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alloc.c
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alloc.c
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/*
* Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
* Copyright (c) 1991-1996 by Xerox Corporation. All rights reserved.
* Copyright (c) 1998 by Silicon Graphics. All rights reserved.
* Copyright (c) 1999-2004 Hewlett-Packard Development Company, L.P.
*
* 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.
*
*/
#include "private/gc_priv.h"
#include <stdio.h>
#if !defined(MACOS) && !defined(MSWINCE)
# include <signal.h>
# if !defined(__CC_ARM)
# include <sys/types.h>
# endif
#endif
/*
* Separate free lists are maintained for different sized objects
* up to MAXOBJBYTES.
* The call GC_allocobj(i,k) ensures that the freelist for
* kind k objects of size i points to a non-empty
* free list. It returns a pointer to the first entry on the free list.
* In a single-threaded world, GC_allocobj may be called to allocate
* an object of (small) size lb as follows:
*
* lg = GC_size_map[lb];
* op = GC_objfreelist[lg];
* if (NULL == op) {
* op = GENERAL_MALLOC(lb, NORMAL);
* } else {
* GC_objfreelist[lg] = obj_link(op);
* }
*
* Note that this is very fast if the free list is non-empty; it should
* only involve the execution of 4 or 5 simple instructions.
* All composite objects on freelists are cleared, except for
* their first word.
*/
/*
* The allocator uses GC_allochblk to allocate large chunks of objects.
* These chunks all start on addresses which are multiples of
* HBLKSZ. Each allocated chunk has an associated header,
* which can be located quickly based on the address of the chunk.
* (See headers.c for details.)
* This makes it possible to check quickly whether an
* arbitrary address corresponds to an object administered by the
* allocator.
*/
word GC_non_gc_bytes = 0; /* Number of bytes not intended to be collected */
word GC_gc_no = 0;
#ifndef GC_DISABLE_INCREMENTAL
GC_INNER int GC_incremental = 0; /* By default, stop the world. */
#endif
#ifdef THREADS
int GC_parallel = FALSE; /* By default, parallel GC is off. */
#endif
#ifndef GC_FULL_FREQ
# define GC_FULL_FREQ 19 /* Every 20th collection is a full */
/* collection, whether we need it */
/* or not. */
#endif
int GC_full_freq = GC_FULL_FREQ;
STATIC GC_bool GC_need_full_gc = FALSE;
/* Need full GC do to heap growth. */
#ifdef THREAD_LOCAL_ALLOC
GC_INNER GC_bool GC_world_stopped = FALSE;
#endif
STATIC word GC_used_heap_size_after_full = 0;
/* GC_copyright symbol is externally visible. */
char * const GC_copyright[] =
{"Copyright 1988,1989 Hans-J. Boehm and Alan J. Demers ",
"Copyright (c) 1991-1995 by Xerox Corporation. All rights reserved. ",
"Copyright (c) 1996-1998 by Silicon Graphics. All rights reserved. ",
"Copyright (c) 1999-2009 by Hewlett-Packard Company. All rights reserved. ",
"THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY",
" EXPRESSED OR IMPLIED. ANY USE IS AT YOUR OWN RISK.",
"See source code for details." };
/* Version macros are now defined in gc_version.h, which is included by */
/* gc.h, which is included by gc_priv.h. */
#ifndef GC_NO_VERSION_VAR
const unsigned GC_version = ((GC_VERSION_MAJOR << 16) |
(GC_VERSION_MINOR << 8) | GC_VERSION_MICRO);
#endif
GC_API unsigned GC_CALL GC_get_version(void)
{
return (GC_VERSION_MAJOR << 16) | (GC_VERSION_MINOR << 8) |
GC_VERSION_MICRO;
}
/* some more variables */
#ifdef GC_DONT_EXPAND
int GC_dont_expand = TRUE;
#else
int GC_dont_expand = FALSE;
#endif
#ifndef GC_FREE_SPACE_DIVISOR
# define GC_FREE_SPACE_DIVISOR 3 /* must be > 0 */
#endif
word GC_free_space_divisor = GC_FREE_SPACE_DIVISOR;
GC_INNER int GC_CALLBACK GC_never_stop_func(void)
