Subversion Repositories scarts

/*

 * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers

 * Copyright (c) 1991-1996 by Xerox Corporation.  All rights reserved.

 * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.

 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED

 * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.

 *

 * Permission is hereby granted to use or copy this program

 * for any purpose,  provided the above notices are retained on all copies.

 * Permission to modify the code and to distribute modified code is granted,

 * provided the above notices are retained, and a notice that the code was

 * modified is included with the above copyright notice.

 */

/* Boehm, February 1, 1996 1:19 pm PST */

# define I_HIDE_POINTERS

# include "private/gc_pmark.h"

# ifdef FINALIZE_ON_DEMAND

    int GC_finalize_on_demand = 1;

# else

    int GC_finalize_on_demand = 0;

# endif

# ifdef JAVA_FINALIZATION

    int GC_java_finalization = 1;

# else

    int GC_java_finalization = 0;

# endif

/* Type of mark procedure used for marking from finalizable object.     */

/* This procedure normally does not mark the object, only its           */

/* descendents.                                                         */

typedef void finalization_mark_proc(/* ptr_t finalizable_obj_ptr */);

# define HASH3(addr,size,log_size) \

    ((((word)(addr) >> 3) ^ ((word)(addr) >> (3+(log_size)))) \

    & ((size) - 1))

#define HASH2(addr,log_size) HASH3(addr, 1 << log_size, log_size)

struct hash_chain_entry {

    word hidden_key;

    struct hash_chain_entry * next;

};

unsigned GC_finalization_failures = 0;

        /* Number of finalization requests that failed for lack of memory. */

static struct disappearing_link {

    struct hash_chain_entry prolog;

#   define dl_hidden_link prolog.hidden_key

                                /* Field to be cleared.         */

#   define dl_next(x) (struct disappearing_link *)((x) -> prolog.next)

#   define dl_set_next(x,y) (x) -> prolog.next = (struct hash_chain_entry *)(y)

    word dl_hidden_obj;         /* Pointer to object base       */

} **dl_head = 0;

static signed_word log_dl_table_size = -1;

                        /* Binary log of                                */

                        /* current size of array pointed to by dl_head. */

                        /* -1 ==> size is 0.                            */

word GC_dl_entries = 0;  /* Number of entries currently in disappearing  */

                        /* link table.                                  */

static struct finalizable_object {

    struct hash_chain_entry prolog;

#   define fo_hidden_base prolog.hidden_key

                                /* Pointer to object base.      */

                                /* No longer hidden once object */

                                /* is on finalize_now queue.    */

#   define fo_next(x) (struct finalizable_object *)((x) -> prolog.next)

#   define fo_set_next(x,y) (x) -> prolog.next = (struct hash_chain_entry *)(y)

    GC_finalization_proc fo_fn; /* Finalizer.                   */

    ptr_t fo_client_data;

    word fo_object_size;        /* In bytes.                    */

    finalization_mark_proc * fo_mark_proc;      /* Mark-through procedure */

} **fo_head = 0;

struct finalizable_object * GC_finalize_now = 0;

        /* LIst of objects that should be finalized now.        */

static signed_word log_fo_table_size = -1;

word GC_fo_entries = 0;

void GC_push_finalizer_structures GC_PROTO((void))

{

    GC_push_all((ptr_t)(&dl_head), (ptr_t)(&dl_head) + sizeof(word));

    GC_push_all((ptr_t)(&fo_head), (ptr_t)(&fo_head) + sizeof(word));

    GC_push_all((ptr_t)(&GC_finalize_now),

                (ptr_t)(&GC_finalize_now) + sizeof(word));

}

/* Double the size of a hash table. *size_ptr is the log of its current */

/* size.  May be a noop.                                                */

/* *table is a pointer to an array of hash headers.  If we succeed, we  */

/* update both *table and *log_size_ptr.                                */

/* Lock is held.  Signals are disabled.                                 */

void GC_grow_table(table, log_size_ptr)

struct hash_chain_entry ***table;

signed_word * log_size_ptr;

