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gecko-dev/js/src/jsgc.c
brendan%mozilla.org 69f7de4572 Fix O(n^2) growth bug in js_GetSrcNote (347306, r=igor).
2006-10-07 19:14:55 +00:00

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/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=8 sw=4 et tw=78:
*
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla Communicator client code, released
* March 31, 1998.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/*
* JS Mark-and-Sweep Garbage Collector.
*
* This GC allocates fixed-sized things with sizes up to GC_NBYTES_MAX (see
* jsgc.h). It allocates from a special GC arena pool with each arena allocated
* using malloc. It uses an ideally parallel array of flag bytes to hold the
* mark bit, finalizer type index, etc.
*
* XXX swizzle page to freelist for better locality of reference
*/
#include "jsstddef.h"
#include <stdlib.h> /* for free */
#include <string.h> /* for memset used when DEBUG */
#include "jstypes.h"
#include "jsutil.h" /* Added by JSIFY */
#include "jshash.h" /* Added by JSIFY */
#include "jsapi.h"
#include "jsatom.h"
#include "jsbit.h"
#include "jsclist.h"
#include "jscntxt.h"
#include "jsconfig.h"
#include "jsdbgapi.h"
#include "jsexn.h"
#include "jsfun.h"
#include "jsgc.h"
#include "jsinterp.h"
#include "jsiter.h"
#include "jslock.h"
#include "jsnum.h"
#include "jsobj.h"
#include "jsscope.h"
#include "jsscript.h"
#include "jsstr.h"
#if JS_HAS_XML_SUPPORT
#include "jsxml.h"
#endif
/*
* GC arena sizing depends on amortizing arena overhead using a large number
* of things per arena, and on the thing/flags ratio of 8:1 on most platforms.
*
* On 64-bit platforms, we would have half as many things per arena because
* pointers are twice as big, so we double the bytes for things per arena.
* This preserves the 1024 byte flags sub-arena size, which relates to the
* GC_PAGE_SIZE (see below for why).
*/
#if JS_BYTES_PER_WORD == 8
# define GC_THINGS_SHIFT 14 /* 16KB for things on Alpha, etc. */
#else
# define GC_THINGS_SHIFT 13 /* 8KB for things on most platforms */
#endif
#define GC_THINGS_SIZE JS_BIT(GC_THINGS_SHIFT)
#define GC_FLAGS_SIZE (GC_THINGS_SIZE / sizeof(JSGCThing))
/*
* A GC arena contains one flag byte for each thing in its heap, and supports
* O(1) lookup of a flag given its thing's address.
*
* To implement this, we take advantage of the thing/flags numerology: given
* the 8K bytes worth of GC-things, there are 1K flag bytes. Within each 9K
* allocation for things+flags there are always 8 consecutive 1K-pages each
* aligned on 1K boundary. We use these pages to allocate things and the
* remaining 1K of space before and after the aligned pages to store flags.
* If we are really lucky and things+flags starts on a 1K boundary, then
* flags would consist of a single 1K chunk that comes after 8K of things.
* Otherwise there are 2 chunks of flags, one before and one after things.
*
* To be able to find the flag byte for a particular thing, we put a
* JSGCPageInfo record at the beginning of each 1K-aligned page to hold that
* page's offset from the beginning of things+flags allocation and we allocate
* things after this record. Thus for each thing |thing_address & ~1023|
* gives the address of a JSGCPageInfo record from which we read page_offset.
* Due to page alignment
* (page_offset & ~1023) + (thing_address & 1023)
* gives thing_offset from the beginning of 8K paged things. We then divide
* thing_offset by sizeof(JSGCThing) to get thing_index.
*
* Now |page_address - page_offset| is things+flags arena_address and
* (page_offset & 1023) is the offset of the first page from the start of
* things+flags area. Thus if
* thing_index < (page_offset & 1023)
* then
* allocation_start_address + thing_index < address_of_the_first_page
* and we use
* allocation_start_address + thing_index
* as the address to store thing's flags. If
* thing_index >= (page_offset & 1023),
* then we use the chunk of flags that comes after the pages with things
* and calculate the address for the flag byte as
* address_of_the_first_page + 8K + (thing_index - (page_offset & 1023))
* which is just
* allocation_start_address + thing_index + 8K.
*
* When we allocate things with size equal to sizeof(JSGCThing), the overhead
* of this scheme for 32 bit platforms is (8+8*(8+1))/(8+9K) or 0.87%
* (assuming 4 bytes for each JSGCArena header, and 8 bytes for each
* JSGCThing and JSGCPageInfo). When thing_size > 8, the scheme wastes the
* flag byte for each extra 8 bytes beyond sizeof(JSGCThing) in thing_size
* and the overhead is close to 1/8 or 12.5%.
* FIXME: How can we avoid this overhead?
*
* Here's some ASCII art showing an arena:
*
* split or the first 1-K aligned address.
* |
* V
* +--+-------+-------+-------+-------+-------+-------+-------+-------+-----+
* |fB| tp0 | tp1 | tp2 | tp3 | tp4 | tp5 | tp6 | tp7 | fA |
* +--+-------+-------+-------+-------+-------+-------+-------+-------+-----+
* ^ ^
* tI ---------+ |
* tJ -------------------------------------------+
*
* - fB are the "before split" flags, fA are the "after split" flags
* - tp0-tp7 are the 8 thing pages
* - thing tI points into tp1, whose flags are below the split, in fB
* - thing tJ points into tp5, clearly above the split
*
* In general, one of the thing pages will have some of its things' flags on
* the low side of the split, and the rest of its things' flags on the high
* side. All the other pages have flags only below or only above.
*
* (If we need to implement card-marking for an incremental GC write barrier,
* we can replace word-sized offsetInArena in JSGCPageInfo by pair of
* uint8 card_mark and uint16 offsetInArena fields as the offset can not exceed
* GC_THINGS_SIZE. This would gives an extremely efficient write barrier:
* when mutating an object obj, just store a 1 byte at
* (uint8 *) ((jsuword)obj & ~1023) on 32-bit platforms.)
*/
#define GC_PAGE_SHIFT 10
#define GC_PAGE_MASK ((jsuword) JS_BITMASK(GC_PAGE_SHIFT))
#define GC_PAGE_SIZE JS_BIT(GC_PAGE_SHIFT)
#define GC_PAGE_COUNT (1 << (GC_THINGS_SHIFT - GC_PAGE_SHIFT))
typedef struct JSGCPageInfo {
jsuword offsetInArena; /* offset from the arena start */
jsuword unscannedBitmap; /* bitset for fast search of marked
but not yet scanned GC things */
} JSGCPageInfo;
struct JSGCArena {
JSGCArenaList *list; /* allocation list for the arena */
JSGCArena *prev; /* link field for allocation list */
JSGCArena *prevUnscanned; /* link field for the list of arenas
with marked but not yet scanned
things */
jsuword unscannedPages; /* bitset for fast search of pages
with marked but not yet scanned
things */
uint8 base[1]; /* things+flags allocation area */
};
#define GC_ARENA_SIZE \
(offsetof(JSGCArena, base) + GC_THINGS_SIZE + GC_FLAGS_SIZE)
#define FIRST_THING_PAGE(a) \
(((jsuword)(a)->base + GC_FLAGS_SIZE - 1) & ~GC_PAGE_MASK)
#define PAGE_TO_ARENA(pi) \
((JSGCArena *)((jsuword)(pi) - (pi)->offsetInArena \
- offsetof(JSGCArena, base)))
#define PAGE_INDEX(pi) \
((size_t)((pi)->offsetInArena >> GC_PAGE_SHIFT))
#define THING_TO_PAGE(thing) \
((JSGCPageInfo *)((jsuword)(thing) & ~GC_PAGE_MASK))
/*
* Given a thing size n, return the size of the gap from the page start before
* the first thing. We know that any n not a power of two packs from
* the end of the page leaving at least enough room for one JSGCPageInfo, but
* not for another thing, at the front of the page (JS_ASSERTs below insist
* on this).
*
* This works because all allocations are a multiple of sizeof(JSGCThing) ==
* sizeof(JSGCPageInfo) in size.
*/
#define PAGE_THING_GAP(n) (((n) & ((n) - 1)) ? (GC_PAGE_SIZE % (n)) : (n))
#ifdef JS_THREADSAFE
/*
* The maximum number of things to put to the local free list by taking
* several things from the global free list or from the tail of the last
* allocated arena to amortize the cost of rt->gcLock.
*
* We use number 8 based on benchmarks from bug 312238.
*/
#define MAX_THREAD_LOCAL_THINGS 8
#endif
JS_STATIC_ASSERT(sizeof(JSGCThing) == sizeof(JSGCPageInfo));
JS_STATIC_ASSERT(sizeof(JSGCThing) >= sizeof(JSObject));
JS_STATIC_ASSERT(sizeof(JSGCThing) >= sizeof(JSString));
JS_STATIC_ASSERT(sizeof(JSGCThing) >= sizeof(jsdouble));
JS_STATIC_ASSERT(GC_FLAGS_SIZE >= GC_PAGE_SIZE);
JS_STATIC_ASSERT(sizeof(JSStackHeader) >= 2 * sizeof(jsval));
/*
* JSPtrTable capacity growth descriptor. The table grows by powers of two
* starting from capacity JSPtrTableInfo.minCapacity, but switching to linear
* growth when capacity reaches JSPtrTableInfo.linearGrowthThreshold.
*/
typedef struct JSPtrTableInfo {
uint16 minCapacity;
uint16 linearGrowthThreshold;
} JSPtrTableInfo;
#define GC_ITERATOR_TABLE_MIN 4
#define GC_ITERATOR_TABLE_LINEAR 1024
static const JSPtrTableInfo iteratorTableInfo = {
GC_ITERATOR_TABLE_MIN,
GC_ITERATOR_TABLE_LINEAR
};
/* Calculate table capacity based on the current value of JSPtrTable.count. */
static size_t
PtrTableCapacity(size_t count, const JSPtrTableInfo *info)
{
size_t linear, log, capacity;
linear = info->linearGrowthThreshold;
JS_ASSERT(info->minCapacity <= linear);
if (count == 0) {
capacity = 0;
} else if (count < linear) {
log = JS_CEILING_LOG2W(count);
JS_ASSERT(log != JS_BITS_PER_WORD);
capacity = (size_t)1 << log;
if (capacity < info->minCapacity)
capacity = info->minCapacity;
} else {
capacity = JS_ROUNDUP(count, linear);
}
JS_ASSERT(capacity >= count);
return capacity;
}
static void
FreePtrTable(JSPtrTable *table, const JSPtrTableInfo *info)
{
if (table->array) {
JS_ASSERT(table->count > 0);
free(table->array);
table->array = NULL;
table->count = 0;
}
JS_ASSERT(table->count == 0);
}
static JSBool
AddToPtrTable(JSContext *cx, JSPtrTable *table, const JSPtrTableInfo *info,
void *ptr)
{
size_t count, capacity;
void **array;
count = table->count;
capacity = PtrTableCapacity(count, info);
if (count == capacity) {
if (capacity < info->minCapacity) {
JS_ASSERT(capacity == 0);
JS_ASSERT(!table->array);
capacity = info->minCapacity;
} else {
/*
* Simplify the overflow detection assuming pointer is bigger
* than byte.