{
return(0);
}
#ifndef GC_TIME_LIMIT
# define GC_TIME_LIMIT 50 /* We try to keep pause times from exceeding */
/* this by much. In milliseconds. */
#endif
unsigned long GC_time_limit = GC_TIME_LIMIT;
#ifndef NO_CLOCK
STATIC CLOCK_TYPE GC_start_time = 0;
/* Time at which we stopped world. */
/* used only in GC_timeout_stop_func. */
#endif
STATIC int GC_n_attempts = 0; /* Number of attempts at finishing */
/* collection within GC_time_limit. */
STATIC GC_stop_func GC_default_stop_func = GC_never_stop_func;
/* accessed holding the lock. */
GC_API void GC_CALL GC_set_stop_func(GC_stop_func stop_func)
{
DCL_LOCK_STATE;
GC_ASSERT(stop_func != 0);
LOCK();
GC_default_stop_func = stop_func;
UNLOCK();
}
GC_API GC_stop_func GC_CALL GC_get_stop_func(void)
{
GC_stop_func stop_func;
DCL_LOCK_STATE;
LOCK();
stop_func = GC_default_stop_func;
UNLOCK();
return stop_func;
}
#if defined(GC_DISABLE_INCREMENTAL) || defined(NO_CLOCK)
# define GC_timeout_stop_func GC_default_stop_func
#else
STATIC int GC_CALLBACK GC_timeout_stop_func (void)
{
CLOCK_TYPE current_time;
static unsigned count = 0;
unsigned long time_diff;
if ((*GC_default_stop_func)())
return(1);
if ((count++ & 3) != 0) return(0);
GET_TIME(current_time);
time_diff = MS_TIME_DIFF(current_time,GC_start_time);
if (time_diff >= GC_time_limit) {
GC_COND_LOG_PRINTF(
"Abandoning stopped marking after %lu msecs (attempt %d)\n",
time_diff, GC_n_attempts);
return(1);
}
return(0);
}
#endif /* !GC_DISABLE_INCREMENTAL */
#ifdef THREADS
GC_INNER word GC_total_stacksize = 0; /* updated on every push_all_stacks */
#endif
/* Return the minimum number of bytes that must be allocated between */
/* collections to amortize the collection cost. Should be non-zero. */
static word min_bytes_allocd(void)
{
word result;
# ifdef STACK_NOT_SCANNED
word stack_size = 0;
# elif defined(STACK_GROWS_UP)
word stack_size = GC_approx_sp() - GC_stackbottom;
/* GC_stackbottom is used only for a single-threaded case. */
# else
word stack_size = GC_stackbottom - GC_approx_sp();
# endif
word total_root_size; /* includes double stack size, */
/* since the stack is expensive */
/* to scan. */
word scan_size; /* Estimate of memory to be scanned */
/* during normal GC. */
# ifdef THREADS
if (GC_need_to_lock) {
/* We are multi-threaded... */
stack_size = GC_total_stacksize;
/* For now, we just use the value computed during the latest GC. */
# ifdef DEBUG_THREADS
GC_log_printf("Total stacks size: %lu\n",
(unsigned long)stack_size);
# endif
}
# endif
total_root_size = 2 * stack_size + GC_root_size;
scan_size = 2 * GC_composite_in_use + GC_atomic_in_use / 4
+ total_root_size;
result = scan_size / GC_free_space_divisor;
if (GC_incremental) {
result /= 2;
}
return result > 0 ? result : 1;
}
STATIC word GC_non_gc_bytes_at_gc = 0;
/* Number of explicitly managed bytes of storage */
/* at last collection. */
/* Return the number of bytes allocated, adjusted for explicit storage */
/* management, etc.. This number is used in deciding when to trigger */
/* collections. */
STATIC word GC_adj_bytes_allocd(void)
{
signed_word result;
signed_word expl_managed = (signed_word)GC_non_gc_bytes
- (signed_word)GC_non_gc_bytes_at_gc;
/* Don't count what was explicitly freed, or newly allocated for */
/* explicit management. Note that deallocating an explicitly */
/* managed object should not alter result, assuming the client */
/* is playing by the rules. */
result = (signed_word)GC_bytes_allocd
+ (signed_word)GC_bytes_dropped
- (signed_word)GC_bytes_freed
+ (signed_word)GC_finalizer_bytes_freed
- expl_managed;
if (result > (signed_word)GC_bytes_allocd) {
result = GC_bytes_allocd;
/* probably client bug or unfortunate scheduling */