{

    register word i;

    register struct hash_chain_entry *p;

    int log_old_size = *log_size_ptr;

    register int log_new_size = log_old_size + 1;

    word old_size = ((log_old_size == -1)? 0: (1 << log_old_size));

    register word new_size = 1 << log_new_size;

    struct hash_chain_entry **new_table = (struct hash_chain_entry **)

        GC_INTERNAL_MALLOC_IGNORE_OFF_PAGE(

                (size_t)new_size * sizeof(struct hash_chain_entry *), NORMAL);

    if (new_table == 0) {

        if (table == 0) {

            ABORT("Insufficient space for initial table allocation");

        } else {

            return;

        }

    }

    for (i = 0; i < old_size; i++) {

      p = (*table)[i];

      while (p != 0) {

        register ptr_t real_key = (ptr_t)REVEAL_POINTER(p -> hidden_key);

        register struct hash_chain_entry *next = p -> next;

        register int new_hash = HASH3(real_key, new_size, log_new_size);

        p -> next = new_table[new_hash];

        new_table[new_hash] = p;

        p = next;

      }

    }

    *log_size_ptr = log_new_size;

    *table = new_table;

}

# if defined(__STDC__) || defined(__cplusplus)

    int GC_register_disappearing_link(GC_PTR * link)

# else

    int GC_register_disappearing_link(link)

    GC_PTR * link;

# endif

{

    ptr_t base;

    base = (ptr_t)GC_base((GC_PTR)link);

    if (base == 0)

        ABORT("Bad arg to GC_register_disappearing_link");

    return(GC_general_register_disappearing_link(link, base));

}

# if defined(__STDC__) || defined(__cplusplus)

    int GC_general_register_disappearing_link(GC_PTR * link,

                                              GC_PTR obj)

# else

    int GC_general_register_disappearing_link(link, obj)

    GC_PTR * link;

    GC_PTR obj;

# endif

{

    struct disappearing_link *curr_dl;

    int index;

    struct disappearing_link * new_dl;

    DCL_LOCK_STATE;

    if ((word)link & (ALIGNMENT-1))

        ABORT("Bad arg to GC_general_register_disappearing_link");

#   ifdef THREADS

        DISABLE_SIGNALS();

        LOCK();

#   endif

    if (log_dl_table_size == -1

        || GC_dl_entries > ((word)1 << log_dl_table_size)) {

#       ifndef THREADS

            DISABLE_SIGNALS();

#       endif

        GC_grow_table((struct hash_chain_entry ***)(&dl_head),

                      &log_dl_table_size);

#       ifdef CONDPRINT

          if (GC_print_stats) {

            GC_printf1("Grew dl table to %lu entries\n",

                        (unsigned long)(1 << log_dl_table_size));

          }

#       endif

#       ifndef THREADS

            ENABLE_SIGNALS();

#       endif

    }

    index = HASH2(link, log_dl_table_size);

    curr_dl = dl_head[index];

    for (curr_dl = dl_head[index]; curr_dl != 0; curr_dl = dl_next(curr_dl)) {

        if (curr_dl -> dl_hidden_link == HIDE_POINTER(link)) {

            curr_dl -> dl_hidden_obj = HIDE_POINTER(obj);

#           ifdef THREADS

                UNLOCK();

                ENABLE_SIGNALS();

#           endif

            return(1);

        }

    }

    new_dl = (struct disappearing_link *)

        GC_INTERNAL_MALLOC(sizeof(struct disappearing_link),NORMAL);

    if (0 == new_dl) {

#     ifdef THREADS

        UNLOCK();

        ENABLE_SIGNALS();

#     endif

      new_dl = (struct disappearing_link *)

              GC_oom_fn(sizeof(struct disappearing_link));

      if (0 == new_dl) {

        GC_finalization_failures++;

        return(0);