*/
JS_STATIC_ASSERT(2 <= sizeof table->array[0]);
capacity = (capacity < info->linearGrowthThreshold)
? 2 * capacity
: capacity + info->linearGrowthThreshold;
if (capacity > (size_t)-1 / sizeof table->array[0])
goto bad;
}
array = (void **) realloc(table->array,
capacity * sizeof table->array[0]);
if (!array)
goto bad;
#ifdef DEBUG
memset(array + count, JS_FREE_PATTERN,
(capacity - count) * sizeof table->array[0]);
#endif
table->array = array;
}
table->array[count] = ptr;
table->count = count + 1;
return JS_TRUE;
bad:
JS_ReportOutOfMemory(cx);
return JS_FALSE;
}
static void
ShrinkPtrTable(JSPtrTable *table, const JSPtrTableInfo *info,
size_t newCount)
{
size_t oldCapacity, capacity;
void **array;
JS_ASSERT(newCount <= table->count);
if (newCount == table->count)
return;
oldCapacity = PtrTableCapacity(table->count, info);
table->count = newCount;
capacity = PtrTableCapacity(newCount, info);
if (oldCapacity != capacity) {
array = table->array;
JS_ASSERT(array);
if (capacity == 0) {
free(array);
table->array = NULL;
return;
}
array = (void **) realloc(array, capacity * sizeof array[0]);
if (array)
table->array = array;
}
#ifdef DEBUG
memset(table->array + newCount, JS_FREE_PATTERN,
(capacity - newCount) * sizeof table->array[0]);
#endif
}
#ifdef JS_GCMETER
# define METER(x) x
#else
# define METER(x) ((void) 0)
#endif
static JSBool
NewGCArena(JSRuntime *rt, JSGCArenaList *arenaList)
{
JSGCArena *a;
jsuword offset;
JSGCPageInfo *pi;
uint32 *bytesptr;
/* Check if we are allowed and can allocate a new arena. */
if (rt->gcBytes >= rt->gcMaxBytes)
return JS_FALSE;
a = (JSGCArena *)malloc(GC_ARENA_SIZE);
if (!a)
return JS_FALSE;
/* Initialize the JSGCPageInfo records at the start of every thing page. */
offset = (GC_PAGE_SIZE - ((jsuword)a->base & GC_PAGE_MASK)) & GC_PAGE_MASK;
JS_ASSERT((jsuword)a->base + offset == FIRST_THING_PAGE(a));
do {
pi = (JSGCPageInfo *) (a->base + offset);
pi->offsetInArena = offset;
pi->unscannedBitmap = 0;
offset += GC_PAGE_SIZE;
} while (offset < GC_THINGS_SIZE);
METER(++arenaList->stats.narenas);
METER(arenaList->stats.maxarenas
= JS_MAX(arenaList->stats.maxarenas, arenaList->stats.narenas));
a->list = arenaList;
a->prev = arenaList->last;
a->prevUnscanned = NULL;
a->unscannedPages = 0;
arenaList->last = a;
arenaList->lastLimit = 0;
bytesptr = (arenaList == &rt->gcArenaList[0])
? &rt->gcBytes
: &rt->gcPrivateBytes;
*bytesptr += GC_ARENA_SIZE;
return JS_TRUE;
}
static void
DestroyGCArena(JSRuntime *rt, JSGCArenaList *arenaList, JSGCArena **ap)
{
JSGCArena *a;
uint32 *bytesptr;
a = *ap;
JS_ASSERT(a);
bytesptr = (arenaList == &rt->gcArenaList[0])
? &rt->gcBytes
: &rt->gcPrivateBytes;
JS_ASSERT(*bytesptr >= GC_ARENA_SIZE);
*bytesptr -= GC_ARENA_SIZE;
METER(rt->gcStats.afree++);
METER(--arenaList->stats.narenas);
if (a == arenaList->last)
arenaList->lastLimit = (uint16)(a->prev ? GC_THINGS_SIZE : 0);
*ap = a->prev;
#ifdef DEBUG
memset(a, JS_FREE_PATTERN, GC_ARENA_SIZE);
#endif
free(a);
}
static void
InitGCArenaLists(JSRuntime *rt)
{
uintN i, thingSize;
JSGCArenaList *arenaList;
for (i = 0; i < GC_NUM_FREELISTS; i++) {
arenaList = &rt->gcArenaList[i];
thingSize = GC_FREELIST_NBYTES(i);
JS_ASSERT((size_t)(uint16)thingSize == thingSize);
arenaList->last = NULL;
arenaList->lastLimit = 0;
arenaList->thingSize = (uint16)thingSize;
arenaList->freeList = NULL;
METER(memset(&arenaList->stats, 0, sizeof arenaList->stats));
}
}
static void
FinishGCArenaLists(JSRuntime *rt)
{
uintN i;
JSGCArenaList *arenaList;
for (i = 0; i < GC_NUM_FREELISTS; i++) {
arenaList = &rt->gcArenaList[i];
while (arenaList->last)
DestroyGCArena(rt, arenaList, &arenaList->last);
arenaList->freeList = NULL;
}
}
uint8 *
js_GetGCThingFlags(void *thing)
{
JSGCPageInfo *pi;
jsuword offsetInArena, thingIndex;
pi = THING_TO_PAGE(thing);
offsetInArena = pi->offsetInArena;
JS_ASSERT(offsetInArena < GC_THINGS_SIZE);
thingIndex = ((offsetInArena & ~GC_PAGE_MASK) |
((jsuword)thing & GC_PAGE_MASK)) / sizeof(JSGCThing);
JS_ASSERT(thingIndex < GC_PAGE_SIZE);
if (thingIndex >= (offsetInArena & GC_PAGE_MASK))
thingIndex += GC_THINGS_SIZE;
return (uint8 *)pi - offsetInArena + thingIndex;
}
JSRuntime*
js_GetGCStringRuntime(JSString *str)
{
JSGCPageInfo *pi;
JSGCArenaList *list;
pi = THING_TO_PAGE(str);
list = PAGE_TO_ARENA(pi)->list;
JS_ASSERT(list->thingSize == sizeof(JSGCThing));
JS_ASSERT(GC_FREELIST_INDEX(sizeof(JSGCThing)) == 0);
return (JSRuntime *)((uint8 *)list - offsetof(JSRuntime, gcArenaList));
}
JSBool
js_IsAboutToBeFinalized(JSContext *cx, void *thing)
{
uint8 flags = *js_GetGCThingFlags(thing);
return !(flags & (GCF_MARK | GCF_LOCK | GCF_FINAL));
}
typedef void (*GCFinalizeOp)(JSContext *cx, JSGCThing *thing);
#ifndef DEBUG
# define js_FinalizeDouble NULL
#endif
#if !JS_HAS_XML_SUPPORT
# define js_FinalizeXMLNamespace NULL
# define js_FinalizeXMLQName NULL
# define js_FinalizeXML NULL
#endif
static GCFinalizeOp gc_finalizers[GCX_NTYPES] = {
(GCFinalizeOp) js_FinalizeObject, /* GCX_OBJECT */
(GCFinalizeOp) js_FinalizeString, /* GCX_STRING */
(GCFinalizeOp) js_FinalizeDouble, /* GCX_DOUBLE */
(GCFinalizeOp) js_FinalizeString, /* GCX_MUTABLE_STRING */
NULL, /* GCX_PRIVATE */
(GCFinalizeOp) js_FinalizeXMLNamespace, /* GCX_NAMESPACE */
(GCFinalizeOp) js_FinalizeXMLQName, /* GCX_QNAME */
(GCFinalizeOp) js_FinalizeXML, /* GCX_XML */
NULL, /* GCX_EXTERNAL_STRING */
NULL,
NULL,
NULL,
NULL,
NULL,
NULL,
NULL
};
#ifdef GC_MARK_DEBUG
static const char newborn_external_string[] = "newborn external string";
static const char *gc_typenames[GCX_NTYPES] = {
"newborn object",
"newborn string",
"newborn double",
"newborn mutable string",
"newborn private",
"newborn Namespace",
"newborn QName",
"newborn XML",
newborn_external_string,
newborn_external_string,
newborn_external_string,
newborn_external_string,
newborn_external_string,
newborn_external_string,
newborn_external_string,
newborn_external_string
};
#endif
intN
js_ChangeExternalStringFinalizer(JSStringFinalizeOp oldop,
JSStringFinalizeOp newop)
{
uintN i;
for (i = GCX_EXTERNAL_STRING; i < GCX_NTYPES; i++) {
if (gc_finalizers[i] == (GCFinalizeOp) oldop) {
gc_finalizers[i] = (GCFinalizeOp) newop;
return (intN) i;
}
}
return -1;
}
/* Initial size of the gcRootsHash table (SWAG, small enough to amortize). */
#define GC_ROOTS_SIZE 256
#define GC_FINALIZE_LEN 1024
JSBool
js_InitGC(JSRuntime *rt, uint32 maxbytes)
{
InitGCArenaLists(rt);
if (!JS_DHashTableInit(&rt->gcRootsHash, JS_DHashGetStubOps(), NULL,
sizeof(JSGCRootHashEntry), GC_ROOTS_SIZE)) {
rt->gcRootsHash.ops = NULL;
return JS_FALSE;
}
rt->gcLocksHash = NULL; /* create lazily */
/*
* Separate gcMaxMallocBytes from gcMaxBytes but initialize to maxbytes
* for default backward API compatibility.
*/
rt->gcMaxBytes = rt->gcMaxMallocBytes = maxbytes;
return JS_TRUE;
}
#ifdef JS_GCMETER
JS_FRIEND_API(void)
js_DumpGCStats(JSRuntime *rt, FILE *fp)
{
uintN i;
size_t totalThings, totalMaxThings, totalBytes;
fprintf(fp, "\nGC allocation statistics:\n");
#define UL(x) ((unsigned long)(x))
#define ULSTAT(x) UL(rt->gcStats.x)
totalThings = 0;
totalMaxThings = 0;
totalBytes = 0;
for (i = 0; i < GC_NUM_FREELISTS; i++) {
JSGCArenaList *list = &rt->gcArenaList[i];
JSGCArenaStats *stats = &list->stats;
if (stats->maxarenas == 0) {
fprintf(fp, "ARENA LIST %u (thing size %lu): NEVER USED\n",
i, UL(GC_FREELIST_NBYTES(i)));
continue;
}
fprintf(fp, "ARENA LIST %u (thing size %lu):\n",
i, UL(GC_FREELIST_NBYTES(i)));
fprintf(fp, " arenas: %lu\n", UL(stats->narenas));
fprintf(fp, " max arenas: %lu\n", UL(stats->maxarenas));
fprintf(fp, " things: %lu\n", UL(stats->nthings));
fprintf(fp, " max things: %lu\n", UL(stats->maxthings));
fprintf(fp, " free list: %lu\n", UL(stats->freelen));
fprintf(fp, " free list density: %.1f%%\n",
stats->narenas == 0
? 0.0
: (100.0 * list->thingSize * (jsdouble)stats->freelen /
(GC_THINGS_SIZE * (jsdouble)stats->narenas)));
fprintf(fp, " average free list density: %.1f%%\n",
stats->totalarenas == 0
? 0.0
: (100.0 * list->thingSize * (jsdouble)stats->totalfreelen /
(GC_THINGS_SIZE * (jsdouble)stats->totalarenas)));
fprintf(fp, " recycles: %lu\n", UL(stats->recycle));
fprintf(fp, " recycle/alloc ratio: %.2f\n",
(jsdouble)stats->recycle /
(jsdouble)(stats->totalnew - stats->recycle));
totalThings += stats->nthings;
totalMaxThings += stats->maxthings;
totalBytes += GC_FREELIST_NBYTES(i) * stats->nthings;
}
fprintf(fp, "TOTAL STATS:\n");
fprintf(fp, " public bytes allocated: %lu\n", UL(rt->gcBytes));
fprintf(fp, " private bytes allocated: %lu\n", UL(rt->gcPrivateBytes));
fprintf(fp, " alloc attempts: %lu\n", ULSTAT(alloc));
#ifdef JS_THREADSAFE
fprintf(fp, " alloc without locks: %1u\n", ULSTAT(localalloc));
#endif
fprintf(fp, " total GC things: %lu\n", UL(totalThings));
fprintf(fp, " max total GC things: %lu\n", UL(totalMaxThings));
fprintf(fp, " GC things size: %lu\n", UL(totalBytes));
fprintf(fp, "allocation retries after GC: %lu\n", ULSTAT(retry));
fprintf(fp, " allocation failures: %lu\n", ULSTAT(fail));
fprintf(fp, " things born locked: %lu\n", ULSTAT(lockborn));
fprintf(fp, " valid lock calls: %lu\n", ULSTAT(lock));
fprintf(fp, " valid unlock calls: %lu\n", ULSTAT(unlock));
fprintf(fp, " mark recursion depth: %lu\n", ULSTAT(depth));
fprintf(fp, " maximum mark recursion: %lu\n", ULSTAT(maxdepth));
fprintf(fp, " mark C recursion depth: %lu\n", ULSTAT(cdepth));
fprintf(fp, " maximum mark C recursion: %lu\n", ULSTAT(maxcdepth));
fprintf(fp, " delayed scan bag adds: %lu\n", ULSTAT(unscanned));
#ifdef DEBUG
fprintf(fp, " max delayed scan bag size: %lu\n", ULSTAT(maxunscanned));
#endif
fprintf(fp, " maximum GC nesting level: %lu\n", ULSTAT(maxlevel));
fprintf(fp, "potentially useful GC calls: %lu\n", ULSTAT(poke));
fprintf(fp, " useless GC calls: %lu\n", ULSTAT(nopoke));
fprintf(fp, " thing arenas freed so far: %lu\n", ULSTAT(afree));
fprintf(fp, " stack segments scanned: %lu\n", ULSTAT(stackseg));
fprintf(fp, "stack segment slots scanned: %lu\n", ULSTAT(segslots));
fprintf(fp, "reachable closeable objects: %lu\n", ULSTAT(nclose));
fprintf(fp, " max reachable closeable: %lu\n", ULSTAT(maxnclose));
fprintf(fp, " scheduled close hooks: %lu\n", ULSTAT(closelater));
fprintf(fp, " max scheduled close hooks: %lu\n", ULSTAT(maxcloselater));
#undef UL
#undef US
#ifdef JS_ARENAMETER
JS_DumpArenaStats(fp);
#endif
}
#endif
#ifdef DEBUG
JS_STATIC_DLL_CALLBACK(JSDHashOperator)
js_root_printer(JSDHashTable *table, JSDHashEntryHdr *hdr, uint32 i, void *arg)
{
uint32 *leakedroots = (uint32 *)arg;
JSGCRootHashEntry *rhe = (JSGCRootHashEntry *)hdr;
(*leakedroots)++;
fprintf(stderr,
"JS engine warning: leaking GC root \'%s\' at %p\n",
rhe->name ? (char *)rhe->name : "", rhe->root);
return JS_DHASH_NEXT;
}
#endif
void
js_FinishGC(JSRuntime *rt)
{
#ifdef JS_ARENAMETER
JS_DumpArenaStats(stdout);
#endif
#ifdef JS_GCMETER
js_DumpGCStats(rt, stdout);
#endif
FreePtrTable(&rt->gcIteratorTable, &iteratorTableInfo);
#if JS_HAS_GENERATORS
rt->gcCloseState.reachableList = NULL;
METER(rt->gcStats.nclose = 0);
rt->gcCloseState.todoQueue = NULL;
#endif
FinishGCArenaLists(rt);
if (rt->gcRootsHash.ops) {
#ifdef DEBUG
uint32 leakedroots = 0;
/* Warn (but don't assert) debug builds of any remaining roots. */
JS_DHashTableEnumerate(&rt->gcRootsHash, js_root_printer,
&leakedroots);
if (leakedroots > 0) {
if (leakedroots == 1) {
fprintf(stderr,
"JS engine warning: 1 GC root remains after destroying the JSRuntime.\n"
" This root may point to freed memory. Objects reachable\n"
" through it have not been finalized.\n");
} else {
fprintf(stderr,
"JS engine warning: %lu GC roots remain after destroying the JSRuntime.\n"
" These roots may point to freed memory. Objects reachable\n"
" through them have not been finalized.\n",
(unsigned long) leakedroots);
}
}
#endif
JS_DHashTableFinish(&rt->gcRootsHash);
rt->gcRootsHash.ops = NULL;
}
if (rt->gcLocksHash) {
JS_DHashTableDestroy(rt->gcLocksHash);
rt->gcLocksHash = NULL;
}
}
JSBool
js_AddRoot(JSContext *cx, void *rp, const char *name)
{
JSBool ok = js_AddRootRT(cx->runtime, rp, name);
if (!ok)
JS_ReportOutOfMemory(cx);
return ok;
}
JSBool
js_AddRootRT(JSRuntime *rt, void *rp, const char *name)
{
JSBool ok;
JSGCRootHashEntry *rhe;
/*
* Due to the long-standing, but now removed, use of rt->gcLock across the
* bulk of js_GC, API users have come to depend on JS_AddRoot etc. locking
* properly with a racing GC, without calling JS_AddRoot from a request.
