE_FINALIZERS();
1011       DISABLE_SIGNALS();
1012       LOCK();
1013     }
1014     UNLOCK();
1015     ENABLE_SIGNALS();
1016 }
1017 #endif
1018
1019 /* Returns true if it is worth calling GC_invoke_finalizers. (Useful if */
1020 /* finalizers can only be called from some kind of `safe state' and     */
1021 /* getting into that safe state is expensive.)                          */
1022 int GC_should_invoke_finalizers GC_PROTO((void))
1023 {
1024     return GC_finalize_now != 0;
1025 }
1026
1027 /* Invoke finalizers for all objects that are ready to be finalized.    */
1028 /* Should be called without allocation lock.                            */
1029 int GC_invoke_finalizers()
1030 {
1031     struct finalizable_object * curr_fo;
1032     int count = 0;
1033     word mem_freed_before;
1034     DCL_LOCK_STATE;
1035
1036     while (GC_finalize_now != 0) {
1037 #       ifdef THREADS
1038             DISABLE_SIGNALS();
1039             LOCK();
1040 #       endif
1041         if (count == 0) {
1042             mem_freed_before = GC_mem_freed;
1043         }
1044         curr_fo = GC_finalize_now;
1045 #       ifdef THREADS
1046             if (curr_fo != 0) GC_finalize_now = fo_next(curr_fo);
1047             UNLOCK();
1048             ENABLE_SIGNALS();
1049             if (curr_fo == 0) break;
1050 #       else
1051             GC_finalize_now = fo_next(curr_fo);
1052 #       endif
1053         fo_set_next(curr_fo, 0);
1054         (*(curr_fo -> fo_fn))((ptr_t)(curr_fo -> fo_hidden_base),
1055                               curr_fo -> fo_client_data);
1056         curr_fo -> fo_client_data = 0;
1057         ++count;
1058 #       ifdef UNDEFINED
1059             /* This is probably a bad idea.  It throws off accounting if */
1060             /* nearly all objects are finalizable.  O.w. it shouldn't    */
1061             /* matter.                                                   */
1062             GC_free((GC_PTR)curr_fo);
1063 #       endif
1064     }
1065     if (count != 0 && mem_freed_before != GC_mem_freed) {
1066         LOCK();
1067         GC_finalizer_mem_freed += (GC_mem_freed - mem_freed_before);
1068         UNLOCK();
1069     }
1070     return count;
1071 }
1072
1073 void (* GC_finalizer_notifier)() = (void (*) GC_PROTO((void)))0;
1074
1075 static GC_word last_finalizer_notification = 0;
1076
1077 void GC_notify_or_invoke_finalizers GC_PROTO((void))
1078 {
1079     /* This is a convenient place to generate backtraces if appropriate, */
1080     /* since that code is not callable with the allocation lock.         */
1081 #   if defined(KEEP_BACK_PTRS) || defined(MAKE_BACK_GRAPH)
1082       static word last_back_trace_gc_no = 1;    /* Skip first one. */
1083
1084       if (GC_gc_no > last_back_trace_gc_no) {
1085         word i;
1086
1087 #       ifdef KEEP_BACK_PTRS
1088           LOCK();
1089           /* Stops when GC_gc_no wraps; that's OK.      */
1090           last_back_trace_gc_no = (word)(-1);  /* disable others. */
1091           for (i = 0; i < GC_backtraces; ++i) {
1092               /* FIXME: This tolerates concurrent heap mutation,        */
1093               /* which may cause occasional mysterious results.         */
1094               /* We need to release the GC lock, since GC_print_callers */
1095               /* acquires it.  It probably shouldn't.                   */
1096               UNLOCK();
1097               GC_generate_random_backtrace_no_gc();
1098               LOCK();
1099           }
1100           last_back_trace_gc_no = GC_gc_no;
1101           UNLOCK();
1102 #       endif
1103 #       ifdef MAKE_BACK_GRAPH
1104           if (GC_print_back_height)
1105             GC_print_back_graph_stats();
1106 #       endif
1107       }
1108 #   endif
1109     if (GC_finalize_now == 0) return;
1110     if (!GC_finalize_on_demand) {
1111         (void) GC_invoke_finalizers();
1112 #       ifndef THREADS
1113           GC_ASSERT(GC_finalize_now == 0);
1114 #       endif   /* Otherwise GC can run concurrently and add more */
1115         return;
1116     }
1117     if (GC_finalizer_notifier != (void (*) GC_PROTO((void)))0
1118         && last_finalizer_notification != GC_gc_no) {
1119         last_finalizer_notification = GC_gc_no;
1120         GC_finalizer_notifier();
1121     }
1122 }
1123
1124 # ifdef __STDC__
1125     GC_PTR GC_call_with_alloc_lock(GC_fn_type fn,
1126                                          GC_PTR client_data)
1127 # else
1128     GC_PTR GC_call_with_alloc_lock(fn, client_data)
1129     GC_fn_type fn;
1130     GC_PTR client_data;
1131 # endif
1132 {
1133     GC_PTR result;
1134     DCL_LOCK_STATE;
1135
1136 #   ifdef THREADS
1137       DISABLE_SIGNALS();
1138       LOCK();
1139       SET_LOCK_HOLDER();
1140 #   endif
1141     result = (*fn)(client_data);
1142 #   ifdef THREADS
1143 #     ifndef GC_ASSERTIONS
1144         UNSET_LOCK_HOLDER();
1145 #     endif /* o.w. UNLOCK() does it implicitly */
1146       UNLOCK();
1147       ENABLE_SIGNALS();
1148 #   endif
1149     return(result);
1150 }
1151
1152 #if !defined(NO_DEBUGGING)
1153
1154 void GC_print_finalization_stats()
1155 {
1156     struct finalizable_object *fo = GC_finalize_now;
1157     size_t ready = 0;
1158
1159     GC_printf3("%lu finalization table entries; %lu/%lu short/long disappearing links alive\n",
1160                GC_fo_entries, (unsigned long)GC_dl_hashtbl.entries, (unsigned long)GC_ll_hashtbl.entries);
1161     for (; 0 != fo; fo = fo_next(fo)) ++ready;
1162     GC_printf1("%lu objects are eligible for immediate finalization\n", ready);
1163 }
1164
1165 #endif /* NO_DEBUGGING */