}
result += GC_bytes_finalized;
/* We count objects enqueued for finalization as though they */
/* had been reallocated this round. Finalization is user */
/* visible progress. And if we don't count this, we have */
/* stability problems for programs that finalize all objects. */
if (result < (signed_word)(GC_bytes_allocd >> 3)) {
/* Always count at least 1/8 of the allocations. We don't want */
/* to collect too infrequently, since that would inhibit */
/* coalescing of free storage blocks. */
/* This also makes us partially robust against client bugs. */
return(GC_bytes_allocd >> 3);
} else {
return(result);
}
}
/* Clear up a few frames worth of garbage left at the top of the stack. */
/* This is used to prevent us from accidentally treating garbage left */
/* on the stack by other parts of the collector as roots. This */
/* differs from the code in misc.c, which actually tries to keep the */
/* stack clear of long-lived, client-generated garbage. */
STATIC void GC_clear_a_few_frames(void)
{
# ifndef CLEAR_NWORDS
# define CLEAR_NWORDS 64
# endif
volatile word frames[CLEAR_NWORDS];
BZERO((word *)frames, CLEAR_NWORDS * sizeof(word));
}
/* Heap size at which we need a collection to avoid expanding past */
/* limits used by blacklisting. */
STATIC word GC_collect_at_heapsize = (word)(-1);
/* Have we allocated enough to amortize a collection? */
GC_INNER GC_bool GC_should_collect(void)
{
static word last_min_bytes_allocd;
static word last_gc_no;
if (last_gc_no != GC_gc_no) {
last_gc_no = GC_gc_no;
last_min_bytes_allocd = min_bytes_allocd();
}
return(GC_adj_bytes_allocd() >= last_min_bytes_allocd
|| GC_heapsize >= GC_collect_at_heapsize);
}
/* STATIC */ GC_start_callback_proc GC_start_call_back = 0;
/* Called at start of full collections. */
/* Not called if 0. Called with the allocation */
/* lock held. Not used by GC itself. */
GC_API void GC_CALL GC_set_start_callback(GC_start_callback_proc fn)
{
DCL_LOCK_STATE;
LOCK();
GC_start_call_back = fn;
UNLOCK();
}
GC_API GC_start_callback_proc GC_CALL GC_get_start_callback(void)
{
GC_start_callback_proc fn;
DCL_LOCK_STATE;
LOCK();
fn = GC_start_call_back;
UNLOCK();
return fn;
}
GC_INLINE void GC_notify_full_gc(void)
{
if (GC_start_call_back != 0) {
(*GC_start_call_back)();
}
}
STATIC GC_bool GC_is_full_gc = FALSE;
STATIC GC_bool GC_stopped_mark(GC_stop_func stop_func);
STATIC void GC_finish_collection(void);
/*
* Initiate a garbage collection if appropriate.
* Choose judiciously
* between partial, full, and stop-world collections.
*/
STATIC void GC_maybe_gc(void)
{
static int n_partial_gcs = 0;
GC_ASSERT(I_HOLD_LOCK());
ASSERT_CANCEL_DISABLED();
if (GC_should_collect()) {
if (!GC_incremental) {
/* FIXME: If possible, GC_default_stop_func should be used here */
GC_try_to_collect_inner(GC_never_stop_func);
n_partial_gcs = 0;
return;
} else {
# ifdef PARALLEL_MARK
if (GC_parallel)
GC_wait_for_reclaim();
# endif
if (GC_need_full_gc || n_partial_gcs >= GC_full_freq) {
GC_COND_LOG_PRINTF(
"***>Full mark for collection #%lu after %lu allocd bytes\n",
(unsigned long)GC_gc_no + 1, (unsigned long)GC_bytes_allocd);
GC_promote_black_lists();
(void)GC_reclaim_all((GC_stop_func)0, TRUE);
GC_notify_full_gc();
GC_clear_marks();
n_partial_gcs = 0;
GC_is_full_gc = TRUE;
} else {
n_partial_gcs++;
}
}
/* We try to mark with the world stopped. */
/* If we run out of time, this turns into */
/* incremental marking. */
# ifndef NO_CLOCK
if (GC_time_limit != GC_TIME_UNLIMITED) { GET_TIME(GC_start_time); }
# endif
/* FIXME: If possible, GC_default_stop_func should be */
/* used instead of GC_never_stop_func here. */
if (GC_stopped_mark(GC_time_limit == GC_TIME_UNLIMITED?