* We have to preserve API compatibility here, now that we avoid holding
* rt->gcLock across the mark phase (including the root hashtable mark).
*
* If the GC is running and we're called on another thread, wait for this
* GC activation to finish. We can safely wait here (in the case where we
* are called within a request on another thread's context) without fear
* of deadlock because the GC doesn't set rt->gcRunning until after it has
* waited for all active requests to end.
*/
JS_LOCK_GC(rt);
#ifdef JS_THREADSAFE
JS_ASSERT(!rt->gcRunning || rt->gcLevel > 0);
if (rt->gcRunning && rt->gcThread->id != js_CurrentThreadId()) {
do {
JS_AWAIT_GC_DONE(rt);
} while (rt->gcLevel > 0);
}
#endif
rhe = (JSGCRootHashEntry *) JS_DHashTableOperate(&rt->gcRootsHash, rp,
JS_DHASH_ADD);
if (rhe) {
rhe->root = rp;
rhe->name = name;
ok = JS_TRUE;
} else {
ok = JS_FALSE;
}
JS_UNLOCK_GC(rt);
return ok;
}
JSBool
js_RemoveRoot(JSRuntime *rt, void *rp)
{
/*
* Due to the JS_RemoveRootRT API, we may be called outside of a request.
* Same synchronization drill as above in js_AddRoot.
*/
JS_LOCK_GC(rt);
#ifdef JS_THREADSAFE
JS_ASSERT(!rt->gcRunning || rt->gcLevel > 0);
if (rt->gcRunning && rt->gcThread->id != js_CurrentThreadId()) {
do {
JS_AWAIT_GC_DONE(rt);
} while (rt->gcLevel > 0);
}
#endif
(void) JS_DHashTableOperate(&rt->gcRootsHash, rp, JS_DHASH_REMOVE);
rt->gcPoke = JS_TRUE;
JS_UNLOCK_GC(rt);
return JS_TRUE;
}
JSBool
js_RegisterCloseableIterator(JSContext *cx, JSObject *obj)
{
JSRuntime *rt;
JSBool ok;
rt = cx->runtime;
JS_ASSERT(!rt->gcRunning);
JS_LOCK_GC(rt);
ok = AddToPtrTable(cx, &rt->gcIteratorTable, &iteratorTableInfo, obj);
JS_UNLOCK_GC(rt);
return ok;
}
static void
CloseIteratorStates(JSContext *cx)
{
JSRuntime *rt;
size_t count, newCount, i;
void **array;
JSObject *obj;
rt = cx->runtime;
count = rt->gcIteratorTable.count;
array = rt->gcIteratorTable.array;
newCount = 0;
for (i = 0; i != count; ++i) {
obj = (JSObject *)array[i];
if (js_IsAboutToBeFinalized(cx, obj))
js_CloseIteratorState(cx, obj);
else
array[newCount++] = obj;
}
ShrinkPtrTable(&rt->gcIteratorTable, &iteratorTableInfo, newCount);
}
#if JS_HAS_GENERATORS
void
js_RegisterGenerator(JSContext *cx, JSGenerator *gen)
{
JSRuntime *rt;
rt = cx->runtime;
JS_ASSERT(!rt->gcRunning);
JS_ASSERT(rt->state != JSRTS_LANDING);
JS_ASSERT(gen->state == JSGEN_NEWBORN);
JS_LOCK_GC(rt);
gen->next = rt->gcCloseState.reachableList;
rt->gcCloseState.reachableList = gen;
METER(rt->gcStats.nclose++);
METER(rt->gcStats.maxnclose = JS_MAX(rt->gcStats.maxnclose,
rt->gcStats.nclose));
JS_UNLOCK_GC(rt);
}
/*
* We do not run close hooks when the parent scope of the generator instance
* becomes unreachable to prevent denial-of-service and resource leakage from
* misbehaved generators.
*
* Called from the GC.
*/
static JSBool
CanScheduleCloseHook(JSGenerator *gen)
{
JSObject *parent;
JSBool canSchedule;
/* Avoid OBJ_GET_PARENT overhead as we are in GC. */
parent = JSVAL_TO_OBJECT(gen->obj->slots[JSSLOT_PARENT]);
canSchedule = *js_GetGCThingFlags(parent) & GCF_MARK;
#ifdef DEBUG_igor
if (!canSchedule) {
fprintf(stderr, "GEN: Kill without schedule, gen=%p parent=%p\n",
(void *)gen, (void *)parent);
}
#endif
return canSchedule;
}
/*
* Check if we should delay execution of the close hook.
*
* Called outside GC or any locks.
*
* XXX The current implementation is a hack that embeds the knowledge of the
* browser embedding pending the resolution of bug 352788. In the browser we
* must not close any generators that came from a page that is currently in
* the browser history. We detect that using the fact in the browser the scope
* is history if scope->outerObject->innerObject != scope.
*/
static JSBool
ShouldDeferCloseHook(JSContext *cx, JSGenerator *gen, JSBool *defer)
{
JSObject *parent, *obj;
JSClass *clasp;
JSExtendedClass *xclasp;
/*
* This is called outside any locks, so use thread-safe macros to access
* parent and classes.
*/
*defer = JS_FALSE;
parent = OBJ_GET_PARENT(cx, gen->obj);
clasp = OBJ_GET_CLASS(cx, parent);
if (clasp->flags & JSCLASS_IS_EXTENDED) {
xclasp = (JSExtendedClass *)clasp;
if (xclasp->outerObject) {
obj = xclasp->outerObject(cx, parent);
if (!obj)
return JS_FALSE;
OBJ_TO_INNER_OBJECT(cx, obj);
if (!obj)
return JS_FALSE;
*defer = obj != parent;
}
}
#ifdef DEBUG_igor
if (*defer) {
fprintf(stderr, "GEN: deferring, gen=%p parent=%p\n",
(void *)gen, (void *)parent);
}
#endif
return JS_TRUE;
}
/*
* Find all unreachable generators and move them to the todo queue from
* rt->gcCloseState.reachableList to execute thier close hooks after the GC
* cycle completes. To ensure liveness during the sweep phase we mark all
* generators we are going to close later.
*/
static void
FindAndMarkObjectsToClose(JSContext *cx, JSGCInvocationKind gckind,
JSGenerator **todoQueueTail)
{
JSRuntime *rt;
JSGenerator *todo, **genp, *gen;
rt = cx->runtime;
todo = NULL;
genp = &rt->gcCloseState.reachableList;
while ((gen = *genp) != NULL) {
if (*js_GetGCThingFlags(gen->obj) & GCF_MARK) {
genp = &gen->next;
} else {
/* Generator must not be executing when it becomes unreachable. */
JS_ASSERT(gen->state == JSGEN_NEWBORN ||
gen->state == JSGEN_OPEN ||
gen->state == JSGEN_CLOSED);
*genp = gen->next;
if (gen->state == JSGEN_OPEN &&
js_FindFinallyHandler(gen->frame.script, gen->frame.pc) &&
CanScheduleCloseHook(gen)) {
/*
* Generator yielded inside a try with a finally block.
* Schedule it for closing.
*
* We keep generators that yielded outside try-with-finally
* with gen->state == JSGEN_OPEN. The finalizer must deal with
* open generators as we may skip the close hooks, see below.
*/
gen->next = NULL;
*todoQueueTail = gen;
todoQueueTail = &gen->next;
if (!todo)
todo = gen;
METER(JS_ASSERT(rt->gcStats.nclose));
METER(rt->gcStats.nclose--);
METER(rt->gcStats.closelater++);
METER(rt->gcStats.maxcloselater
= JS_MAX(rt->gcStats.maxcloselater,
rt->gcStats.closelater));
}
}
}
if (gckind == GC_LAST_CONTEXT) {
/*
* Remove scheduled hooks on shutdown as it is too late to run them:
* we do not allow execution of arbitrary scripts at this point.
*/
rt->gcCloseState.todoQueue = NULL;
} else {
/*
* Mark just-found unreachable generators *after* we scan the global
* list to prevent a generator that refers to other unreachable
* generators from keeping them on gcCloseState.reachableList.
*/
for (gen = todo; gen; gen = gen->next)
GC_MARK(cx, gen->obj, "newly scheduled generator");
}
}
/*
* Mark unreachable generators already scheduled to close and return the tail
* pointer to JSGCCloseState.todoQueue.
*/
static JSGenerator **
MarkScheduledGenerators(JSContext *cx)
{
JSRuntime *rt;
JSGenerator **genp, *gen;
rt = cx->runtime;
genp = &rt->gcCloseState.todoQueue;
while ((gen = *genp) != NULL) {
if (CanScheduleCloseHook(gen)) {
GC_MARK(cx, gen->obj, "scheduled generator");
genp = &gen->next;
} else {
/* Discard the generator from the list if its schedule is over. */
*genp = gen->next;
METER(JS_ASSERT(rt->gcStats.closelater > 0));
METER(rt->gcStats.closelater--);
}
}
return genp;
}
#ifdef JS_THREADSAFE
# define GC_RUNNING_CLOSE_HOOKS_PTR(cx) \
(&(cx)->thread->gcRunningCloseHooks)
#else
# define GC_RUNNING_CLOSE_HOOKS_PTR(cx) \
(&(cx)->runtime->gcCloseState.runningCloseHook)
#endif
typedef struct JSTempCloseList {
JSTempValueRooter tvr;
JSGenerator *head;
} JSTempCloseList;
JS_STATIC_DLL_CALLBACK(void)
mark_temp_close_list(JSContext *cx, JSTempValueRooter *tvr)
{
JSTempCloseList *list = (JSTempCloseList *)tvr;
JSGenerator *gen;
for (gen = list->head; gen; gen = gen->next)
GC_MARK(cx, gen->obj, "temp list generator");
}
#define JS_PUSH_TEMP_CLOSE_LIST(cx, tempList) \
JS_PUSH_TEMP_ROOT_MARKER(cx, mark_temp_close_list, &(tempList)->tvr)
#define JS_POP_TEMP_CLOSE_LIST(cx, tempList) \
JS_BEGIN_MACRO \
JS_ASSERT((tempList)->tvr.u.marker == mark_temp_close_list); \
JS_POP_TEMP_ROOT(cx, &(tempList)->tvr); \
JS_END_MACRO
JSBool
js_RunCloseHooks(JSContext *cx)
{
JSRuntime *rt;
JSTempCloseList tempList;
JSStackFrame *fp;
JSGenerator **genp, *gen;
JSBool ok, defer;
#if JS_GCMETER
uint32 deferCount;
#endif
rt = cx->runtime;
/*
* It is OK to access todoQueue outside the lock here. When many threads
* update the todo list, accessing some older value of todoQueue in the
* worst case just delays the excution of close hooks.
*/
if (!rt->gcCloseState.todoQueue)
return JS_TRUE;
/*
* To prevent an infinite loop when a close hook creats more objects with
* close hooks and then triggers GC we ignore recursive invocations of
* js_RunCloseHooks and limit number of hooks to execute to the initial
* size of the list.
