gecko/js/src/jsgc.cpp
Ryan VanderMeulen 3446362831 Backed out 13 changesets (bug 880917) for Android and B2G test bustage on a CLOSED TREE.
Backed out changeset 71c1ce2cb0a4 (bug 880917)
Backed out changeset cd240e19560f (bug 880917)
Backed out changeset 93509a0001b5 (bug 880917)
Backed out changeset fdbba20e4647 (bug 880917)
Backed out changeset d82060172367 (bug 880917)
Backed out changeset 709f0b699489 (bug 880917)
Backed out changeset 421bdbccfa7c (bug 880917)
Backed out changeset 962c656c7452 (bug 880917)
Backed out changeset 888a5690ccdf (bug 880917)
Backed out changeset 57228f5fcd87 (bug 880917)
Backed out changeset ce8c3e14c234 (bug 880917)
Backed out changeset 08fe7b777450 (bug 880917)
Backed out changeset 5192a9233d83 (bug 880917)
2013-06-13 15:19:50 -04:00

5087 lines
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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=8 sts=4 et sw=4 tw=99:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* JS Mark-and-Sweep Garbage Collector. */
#include "jsgc.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/Util.h"
/*
* This code implements a mark-and-sweep garbage collector. The mark phase is
* incremental. Most sweeping is done on a background thread. A GC is divided
* into slices as follows:
*
* Slice 1: Roots pushed onto the mark stack. The mark stack is processed by
* popping an element, marking it, and pushing its children.
* ... JS code runs ...
* Slice 2: More mark stack processing.
* ... JS code runs ...
* Slice n-1: More mark stack processing.
* ... JS code runs ...
* Slice n: Mark stack is completely drained. Some sweeping is done.
* ... JS code runs, remaining sweeping done on background thread ...
*
* When background sweeping finishes the GC is complete.
*
* Incremental GC requires close collaboration with the mutator (i.e., JS code):
*
* 1. During an incremental GC, if a memory location (except a root) is written
* to, then the value it previously held must be marked. Write barriers ensure
* this.
* 2. Any object that is allocated during incremental GC must start out marked.
* 3. Roots are special memory locations that don't need write
* barriers. However, they must be marked in the first slice. Roots are things
* like the C stack and the VM stack, since it would be too expensive to put
* barriers on them.
*/
#include <string.h> /* for memset used when DEBUG */
#include "jstypes.h"
#include "jsutil.h"
#include "jsapi.h"
#include "jsatom.h"
#include "jscompartment.h"
#include "jscntxt.h"
#include "jsobj.h"
#include "jsproxy.h"
#include "jsscript.h"
#include "jswatchpoint.h"
#include "jsweakmap.h"
#include "gc/FindSCCs.h"
#include "gc/GCInternals.h"
#include "gc/Marking.h"
#include "gc/Memory.h"
#include "vm/Debugger.h"
#include "vm/Shape.h"
#include "vm/String.h"
#include "vm/ForkJoin.h"
#include "ion/IonCode.h"
#ifdef JS_ION
# include "ion/BaselineJIT.h"
#endif
#include "jsgcinlines.h"
#include "jsobjinlines.h"
#include "gc/FindSCCs-inl.h"
#include "vm/String-inl.h"
#ifdef XP_WIN
# include "jswin.h"
#else
# include <unistd.h>
#endif
#if JS_TRACE_LOGGING
#include "TraceLogging.h"
#endif
using namespace js;
using namespace js::gc;
using mozilla::ArrayEnd;
using mozilla::DebugOnly;
using mozilla::Maybe;
/* Perform a Full GC every 20 seconds if MaybeGC is called */
static const uint64_t GC_IDLE_FULL_SPAN = 20 * 1000 * 1000;
/* Increase the IGC marking slice time if we are in highFrequencyGC mode. */
static const int IGC_MARK_SLICE_MULTIPLIER = 2;
/* This array should be const, but that doesn't link right under GCC. */
AllocKind gc::slotsToThingKind[] = {
/* 0 */ FINALIZE_OBJECT0, FINALIZE_OBJECT2, FINALIZE_OBJECT2, FINALIZE_OBJECT4,
/* 4 */ FINALIZE_OBJECT4, FINALIZE_OBJECT8, FINALIZE_OBJECT8, FINALIZE_OBJECT8,
/* 8 */ FINALIZE_OBJECT8, FINALIZE_OBJECT12, FINALIZE_OBJECT12, FINALIZE_OBJECT12,
/* 12 */ FINALIZE_OBJECT12, FINALIZE_OBJECT16, FINALIZE_OBJECT16, FINALIZE_OBJECT16,
/* 16 */ FINALIZE_OBJECT16
};
JS_STATIC_ASSERT(JS_ARRAY_LENGTH(slotsToThingKind) == SLOTS_TO_THING_KIND_LIMIT);
const uint32_t Arena::ThingSizes[] = {
sizeof(JSObject), /* FINALIZE_OBJECT0 */
sizeof(JSObject), /* FINALIZE_OBJECT0_BACKGROUND */
sizeof(JSObject_Slots2), /* FINALIZE_OBJECT2 */
sizeof(JSObject_Slots2), /* FINALIZE_OBJECT2_BACKGROUND */
sizeof(JSObject_Slots4), /* FINALIZE_OBJECT4 */
sizeof(JSObject_Slots4), /* FINALIZE_OBJECT4_BACKGROUND */
sizeof(JSObject_Slots8), /* FINALIZE_OBJECT8 */
sizeof(JSObject_Slots8), /* FINALIZE_OBJECT8_BACKGROUND */
sizeof(JSObject_Slots12), /* FINALIZE_OBJECT12 */
sizeof(JSObject_Slots12), /* FINALIZE_OBJECT12_BACKGROUND */
sizeof(JSObject_Slots16), /* FINALIZE_OBJECT16 */
sizeof(JSObject_Slots16), /* FINALIZE_OBJECT16_BACKGROUND */
sizeof(JSScript), /* FINALIZE_SCRIPT */
sizeof(LazyScript), /* FINALIZE_LAZY_SCRIPT */
sizeof(Shape), /* FINALIZE_SHAPE */
sizeof(BaseShape), /* FINALIZE_BASE_SHAPE */
sizeof(types::TypeObject), /* FINALIZE_TYPE_OBJECT */
sizeof(JSShortString), /* FINALIZE_SHORT_STRING */
sizeof(JSString), /* FINALIZE_STRING */
sizeof(JSExternalString), /* FINALIZE_EXTERNAL_STRING */
sizeof(ion::IonCode), /* FINALIZE_IONCODE */
};
#define OFFSET(type) uint32_t(sizeof(ArenaHeader) + (ArenaSize - sizeof(ArenaHeader)) % sizeof(type))
const uint32_t Arena::FirstThingOffsets[] = {
OFFSET(JSObject), /* FINALIZE_OBJECT0 */
OFFSET(JSObject), /* FINALIZE_OBJECT0_BACKGROUND */
OFFSET(JSObject_Slots2), /* FINALIZE_OBJECT2 */
OFFSET(JSObject_Slots2), /* FINALIZE_OBJECT2_BACKGROUND */
OFFSET(JSObject_Slots4), /* FINALIZE_OBJECT4 */
OFFSET(JSObject_Slots4), /* FINALIZE_OBJECT4_BACKGROUND */
OFFSET(JSObject_Slots8), /* FINALIZE_OBJECT8 */
OFFSET(JSObject_Slots8), /* FINALIZE_OBJECT8_BACKGROUND */
OFFSET(JSObject_Slots12), /* FINALIZE_OBJECT12 */
OFFSET(JSObject_Slots12), /* FINALIZE_OBJECT12_BACKGROUND */
OFFSET(JSObject_Slots16), /* FINALIZE_OBJECT16 */
OFFSET(JSObject_Slots16), /* FINALIZE_OBJECT16_BACKGROUND */
OFFSET(JSScript), /* FINALIZE_SCRIPT */
OFFSET(LazyScript), /* FINALIZE_LAZY_SCRIPT */
OFFSET(Shape), /* FINALIZE_SHAPE */
OFFSET(BaseShape), /* FINALIZE_BASE_SHAPE */
OFFSET(types::TypeObject), /* FINALIZE_TYPE_OBJECT */
OFFSET(JSShortString), /* FINALIZE_SHORT_STRING */
OFFSET(JSString), /* FINALIZE_STRING */
OFFSET(JSExternalString), /* FINALIZE_EXTERNAL_STRING */
OFFSET(ion::IonCode), /* FINALIZE_IONCODE */
};
#undef OFFSET
/*
* Finalization order for incrementally swept things.
*/
static const AllocKind FinalizePhaseStrings[] = {
FINALIZE_EXTERNAL_STRING
};
static const AllocKind FinalizePhaseScripts[] = {
FINALIZE_SCRIPT
};
static const AllocKind FinalizePhaseIonCode[] = {
FINALIZE_IONCODE
};
static const AllocKind* FinalizePhases[] = {
FinalizePhaseStrings,
FinalizePhaseScripts,
FinalizePhaseIonCode
};
static const int FinalizePhaseCount = sizeof(FinalizePhases) / sizeof(AllocKind*);
static const int FinalizePhaseLength[] = {
sizeof(FinalizePhaseStrings) / sizeof(AllocKind),
sizeof(FinalizePhaseScripts) / sizeof(AllocKind),
sizeof(FinalizePhaseIonCode) / sizeof(AllocKind)
};
static const gcstats::Phase FinalizePhaseStatsPhase[] = {
gcstats::PHASE_SWEEP_STRING,
gcstats::PHASE_SWEEP_SCRIPT,
gcstats::PHASE_SWEEP_IONCODE
};
/*
* Finalization order for things swept in the background.
*/
static const AllocKind BackgroundPhaseObjects[] = {
FINALIZE_OBJECT0_BACKGROUND,
FINALIZE_OBJECT2_BACKGROUND,
FINALIZE_OBJECT4_BACKGROUND,
FINALIZE_OBJECT8_BACKGROUND,
FINALIZE_OBJECT12_BACKGROUND,
FINALIZE_OBJECT16_BACKGROUND
};
static const AllocKind BackgroundPhaseStrings[] = {
FINALIZE_SHORT_STRING,
FINALIZE_STRING
};
static const AllocKind BackgroundPhaseShapes[] = {
FINALIZE_LAZY_SCRIPT,
FINALIZE_SHAPE,
FINALIZE_BASE_SHAPE,
FINALIZE_TYPE_OBJECT
};
static const AllocKind* BackgroundPhases[] = {
BackgroundPhaseObjects,
BackgroundPhaseStrings,
BackgroundPhaseShapes
};
static const int BackgroundPhaseCount = sizeof(BackgroundPhases) / sizeof(AllocKind*);
static const int BackgroundPhaseLength[] = {
sizeof(BackgroundPhaseObjects) / sizeof(AllocKind),
sizeof(BackgroundPhaseStrings) / sizeof(AllocKind),
sizeof(BackgroundPhaseShapes) / sizeof(AllocKind)
};
#ifdef DEBUG
void
ArenaHeader::checkSynchronizedWithFreeList() const
{
/*
* Do not allow to access the free list when its real head is still stored
* in FreeLists and is not synchronized with this one.
*/
JS_ASSERT(allocated());
/*
* We can be called from the background finalization thread when the free
* list in the zone can mutate at any moment. We cannot do any
* checks in this case.
*/
if (IsBackgroundFinalized(getAllocKind()) && zone->rt->gcHelperThread.onBackgroundThread())
return;
FreeSpan firstSpan = FreeSpan::decodeOffsets(arenaAddress(), firstFreeSpanOffsets);
if (firstSpan.isEmpty())
return;
const FreeSpan *list = zone->allocator.arenas.getFreeList(getAllocKind());
if (list->isEmpty() || firstSpan.arenaAddress() != list->arenaAddress())
return;
/*
* Here this arena has free things, FreeList::lists[thingKind] is not
* empty and also points to this arena. Thus they must the same.
*/
JS_ASSERT(firstSpan.isSameNonEmptySpan(list));
}
#endif
/* static */ void
Arena::staticAsserts()
{
JS_STATIC_ASSERT(sizeof(Arena) == ArenaSize);
JS_STATIC_ASSERT(JS_ARRAY_LENGTH(ThingSizes) == FINALIZE_LIMIT);
JS_STATIC_ASSERT(JS_ARRAY_LENGTH(FirstThingOffsets) == FINALIZE_LIMIT);
}
template<typename T>
inline bool
Arena::finalize(FreeOp *fop, AllocKind thingKind, size_t thingSize)
{
/* Enforce requirements on size of T. */
JS_ASSERT(thingSize % CellSize == 0);
JS_ASSERT(thingSize <= 255);
JS_ASSERT(aheader.allocated());
JS_ASSERT(thingKind == aheader.getAllocKind());
JS_ASSERT(thingSize == aheader.getThingSize());
JS_ASSERT(!aheader.hasDelayedMarking);
JS_ASSERT(!aheader.markOverflow);
JS_ASSERT(!aheader.allocatedDuringIncremental);
uintptr_t thing = thingsStart(thingKind);
uintptr_t lastByte = thingsEnd() - 1;
FreeSpan nextFree(aheader.getFirstFreeSpan());
nextFree.checkSpan();
FreeSpan newListHead;
FreeSpan *newListTail = &newListHead;
uintptr_t newFreeSpanStart = 0;
bool allClear = true;
DebugOnly<size_t> nmarked = 0;
for (;; thing += thingSize) {
JS_ASSERT(thing <= lastByte + 1);
if (thing == nextFree.first) {
JS_ASSERT(nextFree.last <= lastByte);
if (nextFree.last == lastByte)
break;
JS_ASSERT(Arena::isAligned(nextFree.last, thingSize));
if (!newFreeSpanStart)
newFreeSpanStart = thing;
thing = nextFree.last;
nextFree = *nextFree.nextSpan();
nextFree.checkSpan();
} else {
T *t = reinterpret_cast<T *>(thing);
if (t->isMarked()) {
allClear = false;
nmarked++;
if (newFreeSpanStart) {
JS_ASSERT(thing >= thingsStart(thingKind) + thingSize);
newListTail->first = newFreeSpanStart;
newListTail->last = thing - thingSize;
newListTail = newListTail->nextSpanUnchecked(thingSize);
newFreeSpanStart = 0;
}
} else {
if (!newFreeSpanStart)
newFreeSpanStart = thing;
t->finalize(fop);
JS_POISON(t, JS_FREE_PATTERN, thingSize);
}
}
}
if (allClear) {
JS_ASSERT(newListTail == &newListHead);
JS_ASSERT(newFreeSpanStart == thingsStart(thingKind));
return true;
}
newListTail->first = newFreeSpanStart ? newFreeSpanStart : nextFree.first;
JS_ASSERT(Arena::isAligned(newListTail->first, thingSize));
newListTail->last = lastByte;
#ifdef DEBUG
size_t nfree = 0;
for (const FreeSpan *span = &newListHead; span != newListTail; span = span->nextSpan()) {
span->checkSpan();
JS_ASSERT(Arena::isAligned(span->first, thingSize));
JS_ASSERT(Arena::isAligned(span->last, thingSize));
nfree += (span->last - span->first) / thingSize + 1;
JS_ASSERT(nfree + nmarked <= thingsPerArena(thingSize));
}
nfree += (newListTail->last + 1 - newListTail->first) / thingSize;
JS_ASSERT(nfree + nmarked == thingsPerArena(thingSize));
#endif
aheader.setFirstFreeSpan(&newListHead);
return false;
}
/*
* Insert an arena into the list in appropriate position and update the cursor
* to ensure that any arena before the cursor is full.