GC_never_stop_func : GC_timeout_stop_func)) {
# ifdef SAVE_CALL_CHAIN
GC_save_callers(GC_last_stack);
# endif
GC_finish_collection();
} else {
if (!GC_is_full_gc) {
/* Count this as the first attempt */
GC_n_attempts++;
}
}
}
}
/*
* Stop the world garbage collection. Assumes lock held. If stop_func is
* not GC_never_stop_func then abort if stop_func returns TRUE.
* Return TRUE if we successfully completed the collection.
*/
GC_INNER GC_bool GC_try_to_collect_inner(GC_stop_func stop_func)
{
# ifndef SMALL_CONFIG
CLOCK_TYPE start_time = 0; /* initialized to prevent warning. */
CLOCK_TYPE current_time;
# endif
ASSERT_CANCEL_DISABLED();
if (GC_dont_gc || (*stop_func)()) return FALSE;
if (GC_incremental && GC_collection_in_progress()) {
GC_COND_LOG_PRINTF(
"GC_try_to_collect_inner: finishing collection in progress\n");
/* Just finish collection already in progress. */
while(GC_collection_in_progress()) {
if ((*stop_func)()) return(FALSE);
GC_collect_a_little_inner(1);
}
}
GC_notify_full_gc();
# ifndef SMALL_CONFIG
if (GC_print_stats) {
GET_TIME(start_time);
GC_log_printf("Initiating full world-stop collection!\n");
}
# endif
GC_promote_black_lists();
/* Make sure all blocks have been reclaimed, so sweep routines */
/* don't see cleared mark bits. */
/* If we're guaranteed to finish, then this is unnecessary. */
/* In the find_leak case, we have to finish to guarantee that */
/* previously unmarked objects are not reported as leaks. */
# ifdef PARALLEL_MARK
if (GC_parallel)
GC_wait_for_reclaim();
# endif
if ((GC_find_leak || stop_func != GC_never_stop_func)
&& !GC_reclaim_all(stop_func, FALSE)) {
/* Aborted. So far everything is still consistent. */
return(FALSE);
}
GC_invalidate_mark_state(); /* Flush mark stack. */
GC_clear_marks();
# ifdef SAVE_CALL_CHAIN
GC_save_callers(GC_last_stack);
# endif
GC_is_full_gc = TRUE;
if (!GC_stopped_mark(stop_func)) {
if (!GC_incremental) {
/* We're partially done and have no way to complete or use */
/* current work. Reestablish invariants as cheaply as */
/* possible. */
GC_invalidate_mark_state();
GC_unpromote_black_lists();
} /* else we claim the world is already still consistent. We'll */
/* finish incrementally. */
return(FALSE);
}
GC_finish_collection();
# ifndef SMALL_CONFIG
if (GC_print_stats) {
GET_TIME(current_time);
GC_log_printf("Complete collection took %lu msecs\n",
MS_TIME_DIFF(current_time,start_time));
}
# endif
return(TRUE);
}
/*
* Perform n units of garbage collection work. A unit is intended to touch
* roughly GC_RATE pages. Every once in a while, we do more than that.
* This needs to be a fairly large number with our current incremental
* GC strategy, since otherwise we allocate too much during GC, and the
* cleanup gets expensive.