*/
if (*GC_RUNNING_CLOSE_HOOKS_PTR(cx))
return JS_TRUE;
*GC_RUNNING_CLOSE_HOOKS_PTR(cx) = JS_TRUE;
JS_LOCK_GC(rt);
tempList.head = rt->gcCloseState.todoQueue;
JS_PUSH_TEMP_CLOSE_LIST(cx, &tempList);
rt->gcCloseState.todoQueue = NULL;
METER(rt->gcStats.closelater = 0);
rt->gcPoke = JS_TRUE;
JS_UNLOCK_GC(rt);
/*
* Set aside cx->fp since we do not want a close hook using caller or
* other means to backtrace into whatever stack might be active when
* running the hook. We store the current frame on the dormant list to
* protect against GC that the hook can trigger.
*/
fp = cx->fp;
if (fp) {
JS_ASSERT(!fp->dormantNext);
fp->dormantNext = cx->dormantFrameChain;
cx->dormantFrameChain = fp;
}
cx->fp = NULL;
genp = &tempList.head;
ok = JS_TRUE;
while ((gen = *genp) != NULL) {
ok = ShouldDeferCloseHook(cx, gen, &defer);
if (!ok) {
/* Quit ASAP discarding the hook. */
*genp = gen->next;
break;
}
if (defer) {
genp = &gen->next;
METER(deferCount++);
continue;
}
ok = js_CloseGeneratorObject(cx, gen);
/*
* Unlink the generator after closing it to make sure it always stays
* rooted through tempList.
*/
*genp = gen->next;
if (cx->throwing) {
/*
* Report the exception thrown by the close hook and continue to
* execute the rest of the hooks.
*/
if (!js_ReportUncaughtException(cx))
JS_ClearPendingException(cx);
ok = JS_TRUE;
} else if (!ok) {
/*
* Assume this is a stop signal from the branch callback or
* other quit ASAP condition. Break execution until the next
* invocation of js_RunCloseHooks.
*/
break;
}
}
cx->fp = fp;
if (fp) {
JS_ASSERT(cx->dormantFrameChain == fp);
cx->dormantFrameChain = fp->dormantNext;
fp->dormantNext = NULL;
}
if (tempList.head) {
/*
* Some close hooks were not yet executed, put them back into the
* scheduled list.
*/
while ((gen = *genp) != NULL) {
genp = &gen->next;
METER(deferCount++);
}
/* Now genp is a pointer to the tail of tempList. */
JS_LOCK_GC(rt);
*genp = rt->gcCloseState.todoQueue;
rt->gcCloseState.todoQueue = tempList.head;
METER(rt->gcStats.closelater += deferCount);
METER(rt->gcStats.maxcloselater
= JS_MAX(rt->gcStats.maxcloselater, rt->gcStats.closelater));
JS_UNLOCK_GC(rt);
}
JS_POP_TEMP_CLOSE_LIST(cx, &tempList);
*GC_RUNNING_CLOSE_HOOKS_PTR(cx) = JS_FALSE;
return ok;
}
#endif /* JS_HAS_GENERATORS */
#if defined(DEBUG_brendan) || defined(DEBUG_timeless)
#define DEBUG_gchist
#endif
#ifdef DEBUG_gchist
#define NGCHIST 64
static struct GCHist {
JSBool lastDitch;
JSGCThing *freeList;
} gchist[NGCHIST];
unsigned gchpos;
#endif
void *
js_NewGCThing(JSContext *cx, uintN flags, size_t nbytes)
{
JSRuntime *rt;
uintN flindex;
JSBool doGC;
JSGCThing *thing;
uint8 *flagp, *firstPage;
JSGCArenaList *arenaList;
jsuword offset;
JSGCArena *a;
JSLocalRootStack *lrs;
#ifdef JS_THREADSAFE
JSBool gcLocked;
uintN localMallocBytes;
JSGCThing **flbase, **lastptr;
JSGCThing *tmpthing;
uint8 *tmpflagp;
uintN maxFreeThings; /* max to take from the global free list */
METER(size_t nfree);
#endif
rt = cx->runtime;
METER(rt->gcStats.alloc++); /* this is not thread-safe */
nbytes = JS_ROUNDUP(nbytes, sizeof(JSGCThing));
flindex = GC_FREELIST_INDEX(nbytes);
#ifdef JS_THREADSAFE
gcLocked = JS_FALSE;
JS_ASSERT(cx->thread);
flbase = cx->thread->gcFreeLists;
JS_ASSERT(flbase);
thing = flbase[flindex];
localMallocBytes = cx->thread->gcMallocBytes;
if (thing && rt->gcMaxMallocBytes - rt->gcMallocBytes > localMallocBytes) {
flagp = thing->flagp;
flbase[flindex] = thing->next;
METER(rt->gcStats.localalloc++); /* this is not thread-safe */
goto success;
}
JS_LOCK_GC(rt);
gcLocked = JS_TRUE;
/* Transfer thread-local counter to global one. */
if (localMallocBytes != 0) {
cx->thread->gcMallocBytes = 0;
if (rt->gcMaxMallocBytes - rt->gcMallocBytes < localMallocBytes)
rt->gcMallocBytes = rt->gcMaxMallocBytes;
else
rt->gcMallocBytes += localMallocBytes;
}
#endif
JS_ASSERT(!rt->gcRunning);
if (rt->gcRunning) {
METER(rt->gcStats.finalfail++);
JS_UNLOCK_GC(rt);
return NULL;
}
#ifdef TOO_MUCH_GC
#ifdef WAY_TOO_MUCH_GC
rt->gcPoke = JS_TRUE;
#endif
doGC = JS_TRUE;
#else
doGC = (rt->gcMallocBytes >= rt->gcMaxMallocBytes);
#endif
arenaList = &rt->gcArenaList[flindex];
for (;;) {
if (doGC) {
/*
* Keep rt->gcLock across the call into js_GC so we don't starve
* and lose to racing threads who deplete the heap just after
* js_GC has replenished it (or has synchronized with a racing
* GC that collected a bunch of garbage). This unfair scheduling
* can happen on certain operating systems. For the gory details,
* see bug 162779 at https://bugzilla.mozilla.org/.
*/
js_GC(cx, GC_LAST_DITCH);
METER(rt->gcStats.retry++);
}
/* Try to get thing from the free list. */
thing = arenaList->freeList;
if (thing) {
arenaList->freeList = thing->next;
flagp = thing->flagp;
JS_ASSERT(*flagp & GCF_FINAL);
METER(arenaList->stats.freelen--);
METER(arenaList->stats.recycle++);
#ifdef JS_THREADSAFE
/*
* Refill the local free list by taking several things from the
* global free list unless we are still at rt->gcMaxMallocBytes
* barrier. The latter happens when GC is canceled due to
* !gcCallback(cx, JSGC_BEGIN) or no gcPoke.
*/
if (rt->gcMallocBytes >= rt->gcMaxMallocBytes)
break;
JS_ASSERT(!flbase[flindex]);
tmpthing = arenaList->freeList;
if (tmpthing) {
maxFreeThings = MAX_THREAD_LOCAL_THINGS;
do {
if (!tmpthing->next)
break;
tmpthing = tmpthing->next;
} while (--maxFreeThings != 0);
flbase[flindex] = arenaList->freeList;
arenaList->freeList = tmpthing->next;
tmpthing->next = NULL;
}
#endif
break;
}
/* Allocate from the tail of last arena or from new arena if we can. */
if ((arenaList->last && arenaList->lastLimit != GC_THINGS_SIZE) ||
NewGCArena(rt, arenaList)) {
offset = arenaList->lastLimit;
if ((offset & GC_PAGE_MASK) == 0) {
/*
* Skip JSGCPageInfo record located at GC_PAGE_SIZE boundary.
*/
offset += PAGE_THING_GAP(nbytes);
}
JS_ASSERT(offset + nbytes <= GC_THINGS_SIZE);
arenaList->lastLimit = (uint16)(offset + nbytes);
a = arenaList->last;
firstPage = (uint8 *)FIRST_THING_PAGE(a);
thing = (JSGCThing *)(firstPage + offset);
flagp = a->base + offset / sizeof(JSGCThing);
if (flagp >= firstPage)
flagp += GC_THINGS_SIZE;
METER(++arenaList->stats.nthings);
METER(arenaList->stats.maxthings =
JS_MAX(arenaList->stats.nthings,
arenaList->stats.maxthings));
#ifdef JS_THREADSAFE
/*
* Refill the local free list by taking free things from the last
* arena. Prefer to order free things by ascending address in the
* (unscientific) hope of better cache locality.
*/
if (rt->gcMallocBytes >= rt->gcMaxMallocBytes)
break;
JS_ASSERT(!flbase[flindex]);
METER(nfree = 0);
lastptr = &flbase[flindex];
maxFreeThings = MAX_THREAD_LOCAL_THINGS;
for (offset = arenaList->lastLimit;
offset != GC_THINGS_SIZE && maxFreeThings-- != 0;
offset += nbytes) {
if ((offset & GC_PAGE_MASK) == 0)
offset += PAGE_THING_GAP(nbytes);
JS_ASSERT(offset + nbytes <= GC_THINGS_SIZE);
tmpflagp = a->base + offset / sizeof(JSGCThing);
if (tmpflagp >= firstPage)
tmpflagp += GC_THINGS_SIZE;
tmpthing = (JSGCThing *)(firstPage + offset);
tmpthing->flagp = tmpflagp;
*tmpflagp = GCF_FINAL; /* signifying that thing is free */
*lastptr = tmpthing;
lastptr = &tmpthing->next;
METER(++nfree);
}
arenaList->lastLimit = offset;
*lastptr = NULL;
METER(arenaList->stats.freelen += nfree);
#endif
break;
}
/* Consider doing a "last ditch" GC unless already tried. */
if (doGC)
goto fail;
rt->gcPoke = JS_TRUE;
doGC = JS_TRUE;
}
/* We successfully allocated the thing. */
#ifdef JS_THREADSAFE
success:
#endif
lrs = cx->localRootStack;
if (lrs) {
/*
* If we're in a local root scope, don't set cx->newborn[type] at all,
* to avoid entraining garbage from it for an unbounded amount of time
* on this context. A caller will leave the local root scope and pop
* this reference, allowing thing to be GC'd if it has no other refs.
* See JS_EnterLocalRootScope and related APIs.
*/
if (js_PushLocalRoot(cx, lrs, (jsval) thing) < 0) {
/*
* When we fail for a thing allocated through the tail of the last
* arena, thing's flag byte is not initialized. So to prevent GC
* accessing the uninitialized flags during the finalization, we
* always mark the thing as final. See bug 337407.
*/
*flagp = GCF_FINAL;
goto fail;
}
} else {
/*
* No local root scope, so we're stuck with the old, fragile model of
* depending on a pigeon-hole newborn per type per context.
*/
cx->newborn[flags & GCF_TYPEMASK] = thing;
}
/* We can't fail now, so update flags and rt->gc{,Private}Bytes. */
*flagp = (uint8)flags;
/*
* Clear thing before unlocking in case a GC run is about to scan it,
* finding it via cx->newborn[].
*/
thing->next = NULL;
thing->flagp = NULL;
#ifdef DEBUG_gchist
gchist[gchpos].lastDitch = doGC;
gchist[gchpos].freeList = rt->gcArenaList[flindex].freeList;
if (++gchpos == NGCHIST)
gchpos = 0;
#endif
METER(if (flags & GCF_LOCK) rt->gcStats.lockborn++);
METER(++rt->gcArenaList[flindex].stats.totalnew);
#ifdef JS_THREADSAFE
if (gcLocked)
JS_UNLOCK_GC(rt);
#endif
return thing;
fail:
#ifdef JS_THREADSAFE
if (gcLocked)
JS_UNLOCK_GC(rt);
#endif
METER(rt->gcStats.fail++);
JS_ReportOutOfMemory(cx);
return NULL;
}
JSBool
js_LockGCThing(JSContext *cx, void *thing)
{
JSBool ok = js_LockGCThingRT(cx->runtime, thing);
if (!ok)
JS_ReportOutOfMemory(cx);
return ok;
}
/*
* Deep GC-things can't be locked just by setting the GCF_LOCK bit, because
* their descendants must be marked by the GC. To find them during the mark
* phase, they are added to rt->gcLocksHash, which is created lazily.
*
* NB: we depend on the order of GC-thing type indexes here!
*/
#define GC_TYPE_IS_STRING(t) ((t) == GCX_STRING || \
(t) >= GCX_EXTERNAL_STRING)
#define GC_TYPE_IS_XML(t) ((unsigned)((t) - GCX_NAMESPACE) <= \
(unsigned)(GCX_XML - GCX_NAMESPACE))
#define GC_TYPE_IS_DEEP(t) ((t) == GCX_OBJECT || GC_TYPE_IS_XML(t))
#define IS_DEEP_STRING(t,o) (GC_TYPE_IS_STRING(t) && \
JSSTRING_IS_DEPENDENT((JSString *)(o)))
#define GC_THING_IS_DEEP(t,o) (GC_TYPE_IS_DEEP(t) || IS_DEEP_STRING(t, o))
JSBool
js_LockGCThingRT(JSRuntime *rt, void *thing)
{
JSBool ok, deep;
uint8 *flagp;
uintN flags, lock, type;
JSGCLockHashEntry *lhe;
ok = JS_TRUE;
if (!thing)
return ok;
flagp = js_GetGCThingFlags(thing);
JS_LOCK_GC(rt);
flags = *flagp;
lock = (flags & GCF_LOCK);
type = (flags & GCF_TYPEMASK);
deep = GC_THING_IS_DEEP(type, thing);
/*
* Avoid adding a rt->gcLocksHash entry for shallow things until someone
* nests a lock -- then start such an entry with a count of 2, not 1.