*/
void ArenaList::insert(ArenaHeader *a)
{
JS_ASSERT(a);
JS_ASSERT_IF(!head, cursor == &head);
a->next = *cursor;
*cursor = a;
if (!a->hasFreeThings())
cursor = &a->next;
}
template<typename T>
static inline bool
FinalizeTypedArenas(FreeOp *fop,
ArenaHeader **src,
ArenaList &dest,
AllocKind thingKind,
SliceBudget &budget)
{
/*
* Finalize arenas from src list, releasing empty arenas and inserting the
* others into dest in an appropriate position.
*/
size_t thingSize = Arena::thingSize(thingKind);
while (ArenaHeader *aheader = *src) {
*src = aheader->next;
bool allClear = aheader->getArena()->finalize<T>(fop, thingKind, thingSize);
if (allClear)
aheader->chunk()->releaseArena(aheader);
else
dest.insert(aheader);
budget.step(Arena::thingsPerArena(thingSize));
if (budget.isOverBudget())
return false;
}
return true;
}
/*
* Finalize the list. On return al->cursor points to the first non-empty arena
* after the al->head.
*/
static bool
FinalizeArenas(FreeOp *fop,
ArenaHeader **src,
ArenaList &dest,
AllocKind thingKind,
SliceBudget &budget)
{
switch(thingKind) {
case FINALIZE_OBJECT0:
case FINALIZE_OBJECT0_BACKGROUND:
case FINALIZE_OBJECT2:
case FINALIZE_OBJECT2_BACKGROUND:
case FINALIZE_OBJECT4:
case FINALIZE_OBJECT4_BACKGROUND:
case FINALIZE_OBJECT8:
case FINALIZE_OBJECT8_BACKGROUND:
case FINALIZE_OBJECT12:
case FINALIZE_OBJECT12_BACKGROUND:
case FINALIZE_OBJECT16:
case FINALIZE_OBJECT16_BACKGROUND:
return FinalizeTypedArenas<JSObject>(fop, src, dest, thingKind, budget);
case FINALIZE_SCRIPT:
return FinalizeTypedArenas<JSScript>(fop, src, dest, thingKind, budget);
case FINALIZE_LAZY_SCRIPT:
return FinalizeTypedArenas<LazyScript>(fop, src, dest, thingKind, budget);
case FINALIZE_SHAPE:
return FinalizeTypedArenas<Shape>(fop, src, dest, thingKind, budget);
case FINALIZE_BASE_SHAPE:
return FinalizeTypedArenas<BaseShape>(fop, src, dest, thingKind, budget);
case FINALIZE_TYPE_OBJECT:
return FinalizeTypedArenas<types::TypeObject>(fop, src, dest, thingKind, budget);
case FINALIZE_STRING:
return FinalizeTypedArenas<JSString>(fop, src, dest, thingKind, budget);
case FINALIZE_SHORT_STRING:
return FinalizeTypedArenas<JSShortString>(fop, src, dest, thingKind, budget);
case FINALIZE_EXTERNAL_STRING:
return FinalizeTypedArenas<JSExternalString>(fop, src, dest, thingKind, budget);
case FINALIZE_IONCODE:
#ifdef JS_ION
return FinalizeTypedArenas<ion::IonCode>(fop, src, dest, thingKind, budget);
#endif
default:
JS_NOT_REACHED("Invalid alloc kind");
return true;
}
}
static inline Chunk *
AllocChunk() {
return static_cast<Chunk *>(MapAlignedPages(ChunkSize, ChunkSize));
}
static inline void
FreeChunk(Chunk *p) {
UnmapPages(static_cast<void *>(p), ChunkSize);
}
inline bool
ChunkPool::wantBackgroundAllocation(JSRuntime *rt) const
{
/*
* To minimize memory waste we do not want to run the background chunk
* allocation if we have empty chunks or when the runtime needs just few
* of them.
*/
return rt->gcHelperThread.canBackgroundAllocate() &&
emptyCount == 0 &&
rt->gcChunkSet.count() >= 4;
}
/* Must be called with the GC lock taken. */
inline Chunk *
ChunkPool::get(JSRuntime *rt)
{
JS_ASSERT(this == &rt->gcChunkPool);
Chunk *chunk = emptyChunkListHead;
if (chunk) {
JS_ASSERT(emptyCount);
emptyChunkListHead = chunk->info.next;
--emptyCount;
} else {
JS_ASSERT(!emptyCount);
chunk = Chunk::allocate(rt);
if (!chunk)
return NULL;
JS_ASSERT(chunk->info.numArenasFreeCommitted == ArenasPerChunk);
rt->gcNumArenasFreeCommitted += ArenasPerChunk;
}
JS_ASSERT(chunk->unused());
JS_ASSERT(!rt->gcChunkSet.has(chunk));
if (wantBackgroundAllocation(rt))
rt->gcHelperThread.startBackgroundAllocationIfIdle();
return chunk;
}
/* Must be called either during the GC or with the GC lock taken. */
inline void
ChunkPool::put(Chunk *chunk)
{
chunk->info.age = 0;
chunk->info.next = emptyChunkListHead;
emptyChunkListHead = chunk;
emptyCount++;
}
/* Must be called either during the GC or with the GC lock taken. */
Chunk *
ChunkPool::expire(JSRuntime *rt, bool releaseAll)
{
JS_ASSERT(this == &rt->gcChunkPool);
/*
* Return old empty chunks to the system while preserving the order of
* other chunks in the list. This way, if the GC runs several times
* without emptying the list, the older chunks will stay at the tail
* and are more likely to reach the max age.
*/
Chunk *freeList = NULL;
for (Chunk **chunkp = &emptyChunkListHead; *chunkp; ) {
JS_ASSERT(emptyCount);
Chunk *chunk = *chunkp;
JS_ASSERT(chunk->unused());
JS_ASSERT(!rt->gcChunkSet.has(chunk));
JS_ASSERT(chunk->info.age <= MAX_EMPTY_CHUNK_AGE);
if (releaseAll || chunk->info.age == MAX_EMPTY_CHUNK_AGE) {
*chunkp = chunk->info.next;
--emptyCount;
chunk->prepareToBeFreed(rt);
chunk->info.next = freeList;
freeList = chunk;
} else {
/* Keep the chunk but increase its age. */
++chunk->info.age;
chunkp = &chunk->info.next;
}
}
JS_ASSERT_IF(releaseAll, !emptyCount);
return freeList;
}
static void
FreeChunkList(Chunk *chunkListHead)
{
while (Chunk *chunk = chunkListHead) {
JS_ASSERT(!chunk->info.numArenasFreeCommitted);
chunkListHead = chunk->info.next;
FreeChunk(chunk);
}
}
void
ChunkPool::expireAndFree(JSRuntime *rt, bool releaseAll)
{
FreeChunkList(expire(rt, releaseAll));
}
/* static */ Chunk *
Chunk::allocate(JSRuntime *rt)
{
Chunk *chunk = static_cast<Chunk *>(AllocChunk());
#ifdef JSGC_ROOT_ANALYSIS
// Our poison pointers are not guaranteed to be invalid on 64-bit
// architectures, and often are valid. We can't just reserve the full
// poison range, because it might already have been taken up by something
// else (shared library, previous allocation). So we'll just loop and
// discard poison pointers until we get something valid.
//
// This leaks all of these poisoned pointers. It would be better if they
// were marked as uncommitted, but it's a little complicated to avoid
// clobbering pre-existing unrelated mappings.
while (IsPoisonedPtr(chunk))
chunk = static_cast<Chunk *>(AllocChunk());
#endif
if (!chunk)
return NULL;
chunk->init(rt);
rt->gcStats.count(gcstats::STAT_NEW_CHUNK);
return chunk;
}
/* Must be called with the GC lock taken. */
/* static */ inline void
Chunk::release(JSRuntime *rt, Chunk *chunk)
{
JS_ASSERT(chunk);
chunk->prepareToBeFreed(rt);
FreeChunk(chunk);
}
inline void
Chunk::prepareToBeFreed(JSRuntime *rt)
{
JS_ASSERT(rt->gcNumArenasFreeCommitted >= info.numArenasFreeCommitted);
rt->gcNumArenasFreeCommitted -= info.numArenasFreeCommitted;
rt->gcStats.count(gcstats::STAT_DESTROY_CHUNK);
#ifdef DEBUG
/*
* Let FreeChunkList detect a missing prepareToBeFreed call before it
* frees chunk.
*/
info.numArenasFreeCommitted = 0;
#endif
}
void
Chunk::init(JSRuntime *rt)
{
JS_POISON(this, JS_FREE_PATTERN, ChunkSize);
/*
* We clear the bitmap to guard against xpc_IsGrayGCThing being called on
* uninitialized data, which would happen before the first GC cycle.
*/
bitmap.clear();
/* Initialize the arena tracking bitmap. */
decommittedArenas.clear(false);
/* Initialize the chunk info. */
info.freeArenasHead = &arenas[0].aheader;
info.lastDecommittedArenaOffset = 0;
info.numArenasFree = ArenasPerChunk;
info.numArenasFreeCommitted = ArenasPerChunk;
info.age = 0;
info.runtime = rt;
/* Initialize the arena header state. */
for (unsigned i = 0; i < ArenasPerChunk; i++) {
arenas[i].aheader.setAsNotAllocated();
arenas[i].aheader.next = (i + 1 < ArenasPerChunk)
? &arenas[i + 1].aheader
: NULL;
}
/* The rest of info fields are initialized in PickChunk. */
}
static inline Chunk **
GetAvailableChunkList(Zone *zone)
{
JSRuntime *rt = zone->rt;
return zone->isSystem
? &rt->gcSystemAvailableChunkListHead
: &rt->gcUserAvailableChunkListHead;
}
inline void
Chunk::addToAvailableList(Zone *zone)
{
insertToAvailableList(GetAvailableChunkList(zone));
}
inline void
Chunk::insertToAvailableList(Chunk **insertPoint)
{
JS_ASSERT(hasAvailableArenas());
JS_ASSERT(!info.prevp);
JS_ASSERT(!info.next);
info.prevp = insertPoint;
Chunk *insertBefore = *insertPoint;
if (insertBefore) {
JS_ASSERT(insertBefore->info.prevp == insertPoint);
insertBefore->info.prevp = &info.next;
}
info.next = insertBefore;
*insertPoint = this;
}
inline void
Chunk::removeFromAvailableList()
{
JS_ASSERT(info.prevp);
*info.prevp = info.next;
if (info.next) {
JS_ASSERT(info.next->info.prevp == &info.next);
info.next->info.prevp = info.prevp;
}
info.prevp = NULL;
info.next = NULL;
}
/*
* Search for and return the next decommitted Arena. Our goal is to keep
* lastDecommittedArenaOffset "close" to a free arena. We do this by setting
* it to the most recently freed arena when we free, and forcing it to
* the last alloc + 1 when we allocate.
