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gecko-dev/gc/boehm/finalize.c
beard%netscape.com a84fd8080b First Checked In.
1999-09-30 02:59:32 +00:00

736 lines
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/*
* Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
* Copyright (c) 1991-1996 by Xerox Corporation. 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 "gc_priv.h"
# include "gc_mark.h"
/* 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;
# ifdef SRC_M3
void GC_push_finalizer_structures()
{
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));
}
# endif
/* 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_generic_malloc_inner_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 PRINTSTATS
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);
}
}
# ifdef THREADS
new_dl = (struct disappearing_link *)
GC_generic_malloc_inner(sizeof(struct disappearing_link),NORMAL);
# else
new_dl = (struct disappearing_link *)
GC_malloc(sizeof(struct disappearing_link));
# endif
if (new_dl != 0) {
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++;
} else {
GC_finalization_failures++;
}
# 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();
GC_free((GC_PTR)curr_dl);
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. */
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. */
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 & DS_TAGS) == 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*/
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. */
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;
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 PRINTSTATS
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. */
# ifndef THREADS
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;
}
# ifdef THREADS
new_fo = (struct finalizable_object *)
GC_generic_malloc_inner(sizeof(struct finalizable_object),NORMAL);
# else
new_fo = (struct finalizable_object *)
GC_malloc(sizeof(struct finalizable_object));
# endif
if (new_fo != 0) {
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 = GC_size(base);
new_fo -> fo_mark_proc = mp;
fo_set_next(new_fo, fo_head[index]);
GC_fo_entries++;
fo_head[index] = new_fo;
} else {
GC_finalization_failures++;
}
# 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);
}
/* 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. */
# ifdef PRINTSTATS
if (GC_mark_state != MS_NONE) ABORT("Bad mark state");
# endif
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_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)) {
# ifndef JAVA_FINALIZATION
GC_set_mark_bit(real_ptr);
# endif
/* 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));
# ifdef PRINTSTATS
if (!GC_is_marked((ptr_t)curr_fo)) {
ABORT("GC_finalize: found accessible unmarked object\n");
}
# endif
curr_fo = next_fo;
} else {
prev_fo = curr_fo;
curr_fo = fo_next(curr_fo);
}
}
}
# ifdef 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);
}
}
# endif
/* 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));
if (real_link != 0 && !GC_is_marked(real_link)) {
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);
}
}
}
}
#ifdef JAVA_FINALIZATION
/* Enqueue all remaining finalizers to be run - Assumes lock is
* held, and signals are disabled */
void GC_enqueue_all_finalizers()
{
struct finalizable_object * curr_fo, * prev_fo, * next_fo;
ptr_t real_ptr, real_link;
register int i;
int fo_size;
fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);
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);
GC_MARK_FO(real_ptr, GC_normal_finalize_mark_proc);
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));
curr_fo = next_fo;
}
}
return;
}
/* Invoke all remaining finalizers that haven't yet been run.
* This is needed for strict compliance with the Java standard,
* which can make the runtime guarantee that all finalizers are run.
* Unfortunately, the Java standard implies we have to keep running
* finalizers until there are no more left, a potential infinite loop.
* YUCK.
* This routine is externally callable, so is called without
* the allocation lock.
*/
void GC_finalize_all()
{
DCL_LOCK_STATE;
DISABLE_SIGNALS();
LOCK();
while (GC_fo_entries > 0) {
GC_enqueue_all_finalizers();
UNLOCK();
ENABLE_SIGNALS();
GC_INVOKE_FINALIZERS();
DISABLE_SIGNALS();
LOCK();
}
UNLOCK();
ENABLE_SIGNALS();
}
#endif
/* Invoke finalizers for all objects that are ready to be finalized. */
/* Should be called without allocation lock. */
int GC_invoke_finalizers()
{
register struct finalizable_object * curr_fo;
register int count = 0;
DCL_LOCK_STATE;
while (GC_finalize_now != 0) {
# ifdef THREADS
DISABLE_SIGNALS();
LOCK();
# endif
curr_fo = GC_finalize_now;
# ifdef THREADS
if (curr_fo != 0) GC_finalize_now = fo_next(curr_fo);
UNLOCK();
ENABLE_SIGNALS();
if (curr_fo == 0) break;
# else
GC_finalize_now = fo_next(curr_fo);
# endif
fo_set_next(curr_fo, 0);
(*(curr_fo -> fo_fn))((ptr_t)(curr_fo -> fo_hidden_base),
curr_fo -> fo_client_data);
curr_fo -> fo_client_data = 0;
++count;
# ifdef UNDEFINED
/* This is probably a bad idea. It throws off accounting if */
/* nearly all objects are finalizable. O.w. it shouldn't */
/* matter. */
GC_free((GC_PTR)curr_fo);
# endif
}
return count;
}
# ifdef __STDC__
GC_PTR GC_call_with_alloc_lock(GC_fn_type fn,
GC_PTR client_data)
# else
GC_PTR GC_call_with_alloc_lock(fn, client_data)
GC_fn_type fn;
GC_PTR client_data;
# endif
{
GC_PTR result;
DCL_LOCK_STATE;
# ifdef THREADS
DISABLE_SIGNALS();
LOCK();
SET_LOCK_HOLDER();
# endif
result = (*fn)(client_data);
# ifdef THREADS
UNSET_LOCK_HOLDER();
UNLOCK();
ENABLE_SIGNALS();
# endif
return(result);
}
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