      }

      /* It's not likely we'll make it here, but ... */

#     ifdef THREADS

        DISABLE_SIGNALS();

        LOCK();

#     endif

    }

    new_dl -> dl_hidden_obj = HIDE_POINTER(obj);

    new_dl -> dl_hidden_link = HIDE_POINTER(link);

    dl_set_next(new_dl, dl_head[index]);

    dl_head[index] = new_dl;

    GC_dl_entries++;

#   ifdef THREADS

        UNLOCK();

        ENABLE_SIGNALS();

#   endif

    return(0);

}

# if defined(__STDC__) || defined(__cplusplus)

    int GC_unregister_disappearing_link(GC_PTR * link)

# else

    int GC_unregister_disappearing_link(link)

    GC_PTR * link;

# endif

{

    struct disappearing_link *curr_dl, *prev_dl;

    int index;

    DCL_LOCK_STATE;

    DISABLE_SIGNALS();

    LOCK();

    index = HASH2(link, log_dl_table_size);

    if (((unsigned long)link & (ALIGNMENT-1))) goto out;

    prev_dl = 0; curr_dl = dl_head[index];

    while (curr_dl != 0) {

        if (curr_dl -> dl_hidden_link == HIDE_POINTER(link)) {

            if (prev_dl == 0) {

                dl_head[index] = dl_next(curr_dl);

            } else {

                dl_set_next(prev_dl, dl_next(curr_dl));

            }

            GC_dl_entries--;

            UNLOCK();

            ENABLE_SIGNALS();

#           ifdef DBG_HDRS_ALL

              dl_set_next(curr_dl, 0);

#           else

              GC_free((GC_PTR)curr_dl);

#           endif

            return(1);

        }

        prev_dl = curr_dl;

        curr_dl = dl_next(curr_dl);

    }

out:

    UNLOCK();

    ENABLE_SIGNALS();

    return(0);

}

/* Possible finalization_marker procedures.  Note that mark stack       */

/* overflow is handled by the caller, and is not a disaster.            */

GC_API void GC_normal_finalize_mark_proc(p)

ptr_t p;

{

    hdr * hhdr = HDR(p);

    PUSH_OBJ((word *)p, hhdr, GC_mark_stack_top,

             &(GC_mark_stack[GC_mark_stack_size]));

}

/* This only pays very partial attention to the mark descriptor.        */

/* It does the right thing for normal and atomic objects, and treats    */

/* most others as normal.                                               */

GC_API void GC_ignore_self_finalize_mark_proc(p)

ptr_t p;

{

    hdr * hhdr = HDR(p);

    word descr = hhdr -> hb_descr;

    ptr_t q, r;

    ptr_t scan_limit;

    ptr_t target_limit = p + WORDS_TO_BYTES(hhdr -> hb_sz) - 1;

    if ((descr & GC_DS_TAGS) == GC_DS_LENGTH) {

       scan_limit = p + descr - sizeof(word);

    } else {

       scan_limit = target_limit + 1 - sizeof(word);

    }

    for (q = p; q <= scan_limit; q += ALIGNMENT) {

        r = *(ptr_t *)q;

        if (r < p || r > target_limit) {

            GC_PUSH_ONE_HEAP((word)r, q);

        }

    }

}

/*ARGSUSED*/

GC_API void GC_null_finalize_mark_proc(p)

ptr_t p;

{

}

/* Register a finalization function.  See gc.h for details.     */

/* in the nonthreads case, we try to avoid disabling signals,   */

/* since it can be expensive.  Threads packages typically       */

/* make it cheaper.                                             */

/* The last parameter is a procedure that determines            */

/* marking for finalization ordering.  Any objects marked       */

/* by that procedure will be guaranteed to not have been        */

/* finalized when this finalizer is invoked.                    */

GC_API void GC_register_finalizer_inner(obj, fn, cd, ofn, ocd, mp)

GC_PTR obj;