*/
uint32_t
Chunk::findDecommittedArenaOffset()
{
/* Note: lastFreeArenaOffset can be past the end of the list. */
for (unsigned i = info.lastDecommittedArenaOffset; i < ArenasPerChunk; i++)
if (decommittedArenas.get(i))
return i;
for (unsigned i = 0; i < info.lastDecommittedArenaOffset; i++)
if (decommittedArenas.get(i))
return i;
JS_NOT_REACHED("No decommitted arenas found.");
return -1;
}
ArenaHeader *
Chunk::fetchNextDecommittedArena()
{
JS_ASSERT(info.numArenasFreeCommitted == 0);
JS_ASSERT(info.numArenasFree > 0);
unsigned offset = findDecommittedArenaOffset();
info.lastDecommittedArenaOffset = offset + 1;
--info.numArenasFree;
decommittedArenas.unset(offset);
Arena *arena = &arenas[offset];
MarkPagesInUse(arena, ArenaSize);
arena->aheader.setAsNotAllocated();
return &arena->aheader;
}
inline ArenaHeader *
Chunk::fetchNextFreeArena(JSRuntime *rt)
{
JS_ASSERT(info.numArenasFreeCommitted > 0);
JS_ASSERT(info.numArenasFreeCommitted <= info.numArenasFree);
JS_ASSERT(info.numArenasFreeCommitted <= rt->gcNumArenasFreeCommitted);
ArenaHeader *aheader = info.freeArenasHead;
info.freeArenasHead = aheader->next;
--info.numArenasFreeCommitted;
--info.numArenasFree;
--rt->gcNumArenasFreeCommitted;
return aheader;
}
ArenaHeader *
Chunk::allocateArena(Zone *zone, AllocKind thingKind)
{
JS_ASSERT(hasAvailableArenas());
JSRuntime *rt = zone->rt;
if (!rt->isHeapMinorCollecting() && rt->gcBytes >= rt->gcMaxBytes)
return NULL;
ArenaHeader *aheader = JS_LIKELY(info.numArenasFreeCommitted > 0)
? fetchNextFreeArena(rt)
: fetchNextDecommittedArena();
aheader->init(zone, thingKind);
if (JS_UNLIKELY(!hasAvailableArenas()))
removeFromAvailableList();
rt->gcBytes += ArenaSize;
zone->gcBytes += ArenaSize;
if (zone->gcBytes >= zone->gcTriggerBytes)
TriggerZoneGC(zone, JS::gcreason::ALLOC_TRIGGER);
return aheader;
}
inline void
Chunk::addArenaToFreeList(JSRuntime *rt, ArenaHeader *aheader)
{
JS_ASSERT(!aheader->allocated());
aheader->next = info.freeArenasHead;
info.freeArenasHead = aheader;
++info.numArenasFreeCommitted;
++info.numArenasFree;
++rt->gcNumArenasFreeCommitted;
}
void
Chunk::releaseArena(ArenaHeader *aheader)
{
JS_ASSERT(aheader->allocated());
JS_ASSERT(!aheader->hasDelayedMarking);
Zone *zone = aheader->zone;
JSRuntime *rt = zone->rt;
AutoLockGC maybeLock;
if (rt->gcHelperThread.sweeping())
maybeLock.lock(rt);
JS_ASSERT(rt->gcBytes >= ArenaSize);
JS_ASSERT(zone->gcBytes >= ArenaSize);
if (rt->gcHelperThread.sweeping())
zone->reduceGCTriggerBytes(zone->gcHeapGrowthFactor * ArenaSize);
rt->gcBytes -= ArenaSize;
zone->gcBytes -= ArenaSize;
aheader->setAsNotAllocated();
addArenaToFreeList(rt, aheader);
if (info.numArenasFree == 1) {
JS_ASSERT(!info.prevp);
JS_ASSERT(!info.next);
addToAvailableList(zone);
} else if (!unused()) {
JS_ASSERT(info.prevp);
} else {
rt->gcChunkSet.remove(this);
removeFromAvailableList();
rt->gcChunkPool.put(this);
}
}
/* The caller must hold the GC lock. */
static Chunk *
PickChunk(Zone *zone)
{
JSRuntime *rt = zone->rt;
Chunk **listHeadp = GetAvailableChunkList(zone);
Chunk *chunk = *listHeadp;
if (chunk)
return chunk;
chunk = rt->gcChunkPool.get(rt);
if (!chunk)
return NULL;
rt->gcChunkAllocationSinceLastGC = true;
/*
* FIXME bug 583732 - chunk is newly allocated and cannot be present in
* the table so using ordinary lookupForAdd is suboptimal here.
*/
GCChunkSet::AddPtr p = rt->gcChunkSet.lookupForAdd(chunk);
JS_ASSERT(!p);
if (!rt->gcChunkSet.add(p, chunk)) {
Chunk::release(rt, chunk);
return NULL;
}
chunk->info.prevp = NULL;
chunk->info.next = NULL;
chunk->addToAvailableList(zone);
return chunk;
}
#ifdef JS_GC_ZEAL
extern void
js::SetGCZeal(JSRuntime *rt, uint8_t zeal, uint32_t frequency)
{
if (zeal == 0) {
if (rt->gcVerifyPreData)
VerifyBarriers(rt, PreBarrierVerifier);
if (rt->gcVerifyPostData)
VerifyBarriers(rt, PostBarrierVerifier);
}
bool schedule = zeal >= js::gc::ZealAllocValue;
rt->gcZeal_ = zeal;
rt->gcZealFrequency = frequency;
rt->gcNextScheduled = schedule ? frequency : 0;
}
static bool
InitGCZeal(JSRuntime *rt)
{
const char *env = getenv("JS_GC_ZEAL");
if (!env)
return true;
int zeal = -1;
int frequency = JS_DEFAULT_ZEAL_FREQ;
if (strcmp(env, "help") != 0) {
zeal = atoi(env);
const char *p = strchr(env, ',');
if (p)
frequency = atoi(p + 1);
}
if (zeal < 0 || zeal > ZealLimit || frequency < 0) {
fprintf(stderr,
"Format: JS_GC_ZEAL=N[,F]\n"
"N indicates \"zealousness\":\n"
" 0: no additional GCs\n"
" 1: additional GCs at common danger points\n"
" 2: GC every F allocations (default: 100)\n"
" 3: GC when the window paints (browser only)\n"
" 4: Verify pre write barriers between instructions\n"
" 5: Verify pre write barriers between paints\n"
" 6: Verify stack rooting\n"
" 7: Verify stack rooting (yes, it's the same as 6)\n"
" 8: Incremental GC in two slices: 1) mark roots 2) finish collection\n"
" 9: Incremental GC in two slices: 1) mark all 2) new marking and finish\n"
" 10: Incremental GC in multiple slices\n"
" 11: Verify post write barriers between instructions\n"
" 12: Verify post write barriers between paints\n"
" 13: Purge analysis state every F allocations (default: 100)\n");
return false;
}
SetGCZeal(rt, zeal, frequency);
return true;
}
#endif
/* Lifetime for type sets attached to scripts containing observed types. */
static const int64_t JIT_SCRIPT_RELEASE_TYPES_INTERVAL = 60 * 1000 * 1000;
JSBool
js_InitGC(JSRuntime *rt, uint32_t maxbytes)
{
if (!rt->gcChunkSet.init(INITIAL_CHUNK_CAPACITY))
return false;
if (!rt->gcRootsHash.init(256))
return false;
#ifdef JS_THREADSAFE
rt->gcLock = PR_NewLock();
if (!rt->gcLock)
return false;
#endif
if (!rt->gcHelperThread.init())
return false;
/*
* Separate gcMaxMallocBytes from gcMaxBytes but initialize to maxbytes
* for default backward API compatibility.
*/
rt->gcMaxBytes = maxbytes;
rt->setGCMaxMallocBytes(maxbytes);
#ifndef JS_MORE_DETERMINISTIC
rt->gcJitReleaseTime = PRMJ_Now() + JIT_SCRIPT_RELEASE_TYPES_INTERVAL;
#endif
#ifdef JSGC_GENERATIONAL
if (!rt->gcNursery.init())
return false;
if (!rt->gcStoreBuffer.enable())
return false;
#endif
#ifdef JS_GC_ZEAL
if (!InitGCZeal(rt))
return false;
#endif
return true;
}
static void
RecordNativeStackTopForGC(JSRuntime *rt)
{
ConservativeGCData *cgcd = &rt->conservativeGC;
#ifdef JS_THREADSAFE
/* Record the stack top here only if we are called from a request. */
if (!rt->requestDepth)
return;
#endif
cgcd->recordStackTop();
}
void
js_FinishGC(JSRuntime *rt)
{
/*
* Wait until the background finalization stops and the helper thread
* shuts down before we forcefully release any remaining GC memory.
*/
rt->gcHelperThread.finish();
#ifdef JS_GC_ZEAL
/* Free memory associated with GC verification. */
FinishVerifier(rt);
#endif
/* Delete all remaining zones. */
for (ZonesIter zone(rt); !zone.done(); zone.next()) {
for (CompartmentsInZoneIter comp(zone); !comp.done(); comp.next())
js_delete(comp.get());
js_delete(zone.get());
}
rt->zones.clear();
rt->atomsCompartment = NULL;
rt->gcSystemAvailableChunkListHead = NULL;
rt->gcUserAvailableChunkListHead = NULL;
for (GCChunkSet::Range r(rt->gcChunkSet.all()); !r.empty(); r.popFront())
Chunk::release(rt, r.front());
rt->gcChunkSet.clear();
rt->gcChunkPool.expireAndFree(rt, true);
rt->gcRootsHash.clear();
}
template <typename T> struct BarrierOwner {};
template <typename T> struct BarrierOwner<T *> { typedef T result; };
template <> struct BarrierOwner<Value> { typedef HeapValue result; };
template <typename T>
static bool
AddRoot(JSRuntime *rt, T *rp, const char *name, JSGCRootType rootType)
{
/*
* Sometimes Firefox will hold weak references to objects and then convert
* them to strong references by calling AddRoot (e.g., via PreserveWrapper,
* or ModifyBusyCount in workers). We need a read barrier to cover these
* cases.
*/
if (rt->gcIncrementalState != NO_INCREMENTAL)
BarrierOwner<T>::result::writeBarrierPre(*rp);
return rt->gcRootsHash.put((void *)rp, RootInfo(name, rootType));
}
template <typename T>
static bool
AddRoot(JSContext *cx, T *rp, const char *name, JSGCRootType rootType)
{
bool ok = AddRoot(cx->runtime(), rp, name, rootType);
if (!ok)
JS_ReportOutOfMemory(cx);
return ok;
}
JSBool
js::AddValueRoot(JSContext *cx, Value *vp, const char *name)
{
return AddRoot(cx, vp, name, JS_GC_ROOT_VALUE_PTR);
}
extern JSBool
js::AddValueRootRT(JSRuntime *rt, js::Value *vp, const char *name)
{
return AddRoot(rt, vp, name, JS_GC_ROOT_VALUE_PTR);
}
extern JSBool
js::AddStringRoot(JSContext *cx, JSString **rp, const char *name)
{
return AddRoot(cx, rp, name, JS_GC_ROOT_STRING_PTR);
}
extern JSBool
js::AddObjectRoot(JSContext *cx, JSObject **rp, const char *name)
{
return AddRoot(cx, rp, name, JS_GC_ROOT_OBJECT_PTR);
}
extern JSBool
js::AddScriptRoot(JSContext *cx, JSScript **rp, const char *name)
{
return AddRoot(cx, rp, name, JS_GC_ROOT_SCRIPT_PTR);
}
JS_FRIEND_API(void)
js_RemoveRoot(JSRuntime *rt, void *rp)
{
rt->gcRootsHash.remove(rp);
rt->gcPoke = true;
}
typedef RootedValueMap::Range RootRange;
typedef RootedValueMap::Entry RootEntry;
typedef RootedValueMap::Enum RootEnum;
static size_t
ComputeTriggerBytes(Zone *zone, size_t lastBytes, size_t maxBytes, JSGCInvocationKind gckind)
{
size_t base = gckind == GC_SHRINK ? lastBytes : Max(lastBytes, zone->rt->gcAllocationThreshold);
float trigger = float(base) * zone->gcHeapGrowthFactor;
return size_t(Min(float(maxBytes), trigger));
}
void
Zone::setGCLastBytes(size_t lastBytes, JSGCInvocationKind gckind)
{
/*
* The heap growth factor depends on the heap size after a GC and the GC frequency.
* For low frequency GCs (more than 1sec between GCs) we let the heap grow to 150%.
* For high frequency GCs we let the heap grow depending on the heap size:
* lastBytes < highFrequencyLowLimit: 300%
* lastBytes > highFrequencyHighLimit: 150%
* otherwise: linear interpolation between 150% and 300% based on lastBytes
*/
if (!rt->gcDynamicHeapGrowth) {
gcHeapGrowthFactor = 3.0;
} else if (lastBytes < 1 * 1024 * 1024) {
gcHeapGrowthFactor = rt->gcLowFrequencyHeapGrowth;
} else {
JS_ASSERT(rt->gcHighFrequencyHighLimitBytes > rt->gcHighFrequencyLowLimitBytes);
uint64_t now = PRMJ_Now();
if (rt->gcLastGCTime && rt->gcLastGCTime + rt->gcHighFrequencyTimeThreshold * PRMJ_USEC_PER_MSEC > now) {
if (lastBytes <= rt->gcHighFrequencyLowLimitBytes) {
gcHeapGrowthFactor = rt->gcHighFrequencyHeapGrowthMax;
} else if (lastBytes >= rt->gcHighFrequencyHighLimitBytes) {
gcHeapGrowthFactor = rt->gcHighFrequencyHeapGrowthMin;
} else {
double k = (rt->gcHighFrequencyHeapGrowthMin - rt->gcHighFrequencyHeapGrowthMax)
/ (double)(rt->gcHighFrequencyHighLimitBytes - rt->gcHighFrequencyLowLimitBytes);
gcHeapGrowthFactor = (k * (lastBytes - rt->gcHighFrequencyLowLimitBytes)
+ rt->gcHighFrequencyHeapGrowthMax);
JS_ASSERT(gcHeapGrowthFactor <= rt->gcHighFrequencyHeapGrowthMax
&& gcHeapGrowthFactor >= rt->gcHighFrequencyHeapGrowthMin);
}
rt->gcHighFrequencyGC = true;
} else {
gcHeapGrowthFactor = rt->gcLowFrequencyHeapGrowth;
rt->gcHighFrequencyGC = false;
}
}
gcTriggerBytes = ComputeTriggerBytes(this, lastBytes, rt->gcMaxBytes, gckind);
}
void
Zone::reduceGCTriggerBytes(size_t amount)
{
JS_ASSERT(amount > 0);
JS_ASSERT(gcTriggerBytes >= amount);
if (gcTriggerBytes - amount < rt->gcAllocationThreshold * gcHeapGrowthFactor)
return;
gcTriggerBytes -= amount;
}
Allocator::Allocator(Zone *zone)
: zone(zone)
{}
inline void
ArenaLists::prepareForIncrementalGC(JSRuntime *rt)
{
for (size_t i = 0; i != FINALIZE_LIMIT; ++i) {
FreeSpan *headSpan = &freeLists[i];
if (!headSpan->isEmpty()) {
ArenaHeader *aheader = headSpan->arenaHeader();
aheader->allocatedDuringIncremental = true;
rt->gcMarker.delayMarkingArena(aheader);
}
}
}
static inline void
PushArenaAllocatedDuringSweep(JSRuntime *runtime, ArenaHeader *arena)
{
arena->setNextAllocDuringSweep(runtime->gcArenasAllocatedDuringSweep);
runtime->gcArenasAllocatedDuringSweep = arena;
}
void *
ArenaLists::parallelAllocate(Zone *zone, AllocKind thingKind, size_t thingSize)
{
/*
* During parallel Rivertrail sections, if no existing arena can
* satisfy the allocation, then a new one is allocated. If that
* fails, then we return NULL which will cause the parallel
* section to abort.