*/
#ifndef GC_RATE
# define GC_RATE 10
#endif
#ifndef MAX_PRIOR_ATTEMPTS
# define MAX_PRIOR_ATTEMPTS 1
#endif
/* Maximum number of prior attempts at world stop marking */
/* A value of 1 means that we finish the second time, no matter */
/* how long it takes. Doesn't count the initial root scan */
/* for a full GC. */
STATIC int GC_deficit = 0;/* The number of extra calls to GC_mark_some */
/* that we have made. */
GC_INNER void GC_collect_a_little_inner(int n)
{
int i;
IF_CANCEL(int cancel_state;)
if (GC_dont_gc) return;
DISABLE_CANCEL(cancel_state);
if (GC_incremental && GC_collection_in_progress()) {
for (i = GC_deficit; i < GC_RATE*n; i++) {
if (GC_mark_some((ptr_t)0)) {
/* Need to finish a collection */
# ifdef SAVE_CALL_CHAIN
GC_save_callers(GC_last_stack);
# endif
# ifdef PARALLEL_MARK
if (GC_parallel)
GC_wait_for_reclaim();
# endif
if (GC_n_attempts < MAX_PRIOR_ATTEMPTS
&& GC_time_limit != GC_TIME_UNLIMITED) {
# ifndef NO_CLOCK
GET_TIME(GC_start_time);
# endif
if (!GC_stopped_mark(GC_timeout_stop_func)) {
GC_n_attempts++;
break;
}
} else {
/* FIXME: If possible, GC_default_stop_func should be */
/* used here. */
(void)GC_stopped_mark(GC_never_stop_func);
}
GC_finish_collection();
break;
}
}
if (GC_deficit > 0) GC_deficit -= GC_RATE*n;
if (GC_deficit < 0) GC_deficit = 0;
} else {
GC_maybe_gc();
}
RESTORE_CANCEL(cancel_state);
}
GC_INNER void (*GC_check_heap)(void) = 0;
GC_INNER void (*GC_print_all_smashed)(void) = 0;
GC_API int GC_CALL GC_collect_a_little(void)
{
int result;
DCL_LOCK_STATE;
LOCK();
GC_collect_a_little_inner(1);
result = (int)GC_collection_in_progress();
UNLOCK();
if (!result && GC_debugging_started) GC_print_all_smashed();
return(result);
}
#ifndef SMALL_CONFIG
/* Variables for world-stop average delay time statistic computation. */
/* "divisor" is incremented every world-stop and halved when reached */
/* its maximum (or upon "total_time" overflow). */
static unsigned world_stopped_total_time = 0;
static unsigned world_stopped_total_divisor = 0;
# ifndef MAX_TOTAL_TIME_DIVISOR
/* We shall not use big values here (so "outdated" delay time */
/* values would have less impact on "average" delay time value than */
/* newer ones). */
# define MAX_TOTAL_TIME_DIVISOR 1000
# endif
#endif
#ifdef USE_MUNMAP
# define IF_USE_MUNMAP(x) x
# define COMMA_IF_USE_MUNMAP(x) /* comma */, x
#else
# define IF_USE_MUNMAP(x) /* empty */
# define COMMA_IF_USE_MUNMAP(x) /* empty */
#endif
/*
* Assumes lock is held. We stop the world and mark from all roots.
* If stop_func() ever returns TRUE, we may fail and return FALSE.
* Increment GC_gc_no if we succeed.
*/
STATIC GC_bool GC_stopped_mark(GC_stop_func stop_func)
{
unsigned i;
# ifndef SMALL_CONFIG
CLOCK_TYPE start_time = 0; /* initialized to prevent warning. */
CLOCK_TYPE current_time;
# endif
# if !defined(REDIRECT_MALLOC) && defined(USE_WINALLOC)
GC_add_current_malloc_heap();
# endif
# if defined(REGISTER_LIBRARIES_EARLY)
GC_cond_register_dynamic_libraries();
# endif
# ifndef SMALL_CONFIG
if (GC_PRINT_STATS_FLAG)
GET_TIME(start_time);
# endif
STOP_WORLD();
# ifdef THREAD_LOCAL_ALLOC
GC_world_stopped = TRUE;
# endif
/* Output blank line for convenience here */
GC_COND_LOG_PRINTF(
"\n--> Marking for collection #%lu after %lu allocated bytes\n",