*/
if (lock || deep) {
if (!rt->gcLocksHash) {
rt->gcLocksHash =
JS_NewDHashTable(JS_DHashGetStubOps(), NULL,
sizeof(JSGCLockHashEntry),
GC_ROOTS_SIZE);
if (!rt->gcLocksHash) {
ok = JS_FALSE;
goto done;
}
} else if (lock == 0) {
#ifdef DEBUG
JSDHashEntryHdr *hdr =
JS_DHashTableOperate(rt->gcLocksHash, thing,
JS_DHASH_LOOKUP);
JS_ASSERT(JS_DHASH_ENTRY_IS_FREE(hdr));
#endif
}
lhe = (JSGCLockHashEntry *)
JS_DHashTableOperate(rt->gcLocksHash, thing, JS_DHASH_ADD);
if (!lhe) {
ok = JS_FALSE;
goto done;
}
if (!lhe->thing) {
lhe->thing = thing;
lhe->count = deep ? 1 : 2;
} else {
JS_ASSERT(lhe->count >= 1);
lhe->count++;
}
}
*flagp = (uint8)(flags | GCF_LOCK);
METER(rt->gcStats.lock++);
ok = JS_TRUE;
done:
JS_UNLOCK_GC(rt);
return ok;
}
JSBool
js_UnlockGCThingRT(JSRuntime *rt, void *thing)
{
uint8 *flagp, flags;
JSGCLockHashEntry *lhe;
if (!thing)
return JS_TRUE;
flagp = js_GetGCThingFlags(thing);
JS_LOCK_GC(rt);
flags = *flagp;
if (flags & GCF_LOCK) {
if (!rt->gcLocksHash ||
(lhe = (JSGCLockHashEntry *)
JS_DHashTableOperate(rt->gcLocksHash, thing,
JS_DHASH_LOOKUP),
JS_DHASH_ENTRY_IS_FREE(&lhe->hdr))) {
/* Shallow GC-thing with an implicit lock count of 1. */
JS_ASSERT(!GC_THING_IS_DEEP(flags & GCF_TYPEMASK, thing));
} else {
/* Basis or nested unlock of a deep thing, or nested of shallow. */
if (--lhe->count != 0)
goto out;
JS_DHashTableOperate(rt->gcLocksHash, thing, JS_DHASH_REMOVE);
}
*flagp = (uint8)(flags & ~GCF_LOCK);
}
rt->gcPoke = JS_TRUE;
out:
METER(rt->gcStats.unlock++);
JS_UNLOCK_GC(rt);
return JS_TRUE;
}
#ifdef GC_MARK_DEBUG
#include <stdio.h>
#include "jsprf.h"
typedef struct GCMarkNode GCMarkNode;
struct GCMarkNode {
void *thing;
const char *name;
GCMarkNode *next;
GCMarkNode *prev;
};
JS_FRIEND_DATA(FILE *) js_DumpGCHeap;
JS_EXPORT_DATA(void *) js_LiveThingToFind;
#ifdef HAVE_XPCONNECT
#include "dump_xpc.h"
#endif
static void
GetObjSlotName(JSScope *scope, JSObject *obj, uint32 slot, char *buf,
size_t bufsize)
{
jsval nval;
JSScopeProperty *sprop;
JSClass *clasp;
uint32 key;
const char *slotname;
if (!scope) {
JS_snprintf(buf, bufsize, "**UNKNOWN OBJECT MAP ENTRY**");
return;
}
sprop = SCOPE_LAST_PROP(scope);
while (sprop && sprop->slot != slot)
sprop = sprop->parent;
if (!sprop) {
switch (slot) {
case JSSLOT_PROTO:
JS_snprintf(buf, bufsize, "__proto__");
break;
case JSSLOT_PARENT:
JS_snprintf(buf, bufsize, "__parent__");
break;
default:
slotname = NULL;
clasp = LOCKED_OBJ_GET_CLASS(obj);
if (clasp->flags & JSCLASS_IS_GLOBAL) {
key = slot - JSSLOT_START(clasp);
#define JS_PROTO(name,code,init) \
if ((code) == key) { slotname = js_##name##_str; goto found; }
#include "jsproto.tbl"
#undef JS_PROTO
}
found:
if (slotname)
JS_snprintf(buf, bufsize, "CLASS_OBJECT(%s)", slotname);
else
JS_snprintf(buf, bufsize, "**UNKNOWN SLOT %ld**", (long)slot);
break;
}
} else {
nval = ID_TO_VALUE(sprop->id);
if (JSVAL_IS_INT(nval)) {
JS_snprintf(buf, bufsize, "%ld", (long)JSVAL_TO_INT(nval));
} else if (JSVAL_IS_STRING(nval)) {
JS_snprintf(buf, bufsize, "%s",
JS_GetStringBytes(JSVAL_TO_STRING(nval)));
} else {
JS_snprintf(buf, bufsize, "**FINALIZED ATOM KEY**");
}
}
}
static const char *
gc_object_class_name(void* thing)
{
uint8 *flagp = js_GetGCThingFlags(thing);
const char *className = "";
static char depbuf[32];
switch (*flagp & GCF_TYPEMASK) {
case GCX_OBJECT: {
JSObject *obj = (JSObject *)thing;
JSClass *clasp = JSVAL_TO_PRIVATE(obj->slots[JSSLOT_CLASS]);
className = clasp->name;
#ifdef HAVE_XPCONNECT
if (clasp->flags & JSCLASS_PRIVATE_IS_NSISUPPORTS) {
jsval privateValue = obj->slots[JSSLOT_PRIVATE];
JS_ASSERT(clasp->flags & JSCLASS_HAS_PRIVATE);
if (!JSVAL_IS_VOID(privateValue)) {
void *privateThing = JSVAL_TO_PRIVATE(privateValue);
const char *xpcClassName = GetXPCObjectClassName(privateThing);
if (xpcClassName)
className = xpcClassName;
}
}
#endif
break;
}
case GCX_STRING:
case GCX_MUTABLE_STRING: {
JSString *str = (JSString *)thing;
if (JSSTRING_IS_DEPENDENT(str)) {
JS_snprintf(depbuf, sizeof depbuf, "start:%u, length:%u",
JSSTRDEP_START(str), JSSTRDEP_LENGTH(str));
className = depbuf;
} else {
className = "string";
}
break;
}
case GCX_DOUBLE:
className = "double";
break;
}
return className;
}
static void
gc_dump_thing(JSContext *cx, JSGCThing *thing, FILE *fp)
{
GCMarkNode *prev = (GCMarkNode *)cx->gcCurrentMarkNode;
GCMarkNode *next = NULL;
char *path = NULL;
while (prev) {
next = prev;
prev = prev->prev;
}
while (next) {
uint8 nextFlags = *js_GetGCThingFlags(next->thing);
if ((nextFlags & GCF_TYPEMASK) == GCX_OBJECT) {
path = JS_sprintf_append(path, "%s(%s @ 0x%08p).",
next->name,
gc_object_class_name(next->thing),
(JSObject*)next->thing);
} else {
path = JS_sprintf_append(path, "%s(%s).",
next->name,
gc_object_class_name(next->thing));
}
next = next->next;
}
if (!path)
return;
fprintf(fp, "%08lx ", (long)thing);
switch (*js_GetGCThingFlags(thing) & GCF_TYPEMASK) {
case GCX_OBJECT:
{
JSObject *obj = (JSObject *)thing;
jsval privateValue = obj->slots[JSSLOT_PRIVATE];
void *privateThing = JSVAL_IS_VOID(privateValue)
? NULL
: JSVAL_TO_PRIVATE(privateValue);
const char *className = gc_object_class_name(thing);
fprintf(fp, "object %8p %s", privateThing, className);
break;
}
#if JS_HAS_XML_SUPPORT
case GCX_NAMESPACE:
{
JSXMLNamespace *ns = (JSXMLNamespace *)thing;
fprintf(fp, "namespace %s:%s",
JS_GetStringBytes(ns->prefix), JS_GetStringBytes(ns->uri));
break;
}
case GCX_QNAME:
{
JSXMLQName *qn = (JSXMLQName *)thing;
fprintf(fp, "qname %s(%s):%s",
JS_GetStringBytes(qn->prefix), JS_GetStringBytes(qn->uri),
JS_GetStringBytes(qn->localName));
break;
}
case GCX_XML:
{
extern const char *js_xml_class_str[];
JSXML *xml = (JSXML *)thing;
fprintf(fp, "xml %8p %s", xml, js_xml_class_str[xml->xml_class]);
break;
}
#endif
case GCX_DOUBLE:
fprintf(fp, "double %g", *(jsdouble *)thing);
break;
case GCX_PRIVATE:
fprintf(fp, "private %8p", (void *)thing);
break;
default:
fprintf(fp, "string %s", JS_GetStringBytes((JSString *)thing));
break;
}
fprintf(fp, " via %s\n", path);
free(path);
}
void
js_MarkNamedGCThing(JSContext *cx, void *thing, const char *name)
{
GCMarkNode markNode;
if (!thing)
return;
markNode.thing = thing;
markNode.name = name;
markNode.next = NULL;
markNode.prev = (GCMarkNode *)cx->gcCurrentMarkNode;
if (markNode.prev)
markNode.prev->next = &markNode;
cx->gcCurrentMarkNode = &markNode;
if (thing == js_LiveThingToFind) {
/*
* Dump js_LiveThingToFind each time we reach it during the marking
* phase of GC to print all live references to the thing.
*/
gc_dump_thing(cx, thing, stderr);
}
js_MarkGCThing(cx, thing);
if (markNode.prev)
markNode.prev->next = NULL;
cx->gcCurrentMarkNode = markNode.prev;
}
#endif /* !GC_MARK_DEBUG */
static void
gc_mark_atom_key_thing(void *thing, void *arg)
{
JSContext *cx = (JSContext *) arg;
GC_MARK(cx, thing, "atom");
}
void
js_MarkAtom(JSContext *cx, JSAtom *atom)
{
jsval key;
if (atom->flags & ATOM_MARK)
return;
atom->flags |= ATOM_MARK;
key = ATOM_KEY(atom);
if (JSVAL_IS_GCTHING(key)) {
#ifdef GC_MARK_DEBUG
char name[32];
if (JSVAL_IS_STRING(key)) {
JS_snprintf(name, sizeof name, "'%s'",
JS_GetStringBytes(JSVAL_TO_STRING(key)));
} else {
JS_snprintf(name, sizeof name, "<%x>", key);
}
#endif
GC_MARK(cx, JSVAL_TO_GCTHING(key), name);
}
if (atom->flags & ATOM_HIDDEN)
js_MarkAtom(cx, atom->entry.value);
}
static void
AddThingToUnscannedBag(JSRuntime *rt, void *thing, uint8 *flagp);
static void
MarkGCThingChildren(JSContext *cx, void *thing, uint8 *flagp,
JSBool shouldCheckRecursion)
{
JSRuntime *rt;
JSObject *obj;
jsval v, *vp, *end;
void *next_thing;
uint8 *next_flagp;
JSString *str;
#ifdef JS_GCMETER
uint32 tailCallNesting;
#endif
#ifdef GC_MARK_DEBUG
JSScope *scope;
char name[32];
#endif
/*
* With JS_GC_ASSUME_LOW_C_STACK defined the mark phase of GC always
* uses the non-recursive code that otherwise would be called only on
* a low C stack condition.