*/
void *t = allocateFromFreeList(thingKind, thingSize);
if (t)
return t;
return allocateFromArenaInline(zone, thingKind);
}
inline void *
ArenaLists::allocateFromArenaInline(Zone *zone, AllocKind thingKind)
{
/*
* Parallel JS Note:
*
* This function can be called from parallel threads all of which
* are associated with the same compartment. In that case, each
* thread will have a distinct ArenaLists. Therefore, whenever we
* fall through to PickChunk() we must be sure that we are holding
* a lock.
*/
Chunk *chunk = NULL;
ArenaList *al = &arenaLists[thingKind];
AutoLockGC maybeLock;
#ifdef JS_THREADSAFE
volatile uintptr_t *bfs = &backgroundFinalizeState[thingKind];
if (*bfs != BFS_DONE) {
/*
* We cannot search the arena list for free things while the
* background finalization runs and can modify head or cursor at any
* moment. So we always allocate a new arena in that case.
*/
maybeLock.lock(zone->rt);
if (*bfs == BFS_RUN) {
JS_ASSERT(!*al->cursor);
chunk = PickChunk(zone);
if (!chunk) {
/*
* Let the caller to wait for the background allocation to
* finish and restart the allocation attempt.
*/
return NULL;
}
} else if (*bfs == BFS_JUST_FINISHED) {
/* See comments before BackgroundFinalizeState definition. */
*bfs = BFS_DONE;
} else {
JS_ASSERT(*bfs == BFS_DONE);
}
}
#endif /* JS_THREADSAFE */
if (!chunk) {
if (ArenaHeader *aheader = *al->cursor) {
JS_ASSERT(aheader->hasFreeThings());
/*
* The empty arenas are returned to the chunk and should not present on
* the list.
*/
JS_ASSERT(!aheader->isEmpty());
al->cursor = &aheader->next;
/*
* Move the free span stored in the arena to the free list and
* allocate from it.
*/
freeLists[thingKind] = aheader->getFirstFreeSpan();
aheader->setAsFullyUsed();
if (JS_UNLIKELY(zone->wasGCStarted())) {
if (zone->needsBarrier()) {
aheader->allocatedDuringIncremental = true;
zone->rt->gcMarker.delayMarkingArena(aheader);
} else if (zone->isGCSweeping()) {
PushArenaAllocatedDuringSweep(zone->rt, aheader);
}
}
return freeLists[thingKind].infallibleAllocate(Arena::thingSize(thingKind));
}
/* Make sure we hold the GC lock before we call PickChunk. */
if (!maybeLock.locked())
maybeLock.lock(zone->rt);
chunk = PickChunk(zone);
if (!chunk)
return NULL;
}
/*
* While we still hold the GC lock get an arena from some chunk, mark it
* as full as its single free span is moved to the free lits, and insert
* it to the list as a fully allocated arena.
*
* We add the arena before the the head, not after the tail pointed by the
* cursor, so after the GC the most recently added arena will be used first
* for allocations improving cache locality.
*/
JS_ASSERT(!*al->cursor);
ArenaHeader *aheader = chunk->allocateArena(zone, thingKind);
if (!aheader)
return NULL;
if (JS_UNLIKELY(zone->wasGCStarted())) {
if (zone->needsBarrier()) {
aheader->allocatedDuringIncremental = true;
zone->rt->gcMarker.delayMarkingArena(aheader);
} else if (zone->isGCSweeping()) {
PushArenaAllocatedDuringSweep(zone->rt, aheader);
}
}
aheader->next = al->head;
if (!al->head) {
JS_ASSERT(al->cursor == &al->head);
al->cursor = &aheader->next;
}
al->head = aheader;
/* See comments before allocateFromNewArena about this assert. */
JS_ASSERT(!aheader->hasFreeThings());
uintptr_t arenaAddr = aheader->arenaAddress();
return freeLists[thingKind].allocateFromNewArena(arenaAddr,
Arena::firstThingOffset(thingKind),
Arena::thingSize(thingKind));
}
void *
ArenaLists::allocateFromArena(JS::Zone *zone, AllocKind thingKind)
{
return allocateFromArenaInline(zone, thingKind);
}
void
ArenaLists::finalizeNow(FreeOp *fop, AllocKind thingKind)
{
JS_ASSERT(!IsBackgroundFinalized(thingKind));
JS_ASSERT(backgroundFinalizeState[thingKind] == BFS_DONE ||
backgroundFinalizeState[thingKind] == BFS_JUST_FINISHED);
ArenaHeader *arenas = arenaLists[thingKind].head;
arenaLists[thingKind].clear();
SliceBudget budget;
FinalizeArenas(fop, &arenas, arenaLists[thingKind], thingKind, budget);
JS_ASSERT(!arenas);
}
void
ArenaLists::queueForForegroundSweep(FreeOp *fop, AllocKind thingKind)
{
JS_ASSERT(!IsBackgroundFinalized(thingKind));
JS_ASSERT(backgroundFinalizeState[thingKind] == BFS_DONE);
JS_ASSERT(!arenaListsToSweep[thingKind]);
arenaListsToSweep[thingKind] = arenaLists[thingKind].head;
arenaLists[thingKind].clear();
}
inline void
ArenaLists::queueForBackgroundSweep(FreeOp *fop, AllocKind thingKind)
{
JS_ASSERT(IsBackgroundFinalized(thingKind));
#ifdef JS_THREADSAFE
JS_ASSERT(!fop->runtime()->gcHelperThread.sweeping());
#endif
ArenaList *al = &arenaLists[thingKind];
if (!al->head) {
JS_ASSERT(backgroundFinalizeState[thingKind] == BFS_DONE);
JS_ASSERT(al->cursor == &al->head);
return;
}
/*
* The state can be done, or just-finished if we have not allocated any GC
* things from the arena list after the previous background finalization.
*/
JS_ASSERT(backgroundFinalizeState[thingKind] == BFS_DONE ||
backgroundFinalizeState[thingKind] == BFS_JUST_FINISHED);
arenaListsToSweep[thingKind] = al->head;
al->clear();
backgroundFinalizeState[thingKind] = BFS_RUN;
}
/*static*/ void
ArenaLists::backgroundFinalize(FreeOp *fop, ArenaHeader *listHead, bool onBackgroundThread)
{
JS_ASSERT(listHead);
AllocKind thingKind = listHead->getAllocKind();
Zone *zone = listHead->zone;
ArenaList finalized;
SliceBudget budget;
FinalizeArenas(fop, &listHead, finalized, thingKind, budget);
JS_ASSERT(!listHead);
/*
* After we finish the finalization al->cursor must point to the end of
* the head list as we emptied the list before the background finalization
* and the allocation adds new arenas before the cursor.
*/
ArenaLists *lists = &zone->allocator.arenas;
ArenaList *al = &lists->arenaLists[thingKind];
AutoLockGC lock(fop->runtime());
JS_ASSERT(lists->backgroundFinalizeState[thingKind] == BFS_RUN);
JS_ASSERT(!*al->cursor);
if (finalized.head) {
*al->cursor = finalized.head;
if (finalized.cursor != &finalized.head)
al->cursor = finalized.cursor;
}
/*
* We must set the state to BFS_JUST_FINISHED if we are running on the
* background thread and we have touched arenaList list, even if we add to
* the list only fully allocated arenas without any free things. It ensures
* that the allocation thread takes the GC lock and all writes to the free
* list elements are propagated. As we always take the GC lock when
* allocating new arenas from the chunks we can set the state to BFS_DONE if
* we have released all finalized arenas back to their chunks.
*/
if (onBackgroundThread && finalized.head)
lists->backgroundFinalizeState[thingKind] = BFS_JUST_FINISHED;
else
lists->backgroundFinalizeState[thingKind] = BFS_DONE;
lists->arenaListsToSweep[thingKind] = NULL;
}
void
ArenaLists::queueObjectsForSweep(FreeOp *fop)
{
gcstats::AutoPhase ap(fop->runtime()->gcStats, gcstats::PHASE_SWEEP_OBJECT);
finalizeNow(fop, FINALIZE_OBJECT0);
finalizeNow(fop, FINALIZE_OBJECT2);
finalizeNow(fop, FINALIZE_OBJECT4);
finalizeNow(fop, FINALIZE_OBJECT8);
finalizeNow(fop, FINALIZE_OBJECT12);
finalizeNow(fop, FINALIZE_OBJECT16);
queueForBackgroundSweep(fop, FINALIZE_OBJECT0_BACKGROUND);
queueForBackgroundSweep(fop, FINALIZE_OBJECT2_BACKGROUND);
queueForBackgroundSweep(fop, FINALIZE_OBJECT4_BACKGROUND);
queueForBackgroundSweep(fop, FINALIZE_OBJECT8_BACKGROUND);
queueForBackgroundSweep(fop, FINALIZE_OBJECT12_BACKGROUND);
queueForBackgroundSweep(fop, FINALIZE_OBJECT16_BACKGROUND);
}
void
ArenaLists::queueStringsForSweep(FreeOp *fop)
{
gcstats::AutoPhase ap(fop->runtime()->gcStats, gcstats::PHASE_SWEEP_STRING);
queueForBackgroundSweep(fop, FINALIZE_SHORT_STRING);
queueForBackgroundSweep(fop, FINALIZE_STRING);
queueForForegroundSweep(fop, FINALIZE_EXTERNAL_STRING);
}
void
ArenaLists::queueScriptsForSweep(FreeOp *fop)
{
gcstats::AutoPhase ap(fop->runtime()->gcStats, gcstats::PHASE_SWEEP_SCRIPT);
queueForForegroundSweep(fop, FINALIZE_SCRIPT);
queueForBackgroundSweep(fop, FINALIZE_LAZY_SCRIPT);
}
void
ArenaLists::queueIonCodeForSweep(FreeOp *fop)
{
gcstats::AutoPhase ap(fop->runtime()->gcStats, gcstats::PHASE_SWEEP_IONCODE);
queueForForegroundSweep(fop, FINALIZE_IONCODE);
}
void
ArenaLists::queueShapesForSweep(FreeOp *fop)
{
gcstats::AutoPhase ap(fop->runtime()->gcStats, gcstats::PHASE_SWEEP_SHAPE);
queueForBackgroundSweep(fop, FINALIZE_SHAPE);
queueForBackgroundSweep(fop, FINALIZE_BASE_SHAPE);
queueForBackgroundSweep(fop, FINALIZE_TYPE_OBJECT);
}
static void *
RunLastDitchGC(JSContext *cx, JS::Zone *zone, AllocKind thingKind)
{
/*
* In parallel sections, we do not attempt to refill the free list
* and hence do not encounter last ditch GC.
*/
JS_ASSERT(!InParallelSection());
PrepareZoneForGC(zone);
JSRuntime *rt = cx->runtime();
/* The last ditch GC preserves all atoms. */
AutoKeepAtoms keep(rt);
GC(rt, GC_NORMAL, JS::gcreason::LAST_DITCH);
/*
* The JSGC_END callback can legitimately allocate new GC
* things and populate the free list. If that happens, just
* return that list head.
*/
size_t thingSize = Arena::thingSize(thingKind);
if (void *thing = zone->allocator.arenas.allocateFromFreeList(thingKind, thingSize))
return thing;
return NULL;
}
template <AllowGC allowGC>
/* static */ void *
ArenaLists::refillFreeList(JSContext *cx, AllocKind thingKind)
{
JS_ASSERT(cx->zone()->allocator.arenas.freeLists[thingKind].isEmpty());
Zone *zone = cx->zone();
JSRuntime *rt = zone->rt;
JS_ASSERT(!rt->isHeapBusy());
bool runGC = rt->gcIncrementalState != NO_INCREMENTAL &&
zone->gcBytes > zone->gcTriggerBytes &&
allowGC;
for (;;) {
if (JS_UNLIKELY(runGC)) {
if (void *thing = RunLastDitchGC(cx, zone, thingKind))
return thing;
}
/*
* allocateFromArena may fail while the background finalization still
* run. In that case we want to wait for it to finish and restart.
* However, checking for that is racy as the background finalization
* could free some things after allocateFromArena decided to fail but
* at this point it may have already stopped. To avoid this race we
* always try to allocate twice.
*/
for (bool secondAttempt = false; ; secondAttempt = true) {
void *thing = zone->allocator.arenas.allocateFromArenaInline(zone, thingKind);
if (JS_LIKELY(!!thing))
return thing;
if (secondAttempt)
break;
rt->gcHelperThread.waitBackgroundSweepEnd();
}
if (!allowGC)
return NULL;
/*
* We failed to allocate. Run the GC if we haven't done it already.
* Otherwise report OOM.