(unsigned long)GC_gc_no + 1, (unsigned long) GC_bytes_allocd);
# ifdef MAKE_BACK_GRAPH
if (GC_print_back_height) {
GC_build_back_graph();
}
# endif
/* Mark from all roots. */
/* Minimize junk left in my registers and on the stack */
GC_clear_a_few_frames();
GC_noop6(0,0,0,0,0,0);
GC_initiate_gc();
for (i = 0;;i++) {
if ((*stop_func)()) {
GC_COND_LOG_PRINTF("Abandoned stopped marking after"
" %u iterations\n", i);
GC_deficit = i; /* Give the mutator a chance. */
# ifdef THREAD_LOCAL_ALLOC
GC_world_stopped = FALSE;
# endif
START_WORLD();
return(FALSE);
}
if (GC_mark_some(GC_approx_sp())) break;
}
GC_gc_no++;
GC_DBGLOG_PRINTF("GC #%lu freed %ld bytes, heap %lu KiB"
IF_USE_MUNMAP(" (+ %lu KiB unmapped)") "\n",
(unsigned long)GC_gc_no, (long)GC_bytes_found,
TO_KiB_UL(GC_heapsize - GC_unmapped_bytes) /*, */
COMMA_IF_USE_MUNMAP(TO_KiB_UL(GC_unmapped_bytes)));
/* Check all debugged objects for consistency */
if (GC_debugging_started) {
(*GC_check_heap)();
}
# ifdef THREAD_LOCAL_ALLOC
GC_world_stopped = FALSE;
# endif
START_WORLD();
# ifndef SMALL_CONFIG
if (GC_PRINT_STATS_FLAG) {
unsigned long time_diff;
unsigned total_time, divisor;
GET_TIME(current_time);
time_diff = MS_TIME_DIFF(current_time,start_time);
/* Compute new world-stop delay total time */
total_time = world_stopped_total_time;
divisor = world_stopped_total_divisor;
if ((int)total_time < 0 || divisor >= MAX_TOTAL_TIME_DIVISOR) {
/* Halve values if overflow occurs */
total_time >>= 1;
divisor >>= 1;
}
total_time += time_diff < (((unsigned)-1) >> 1) ?
(unsigned)time_diff : ((unsigned)-1) >> 1;
/* Update old world_stopped_total_time and its divisor */
world_stopped_total_time = total_time;
world_stopped_total_divisor = ++divisor;
GC_ASSERT(divisor != 0);
GC_log_printf(
"World-stopped marking took %lu msecs (%u in average)\n",
time_diff, total_time / divisor);
}
# endif
return(TRUE);
}
/* Set all mark bits for the free list whose first entry is q */
GC_INNER void GC_set_fl_marks(ptr_t q)
{
struct hblk *h, *last_h;
hdr *hhdr;
IF_PER_OBJ(size_t sz;)
unsigned bit_no;
if (q != NULL) {
h = HBLKPTR(q);
last_h = h;
hhdr = HDR(h);
IF_PER_OBJ(sz = hhdr->hb_sz;)
for (;;) {
bit_no = MARK_BIT_NO((ptr_t)q - (ptr_t)h, sz);
if (!mark_bit_from_hdr(hhdr, bit_no)) {
set_mark_bit_from_hdr(hhdr, bit_no);
++hhdr -> hb_n_marks;
}
q = obj_link(q);
if (q == NULL)
break;
h = HBLKPTR(q);
if (h != last_h) {
last_h = h;
hhdr = HDR(h);
IF_PER_OBJ(sz = hhdr->hb_sz;)
}
}
}
}
#if defined(GC_ASSERTIONS) && defined(THREADS) && defined(THREAD_LOCAL_ALLOC)
/* Check that all mark bits for the free list whose first entry is */
/* (*pfreelist) are set. Check skipped if points to a special value. */
void GC_check_fl_marks(void **pfreelist)
{
# ifdef AO_HAVE_load_acquire_read
AO_t *list = (AO_t *)AO_load_acquire_read((AO_t *)pfreelist);
/* Atomic operations are used because the world is running. */
AO_t *prev;
AO_t *p;
if ((word)list <= HBLKSIZE) return;
prev = (AO_t *)pfreelist;
for (p = list; p != NULL;) {
AO_t *next;
if (!GC_is_marked(p)) {
ABORT_ARG2("Unmarked local free list entry",
": object %p on list %p", (void *)p, (void *)list);
}
/* While traversing the free-list, it re-reads the pointer to */
/* the current node before accepting its next pointer and */
/* bails out if the latter has changed. That way, it won't */