*/
#ifdef JS_GC_ASSUME_LOW_C_STACK
# define RECURSION_TOO_DEEP() shouldCheckRecursion
#else
int stackDummy;
# define RECURSION_TOO_DEEP() (shouldCheckRecursion && \
!JS_CHECK_STACK_SIZE(cx, stackDummy))
#endif
rt = cx->runtime;
METER(tailCallNesting = 0);
METER(if (++rt->gcStats.cdepth > rt->gcStats.maxcdepth)
rt->gcStats.maxcdepth = rt->gcStats.cdepth);
#ifndef GC_MARK_DEBUG
start:
#endif
JS_ASSERT(flagp);
JS_ASSERT(*flagp & GCF_MARK); /* the caller must already mark the thing */
METER(if (++rt->gcStats.depth > rt->gcStats.maxdepth)
rt->gcStats.maxdepth = rt->gcStats.depth);
#ifdef GC_MARK_DEBUG
if (js_DumpGCHeap)
gc_dump_thing(cx, thing, js_DumpGCHeap);
#endif
switch (*flagp & GCF_TYPEMASK) {
case GCX_OBJECT:
if (RECURSION_TOO_DEEP())
goto add_to_unscanned_bag;
/* If obj->slots is null, obj must be a newborn. */
obj = (JSObject *) thing;
vp = obj->slots;
if (!vp)
break;
/* Mark slots if they are small enough to be GC-allocated. */
if ((vp[-1] + 1) * sizeof(jsval) <= GC_NBYTES_MAX)
GC_MARK(cx, vp - 1, "slots");
/* Set up local variables to loop over unmarked things. */
end = vp + ((obj->map->ops->mark)
? obj->map->ops->mark(cx, obj, NULL)
: JS_MIN(obj->map->freeslot, obj->map->nslots));
thing = NULL;
flagp = NULL;
#ifdef GC_MARK_DEBUG
scope = OBJ_IS_NATIVE(obj) ? OBJ_SCOPE(obj) : NULL;
#endif
for (; vp != end; ++vp) {
v = *vp;
if (!JSVAL_IS_GCTHING(v) || v == JSVAL_NULL)
continue;
next_thing = JSVAL_TO_GCTHING(v);
if (next_thing == thing)
continue;
next_flagp = js_GetGCThingFlags(next_thing);
if (*next_flagp & GCF_MARK)
continue;
JS_ASSERT(*next_flagp != GCF_FINAL);
if (thing) {
#ifdef GC_MARK_DEBUG
GC_MARK(cx, thing, name);
#else
*flagp |= GCF_MARK;
MarkGCThingChildren(cx, thing, flagp, JS_TRUE);
#endif
if (*next_flagp & GCF_MARK) {
/*
* This happens when recursive MarkGCThingChildren marks
* the thing with flags referred by *next_flagp.
*/
thing = NULL;
continue;
}
}
#ifdef GC_MARK_DEBUG
GetObjSlotName(scope, obj, vp - obj->slots, name, sizeof name);
#endif
thing = next_thing;
flagp = next_flagp;
}
if (thing) {
/*
* thing came from the last unmarked GC-thing slot and we
* can optimize tail recursion.
*
* Since we already know that there is enough C stack space,
* we clear shouldCheckRecursion to avoid extra checking in
* RECURSION_TOO_DEEP.
*/
shouldCheckRecursion = JS_FALSE;
goto on_tail_recursion;
}
break;
#ifdef DEBUG
case GCX_STRING:
str = (JSString *)thing;
JS_ASSERT(!JSSTRING_IS_DEPENDENT(str));
break;
#endif
case GCX_MUTABLE_STRING:
str = (JSString *)thing;
if (!JSSTRING_IS_DEPENDENT(str))
break;
thing = JSSTRDEP_BASE(str);
flagp = js_GetGCThingFlags(thing);
if (*flagp & GCF_MARK)
break;
#ifdef GC_MARK_DEBUG
strcpy(name, "base");
#endif
/* Fallthrough to code to deal with the tail recursion. */
on_tail_recursion:
#ifdef GC_MARK_DEBUG
/*
* Do not eliminate C recursion when debugging to allow
* js_MarkNamedGCThing to build a full dump of live GC
* things.
*/
GC_MARK(cx, thing, name);
break;
#else
/* Eliminate tail recursion for the last unmarked child. */
JS_ASSERT(*flagp != GCF_FINAL);
METER(++tailCallNesting);
*flagp |= GCF_MARK;
goto start;
#endif
#if JS_HAS_XML_SUPPORT
case GCX_NAMESPACE:
if (RECURSION_TOO_DEEP())
goto add_to_unscanned_bag;
js_MarkXMLNamespace(cx, (JSXMLNamespace *)thing);
break;
case GCX_QNAME:
if (RECURSION_TOO_DEEP())
goto add_to_unscanned_bag;
js_MarkXMLQName(cx, (JSXMLQName *)thing);
break;
case GCX_XML:
if (RECURSION_TOO_DEEP())
goto add_to_unscanned_bag;
js_MarkXML(cx, (JSXML *)thing);
break;
#endif
add_to_unscanned_bag:
AddThingToUnscannedBag(cx->runtime, thing, flagp);
break;
}
#undef RECURSION_TOO_DEEP
METER(rt->gcStats.depth -= 1 + tailCallNesting);
METER(rt->gcStats.cdepth--);
}
/*
* Avoid using PAGE_THING_GAP inside this macro to optimize the
* thingsPerUnscannedChunk calculation when thingSize is a power of two.
*/
#define GET_GAP_AND_CHUNK_SPAN(thingSize, thingsPerUnscannedChunk, pageGap) \
JS_BEGIN_MACRO \
if (0 == ((thingSize) & ((thingSize) - 1))) { \
pageGap = (thingSize); \
thingsPerUnscannedChunk = ((GC_PAGE_SIZE / (thingSize)) \
+ JS_BITS_PER_WORD - 1) \
>> JS_BITS_PER_WORD_LOG2; \
} else { \
pageGap = GC_PAGE_SIZE % (thingSize); \
thingsPerUnscannedChunk = JS_HOWMANY(GC_PAGE_SIZE / (thingSize), \
JS_BITS_PER_WORD); \
} \
JS_END_MACRO
static void
AddThingToUnscannedBag(JSRuntime *rt, void *thing, uint8 *flagp)
{
JSGCPageInfo *pi;
JSGCArena *arena;
size_t thingSize;
size_t thingsPerUnscannedChunk;
size_t pageGap;
size_t chunkIndex;
jsuword bit;
/* Things from delayed scanning bag are marked as GCF_MARK | GCF_FINAL. */
JS_ASSERT((*flagp & (GCF_MARK | GCF_FINAL)) == GCF_MARK);
*flagp |= GCF_FINAL;
METER(rt->gcStats.unscanned++);
#ifdef DEBUG
++rt->gcUnscannedBagSize;
METER(if (rt->gcUnscannedBagSize > rt->gcStats.maxunscanned)
rt->gcStats.maxunscanned = rt->gcUnscannedBagSize);
#endif
pi = THING_TO_PAGE(thing);
arena = PAGE_TO_ARENA(pi);
thingSize = arena->list->thingSize;
GET_GAP_AND_CHUNK_SPAN(thingSize, thingsPerUnscannedChunk, pageGap);
chunkIndex = (((jsuword)thing & GC_PAGE_MASK) - pageGap) /
(thingSize * thingsPerUnscannedChunk);
JS_ASSERT(chunkIndex < JS_BITS_PER_WORD);
bit = (jsuword)1 << chunkIndex;
if (pi->unscannedBitmap != 0) {
JS_ASSERT(rt->gcUnscannedArenaStackTop);
if (thingsPerUnscannedChunk != 1) {
if (pi->unscannedBitmap & bit) {
/* Chunk already contains things to scan later. */
return;
}
} else {
/*
* The chunk must not contain things to scan later if there is
* only one thing per chunk.
*/
JS_ASSERT(!(pi->unscannedBitmap & bit));
}
pi->unscannedBitmap |= bit;
JS_ASSERT(arena->unscannedPages & ((size_t)1 << PAGE_INDEX(pi)));
} else {
/*
* The thing is the first unscanned thing in the page, set the bit
* corresponding to this page arena->unscannedPages.
*/
pi->unscannedBitmap = bit;
JS_ASSERT(PAGE_INDEX(pi) < JS_BITS_PER_WORD);
bit = (jsuword)1 << PAGE_INDEX(pi);
JS_ASSERT(!(arena->unscannedPages & bit));
if (arena->unscannedPages != 0) {
arena->unscannedPages |= bit;
JS_ASSERT(arena->prevUnscanned);
JS_ASSERT(rt->gcUnscannedArenaStackTop);
} else {
/*
* The thing is the first unscanned thing in the whole arena, push
* the arena on the stack of unscanned arenas unless the arena
* has already been pushed. We detect that through prevUnscanned
* field which is NULL only for not yet pushed arenas. To ensure
* that prevUnscanned != NULL even when the stack contains one
* element, we make prevUnscanned for the arena at the bottom
* to point to itself.
*
* See comments in ScanDelayedChildren.
*/
arena->unscannedPages = bit;
if (!arena->prevUnscanned) {
if (!rt->gcUnscannedArenaStackTop) {
/* Stack was empty, mark the arena as bottom element. */
arena->prevUnscanned = arena;
} else {
JS_ASSERT(rt->gcUnscannedArenaStackTop->prevUnscanned);
arena->prevUnscanned = rt->gcUnscannedArenaStackTop;
}
rt->gcUnscannedArenaStackTop = arena;
}
}
}
JS_ASSERT(rt->gcUnscannedArenaStackTop);
}
static void
ScanDelayedChildren(JSContext *cx)
{
JSRuntime *rt;
JSGCArena *arena;
size_t thingSize;
size_t thingsPerUnscannedChunk;
size_t pageGap;
size_t pageIndex;
JSGCPageInfo *pi;
size_t chunkIndex;
size_t thingOffset, thingLimit;
JSGCThing *thing;
uint8 *flagp;
JSGCArena *prevArena;
rt = cx->runtime;
arena = rt->gcUnscannedArenaStackTop;
if (!arena) {
JS_ASSERT(rt->gcUnscannedBagSize == 0);
return;
}
init_size:
thingSize = arena->list->thingSize;
GET_GAP_AND_CHUNK_SPAN(thingSize, thingsPerUnscannedChunk, pageGap);
for (;;) {
/*
* The following assert verifies that the current arena belongs to
* the unscan stack since AddThingToUnscannedBag ensures that even
* for stack's bottom prevUnscanned != NULL but rather points to self.
*/
JS_ASSERT(arena->prevUnscanned);
JS_ASSERT(rt->gcUnscannedArenaStackTop->prevUnscanned);
while (arena->unscannedPages != 0) {
pageIndex = JS_FLOOR_LOG2W(arena->unscannedPages);
JS_ASSERT(pageIndex < GC_PAGE_COUNT);
pi = (JSGCPageInfo *)(FIRST_THING_PAGE(arena) +
pageIndex * GC_PAGE_SIZE);
JS_ASSERT(pi->unscannedBitmap);
chunkIndex = JS_FLOOR_LOG2W(pi->unscannedBitmap);
pi->unscannedBitmap &= ~((jsuword)1 << chunkIndex);
if (pi->unscannedBitmap == 0)
arena->unscannedPages &= ~((jsuword)1 << pageIndex);
thingOffset = (pageGap
+ chunkIndex * thingsPerUnscannedChunk * thingSize);
JS_ASSERT(thingOffset >= sizeof(JSGCPageInfo));
thingLimit = thingOffset + thingsPerUnscannedChunk * thingSize;
if (thingsPerUnscannedChunk != 1) {
/*
* thingLimit can go beyond the last allocated thing for the
* last chunk as the real limit can be inside the chunk.
*/
if (arena->list->last == arena &&
arena->list->lastLimit < (pageIndex * GC_PAGE_SIZE +
thingLimit)) {
thingLimit = (arena->list->lastLimit -
pageIndex * GC_PAGE_SIZE);
} else if (thingLimit > GC_PAGE_SIZE) {
thingLimit = GC_PAGE_SIZE;
}
JS_ASSERT(thingLimit > thingOffset);
}
JS_ASSERT(arena->list->last != arena ||
arena->list->lastLimit >= (pageIndex * GC_PAGE_SIZE +
thingLimit));
JS_ASSERT(thingLimit <= GC_PAGE_SIZE);
for (; thingOffset != thingLimit; thingOffset += thingSize) {
/*
* XXX: inline js_GetGCThingFlags() to use already available
* pi.
*/
thing = (void *)((jsuword)pi + thingOffset);
flagp = js_GetGCThingFlags(thing);
if (thingsPerUnscannedChunk != 1) {
/*
* Skip free or already scanned things that share the chunk
* with unscanned ones.
*/
if ((*flagp & (GCF_MARK|GCF_FINAL)) != (GCF_MARK|GCF_FINAL))
continue;
}
JS_ASSERT((*flagp & (GCF_MARK|GCF_FINAL))
== (GCF_MARK|GCF_FINAL));
*flagp &= ~GCF_FINAL;
#ifdef DEBUG
JS_ASSERT(rt->gcUnscannedBagSize != 0);
--rt->gcUnscannedBagSize;
/*
* Check that GC thing type is consistent with the type of
* things that can be put to the unscanned bag.
*/
switch (*flagp & GCF_TYPEMASK) {
case GCX_OBJECT:
# if JS_HAS_XML_SUPPORT
case GCX_NAMESPACE:
case GCX_QNAME:
case GCX_XML:
# endif
break;
default:
JS_ASSERT(0);
}
#endif
MarkGCThingChildren(cx, thing, flagp, JS_FALSE);
}
}
/*
* We finished scanning of the arena but we can only pop it from
* the stack if the arena is the stack's top.
*
* When MarkGCThingChildren from the above calls
* AddThingToUnscannedBag and the latter pushes new arenas to the
* stack, we have to skip popping of this arena until it becomes
* the top of the stack again.
*/
if (arena == rt->gcUnscannedArenaStackTop) {
prevArena = arena->prevUnscanned;
arena->prevUnscanned = NULL;
if (arena == prevArena) {
/*
* prevUnscanned points to itself and we reached the bottom
* of the stack.