*/
if (runGC)
break;
runGC = true;
}
JS_ASSERT(allowGC);
js_ReportOutOfMemory(cx);
return NULL;
}
template void *
ArenaLists::refillFreeList<NoGC>(JSContext *cx, AllocKind thingKind);
template void *
ArenaLists::refillFreeList<CanGC>(JSContext *cx, AllocKind thingKind);
JSGCTraceKind
js_GetGCThingTraceKind(void *thing)
{
return GetGCThingTraceKind(thing);
}
void
js::InitTracer(JSTracer *trc, JSRuntime *rt, JSTraceCallback callback)
{
trc->runtime = rt;
trc->callback = callback;
trc->debugPrinter = NULL;
trc->debugPrintArg = NULL;
trc->debugPrintIndex = size_t(-1);
trc->eagerlyTraceWeakMaps = TraceWeakMapValues;
#ifdef JS_GC_ZEAL
trc->realLocation = NULL;
#endif
}
/* static */ int64_t
SliceBudget::TimeBudget(int64_t millis)
{
return millis * PRMJ_USEC_PER_MSEC;
}
/* static */ int64_t
SliceBudget::WorkBudget(int64_t work)
{
/* For work = 0 not to mean Unlimited, we subtract 1. */
return -work - 1;
}
SliceBudget::SliceBudget()
: deadline(INT64_MAX),
counter(INTPTR_MAX)
{
}
SliceBudget::SliceBudget(int64_t budget)
{
if (budget == Unlimited) {
deadline = INT64_MAX;
counter = INTPTR_MAX;
} else if (budget > 0) {
deadline = PRMJ_Now() + budget;
counter = CounterReset;
} else {
deadline = 0;
counter = -budget - 1;
}
}
bool
SliceBudget::checkOverBudget()
{
bool over = PRMJ_Now() > deadline;
if (!over)
counter = CounterReset;
return over;
}
GCMarker::GCMarker(JSRuntime *rt)
: stack(size_t(-1)),
color(BLACK),
started(false),
unmarkedArenaStackTop(NULL),
markLaterArenas(0),
grayFailed(false)
{
InitTracer(this, rt, NULL);
}
bool
GCMarker::init()
{
return stack.init(MARK_STACK_LENGTH);
}
void
GCMarker::start()
{
JS_ASSERT(!started);
started = true;
color = BLACK;
JS_ASSERT(!unmarkedArenaStackTop);
JS_ASSERT(markLaterArenas == 0);
/*
* The GC is recomputing the liveness of WeakMap entries, so we delay
* visting entries.
*/
eagerlyTraceWeakMaps = DoNotTraceWeakMaps;
}
void
GCMarker::stop()
{
JS_ASSERT(isDrained());
JS_ASSERT(started);
started = false;
JS_ASSERT(!unmarkedArenaStackTop);
JS_ASSERT(markLaterArenas == 0);
/* Free non-ballast stack memory. */
stack.reset();
resetBufferedGrayRoots();
}
void
GCMarker::reset()
{
color = BLACK;
stack.reset();
JS_ASSERT(isMarkStackEmpty());
while (unmarkedArenaStackTop) {
ArenaHeader *aheader = unmarkedArenaStackTop;
JS_ASSERT(aheader->hasDelayedMarking);
JS_ASSERT(markLaterArenas);
unmarkedArenaStackTop = aheader->getNextDelayedMarking();
aheader->unsetDelayedMarking();
aheader->markOverflow = 0;
aheader->allocatedDuringIncremental = 0;
markLaterArenas--;
}
JS_ASSERT(isDrained());
JS_ASSERT(!markLaterArenas);
}
/*
* When the native stack is low, the GC does not call JS_TraceChildren to mark
* the reachable "children" of the thing. Rather the thing is put aside and
* JS_TraceChildren is called later with more space on the C stack.
*
* To implement such delayed marking of the children with minimal overhead for
* the normal case of sufficient native stack, the code adds a field per
* arena. The field markingDelay->link links all arenas with delayed things
* into a stack list with the pointer to stack top in
* GCMarker::unmarkedArenaStackTop. delayMarkingChildren adds
* arenas to the stack as necessary while markDelayedChildren pops the arenas
* from the stack until it empties.
*/
inline void
GCMarker::delayMarkingArena(ArenaHeader *aheader)
{
if (aheader->hasDelayedMarking) {
/* Arena already scheduled to be marked later */
return;
}
aheader->setNextDelayedMarking(unmarkedArenaStackTop);
unmarkedArenaStackTop = aheader;
markLaterArenas++;
}
void
GCMarker::delayMarkingChildren(const void *thing)
{
const Cell *cell = reinterpret_cast<const Cell *>(thing);
cell->arenaHeader()->markOverflow = 1;
delayMarkingArena(cell->arenaHeader());
}
void
GCMarker::markDelayedChildren(ArenaHeader *aheader)
{
if (aheader->markOverflow) {
bool always = aheader->allocatedDuringIncremental;
aheader->markOverflow = 0;
for (CellIterUnderGC i(aheader); !i.done(); i.next()) {
Cell *t = i.getCell();
if (always || t->isMarked()) {
t->markIfUnmarked();
JS_TraceChildren(this, t, MapAllocToTraceKind(aheader->getAllocKind()));
}
}
} else {
JS_ASSERT(aheader->allocatedDuringIncremental);
PushArena(this, aheader);
}
aheader->allocatedDuringIncremental = 0;
/*
* Note that during an incremental GC we may still be allocating into
* aheader. However, prepareForIncrementalGC sets the
* allocatedDuringIncremental flag if we continue marking.
*/
}
bool
GCMarker::markDelayedChildren(SliceBudget &budget)
{
gcstats::Phase phase = runtime->gcIncrementalState == MARK
? gcstats::PHASE_MARK_DELAYED
: gcstats::PHASE_SWEEP_MARK_DELAYED;
gcstats::AutoPhase ap(runtime->gcStats, phase);
JS_ASSERT(unmarkedArenaStackTop);
do {
/*
* If marking gets delayed at the same arena again, we must repeat
* marking of its things. For that we pop arena from the stack and
* clear its hasDelayedMarking flag before we begin the marking.
*/
ArenaHeader *aheader = unmarkedArenaStackTop;
JS_ASSERT(aheader->hasDelayedMarking);
JS_ASSERT(markLaterArenas);
unmarkedArenaStackTop = aheader->getNextDelayedMarking();
aheader->unsetDelayedMarking();
markLaterArenas--;
markDelayedChildren(aheader);
budget.step(150);
if (budget.isOverBudget())
return false;
} while (unmarkedArenaStackTop);
JS_ASSERT(!markLaterArenas);
return true;
}
#ifdef DEBUG
void
GCMarker::checkZone(void *p)
{
JS_ASSERT(started);
DebugOnly<Cell *> cell = static_cast<Cell *>(p);
JS_ASSERT_IF(cell->isTenured(), cell->tenuredZone()->isCollecting());
}
#endif
bool
GCMarker::hasBufferedGrayRoots() const
{
return !grayFailed;
}
void
GCMarker::startBufferingGrayRoots()
{
JS_ASSERT(!grayFailed);
for (GCZonesIter zone(runtime); !zone.done(); zone.next())
JS_ASSERT(zone->gcGrayRoots.empty());
JS_ASSERT(!callback);
callback = GrayCallback;
JS_ASSERT(IS_GC_MARKING_TRACER(this));
}
void
GCMarker::endBufferingGrayRoots()
{
JS_ASSERT(callback == GrayCallback);
callback = NULL;
JS_ASSERT(IS_GC_MARKING_TRACER(this));
}
void
GCMarker::resetBufferedGrayRoots()
{
for (GCZonesIter zone(runtime); !zone.done(); zone.next())
zone->gcGrayRoots.clearAndFree();
grayFailed = false;
}
void
GCMarker::markBufferedGrayRoots(JS::Zone *zone)
{
JS_ASSERT(!grayFailed);
JS_ASSERT(zone->isGCMarkingGray());
for (GrayRoot *elem = zone->gcGrayRoots.begin(); elem != zone->gcGrayRoots.end(); elem++) {
#ifdef DEBUG
debugPrinter = elem->debugPrinter;
debugPrintArg = elem->debugPrintArg;
debugPrintIndex = elem->debugPrintIndex;
#endif
void *tmp = elem->thing;
JS_SET_TRACING_LOCATION(this, (void *)&elem->thing);
MarkKind(this, &tmp, elem->kind);
JS_ASSERT(tmp == elem->thing);
}
}
void
GCMarker::appendGrayRoot(void *thing, JSGCTraceKind kind)
{
JS_ASSERT(started);
if (grayFailed)
return;
GrayRoot root(thing, kind);
#ifdef DEBUG
root.debugPrinter = debugPrinter;
root.debugPrintArg = debugPrintArg;
root.debugPrintIndex = debugPrintIndex;
#endif
Zone *zone = static_cast<Cell *>(thing)->tenuredZone();
if (zone->isCollecting()) {
zone->maybeAlive = true;
if (!zone->gcGrayRoots.append(root)) {
grayFailed = true;
resetBufferedGrayRoots();
}
}
}
void
GCMarker::GrayCallback(JSTracer *trc, void **thingp, JSGCTraceKind kind)
{
GCMarker *gcmarker = static_cast<GCMarker *>(trc);
gcmarker->appendGrayRoot(*thingp, kind);
}
size_t
GCMarker::sizeOfExcludingThis(JSMallocSizeOfFun mallocSizeOf) const
{
size_t size = stack.sizeOfExcludingThis(mallocSizeOf);
for (ZonesIter zone(runtime); !zone.done(); zone.next())
size += zone->gcGrayRoots.sizeOfExcludingThis(mallocSizeOf);
return size;
}
void
js::SetMarkStackLimit(JSRuntime *rt, size_t limit)
{
JS_ASSERT(!rt->isHeapBusy());
rt->gcMarker.setSizeLimit(limit);
}
void
js::MarkCompartmentActive(StackFrame *fp)
{
fp->script()->compartment()->zone()->active = true;
}
static void
TriggerOperationCallback(JSRuntime *rt, JS::gcreason::Reason reason)
{
if (rt->gcIsNeeded)
return;
rt->gcIsNeeded = true;
rt->gcTriggerReason = reason;
rt->triggerOperationCallback();
}
void
js::TriggerGC(JSRuntime *rt, JS::gcreason::Reason reason)
{
/* Wait till end of parallel section to trigger GC. */
if (InParallelSection()) {
ForkJoinSlice::Current()->requestGC(reason);
return;
}
rt->assertValidThread();
if (rt->isHeapBusy())
return;
JS::PrepareForFullGC(rt);
TriggerOperationCallback(rt, reason);
}
void
js::TriggerZoneGC(Zone *zone, JS::gcreason::Reason reason)
{
/*
* If parallel threads are running, wait till they
* are stopped to trigger GC.
*/
if (InParallelSection()) {
ForkJoinSlice::Current()->requestZoneGC(zone, reason);
return;
}
JSRuntime *rt = zone->rt;
rt->assertValidThread();
if (rt->isHeapBusy())
return;
if (rt->gcZeal() == ZealAllocValue) {
TriggerGC(rt, reason);
return;
}
if (zone == rt->atomsCompartment->zone()) {
/* We can't do a zone GC of the atoms compartment. */
TriggerGC(rt, reason);
return;
}
PrepareZoneForGC(zone);
TriggerOperationCallback(rt, reason);
}
void
js::MaybeGC(JSContext *cx)
{
JSRuntime *rt = cx->runtime();
rt->assertValidThread();
if (rt->gcZeal() == ZealAllocValue || rt->gcZeal() == ZealPokeValue) {
JS::PrepareForFullGC(rt);
GC(rt, GC_NORMAL, JS::gcreason::MAYBEGC);
return;
}
if (rt->gcIsNeeded) {
GCSlice(rt, GC_NORMAL, JS::gcreason::MAYBEGC);
return;
}
double factor = rt->gcHighFrequencyGC ? 0.85 : 0.9;
Zone *zone = cx->zone();
if (zone->gcBytes > 1024 * 1024 &&
zone->gcBytes >= factor * zone->gcTriggerBytes &&
rt->gcIncrementalState == NO_INCREMENTAL &&
!rt->gcHelperThread.sweeping())
{
PrepareZoneForGC(zone);
GCSlice(rt, GC_NORMAL, JS::gcreason::MAYBEGC);
return;
}
#ifndef JS_MORE_DETERMINISTIC
/*
* Access to the counters and, on 32 bit, setting gcNextFullGCTime below
* is not atomic and a race condition could trigger or suppress the GC. We
* tolerate this.
*/
int64_t now = PRMJ_Now();
if (rt->gcNextFullGCTime && rt->gcNextFullGCTime <= now) {
if (rt->gcChunkAllocationSinceLastGC ||
rt->gcNumArenasFreeCommitted > FreeCommittedArenasThreshold)
{
JS::PrepareForFullGC(rt);
GCSlice(rt, GC_SHRINK, JS::gcreason::MAYBEGC);
} else {
rt->gcNextFullGCTime = now + GC_IDLE_FULL_SPAN;
}
}
#endif
}
static void
DecommitArenasFromAvailableList(JSRuntime *rt, Chunk **availableListHeadp)
{
Chunk *chunk = *availableListHeadp;
if (!chunk)
return;
/*
* Decommit is expensive so we avoid holding the GC lock while calling it.
*
* We decommit from the tail of the list to minimize interference with the
* main thread that may start to allocate things at this point.
*
* The arena that is been decommitted outside the GC lock must not be
* available for allocations either via the free list or via the
* decommittedArenas bitmap. For that we just fetch the arena from the
* free list before the decommit pretending as it was allocated. If this
* arena also is the single free arena in the chunk, then we must remove
* from the available list before we release the lock so the allocation
* thread would not see chunks with no free arenas on the available list.
*
* After we retake the lock, we mark the arena as free and decommitted if
* the decommit was successful. We must also add the chunk back to the
* available list if we removed it previously or when the main thread
* have allocated all remaining free arenas in the chunk.
*
* We also must make sure that the aheader is not accessed again after we
* decommit the arena.