GC_finalization_proc fn;

GC_PTR cd;

GC_finalization_proc * ofn;

GC_PTR * ocd;

finalization_mark_proc * mp;

{

    ptr_t base;

    struct finalizable_object * curr_fo, * prev_fo;

    int index;

    struct finalizable_object *new_fo;

    hdr *hhdr;

    DCL_LOCK_STATE;

#   ifdef THREADS

        DISABLE_SIGNALS();

        LOCK();

#   endif

    if (log_fo_table_size == -1

        || GC_fo_entries > ((word)1 << log_fo_table_size)) {

#       ifndef THREADS

            DISABLE_SIGNALS();

#       endif

        GC_grow_table((struct hash_chain_entry ***)(&fo_head),

                      &log_fo_table_size);

#       ifdef CONDPRINT

          if (GC_print_stats) {

            GC_printf1("Grew fo table to %lu entries\n",

                        (unsigned long)(1 << log_fo_table_size));

          }

#       endif

#       ifndef THREADS

            ENABLE_SIGNALS();

#       endif

    }

    /* in the THREADS case signals are disabled and we hold allocation  */

    /* lock; otherwise neither is true.  Proceed carefully.             */

    base = (ptr_t)obj;

    index = HASH2(base, log_fo_table_size);

    prev_fo = 0; curr_fo = fo_head[index];

    while (curr_fo != 0) {

        if (curr_fo -> fo_hidden_base == HIDE_POINTER(base)) {

            /* Interruption by a signal in the middle of this   */

            /* should be safe.  The client may see only *ocd    */

            /* updated, but we'll declare that to be his        */

            /* problem.                                         */

            if (ocd) *ocd = (GC_PTR) curr_fo -> fo_client_data;

            if (ofn) *ofn = curr_fo -> fo_fn;

            /* Delete the structure for base. */

                if (prev_fo == 0) {

                  fo_head[index] = fo_next(curr_fo);

                } else {

                  fo_set_next(prev_fo, fo_next(curr_fo));

                }

            if (fn == 0) {

                GC_fo_entries--;

                  /* May not happen if we get a signal.  But a high     */

                  /* estimate will only make the table larger than      */

                  /* necessary.                                         */

#               if !defined(THREADS) && !defined(DBG_HDRS_ALL)

                  GC_free((GC_PTR)curr_fo);

#               endif

            } else {

                curr_fo -> fo_fn = fn;

                curr_fo -> fo_client_data = (ptr_t)cd;

                curr_fo -> fo_mark_proc = mp;

                /* Reinsert it.  We deleted it first to maintain        */

                /* consistency in the event of a signal.                */

                if (prev_fo == 0) {

                  fo_head[index] = curr_fo;

                } else {

                  fo_set_next(prev_fo, curr_fo);

                }

            }

#           ifdef THREADS

                UNLOCK();

                ENABLE_SIGNALS();

#           endif

            return;

        }

        prev_fo = curr_fo;

        curr_fo = fo_next(curr_fo);

    }

    if (ofn) *ofn = 0;

    if (ocd) *ocd = 0;

    if (fn == 0) {

#       ifdef THREADS

            UNLOCK();

            ENABLE_SIGNALS();

#       endif

        return;

    }

    GET_HDR(base, hhdr);

    if (0 == hhdr) {

      /* We won't collect it, hence finalizer wouldn't be run. */

#     ifdef THREADS

          UNLOCK();

          ENABLE_SIGNALS();

#     endif

      return;

    }

    new_fo = (struct finalizable_object *)

        GC_INTERNAL_MALLOC(sizeof(struct finalizable_object),NORMAL);

    if (0 == new_fo) {

#     ifdef THREADS

        UNLOCK();

        ENABLE_SIGNALS();

#     endif

      new_fo = (struct finalizable_object *)

              GC_oom_fn(sizeof(struct finalizable_object));

      if (0 == new_fo) {

        GC_finalization_failures++;

        return;