/* try to follow the pointer which might be been modified */
/* after the object was returned to the client. It might */
/* perform the mark-check on the just allocated object but */
/* that should be harmless. */
next = (AO_t *)AO_load_acquire_read(p);
if (AO_load(prev) != (AO_t)p)
break;
prev = p;
p = next;
}
# else
/* FIXME: Not implemented (just skipped). */
(void)pfreelist;
# endif
}
#endif /* GC_ASSERTIONS && THREAD_LOCAL_ALLOC */
/* Clear all mark bits for the free list whose first entry is q */
/* Decrement GC_bytes_found by number of bytes on free list. */
STATIC void GC_clear_fl_marks(ptr_t q)
{
struct hblk *h, *last_h;
hdr *hhdr;
size_t sz;
unsigned bit_no;
if (q != NULL) {
h = HBLKPTR(q);
last_h = h;
hhdr = HDR(h);
sz = hhdr->hb_sz; /* Normally set only once. */
for (;;) {
bit_no = MARK_BIT_NO((ptr_t)q - (ptr_t)h, sz);
if (mark_bit_from_hdr(hhdr, bit_no)) {
size_t n_marks = hhdr -> hb_n_marks - 1;
clear_mark_bit_from_hdr(hhdr, bit_no);
# ifdef PARALLEL_MARK
/* Appr. count, don't decrement to zero! */
if (0 != n_marks || !GC_parallel) {
hhdr -> hb_n_marks = n_marks;
}
# else
hhdr -> hb_n_marks = n_marks;
# endif
}
GC_bytes_found -= sz;
q = obj_link(q);
if (q == NULL)
break;
h = HBLKPTR(q);
if (h != last_h) {
last_h = h;
hhdr = HDR(h);
sz = hhdr->hb_sz;
}
}
}
}
#if defined(GC_ASSERTIONS) && defined(THREADS) && defined(THREAD_LOCAL_ALLOC)
void GC_check_tls(void);
#endif
GC_on_heap_resize_proc GC_on_heap_resize = 0;
/* Used for logging only. */
GC_INLINE int GC_compute_heap_usage_percent(void)
{
word used = GC_composite_in_use + GC_atomic_in_use;
word heap_sz = GC_heapsize - GC_unmapped_bytes;
return used >= heap_sz ? 0 : used < ((word)-1) / 100 ?
(int)((used * 100) / heap_sz) : (int)(used / (heap_sz / 100));
}
/* Finish up a collection. Assumes mark bits are consistent, lock is */
/* held, but the world is otherwise running. */
STATIC void GC_finish_collection(void)
{
# ifndef SMALL_CONFIG
CLOCK_TYPE start_time = 0; /* initialized to prevent warning. */
CLOCK_TYPE finalize_time = 0;
CLOCK_TYPE done_time;
# endif
# if defined(GC_ASSERTIONS) && defined(THREADS) \
&& defined(THREAD_LOCAL_ALLOC) && !defined(DBG_HDRS_ALL)
/* Check that we marked some of our own data. */
/* FIXME: Add more checks. */
GC_check_tls();
# endif
# ifndef SMALL_CONFIG
if (GC_print_stats)
GET_TIME(start_time);
# endif
# ifndef GC_GET_HEAP_USAGE_NOT_NEEDED
if (GC_bytes_found > 0)
GC_reclaimed_bytes_before_gc += (word)GC_bytes_found;
# endif
GC_bytes_found = 0;
# if defined(LINUX) && defined(__ELF__) && !defined(SMALL_CONFIG)
if (GETENV("GC_PRINT_ADDRESS_MAP") != 0) {
GC_print_address_map();
}
# endif
COND_DUMP;
if (GC_find_leak) {
/* Mark all objects on the free list. All objects should be */
/* marked when we're done. */
word size; /* current object size */
unsigned kind;
ptr_t q;
for (kind = 0; kind < GC_n_kinds; kind++) {
for (size = 1; size <= MAXOBJGRANULES; size++) {
q = GC_obj_kinds[kind].ok_freelist[size];
if (q != 0) GC_set_fl_marks(q);
}
}
GC_start_reclaim(TRUE);
/* The above just checks; it doesn't really reclaim anything. */
}
# ifndef GC_NO_FINALIZATION
GC_finalize();
# endif
# ifdef STUBBORN_ALLOC
GC_clean_changing_list();
# endif
# ifndef SMALL_CONFIG
if (GC_print_stats)
GET_TIME(finalize_time);
# endif
if (GC_print_back_height) {