*/
JS_ASSERT(chunk->info.prevp == availableListHeadp);
while (Chunk *next = chunk->info.next) {
JS_ASSERT(next->info.prevp == &chunk->info.next);
chunk = next;
}
for (;;) {
while (chunk->info.numArenasFreeCommitted != 0) {
ArenaHeader *aheader = chunk->fetchNextFreeArena(rt);
Chunk **savedPrevp = chunk->info.prevp;
if (!chunk->hasAvailableArenas())
chunk->removeFromAvailableList();
size_t arenaIndex = Chunk::arenaIndex(aheader->arenaAddress());
bool ok;
{
/*
* If the main thread waits for the decommit to finish, skip
* potentially expensive unlock/lock pair on the contested
* lock.
*/
Maybe<AutoUnlockGC> maybeUnlock;
if (!rt->isHeapBusy())
maybeUnlock.construct(rt);
ok = MarkPagesUnused(aheader->getArena(), ArenaSize);
}
if (ok) {
++chunk->info.numArenasFree;
chunk->decommittedArenas.set(arenaIndex);
} else {
chunk->addArenaToFreeList(rt, aheader);
}
JS_ASSERT(chunk->hasAvailableArenas());
JS_ASSERT(!chunk->unused());
if (chunk->info.numArenasFree == 1) {
/*
* Put the chunk back to the available list either at the
* point where it was before to preserve the available list
* that we enumerate, or, when the allocation thread has fully
* used all the previous chunks, at the beginning of the
* available list.
*/
Chunk **insertPoint = savedPrevp;
if (savedPrevp != availableListHeadp) {
Chunk *prev = Chunk::fromPointerToNext(savedPrevp);
if (!prev->hasAvailableArenas())
insertPoint = availableListHeadp;
}
chunk->insertToAvailableList(insertPoint);
} else {
JS_ASSERT(chunk->info.prevp);
}
if (rt->gcChunkAllocationSinceLastGC) {
/*
* The allocator thread has started to get new chunks. We should stop
* to avoid decommitting arenas in just allocated chunks.
*/
return;
}
}
/*
* chunk->info.prevp becomes null when the allocator thread consumed
* all chunks from the available list.
*/
JS_ASSERT_IF(chunk->info.prevp, *chunk->info.prevp == chunk);
if (chunk->info.prevp == availableListHeadp || !chunk->info.prevp)
break;
/*
* prevp exists and is not the list head. It must point to the next
* field of the previous chunk.
*/
chunk = chunk->getPrevious();
}
}
static void
DecommitArenas(JSRuntime *rt)
{
DecommitArenasFromAvailableList(rt, &rt->gcSystemAvailableChunkListHead);
DecommitArenasFromAvailableList(rt, &rt->gcUserAvailableChunkListHead);
}
/* Must be called with the GC lock taken. */
static void
ExpireChunksAndArenas(JSRuntime *rt, bool shouldShrink)
{
if (Chunk *toFree = rt->gcChunkPool.expire(rt, shouldShrink)) {
AutoUnlockGC unlock(rt);
FreeChunkList(toFree);
}
if (shouldShrink)
DecommitArenas(rt);
}
static void
SweepBackgroundThings(JSRuntime* rt, bool onBackgroundThread)
{
/*
* We must finalize in the correct order, see comments in
* finalizeObjects.
*/
FreeOp fop(rt, false);
for (int phase = 0 ; phase < BackgroundPhaseCount ; ++phase) {
for (Zone *zone = rt->gcSweepingZones; zone; zone = zone->gcNextGraphNode) {
for (int index = 0 ; index < BackgroundPhaseLength[phase] ; ++index) {
AllocKind kind = BackgroundPhases[phase][index];
ArenaHeader *arenas = zone->allocator.arenas.arenaListsToSweep[kind];
if (arenas)
ArenaLists::backgroundFinalize(&fop, arenas, onBackgroundThread);
}
}
}
rt->gcSweepingZones = NULL;
}
#ifdef JS_THREADSAFE
static void
AssertBackgroundSweepingFinished(JSRuntime *rt)
{
JS_ASSERT(!rt->gcSweepingZones);
for (ZonesIter zone(rt); !zone.done(); zone.next()) {
for (unsigned i = 0; i < FINALIZE_LIMIT; ++i) {
JS_ASSERT(!zone->allocator.arenas.arenaListsToSweep[i]);
JS_ASSERT(zone->allocator.arenas.doneBackgroundFinalize(AllocKind(i)));
}
}
}
unsigned
js::GetCPUCount()
{
static unsigned ncpus = 0;
if (ncpus == 0) {
# ifdef XP_WIN
SYSTEM_INFO sysinfo;
GetSystemInfo(&sysinfo);
ncpus = unsigned(sysinfo.dwNumberOfProcessors);
# else
long n = sysconf(_SC_NPROCESSORS_ONLN);
ncpus = (n > 0) ? unsigned(n) : 1;
# endif
}
return ncpus;
}
#endif /* JS_THREADSAFE */
bool
GCHelperThread::init()
{
if (!rt->useHelperThreads()) {
backgroundAllocation = false;
return true;
}
#ifdef JS_THREADSAFE
if (!(wakeup = PR_NewCondVar(rt->gcLock)))
return false;
if (!(done = PR_NewCondVar(rt->gcLock)))
return false;
thread = PR_CreateThread(PR_USER_THREAD, threadMain, this, PR_PRIORITY_NORMAL,
PR_GLOBAL_THREAD, PR_JOINABLE_THREAD, 0);
if (!thread)
return false;
backgroundAllocation = (GetCPUCount() >= 2);
#endif /* JS_THREADSAFE */
return true;
}
void
GCHelperThread::finish()
{
if (!rt->useHelperThreads()) {
JS_ASSERT(state == IDLE);
return;
}
#ifdef JS_THREADSAFE
PRThread *join = NULL;
{
AutoLockGC lock(rt);
if (thread && state != SHUTDOWN) {
/*
* We cannot be in the ALLOCATING or CANCEL_ALLOCATION states as
* the allocations should have been stopped during the last GC.
*/
JS_ASSERT(state == IDLE || state == SWEEPING);
if (state == IDLE)
PR_NotifyCondVar(wakeup);
state = SHUTDOWN;
join = thread;
}
}
if (join) {
/* PR_DestroyThread is not necessary. */
PR_JoinThread(join);
}
if (wakeup)
PR_DestroyCondVar(wakeup);
if (done)
PR_DestroyCondVar(done);
#endif /* JS_THREADSAFE */
}
#ifdef JS_THREADSAFE
/* static */
void
GCHelperThread::threadMain(void *arg)
{
PR_SetCurrentThreadName("JS GC Helper");
static_cast<GCHelperThread *>(arg)->threadLoop();
}
void
GCHelperThread::threadLoop()
{
AutoLockGC lock(rt);
/*
* Even on the first iteration the state can be SHUTDOWN or SWEEPING if
* the stop request or the GC and the corresponding startBackgroundSweep call
* happen before this thread has a chance to run.
*/
for (;;) {
switch (state) {
case SHUTDOWN:
return;
case IDLE:
PR_WaitCondVar(wakeup, PR_INTERVAL_NO_TIMEOUT);
break;
case SWEEPING:
doSweep();
if (state == SWEEPING)
state = IDLE;
PR_NotifyAllCondVar(done);
break;
case ALLOCATING:
do {
Chunk *chunk;
{
AutoUnlockGC unlock(rt);
chunk = Chunk::allocate(rt);
}
/* OOM stops the background allocation. */
if (!chunk)
break;
JS_ASSERT(chunk->info.numArenasFreeCommitted == ArenasPerChunk);
rt->gcNumArenasFreeCommitted += ArenasPerChunk;
rt->gcChunkPool.put(chunk);
} while (state == ALLOCATING && rt->gcChunkPool.wantBackgroundAllocation(rt));
if (state == ALLOCATING)
state = IDLE;
break;
case CANCEL_ALLOCATION:
state = IDLE;
PR_NotifyAllCondVar(done);
break;
}
}
}
#endif /* JS_THREADSAFE */
void
GCHelperThread::startBackgroundSweep(bool shouldShrink)
{
JS_ASSERT(rt->useHelperThreads());
#ifdef JS_THREADSAFE
AutoLockGC lock(rt);
JS_ASSERT(state == IDLE);
JS_ASSERT(!sweepFlag);
sweepFlag = true;
shrinkFlag = shouldShrink;
state = SWEEPING;
PR_NotifyCondVar(wakeup);
#endif /* JS_THREADSAFE */
}
/* Must be called with the GC lock taken. */
void
GCHelperThread::startBackgroundShrink()
{
JS_ASSERT(rt->useHelperThreads());
#ifdef JS_THREADSAFE
switch (state) {
case IDLE:
JS_ASSERT(!sweepFlag);
shrinkFlag = true;
state = SWEEPING;
PR_NotifyCondVar(wakeup);
break;
case SWEEPING:
shrinkFlag = true;
break;
case ALLOCATING:
case CANCEL_ALLOCATION:
/*
* If we have started background allocation there is nothing to
* shrink.
*/
break;
case SHUTDOWN:
JS_NOT_REACHED("No shrink on shutdown");
}
#endif /* JS_THREADSAFE */
}
void
GCHelperThread::waitBackgroundSweepEnd()
{
if (!rt->useHelperThreads()) {
JS_ASSERT(state == IDLE);
return;
}
#ifdef JS_THREADSAFE
AutoLockGC lock(rt);
while (state == SWEEPING)
PR_WaitCondVar(done, PR_INTERVAL_NO_TIMEOUT);
if (rt->gcIncrementalState == NO_INCREMENTAL)
AssertBackgroundSweepingFinished(rt);
#endif /* JS_THREADSAFE */
}
void
GCHelperThread::waitBackgroundSweepOrAllocEnd()
{
if (!rt->useHelperThreads()) {
JS_ASSERT(state == IDLE);
return;
}
#ifdef JS_THREADSAFE
AutoLockGC lock(rt);
if (state == ALLOCATING)
state = CANCEL_ALLOCATION;
while (state == SWEEPING || state == CANCEL_ALLOCATION)
PR_WaitCondVar(done, PR_INTERVAL_NO_TIMEOUT);
if (rt->gcIncrementalState == NO_INCREMENTAL)
AssertBackgroundSweepingFinished(rt);
#endif /* JS_THREADSAFE */
}
/* Must be called with the GC lock taken. */
inline void
GCHelperThread::startBackgroundAllocationIfIdle()
{
JS_ASSERT(rt->useHelperThreads());
#ifdef JS_THREADSAFE
if (state == IDLE) {
state = ALLOCATING;
PR_NotifyCondVar(wakeup);
}
#endif /* JS_THREADSAFE */
}
void
GCHelperThread::replenishAndFreeLater(void *ptr)
{
JS_ASSERT(freeCursor == freeCursorEnd);
do {
if (freeCursor && !freeVector.append(freeCursorEnd - FREE_ARRAY_LENGTH))
break;
freeCursor = (void **) js_malloc(FREE_ARRAY_SIZE);
if (!freeCursor) {
freeCursorEnd = NULL;
break;
}
freeCursorEnd = freeCursor + FREE_ARRAY_LENGTH;
*freeCursor++ = ptr;
return;
} while (false);
js_free(ptr);
}
#ifdef JS_THREADSAFE
/* Must be called with the GC lock taken. */
void
GCHelperThread::doSweep()
{
if (sweepFlag) {
sweepFlag = false;
AutoUnlockGC unlock(rt);
SweepBackgroundThings(rt, true);
if (freeCursor) {
void **array = freeCursorEnd - FREE_ARRAY_LENGTH;
freeElementsAndArray(array, freeCursor);
freeCursor = freeCursorEnd = NULL;
} else {
JS_ASSERT(!freeCursorEnd);
}
for (void ***iter = freeVector.begin(); iter != freeVector.end(); ++iter) {
void **array = *iter;
freeElementsAndArray(array, array + FREE_ARRAY_LENGTH);
}
freeVector.resize(0);
rt->freeLifoAlloc.freeAll();
}
bool shrinking = shrinkFlag;
ExpireChunksAndArenas(rt, shrinking);
/*
* The main thread may have called ShrinkGCBuffers while
* ExpireChunksAndArenas(rt, false) was running, so we recheck the flag
* afterwards.
*/
if (!shrinking && shrinkFlag) {
shrinkFlag = false;
ExpireChunksAndArenas(rt, true);
}
}
#endif /* JS_THREADSAFE */
bool
GCHelperThread::onBackgroundThread()
{
#ifdef JS_THREADSAFE
return PR_GetCurrentThread() == getThread();
#else
return false;
#endif
}
static bool
ReleaseObservedTypes(JSRuntime *rt)
{
bool releaseTypes = rt->gcZeal() != 0;
#ifndef JS_MORE_DETERMINISTIC
int64_t now = PRMJ_Now();
if (now >= rt->gcJitReleaseTime)
releaseTypes = true;
if (releaseTypes)
rt->gcJitReleaseTime = now + JIT_SCRIPT_RELEASE_TYPES_INTERVAL;
#endif
return releaseTypes;
}
/*
* It's simpler if we preserve the invariant that every zone has at least one
* compartment. If we know we're deleting the entire zone, then
* SweepCompartments is allowed to delete all compartments. In this case,
* |keepAtleastOne| is false. If some objects remain in the zone so that it
* cannot be deleted, then we set |keepAtleastOne| to true, which prohibits
* SweepCompartments from deleting every compartment. Instead, it preserves an
* arbitrary compartment in the zone.
*/
static void
SweepCompartments(FreeOp *fop, Zone *zone, bool keepAtleastOne, bool lastGC)
{
JSRuntime *rt = zone->rt;
JSDestroyCompartmentCallback callback = rt->destroyCompartmentCallback;
JSCompartment **read = zone->compartments.begin();
JSCompartment **end = zone->compartments.end();
JSCompartment **write = read;
bool foundOne = false;
while (read < end) {
JSCompartment *comp = *read++;
JS_ASSERT(comp != rt->atomsCompartment);
/*
* Don't delete the last compartment if all the ones before it were
* deleted and keepAtleastOne is true.