      }

      /* It's not likely we'll make it here, but ... */

#     ifdef THREADS

        DISABLE_SIGNALS();

        LOCK();

#     endif

    }

    new_fo -> fo_hidden_base = (word)HIDE_POINTER(base);

    new_fo -> fo_fn = fn;

    new_fo -> fo_client_data = (ptr_t)cd;

    new_fo -> fo_object_size = hhdr -> hb_sz;

    new_fo -> fo_mark_proc = mp;

    fo_set_next(new_fo, fo_head[index]);

    GC_fo_entries++;

    fo_head[index] = new_fo;

#   ifdef THREADS

        UNLOCK();

        ENABLE_SIGNALS();

#   endif

}

# if defined(__STDC__)

    void GC_register_finalizer(void * obj,

                               GC_finalization_proc fn, void * cd,

                               GC_finalization_proc *ofn, void ** ocd)

# else

    void GC_register_finalizer(obj, fn, cd, ofn, ocd)

    GC_PTR obj;

    GC_finalization_proc fn;

    GC_PTR cd;

    GC_finalization_proc * ofn;

    GC_PTR * ocd;

# endif

{

    GC_register_finalizer_inner(obj, fn, cd, ofn,

                                ocd, GC_normal_finalize_mark_proc);

}

# if defined(__STDC__)

    void GC_register_finalizer_ignore_self(void * obj,

                               GC_finalization_proc fn, void * cd,

                               GC_finalization_proc *ofn, void ** ocd)

# else

    void GC_register_finalizer_ignore_self(obj, fn, cd, ofn, ocd)

    GC_PTR obj;

    GC_finalization_proc fn;

    GC_PTR cd;

    GC_finalization_proc * ofn;

    GC_PTR * ocd;

# endif

{

    GC_register_finalizer_inner(obj, fn, cd, ofn,

                                ocd, GC_ignore_self_finalize_mark_proc);

}

# if defined(__STDC__)

    void GC_register_finalizer_no_order(void * obj,

                               GC_finalization_proc fn, void * cd,

                               GC_finalization_proc *ofn, void ** ocd)

# else

    void GC_register_finalizer_no_order(obj, fn, cd, ofn, ocd)

    GC_PTR obj;

    GC_finalization_proc fn;

    GC_PTR cd;

    GC_finalization_proc * ofn;

    GC_PTR * ocd;

# endif

{

    GC_register_finalizer_inner(obj, fn, cd, ofn,

                                ocd, GC_null_finalize_mark_proc);

}

#ifndef NO_DEBUGGING

void GC_dump_finalization()

{

    struct disappearing_link * curr_dl;

    struct finalizable_object * curr_fo;

    ptr_t real_ptr, real_link;

    int dl_size = (log_dl_table_size == -1 ) ? 0 : (1 << log_dl_table_size);

    int fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);

    int i;

    GC_printf0("Disappearing links:\n");

    for (i = 0; i < dl_size; i++) {

      for (curr_dl = dl_head[i]; curr_dl != 0; curr_dl = dl_next(curr_dl)) {

        real_ptr = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_obj);

        real_link = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link);

        GC_printf2("Object: 0x%lx, Link:0x%lx\n", real_ptr, real_link);

      }

    }

    GC_printf0("Finalizers:\n");

    for (i = 0; i < fo_size; i++) {

      for (curr_fo = fo_head[i]; curr_fo != 0; curr_fo = fo_next(curr_fo)) {

        real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);

        GC_printf1("Finalizable object: 0x%lx\n", real_ptr);

      }

    }

}

#endif

/* Called with world stopped.  Cause disappearing links to disappear,   */

/* and invoke finalizers.                                               */

void GC_finalize()

{

    struct disappearing_link * curr_dl, * prev_dl, * next_dl;

    struct finalizable_object * curr_fo, * prev_fo, * next_fo;

    ptr_t real_ptr, real_link;

    register int i;

    int dl_size = (log_dl_table_size == -1 ) ? 0 : (1 << log_dl_table_size);

    int fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);