*/
break;
}
rt->gcUnscannedArenaStackTop = arena = prevArena;
} else {
arena = rt->gcUnscannedArenaStackTop;
}
if (arena->list->thingSize != thingSize)
goto init_size;
}
JS_ASSERT(rt->gcUnscannedArenaStackTop);
JS_ASSERT(!rt->gcUnscannedArenaStackTop->prevUnscanned);
rt->gcUnscannedArenaStackTop = NULL;
JS_ASSERT(rt->gcUnscannedBagSize == 0);
}
void
js_MarkGCThing(JSContext *cx, void *thing)
{
uint8 *flagp;
if (!thing)
return;
flagp = js_GetGCThingFlags(thing);
JS_ASSERT(*flagp != GCF_FINAL);
if (*flagp & GCF_MARK)
return;
*flagp |= GCF_MARK;
if (!cx->insideGCMarkCallback) {
MarkGCThingChildren(cx, thing, flagp, JS_TRUE);
} else {
/*
* For API compatibility we allow for the callback to assume that
* after it calls js_MarkGCThing for the last time, the callback
* can start to finalize its own objects that are only referenced
* by unmarked GC things.
*
* Since we do not know which call from inside the callback is the
* last, we ensure that the unscanned bag is always empty when we
* return to the callback and all marked things are scanned.
*
* As an optimization we do not check for the stack size here and
* pass JS_FALSE as the last argument to MarkGCThingChildren.
* Otherwise with low C stack the thing would be pushed to the bag
* just to be feed to MarkGCThingChildren from inside
* ScanDelayedChildren.
*/
cx->insideGCMarkCallback = JS_FALSE;
MarkGCThingChildren(cx, thing, flagp, JS_FALSE);
ScanDelayedChildren(cx);
cx->insideGCMarkCallback = JS_TRUE;
}
}
JS_STATIC_DLL_CALLBACK(JSDHashOperator)
gc_root_marker(JSDHashTable *table, JSDHashEntryHdr *hdr, uint32 num, void *arg)
{
JSGCRootHashEntry *rhe = (JSGCRootHashEntry *)hdr;
jsval *rp = (jsval *)rhe->root;
jsval v = *rp;
/* Ignore null object and scalar values. */
if (!JSVAL_IS_NULL(v) && JSVAL_IS_GCTHING(v)) {
JSContext *cx = (JSContext *)arg;
#ifdef DEBUG
JSBool root_points_to_gcArenaList = JS_FALSE;
jsuword thing = (jsuword) JSVAL_TO_GCTHING(v);
uintN i;
JSGCArenaList *arenaList;
JSGCArena *a;
size_t limit;
for (i = 0; i < GC_NUM_FREELISTS; i++) {
arenaList = &cx->runtime->gcArenaList[i];
limit = arenaList->lastLimit;
for (a = arenaList->last; a; a = a->prev) {
if (thing - FIRST_THING_PAGE(a) < limit) {
root_points_to_gcArenaList = JS_TRUE;
break;
}
limit = GC_THINGS_SIZE;
}
}
if (!root_points_to_gcArenaList && rhe->name) {
fprintf(stderr,
"JS API usage error: the address passed to JS_AddNamedRoot currently holds an\n"
"invalid jsval. This is usually caused by a missing call to JS_RemoveRoot.\n"
"The root's name is \"%s\".\n",
rhe->name);
}
JS_ASSERT(root_points_to_gcArenaList);
#endif
GC_MARK(cx, JSVAL_TO_GCTHING(v), rhe->name ? rhe->name : "root");
}
return JS_DHASH_NEXT;
}
JS_STATIC_DLL_CALLBACK(JSDHashOperator)
gc_lock_marker(JSDHashTable *table, JSDHashEntryHdr *hdr, uint32 num, void *arg)
{
JSGCLockHashEntry *lhe = (JSGCLockHashEntry *)hdr;
void *thing = (void *)lhe->thing;
JSContext *cx = (JSContext *)arg;
GC_MARK(cx, thing, "locked object");
return JS_DHASH_NEXT;
}
#define GC_MARK_JSVALS(cx, len, vec, name) \
JS_BEGIN_MACRO \
jsval _v, *_vp, *_end; \
\
for (_vp = vec, _end = _vp + len; _vp < _end; _vp++) { \
_v = *_vp; \
if (JSVAL_IS_GCTHING(_v)) \
GC_MARK(cx, JSVAL_TO_GCTHING(_v), name); \
} \
JS_END_MACRO
void
js_MarkStackFrame(JSContext *cx, JSStackFrame *fp)
{
uintN depth, nslots;
if (fp->callobj)
GC_MARK(cx, fp->callobj, "call object");
if (fp->argsobj)
GC_MARK(cx, fp->argsobj, "arguments object");
if (fp->varobj)
GC_MARK(cx, fp->varobj, "variables object");
if (fp->script) {
js_MarkScript(cx, fp->script);
if (fp->spbase) {
/*
* Don't mark what has not been pushed yet, or what has been
* popped already.
*/
depth = fp->script->depth;
nslots = (JS_UPTRDIFF(fp->sp, fp->spbase)
< depth * sizeof(jsval))
? (uintN)(fp->sp - fp->spbase)
: depth;
GC_MARK_JSVALS(cx, nslots, fp->spbase, "operand");
}
}
/* Allow for primitive this parameter due to JSFUN_THISP_* flags. */
JS_ASSERT(JSVAL_IS_OBJECT((jsval)fp->thisp) ||
(fp->fun && JSFUN_THISP_FLAGS(fp->fun->flags)));
if (JSVAL_IS_GCTHING((jsval)fp->thisp))
GC_MARK(cx, JSVAL_TO_GCTHING((jsval)fp->thisp), "this");
/*
* Mark fp->argv, even though in the common case it will be marked via our
* caller's frame, or via a JSStackHeader if fp was pushed by an external
* invocation.
*
* The hard case is when there is not enough contiguous space in the stack
* arena for actual, missing formal, and local root (JSFunctionSpec.extra)
* slots. In this case, fp->argv points to new space in a new arena, and
* marking the caller's operand stack, or an external caller's allocated
* stack tracked by a JSStackHeader, will not mark all the values stored
* and addressable via fp->argv.
*
* But note that fp->argv[-2] will be marked via the caller, even when the
* arg-vector moves. And fp->argv[-1] will be marked as well, and we mark
* it redundantly just above this comment.
*
* So in summary, solely for the hard case of moving argv due to missing
* formals and extra roots, we must mark actuals, missing formals, and any
* local roots arrayed at fp->argv here.
*
* It would be good to avoid redundant marking of the same reference, in
* the case where fp->argv does point into caller-allocated space tracked
* by fp->down->spbase or cx->stackHeaders. This would allow callbacks
* such as the forthcoming rt->gcThingCallback (bug 333078) to compute JS
* reference counts. So this comment deserves a FIXME bug to cite.
*/
if (fp->argv) {
nslots = fp->argc;
if (fp->fun) {
if (fp->fun->nargs > nslots)
nslots = fp->fun->nargs;
if (!FUN_INTERPRETED(fp->fun))
nslots += fp->fun->u.n.extra;
}
GC_MARK_JSVALS(cx, nslots, fp->argv, "arg");
}
if (JSVAL_IS_GCTHING(fp->rval))
GC_MARK(cx, JSVAL_TO_GCTHING(fp->rval), "rval");
if (fp->vars)
GC_MARK_JSVALS(cx, fp->nvars, fp->vars, "var");
GC_MARK(cx, fp->scopeChain, "scope chain");
if (fp->sharpArray)
GC_MARK(cx, fp->sharpArray, "sharp array");
if (fp->xmlNamespace)
GC_MARK(cx, fp->xmlNamespace, "xmlNamespace");
}
/*
* Return false when the branch callback wants to stop exeution ASAP and true
* otherwise.
*
* When gckind is GC_LAST_DITCH, it indicates a call from js_NewGCThing with
* rt->gcLock already held and when the lock should be kept on return.
*/
void
js_GC(JSContext *cx, JSGCInvocationKind gckind)
{
JSRuntime *rt;
JSBool keepAtoms;
uintN i, type;
JSContext *iter, *acx;
#if JS_HAS_GENERATORS
JSGenerator **genTodoTail;
#endif
JSStackFrame *fp, *chain;
JSStackHeader *sh;
JSTempValueRooter *tvr;
size_t nbytes, limit, offset;
JSGCArena *a, **ap;
uint8 flags, *flagp, *firstPage;
JSGCThing *thing, *freeList;
JSGCArenaList *arenaList;
GCFinalizeOp finalizer;
JSBool allClear;
#ifdef JS_THREADSAFE
uint32 requestDebit;
#endif
rt = cx->runtime;
#ifdef JS_THREADSAFE
/* Avoid deadlock. */
JS_ASSERT(!JS_IS_RUNTIME_LOCKED(rt));
#endif
if (gckind == GC_LAST_DITCH) {
/* The last ditch GC preserves all atoms and cx->newborn. */
keepAtoms = JS_TRUE;
} else {
for (i = 0; i < GCX_NTYPES; i++)
cx->newborn[i] = NULL;
cx->lastAtom = NULL;
rt->gcPoke = JS_TRUE;
/* Keep atoms when a suspended compile is running on another context. */
keepAtoms = (rt->gcKeepAtoms != 0);
}
/*
* Don't collect garbage if the runtime isn't up, and cx is not the last
* context in the runtime. The last context must force a GC, and nothing
* should suppress that final collection or there may be shutdown leaks,
* or runtime bloat until the next context is created.
*/
if (rt->state != JSRTS_UP && gckind != GC_LAST_CONTEXT)
return;
restart_after_callback:
/*
* Let the API user decide to defer a GC if it wants to (unless this
* is the last context). Invoke the callback regardless.
*/
if (rt->gcCallback &&
!rt->gcCallback(cx, JSGC_BEGIN) &&
gckind != GC_LAST_CONTEXT) {
return;
}
/* Lock out other GC allocator and collector invocations. */
if (gckind != GC_LAST_DITCH)
JS_LOCK_GC(rt);
/* Do nothing if no mutator has executed since the last GC. */
if (!rt->gcPoke) {
METER(rt->gcStats.nopoke++);
if (gckind != GC_LAST_DITCH)
JS_UNLOCK_GC(rt);
return;
}
METER(rt->gcStats.poke++);
rt->gcPoke = JS_FALSE;
#ifdef JS_THREADSAFE
JS_ASSERT(cx->thread->id == js_CurrentThreadId());
/* Bump gcLevel and return rather than nest on this thread. */
if (rt->gcThread == cx->thread) {
JS_ASSERT(rt->gcLevel > 0);
rt->gcLevel++;
METER(if (rt->gcLevel > rt->gcStats.maxlevel)
rt->gcStats.maxlevel = rt->gcLevel);
if (gckind != GC_LAST_DITCH)
JS_UNLOCK_GC(rt);
return;
}
/*
* If we're in one or more requests (possibly on more than one context)
* running on the current thread, indicate, temporarily, that all these
* requests are inactive. If cx->thread is NULL, then cx is not using
* the request model, and does not contribute to rt->requestCount.
*/
requestDebit = 0;
if (cx->thread) {
JSCList *head, *link;
/*
* Check all contexts on cx->thread->contextList for active requests,
* counting each such context against requestDebit.
*/
head = &cx->thread->contextList;
for (link = head->next; link != head; link = link->next) {
acx = CX_FROM_THREAD_LINKS(link);
JS_ASSERT(acx->thread == cx->thread);
if (acx->requestDepth)
requestDebit++;
}
} else {
/*
* We assert, but check anyway, in case someone is misusing the API.
* Avoiding the loop over all of rt's contexts is a win in the event
* that the GC runs only on request-less contexts with null threads,
* in a special thread such as might be used by the UI/DOM/Layout
* "mozilla" or "main" thread in Mozilla-the-browser.
*/
JS_ASSERT(cx->requestDepth == 0);
if (cx->requestDepth)
requestDebit = 1;
}
if (requestDebit) {
JS_ASSERT(requestDebit <= rt->requestCount);
rt->requestCount -= requestDebit;
if (rt->requestCount == 0)
JS_NOTIFY_REQUEST_DONE(rt);
}
/* If another thread is already in GC, don't attempt GC; wait instead. */
if (rt->gcLevel > 0) {
/* Bump gcLevel to restart the current GC, so it finds new garbage. */
rt->gcLevel++;
METER(if (rt->gcLevel > rt->gcStats.maxlevel)
rt->gcStats.maxlevel = rt->gcLevel);
/* Wait for the other thread to finish, then resume our request. */
while (rt->gcLevel > 0)
JS_AWAIT_GC_DONE(rt);
if (requestDebit)
rt->requestCount += requestDebit;
if (gckind != GC_LAST_DITCH)
JS_UNLOCK_GC(rt);
return;
}
/* No other thread is in GC, so indicate that we're now in GC. */
rt->gcLevel = 1;
rt->gcThread = cx->thread;
/* Wait for all other requests to finish. */
while (rt->requestCount > 0)
JS_AWAIT_REQUEST_DONE(rt);
#else /* !JS_THREADSAFE */
/* Bump gcLevel and return rather than nest; the outer gc will restart. */
rt->gcLevel++;
METER(if (rt->gcLevel > rt->gcStats.maxlevel)
rt->gcStats.maxlevel = rt->gcLevel);
if (rt->gcLevel > 1)
return;
#endif /* !JS_THREADSAFE */
/*
* Set rt->gcRunning here within the GC lock, and after waiting for any
* active requests to end, so that new requests that try to JS_AddRoot,
* JS_RemoveRoot, or JS_RemoveRootRT block in JS_BeginRequest waiting for
* rt->gcLevel to drop to zero, while request-less calls to the *Root*
* APIs block in js_AddRoot or js_RemoveRoot (see above in this file),
* waiting for GC to finish.