# ifdef MAKE_BACK_GRAPH
GC_traverse_back_graph();
# elif !defined(SMALL_CONFIG)
GC_err_printf("Back height not available: "
"Rebuild collector with -DMAKE_BACK_GRAPH\n");
# endif
}
/* Clear free list mark bits, in case they got accidentally marked */
/* (or GC_find_leak is set and they were intentionally marked). */
/* Also subtract memory remaining from GC_bytes_found count. */
/* Note that composite objects on free list are cleared. */
/* Thus accidentally marking a free list is not a problem; only */
/* objects on the list itself will be marked, and that's fixed here. */
{
word size; /* current object size */
ptr_t q; /* pointer to current object */
unsigned kind;
for (kind = 0; kind < GC_n_kinds; kind++) {
for (size = 1; size <= MAXOBJGRANULES; size++) {
q = GC_obj_kinds[kind].ok_freelist[size];
if (q != 0) GC_clear_fl_marks(q);
}
}
}
GC_VERBOSE_LOG_PRINTF("Bytes recovered before sweep - f.l. count = %ld\n",
(long)GC_bytes_found);
/* Reconstruct free lists to contain everything not marked */
GC_start_reclaim(FALSE);
GC_DBGLOG_PRINTF("In-use heap: %d%% (%lu KiB pointers + %lu KiB other)\n",
GC_compute_heap_usage_percent(),
TO_KiB_UL(GC_composite_in_use),
TO_KiB_UL(GC_atomic_in_use));
if (GC_is_full_gc) {
GC_used_heap_size_after_full = USED_HEAP_SIZE;
GC_need_full_gc = FALSE;
} else {
GC_need_full_gc = USED_HEAP_SIZE - GC_used_heap_size_after_full
> min_bytes_allocd();
}
GC_VERBOSE_LOG_PRINTF("Immediately reclaimed %ld bytes, heapsize:"
" %lu bytes" IF_USE_MUNMAP(" (%lu unmapped)") "\n",
(long)GC_bytes_found,
(unsigned long)GC_heapsize /*, */
COMMA_IF_USE_MUNMAP((unsigned long)
GC_unmapped_bytes));
/* Reset or increment counters for next cycle */
GC_n_attempts = 0;
GC_is_full_gc = FALSE;
GC_bytes_allocd_before_gc += GC_bytes_allocd;
GC_non_gc_bytes_at_gc = GC_non_gc_bytes;
GC_bytes_allocd = 0;
GC_bytes_dropped = 0;
GC_bytes_freed = 0;
GC_finalizer_bytes_freed = 0;
IF_USE_MUNMAP(GC_unmap_old());
# ifndef SMALL_CONFIG
if (GC_print_stats) {
GET_TIME(done_time);
# ifndef GC_NO_FINALIZATION
/* A convenient place to output finalization statistics. */
GC_print_finalization_stats();
# endif
GC_log_printf("Finalize plus initiate sweep took %lu + %lu msecs\n",
MS_TIME_DIFF(finalize_time,start_time),
MS_TIME_DIFF(done_time,finalize_time));
}
# endif
}
/* If stop_func == 0 then GC_default_stop_func is used instead. */
STATIC GC_bool GC_try_to_collect_general(GC_stop_func stop_func,
GC_bool force_unmap GC_ATTR_UNUSED)
{
GC_bool result;
IF_USE_MUNMAP(int old_unmap_threshold;)
IF_CANCEL(int cancel_state;)
DCL_LOCK_STATE;
if (!EXPECT(GC_is_initialized, TRUE)) GC_init();
if (GC_debugging_started) GC_print_all_smashed();
GC_INVOKE_FINALIZERS();
LOCK();
DISABLE_CANCEL(cancel_state);
# ifdef USE_MUNMAP
old_unmap_threshold = GC_unmap_threshold;
if (force_unmap ||
(GC_force_unmap_on_gcollect && old_unmap_threshold > 0))
GC_unmap_threshold = 1; /* unmap as much as possible */
# endif
ENTER_GC();
/* Minimize junk left in my registers */
GC_noop6(0,0,0,0,0,0);
result = GC_try_to_collect_inner(stop_func != 0 ? stop_func :
GC_default_stop_func);
EXIT_GC();
IF_USE_MUNMAP(GC_unmap_threshold = old_unmap_threshold); /* restore */
RESTORE_CANCEL(cancel_state);
UNLOCK();
if (result) {
if (GC_debugging_started) GC_print_all_smashed();
GC_INVOKE_FINALIZERS();
}