  /* Make disappearing links disappear */

    for (i = 0; i < dl_size; i++) {

      curr_dl = dl_head[i];

      prev_dl = 0;

      while (curr_dl != 0) {

        real_ptr = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_obj);

        real_link = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link);

        if (!GC_is_marked(real_ptr)) {

            *(word *)real_link = 0;

            next_dl = dl_next(curr_dl);

            if (prev_dl == 0) {

                dl_head[i] = next_dl;

            } else {

                dl_set_next(prev_dl, next_dl);

            }

            GC_clear_mark_bit((ptr_t)curr_dl);

            GC_dl_entries--;

            curr_dl = next_dl;

        } else {

            prev_dl = curr_dl;

            curr_dl = dl_next(curr_dl);

        }

      }

    }

  /* Mark all objects reachable via chains of 1 or more pointers        */

  /* from finalizable objects.                                          */

    GC_ASSERT(GC_mark_state == MS_NONE);

    for (i = 0; i < fo_size; i++) {

      for (curr_fo = fo_head[i]; curr_fo != 0; curr_fo = fo_next(curr_fo)) {

        real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);

        if (!GC_is_marked(real_ptr)) {

            GC_MARKED_FOR_FINALIZATION(real_ptr);

            GC_MARK_FO(real_ptr, curr_fo -> fo_mark_proc);

            if (GC_is_marked(real_ptr)) {

                WARN("Finalization cycle involving %lx\n", real_ptr);

            }

        }

      }

    }

  /* Enqueue for finalization all objects that are still                */

  /* unreachable.                                                       */

    GC_words_finalized = 0;

    for (i = 0; i < fo_size; i++) {

      curr_fo = fo_head[i];

      prev_fo = 0;

      while (curr_fo != 0) {

        real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);

        if (!GC_is_marked(real_ptr)) {

            if (!GC_java_finalization) {

              GC_set_mark_bit(real_ptr);

            }

            /* Delete from hash table */

              next_fo = fo_next(curr_fo);

              if (prev_fo == 0) {

                fo_head[i] = next_fo;

              } else {

                fo_set_next(prev_fo, next_fo);

              }

              GC_fo_entries--;

            /* Add to list of objects awaiting finalization.    */

              fo_set_next(curr_fo, GC_finalize_now);

              GC_finalize_now = curr_fo;

              /* unhide object pointer so any future collections will   */

              /* see it.                                                */

              curr_fo -> fo_hidden_base =

                        (word) REVEAL_POINTER(curr_fo -> fo_hidden_base);

              GC_words_finalized +=

                        ALIGNED_WORDS(curr_fo -> fo_object_size)

                        + ALIGNED_WORDS(sizeof(struct finalizable_object));

            GC_ASSERT(GC_is_marked(GC_base((ptr_t)curr_fo)));

            curr_fo = next_fo;

        } else {

            prev_fo = curr_fo;

            curr_fo = fo_next(curr_fo);

        }

      }

    }

  if (GC_java_finalization) {

    /* make sure we mark everything reachable from objects finalized

       using the no_order mark_proc */

      for (curr_fo = GC_finalize_now;

         curr_fo != NULL; curr_fo = fo_next(curr_fo)) {

        real_ptr = (ptr_t)curr_fo -> fo_hidden_base;

        if (!GC_is_marked(real_ptr)) {

            if (curr_fo -> fo_mark_proc == GC_null_finalize_mark_proc) {

                GC_MARK_FO(real_ptr, GC_normal_finalize_mark_proc);

            }

            GC_set_mark_bit(real_ptr);

        }

      }

  }

  /* Remove dangling disappearing links. */

    for (i = 0; i < dl_size; i++) {

      curr_dl = dl_head[i];

      prev_dl = 0;

      while (curr_dl != 0) {

        real_link = GC_base((ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link));