*/
rt->gcRunning = JS_TRUE;
JS_UNLOCK_GC(rt);
/* Reset malloc counter. */
rt->gcMallocBytes = 0;
/* Drop atoms held by the property cache, and clear property weak links. */
js_DisablePropertyCache(cx);
js_FlushPropertyCache(cx);
#ifdef DEBUG_scopemeters
{ extern void js_DumpScopeMeters(JSRuntime *rt);
js_DumpScopeMeters(rt);
}
#endif
#ifdef JS_THREADSAFE
/*
* Set all thread local freelists to NULL. We may visit a thread's
* freelist more than once. To avoid redundant clearing we unroll the
* current thread's step.
*
* Also, in case a JSScript wrapped in an object was finalized, we clear
* the acx->gsnCache.script pointer and finish the cache's hashtable.
*/
memset(cx->thread->gcFreeLists, 0, sizeof cx->thread->gcFreeLists);
iter = NULL;
while ((acx = js_ContextIterator(rt, JS_FALSE, &iter)) != NULL) {
if (!acx->thread || acx->thread == cx->thread)
continue;
memset(acx->thread->gcFreeLists, 0, sizeof acx->thread->gcFreeLists);
JS_CLEAR_GSN_CACHE(acx);
}
#endif
restart:
rt->gcNumber++;
JS_ASSERT(!rt->gcUnscannedArenaStackTop);
JS_ASSERT(rt->gcUnscannedBagSize == 0);
/*
* Mark phase.
*/
JS_DHashTableEnumerate(&rt->gcRootsHash, gc_root_marker, cx);
if (rt->gcLocksHash)
JS_DHashTableEnumerate(rt->gcLocksHash, gc_lock_marker, cx);
js_MarkAtomState(&rt->atomState, keepAtoms, gc_mark_atom_key_thing, cx);
js_MarkWatchPoints(rt);
js_MarkScriptFilenames(rt, keepAtoms);
js_MarkNativeIteratorStates(cx);
#if JS_HAS_GENERATORS
genTodoTail = MarkScheduledGenerators(cx);
JS_ASSERT(!*genTodoTail);
#endif
iter = NULL;
while ((acx = js_ContextIterator(rt, JS_TRUE, &iter)) != NULL) {
/*
* Iterate frame chain and dormant chains. Temporarily tack current
* frame onto the head of the dormant list to ease iteration.
*
* (NB: see comment on this whole "dormant" thing in js_Execute.)
*/
chain = acx->fp;
if (chain) {
JS_ASSERT(!chain->dormantNext);
chain->dormantNext = acx->dormantFrameChain;
} else {
chain = acx->dormantFrameChain;
}
for (fp = chain; fp; fp = chain = chain->dormantNext) {
do {
js_MarkStackFrame(cx, fp);
} while ((fp = fp->down) != NULL);
}
/* Cleanup temporary "dormant" linkage. */
if (acx->fp)
acx->fp->dormantNext = NULL;
/* Mark other roots-by-definition in acx. */
GC_MARK(cx, acx->globalObject, "global object");
for (i = 0; i < GCX_NTYPES; i++)
GC_MARK(cx, acx->newborn[i], gc_typenames[i]);
if (acx->lastAtom)
GC_MARK_ATOM(cx, acx->lastAtom);
if (JSVAL_IS_GCTHING(acx->lastInternalResult)) {
thing = JSVAL_TO_GCTHING(acx->lastInternalResult);
if (thing)
GC_MARK(cx, thing, "lastInternalResult");
}
if (acx->throwing && JSVAL_IS_GCTHING(acx->exception))
GC_MARK(cx, JSVAL_TO_GCTHING(acx->exception), "exception");
#if JS_HAS_LVALUE_RETURN
if (acx->rval2set && JSVAL_IS_GCTHING(acx->rval2))
GC_MARK(cx, JSVAL_TO_GCTHING(acx->rval2), "rval2");
#endif
for (sh = acx->stackHeaders; sh; sh = sh->down) {
METER(rt->gcStats.stackseg++);
METER(rt->gcStats.segslots += sh->nslots);
GC_MARK_JSVALS(cx, sh->nslots, JS_STACK_SEGMENT(sh), "stack");
}
if (acx->localRootStack)
js_MarkLocalRoots(cx, acx->localRootStack);
for (tvr = acx->tempValueRooters; tvr; tvr = tvr->down) {
if (tvr->count == -1) {
if (JSVAL_IS_GCTHING(tvr->u.value)) {
GC_MARK(cx, JSVAL_TO_GCTHING(tvr->u.value),
"tvr->u.value");
}
} else if (tvr->count == -2) {
tvr->u.marker(cx, tvr);
} else {
JS_ASSERT(tvr->count >= 0);
GC_MARK_JSVALS(cx, tvr->count, tvr->u.array, "tvr->u.array");
}
}
if (acx->sharpObjectMap.depth > 0)
js_GCMarkSharpMap(cx, &acx->sharpObjectMap);
}
#ifdef DUMP_CALL_TABLE
js_DumpCallTable(cx);
#endif
/*
* Mark children of things that caused too deep recursion during above
* marking phase.
*/
ScanDelayedChildren(cx);
#if JS_HAS_GENERATORS
/*
* Close phase: search and mark part. See comments in
* FindAndMarkObjectsToClose for details.
*/
FindAndMarkObjectsToClose(cx, gckind, genTodoTail);
/*
* Mark children of things that caused too deep recursion during the
* just-completed marking part of the close phase.
*/
ScanDelayedChildren(cx);
#endif
JS_ASSERT(!cx->insideGCMarkCallback);
if (rt->gcCallback) {
cx->insideGCMarkCallback = JS_TRUE;
(void) rt->gcCallback(cx, JSGC_MARK_END);
JS_ASSERT(cx->insideGCMarkCallback);
cx->insideGCMarkCallback = JS_FALSE;
}
JS_ASSERT(rt->gcUnscannedBagSize == 0);
/* Finalize iterator states before the objects they iterate over. */
CloseIteratorStates(cx);
/*
* Sweep phase.
*
* Finalize as we sweep, outside of rt->gcLock but with rt->gcRunning set
* so that any attempt to allocate a GC-thing from a finalizer will fail,
* rather than nest badly and leave the unmarked newborn to be swept.
*/
js_SweepAtomState(&rt->atomState);
js_SweepScopeProperties(rt);
/*
* Finalize smaller objects before larger, to guarantee finalization of
* GC-allocated obj->slots after obj. See FreeSlots in jsobj.c.
*/
for (i = 0; i < GC_NUM_FREELISTS; i++) {
arenaList = &rt->gcArenaList[i];
nbytes = GC_FREELIST_NBYTES(i);
limit = arenaList->lastLimit;
for (a = arenaList->last; a; a = a->prev) {
JS_ASSERT(!a->prevUnscanned);
JS_ASSERT(a->unscannedPages == 0);
firstPage = (uint8 *) FIRST_THING_PAGE(a);
for (offset = 0; offset != limit; offset += nbytes) {
if ((offset & GC_PAGE_MASK) == 0) {
JS_ASSERT(((JSGCPageInfo *)(firstPage + offset))->
unscannedBitmap == 0);
offset += PAGE_THING_GAP(nbytes);
}
JS_ASSERT(offset < limit);
flagp = a->base + offset / sizeof(JSGCThing);
if (flagp >= firstPage)
flagp += GC_THINGS_SIZE;
flags = *flagp;
if (flags & GCF_MARK) {
*flagp &= ~GCF_MARK;
} else if (!(flags & (GCF_LOCK | GCF_FINAL))) {
/* Call the finalizer with GCF_FINAL ORed into flags. */
type = flags & GCF_TYPEMASK;
finalizer = gc_finalizers[type];
if (finalizer) {
thing = (JSGCThing *)(firstPage + offset);
*flagp = (uint8)(flags | GCF_FINAL);
if (type >= GCX_EXTERNAL_STRING)
js_PurgeDeflatedStringCache(rt, (JSString *)thing);
finalizer(cx, thing);
}
/* Set flags to GCF_FINAL, signifying that thing is free. */
*flagp = GCF_FINAL;
}
}
limit = GC_THINGS_SIZE;
}
}
/*
* Sweep script filenames after sweeping functions in the generic loop
* above. In this way when scripted function's finalizer destroys script
* triggering a call to rt->destroyScriptHook, the hook can still access
* script's filename. See bug 323267.
*/
js_SweepScriptFilenames(rt);
/*
* Free phase.
* Free any unused arenas and rebuild the JSGCThing freelist.
*/
for (i = 0; i < GC_NUM_FREELISTS; i++) {
arenaList = &rt->gcArenaList[i];
ap = &arenaList->last;
a = *ap;
if (!a)
continue;
allClear = JS_TRUE;
arenaList->freeList = NULL;
freeList = NULL;
METER(arenaList->stats.nthings = 0);
METER(arenaList->stats.freelen = 0);
nbytes = GC_FREELIST_NBYTES(i);
limit = arenaList->lastLimit;
do {
METER(size_t nfree = 0);
firstPage = (uint8 *) FIRST_THING_PAGE(a);
for (offset = 0; offset != limit; offset += nbytes) {
if ((offset & GC_PAGE_MASK) == 0)
offset += PAGE_THING_GAP(nbytes);
JS_ASSERT(offset < limit);
flagp = a->base + offset / sizeof(JSGCThing);
if (flagp >= firstPage)
flagp += GC_THINGS_SIZE;
if (*flagp != GCF_FINAL) {
allClear = JS_FALSE;
METER(++arenaList->stats.nthings);
} else {
thing = (JSGCThing *)(firstPage + offset);
thing->flagp = flagp;
thing->next = freeList;
freeList = thing;
METER(++nfree);
}
}
if (allClear) {
/*
* Forget just assembled free list head for the arena
* and destroy the arena itself.
*/
freeList = arenaList->freeList;
DestroyGCArena(rt, arenaList, ap);
} else {
allClear = JS_TRUE;
arenaList->freeList = freeList;
ap = &a->prev;
METER(arenaList->stats.freelen += nfree);
METER(arenaList->stats.totalfreelen += nfree);
METER(++arenaList->stats.totalarenas);
}
limit = GC_THINGS_SIZE;
} while ((a = *ap) != NULL);
}
if (rt->gcCallback)
(void) rt->gcCallback(cx, JSGC_FINALIZE_END);
#ifdef DEBUG_srcnotesize
{ extern void DumpSrcNoteSizeHist();
DumpSrcNoteSizeHist();
printf("GC HEAP SIZE %lu (%lu)\n",
(unsigned long)rt->gcBytes, (unsigned long)rt->gcPrivateBytes);
}
#endif
JS_LOCK_GC(rt);
/*
* We want to restart GC if js_GC was called recursively or if any of the
* finalizers called js_RemoveRoot or js_UnlockGCThingRT.
*/
if (rt->gcLevel > 1 || rt->gcPoke) {
rt->gcLevel = 1;
rt->gcPoke = JS_FALSE;
JS_UNLOCK_GC(rt);
goto restart;
}
js_EnablePropertyCache(cx);
rt->gcLevel = 0;
rt->gcLastBytes = rt->gcBytes;
rt->gcRunning = JS_FALSE;
#ifdef JS_THREADSAFE
/* If we were invoked during a request, pay back the temporary debit. */
if (requestDebit)
rt->requestCount += requestDebit;
rt->gcThread = NULL;
JS_NOTIFY_GC_DONE(rt);
/*
* Unlock unless we have GC_LAST_DITCH which requires locked GC on return.
*/
if (gckind != GC_LAST_DITCH)
JS_UNLOCK_GC(rt);
#endif
if (rt->gcCallback) {
/* Execute JSGC_END callback outside the lock. */
if (gckind == GC_LAST_DITCH)
JS_UNLOCK_GC(rt);
(void) rt->gcCallback(cx, JSGC_END);
/*
* On shutdown iterate until JSGC_END callback stops creating garbage.
*/
if (gckind == GC_LAST_CONTEXT && rt->gcPoke)
goto restart_after_callback;
if (gckind == GC_LAST_DITCH)
JS_LOCK_GC(rt);
}
}
void
js_UpdateMallocCounter(JSContext *cx, size_t nbytes)
{
uint32 *pbytes, bytes;
#ifdef JS_THREADSAFE
pbytes = &cx->thread->gcMallocBytes;
#else
pbytes = &cx->runtime->gcMallocBytes;
#endif
bytes = *pbytes;
*pbytes = ((uint32)-1 - bytes <= nbytes) ? (uint32)-1 : bytes + nbytes;
}
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