*/
bool dontDelete = read == end && !foundOne && keepAtleastOne;
if ((!comp->marked && !dontDelete) || lastGC) {
if (callback)
callback(fop, comp);
if (comp->principals)
JS_DropPrincipals(rt, comp->principals);
js_delete(comp);
} else {
*write++ = comp;
foundOne = true;
}
}
zone->compartments.resize(write - zone->compartments.begin());
JS_ASSERT_IF(keepAtleastOne, !zone->compartments.empty());
}
static void
SweepZones(FreeOp *fop, bool lastGC)
{
JSRuntime *rt = fop->runtime();
JS_ASSERT_IF(lastGC, !rt->hasContexts());
/* Skip the atomsCompartment zone. */
Zone **read = rt->zones.begin() + 1;
Zone **end = rt->zones.end();
Zone **write = read;
JS_ASSERT(rt->zones.length() >= 1);
JS_ASSERT(rt->zones[0] == rt->atomsCompartment->zone());
while (read < end) {
Zone *zone = *read++;
if (!zone->hold && zone->wasGCStarted()) {
if (zone->allocator.arenas.arenaListsAreEmpty() || lastGC) {
zone->allocator.arenas.checkEmptyFreeLists();
SweepCompartments(fop, zone, false, lastGC);
JS_ASSERT(zone->compartments.empty());
fop->delete_(zone);
continue;
}
SweepCompartments(fop, zone, true, lastGC);
}
*write++ = zone;
}
rt->zones.resize(write - rt->zones.begin());
}
static void
PurgeRuntime(JSRuntime *rt)
{
for (GCCompartmentsIter comp(rt); !comp.done(); comp.next())
comp->purge();
rt->freeLifoAlloc.transferUnusedFrom(&rt->tempLifoAlloc);
rt->gsnCache.purge();
rt->propertyCache.purge(rt);
rt->newObjectCache.purge();
rt->nativeIterCache.purge();
rt->sourceDataCache.purge();
rt->evalCache.clear();
if (!rt->activeCompilations)
rt->parseMapPool.purgeAll();
}
static bool
ShouldPreserveJITCode(JSCompartment *comp, int64_t currentTime)
{
if (comp->rt->gcShouldCleanUpEverything || !comp->zone()->types.inferenceEnabled)
return false;
if (comp->rt->alwaysPreserveCode)
return true;
if (comp->lastAnimationTime + PRMJ_USEC_PER_SEC >= currentTime &&
comp->lastCodeRelease + (PRMJ_USEC_PER_SEC * 300) >= currentTime)
{
return true;
}
comp->lastCodeRelease = currentTime;
return false;
}
#ifdef DEBUG
struct CompartmentCheckTracer : public JSTracer
{
Cell *src;
JSGCTraceKind srcKind;
Zone *zone;
JSCompartment *compartment;
};
static bool
InCrossCompartmentMap(JSObject *src, Cell *dst, JSGCTraceKind dstKind)
{
JSCompartment *srccomp = src->compartment();
if (dstKind == JSTRACE_OBJECT) {
Value key = ObjectValue(*static_cast<JSObject *>(dst));
if (WrapperMap::Ptr p = srccomp->lookupWrapper(key)) {
if (*p->value.unsafeGet() == ObjectValue(*src))
return true;
}
}
/*
* If the cross-compartment edge is caused by the debugger, then we don't
* know the right hashtable key, so we have to iterate.
*/
for (JSCompartment::WrapperEnum e(srccomp); !e.empty(); e.popFront()) {
if (e.front().key.wrapped == dst && ToMarkable(e.front().value) == src)
return true;
}
return false;
}
static void
CheckCompartment(CompartmentCheckTracer *trc, JSCompartment *thingCompartment,
Cell *thing, JSGCTraceKind kind)
{
JS_ASSERT(thingCompartment == trc->compartment ||
thingCompartment == trc->runtime->atomsCompartment ||
(trc->srcKind == JSTRACE_OBJECT &&
InCrossCompartmentMap((JSObject *)trc->src, thing, kind)));
}
static JSCompartment *
CompartmentOfCell(Cell *thing, JSGCTraceKind kind)
{
if (kind == JSTRACE_OBJECT)
return static_cast<JSObject *>(thing)->compartment();
else if (kind == JSTRACE_SHAPE)
return static_cast<Shape *>(thing)->compartment();
else if (kind == JSTRACE_BASE_SHAPE)
return static_cast<BaseShape *>(thing)->compartment();
else if (kind == JSTRACE_SCRIPT)
return static_cast<JSScript *>(thing)->compartment();
else
return NULL;
}
static void
CheckCompartmentCallback(JSTracer *trcArg, void **thingp, JSGCTraceKind kind)
{
CompartmentCheckTracer *trc = static_cast<CompartmentCheckTracer *>(trcArg);
Cell *thing = (Cell *)*thingp;
JSCompartment *comp = CompartmentOfCell(thing, kind);
if (comp && trc->compartment) {
CheckCompartment(trc, comp, thing, kind);
} else {
JS_ASSERT(thing->tenuredZone() == trc->zone ||
thing->tenuredZone() == trc->runtime->atomsCompartment->zone());
}
}
static void
CheckForCompartmentMismatches(JSRuntime *rt)
{
if (rt->gcDisableStrictProxyCheckingCount)
return;
CompartmentCheckTracer trc;
JS_TracerInit(&trc, rt, CheckCompartmentCallback);
for (ZonesIter zone(rt); !zone.done(); zone.next()) {
trc.zone = zone;
for (size_t thingKind = 0; thingKind < FINALIZE_LAST; thingKind++) {
for (CellIterUnderGC i(zone, AllocKind(thingKind)); !i.done(); i.next()) {
trc.src = i.getCell();
trc.srcKind = MapAllocToTraceKind(AllocKind(thingKind));
trc.compartment = CompartmentOfCell(trc.src, trc.srcKind);
JS_TraceChildren(&trc, trc.src, trc.srcKind);
}
}
}
}
#endif
static bool
BeginMarkPhase(JSRuntime *rt)
{
int64_t currentTime = PRMJ_Now();
#ifdef DEBUG
if (rt->gcFullCompartmentChecks)
CheckForCompartmentMismatches(rt);
#endif
rt->gcIsFull = true;
bool any = false;
for (ZonesIter zone(rt); !zone.done(); zone.next()) {
/* Assert that zone state is as we expect */
JS_ASSERT(!zone->isCollecting());
JS_ASSERT(!zone->compartments.empty());
for (unsigned i = 0; i < FINALIZE_LIMIT; ++i)
JS_ASSERT(!zone->allocator.arenas.arenaListsToSweep[i]);
/* Set up which zones will be collected. */
if (zone->isGCScheduled()) {
if (zone != rt->atomsCompartment->zone()) {
any = true;
zone->setGCState(Zone::Mark);
}
} else {
rt->gcIsFull = false;
}
zone->scheduledForDestruction = false;
zone->maybeAlive = zone->hold;
zone->setPreservingCode(false);
}
for (CompartmentsIter c(rt); !c.done(); c.next()) {
JS_ASSERT(!c->gcLiveArrayBuffers);
c->marked = false;
if (ShouldPreserveJITCode(c, currentTime))
c->zone()->setPreservingCode(true);
}
/* Check that at least one zone is scheduled for collection. */
if (!any)
return false;
/*
* Atoms are not in the cross-compartment map. So if there are any
* zones that are not being collected, we are not allowed to collect
* atoms. Otherwise, the non-collected zones could contain pointers
* to atoms that we would miss.
*/
Zone *atomsZone = rt->atomsCompartment->zone();
if (atomsZone->isGCScheduled() && rt->gcIsFull && !rt->gcKeepAtoms) {
JS_ASSERT(!atomsZone->isCollecting());
atomsZone->setGCState(Zone::Mark);
}
/*
* At the end of each incremental slice, we call prepareForIncrementalGC,
* which marks objects in all arenas that we're currently allocating
* into. This can cause leaks if unreachable objects are in these
* arenas. This purge call ensures that we only mark arenas that have had
* allocations after the incremental GC started.
*/
if (rt->gcIsIncremental) {
for (GCZonesIter zone(rt); !zone.done(); zone.next())
zone->allocator.arenas.purge();
}
rt->gcMarker.start();
JS_ASSERT(!rt->gcMarker.callback);
JS_ASSERT(IS_GC_MARKING_TRACER(&rt->gcMarker));
/* For non-incremental GC the following sweep discards the jit code. */
if (rt->gcIsIncremental) {
for (GCZonesIter zone(rt); !zone.done(); zone.next()) {
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_MARK_DISCARD_CODE);
zone->discardJitCode(rt->defaultFreeOp(), false);
}
}
GCMarker *gcmarker = &rt->gcMarker;
rt->gcStartNumber = rt->gcNumber;
/*
* We must purge the runtime at the beginning of an incremental GC. The
* danger if we purge later is that the snapshot invariant of incremental
* GC will be broken, as follows. If some object is reachable only through
* some cache (say the dtoaCache) then it will not be part of the snapshot.
* If we purge after root marking, then the mutator could obtain a pointer
* to the object and start using it. This object might never be marked, so
* a GC hazard would exist.
*/
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_PURGE);
PurgeRuntime(rt);
}
/*
* Mark phase.
*/
gcstats::AutoPhase ap1(rt->gcStats, gcstats::PHASE_MARK);
gcstats::AutoPhase ap2(rt->gcStats, gcstats::PHASE_MARK_ROOTS);
for (GCZonesIter zone(rt); !zone.done(); zone.next()) {
/* Unmark everything in the zones being collected. */
zone->allocator.arenas.unmarkAll();
}
for (GCCompartmentsIter c(rt); !c.done(); c.next()) {
/* Reset weak map list for the compartments being collected. */
WeakMapBase::resetCompartmentWeakMapList(c);
}
MarkRuntime(gcmarker);
BufferGrayRoots(gcmarker);
/*
* This code ensures that if a zone is "dead", then it will be
* collected in this GC. A zone is considered dead if its maybeAlive
* flag is false. The maybeAlive flag is set if:
* (1) the zone has incoming cross-compartment edges, or
* (2) an object in the zone was marked during root marking, either
* as a black root or a gray root.
* If the maybeAlive is false, then we set the scheduledForDestruction flag.
* At any time later in the GC, if we try to mark an object whose
* zone is scheduled for destruction, we will assert.
* NOTE: Due to bug 811587, we only assert if gcManipulatingDeadCompartments
* is true (e.g., if we're doing a brain transplant).
*
* The purpose of this check is to ensure that a zone that we would
* normally destroy is not resurrected by a read barrier or an
* allocation. This might happen during a function like JS_TransplantObject,
* which iterates over all compartments, live or dead, and operates on their
* objects. See bug 803376 for details on this problem. To avoid the
* problem, we are very careful to avoid allocation and read barriers during
* JS_TransplantObject and the like. The code here ensures that we don't
* regress.
*
* Note that there are certain cases where allocations or read barriers in
* dead zone are difficult to avoid. We detect such cases (via the
* gcObjectsMarkedInDeadCompartment counter) and redo any ongoing GCs after
* the JS_TransplantObject function has finished. This ensures that the dead
* zones will be cleaned up. See AutoMarkInDeadZone and
* AutoMaybeTouchDeadZones for details.
*/
/* Set the maybeAlive flag based on cross-compartment edges. */
for (CompartmentsIter c(rt); !c.done(); c.next()) {
for (JSCompartment::WrapperEnum e(c); !e.empty(); e.popFront()) {
Cell *dst = e.front().key.wrapped;
dst->tenuredZone()->maybeAlive = true;
}
}
/*
* For black roots, code in gc/Marking.cpp will already have set maybeAlive
* during MarkRuntime.
*/
for (GCZonesIter zone(rt); !zone.done(); zone.next()) {
if (!zone->maybeAlive)
zone->scheduledForDestruction = true;
}
rt->gcFoundBlackGrayEdges = false;
return true;
}
template <class CompartmentIterT>
static void
MarkWeakReferences(JSRuntime *rt, gcstats::Phase phase)
{
GCMarker *gcmarker = &rt->gcMarker;
JS_ASSERT(gcmarker->isDrained());
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_SWEEP_MARK);
gcstats::AutoPhase ap1(rt->gcStats, phase);
for (;;) {
bool markedAny = false;
for (CompartmentIterT c(rt); !c.done(); c.next()) {
markedAny |= WatchpointMap::markCompartmentIteratively(c, gcmarker);
markedAny |= WeakMapBase::markCompartmentIteratively(c, gcmarker);
}
markedAny |= Debugger::markAllIteratively(gcmarker);
if (!markedAny)
break;
SliceBudget budget;
gcmarker->drainMarkStack(budget);
}
JS_ASSERT(gcmarker->isDrained());
}
static void
MarkWeakReferencesInCurrentGroup(JSRuntime *rt, gcstats::Phase phase)
{
MarkWeakReferences<GCCompartmentGroupIter>(rt, phase);
}
template <class ZoneIterT, class CompartmentIterT>
static void
MarkGrayReferences(JSRuntime *rt)
{
GCMarker *gcmarker = &rt->gcMarker;
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_SWEEP_MARK);
gcstats::AutoPhase ap1(rt->gcStats, gcstats::PHASE_SWEEP_MARK_GRAY);
gcmarker->setMarkColorGray();
if (gcmarker->hasBufferedGrayRoots()) {
for (ZoneIterT zone(rt); !zone.done(); zone.next())
gcmarker->markBufferedGrayRoots(zone);
} else {
JS_ASSERT(!rt->gcIsIncremental);
if (JSTraceDataOp op = rt->gcGrayRootsTraceOp)
(*op)(gcmarker, rt->gcGrayRootsData);
}
SliceBudget budget;
gcmarker->drainMarkStack(budget);
}
MarkWeakReferences<CompartmentIterT>(rt, gcstats::PHASE_SWEEP_MARK_GRAY_WEAK);
JS_ASSERT(gcmarker->isDrained());
gcmarker->setMarkColorBlack();
}
static void
MarkGrayReferencesInCurrentGroup(JSRuntime *rt)
{
MarkGrayReferences<GCZoneGroupIter, GCCompartmentGroupIter>(rt);
}
#ifdef DEBUG
static void
MarkAllWeakReferences(JSRuntime *rt, gcstats::Phase phase)
{
MarkWeakReferences<GCCompartmentsIter>(rt, phase);
}
static void
MarkAllGrayReferences(JSRuntime *rt)
{
MarkGrayReferences<GCZonesIter, GCCompartmentsIter>(rt);
}
class js::gc::MarkingValidator
{
public:
MarkingValidator(JSRuntime *rt);
~MarkingValidator();
void nonIncrementalMark();
void validate();
private:
JSRuntime *runtime;
bool initialized;
typedef HashMap<Chunk *, ChunkBitmap *, GCChunkHasher, SystemAllocPolicy> BitmapMap;
BitmapMap map;
};
js::gc::MarkingValidator::MarkingValidator(JSRuntime *rt)
: runtime(rt),
initialized(false)
{}
js::gc::MarkingValidator::~MarkingValidator()
{
if (!map.initialized())
return;
for (BitmapMap::Range r(map.all()); !r.empty(); r.popFront())
js_delete(r.front().value);
}
void
js::gc::MarkingValidator::nonIncrementalMark()
{
/*
* Perform a non-incremental mark for all collecting zones and record
* the results for later comparison.
*
* Currently this does not validate gray marking.
*/
if (!map.init())
return;
GCMarker *gcmarker = &runtime->gcMarker;
/* Save existing mark bits. */
for (GCChunkSet::Range r(runtime->gcChunkSet.all()); !r.empty(); r.popFront()) {
ChunkBitmap *bitmap = &r.front()->bitmap;
ChunkBitmap *entry = js_new<ChunkBitmap>();
if (!entry)
return;
memcpy((void *)entry->bitmap, (void *)bitmap->bitmap, sizeof(bitmap->bitmap));
if (!map.putNew(r.front(), entry))
return;
}
/*
* Save the lists of live weakmaps and array buffers for the compartments we
* are collecting.
*/
WeakMapVector weakmaps;
ArrayBufferVector arrayBuffers;
for (GCCompartmentsIter c(runtime); !c.done(); c.next()) {
if (!WeakMapBase::saveCompartmentWeakMapList(c, weakmaps) ||
!ArrayBufferObject::saveArrayBufferList(c, arrayBuffers))
{
return;
}
}
/*
* After this point, the function should run to completion, so we shouldn't
* do anything fallible.
*/
initialized = true;
/*
* Reset the lists of live weakmaps and array buffers for the compartments we
* are collecting.
*/
for (GCCompartmentsIter c(runtime); !c.done(); c.next()) {
WeakMapBase::resetCompartmentWeakMapList(c);
ArrayBufferObject::resetArrayBufferList(c);
}
/* Re-do all the marking, but non-incrementally. */
js::gc::State state = runtime->gcIncrementalState;
runtime->gcIncrementalState = MARK_ROOTS;
JS_ASSERT(gcmarker->isDrained());
gcmarker->reset();
for (GCChunkSet::Range r(runtime->gcChunkSet.all()); !r.empty(); r.popFront())
r.front()->bitmap.clear();
{
gcstats::AutoPhase ap1(runtime->gcStats, gcstats::PHASE_MARK);
gcstats::AutoPhase ap2(runtime->gcStats, gcstats::PHASE_MARK_ROOTS);
MarkRuntime(gcmarker, true);
}
SliceBudget budget;
runtime->gcIncrementalState = MARK;
runtime->gcMarker.drainMarkStack(budget);
{
gcstats::AutoPhase ap(runtime->gcStats, gcstats::PHASE_SWEEP);
MarkAllWeakReferences(runtime, gcstats::PHASE_SWEEP_MARK_WEAK);
/* Update zone state for gray marking. */
for (GCZonesIter zone(runtime); !zone.done(); zone.next()) {
JS_ASSERT(zone->isGCMarkingBlack());
zone->setGCState(Zone::MarkGray);
}
MarkAllGrayReferences(runtime);
/* Restore zone state. */
for (GCZonesIter zone(runtime); !zone.done(); zone.next()) {
JS_ASSERT(zone->isGCMarkingGray());
zone->setGCState(Zone::Mark);
}
}
/* Take a copy of the non-incremental mark state and restore the original. */
for (GCChunkSet::Range r(runtime->gcChunkSet.all()); !r.empty(); r.popFront()) {
Chunk *chunk = r.front();
ChunkBitmap *bitmap = &chunk->bitmap;
ChunkBitmap *entry = map.lookup(chunk)->value;
js::Swap(*entry, *bitmap);
}
/* Restore the weak map and array buffer lists. */
for (GCCompartmentsIter c(runtime); !c.done(); c.next()) {
WeakMapBase::resetCompartmentWeakMapList(c);
ArrayBufferObject::resetArrayBufferList(c);
}
WeakMapBase::restoreCompartmentWeakMapLists(weakmaps);
ArrayBufferObject::restoreArrayBufferLists(arrayBuffers);
runtime->gcIncrementalState = state;
}
void
js::gc::MarkingValidator::validate()
{
/*
* Validates the incremental marking for a single compartment by comparing
* the mark bits to those previously recorded for a non-incremental mark.
*/
if (!initialized)
return;
for (GCChunkSet::Range r(runtime->gcChunkSet.all()); !r.empty(); r.popFront()) {
Chunk *chunk = r.front();
BitmapMap::Ptr ptr = map.lookup(chunk);
if (!ptr)
continue; /* Allocated after we did the non-incremental mark. */
ChunkBitmap *bitmap = ptr->value;
ChunkBitmap *incBitmap = &chunk->bitmap;
for (size_t i = 0; i < ArenasPerChunk; i++) {
if (chunk->decommittedArenas.get(i))
continue;
Arena *arena = &chunk->arenas[i];
if (!arena->aheader.allocated())
continue;
if (!arena->aheader.zone->isGCSweeping())
continue;
if (arena->aheader.allocatedDuringIncremental)
continue;
AllocKind kind = arena->aheader.getAllocKind();
uintptr_t thing = arena->thingsStart(kind);
uintptr_t end = arena->thingsEnd();
while (thing < end) {
Cell *cell = (Cell *)thing;
/*
* If a non-incremental GC wouldn't have collected a cell, then
* an incremental GC won't collect it.
*/
JS_ASSERT_IF(bitmap->isMarked(cell, BLACK), incBitmap->isMarked(cell, BLACK));
/*
* If the cycle collector isn't allowed to collect an object
* after a non-incremental GC has run, then it isn't allowed to
* collected it after an incremental GC.
*/
JS_ASSERT_IF(!bitmap->isMarked(cell, GRAY), !incBitmap->isMarked(cell, GRAY));
thing += Arena::thingSize(kind);
}
}
}
}
#endif
static void
ComputeNonIncrementalMarkingForValidation(JSRuntime *rt)
{
#ifdef DEBUG
JS_ASSERT(!rt->gcMarkingValidator);
if (rt->gcIsIncremental && rt->gcValidate)
rt->gcMarkingValidator = js_new<MarkingValidator>(rt);
if (rt->gcMarkingValidator)
rt->gcMarkingValidator->nonIncrementalMark();
#endif
}
static void
ValidateIncrementalMarking(JSRuntime *rt)
{
#ifdef DEBUG
if (rt->gcMarkingValidator)
rt->gcMarkingValidator->validate();
#endif
}
static void
FinishMarkingValidation(JSRuntime *rt)
{
#ifdef DEBUG
js_delete(rt->gcMarkingValidator);
rt->gcMarkingValidator = NULL;
#endif
}
static void
AssertNeedsBarrierFlagsConsistent(JSRuntime *rt)
{
#ifdef DEBUG
bool anyNeedsBarrier = false;
for (ZonesIter zone(rt); !zone.done(); zone.next())
anyNeedsBarrier |= zone->needsBarrier();
JS_ASSERT(rt->needsBarrier() == anyNeedsBarrier);
#endif
}
static void
DropStringWrappers(JSRuntime *rt)
{
/*
* String "wrappers" are dropped on GC because their presence would require
* us to sweep the wrappers in all compartments every time we sweep a
* compartment group.
*/
for (CompartmentsIter c(rt); !c.done(); c.next()) {
for (JSCompartment::WrapperEnum e(c); !e.empty(); e.popFront()) {
if (e.front().key.kind == CrossCompartmentKey::StringWrapper)
e.removeFront();
}
}
}
/*
* Group zones that must be swept at the same time.
*
* If compartment A has an edge to an unmarked object in compartment B, then we
* must not sweep A in a later slice than we sweep B. That's because a write
* barrier in A that could lead to the unmarked object in B becoming
* marked. However, if we had already swept that object, we would be in trouble.
*
* If we consider these dependencies as a graph, then all the compartments in
* any strongly-connected component of this graph must be swept in the same
* slice.
*
* Tarjan's algorithm is used to calculate the components.
*/
void
JSCompartment::findOutgoingEdges(ComponentFinder<JS::Zone> &finder)
{
for (js::WrapperMap::Enum e(crossCompartmentWrappers); !e.empty(); e.popFront()) {
CrossCompartmentKey::Kind kind = e.front().key.kind;
JS_ASSERT(kind != CrossCompartmentKey::StringWrapper);
Cell *other = e.front().key.wrapped;
if (kind == CrossCompartmentKey::ObjectWrapper) {
/*
* Add edge to wrapped object compartment if wrapped object is not
* marked black to indicate that wrapper compartment not be swept
* after wrapped compartment.
*/
if (!other->isMarked(BLACK) || other->isMarked(GRAY)) {
JS::Zone *w = other->tenuredZone();
if (w->isGCMarking())
finder.addEdgeTo(w);
}
} else {
JS_ASSERT(kind == CrossCompartmentKey::DebuggerScript ||
kind == CrossCompartmentKey::DebuggerSource ||
kind == CrossCompartmentKey::DebuggerObject ||
kind == CrossCompartmentKey::DebuggerEnvironment);
/*
* Add edge for debugger object wrappers, to ensure (in conjuction
* with call to Debugger::findCompartmentEdges below) that debugger
* and debuggee objects are always swept in the same group.
*/
JS::Zone *w = other->tenuredZone();
if (w->isGCMarking())
finder.addEdgeTo(w);
}
}
Debugger::findCompartmentEdges(zone(), finder);
}
void
Zone::findOutgoingEdges(ComponentFinder<JS::Zone> &finder)
{
/*
* Any compartment may have a pointer to an atom in the atoms
* compartment, and these aren't in the cross compartment map.
*/
if (rt->atomsCompartment->zone()->isGCMarking())
finder.addEdgeTo(rt->atomsCompartment->zone());
for (CompartmentsInZoneIter comp(this); !comp.done(); comp.next())
comp->findOutgoingEdges(finder);
}
static void
FindZoneGroups(JSRuntime *rt)
{
ComponentFinder<Zone> finder(rt->mainThread.nativeStackLimit);
if (!rt->gcIsIncremental)
finder.useOneComponent();
for (GCZonesIter zone(rt); !zone.done(); zone.next()) {
JS_ASSERT(zone->isGCMarking());
finder.addNode(zone);
}
rt->gcZoneGroups = finder.getResultsList();
rt->gcCurrentZoneGroup = rt->gcZoneGroups;
rt->gcZoneGroupIndex = 0;
}
static void
ResetGrayList(JSCompartment* comp);
static void
GetNextZoneGroup(JSRuntime *rt)
{
rt->gcCurrentZoneGroup = rt->gcCurrentZoneGroup->nextGroup();
++rt->gcZoneGroupIndex;
if (!rt->gcCurrentZoneGroup) {
rt->gcAbortSweepAfterCurrentGroup = false;
return;
}
if (!rt->gcIsIncremental)
ComponentFinder<Zone>::mergeGroups(rt->gcCurrentZoneGroup);
if (rt->gcAbortSweepAfterCurrentGroup) {
JS_ASSERT(!rt->gcIsIncremental);
for (GCZoneGroupIter zone(rt); !zone.done(); zone.next()) {
JS_ASSERT(!zone->gcNextGraphComponent);
JS_ASSERT(zone->isGCMarking());
zone->setNeedsBarrier(false, Zone::UpdateIon);
zone->setGCState(Zone::NoGC);
zone->gcGrayRoots.clearAndFree();
}
rt->setNeedsBarrier(false);
AssertNeedsBarrierFlagsConsistent(rt);
for (GCCompartmentGroupIter comp(rt); !comp.done(); comp.next()) {
ArrayBufferObject::resetArrayBufferList(comp);
ResetGrayList(comp);
}
rt->gcAbortSweepAfterCurrentGroup = false;
rt->gcCurrentZoneGroup = NULL;
}
}
/*
* Gray marking:
*
* At the end of collection, anything reachable from a gray root that has not
* otherwise been marked black must be marked gray.
*
* This means that when marking things gray we must not allow marking to leave
* the current compartment group, as that could result in things being marked
* grey when they might subsequently be marked black. To achieve this, when we
* find a cross compartment pointer we don't mark the referent but add it to a
* singly-linked list of incoming gray pointers that is stored with each
* compartment.
*
* The list head is stored in JSCompartment::gcIncomingGrayPointers and contains
* cross compartment wrapper objects. The next pointer is stored in the second
* extra slot of the cross compartment wrapper.
*
* The list is created during gray marking when one of the
* MarkCrossCompartmentXXX functions is called for a pointer that leaves the
* current compartent group. This calls DelayCrossCompartmentGrayMarking to
* push the referring object onto the list.
*
* The list is traversed and then unlinked in
* MarkIncomingCrossCompartmentPointers.
*/
static bool
IsGrayListObject(JSObject *obj)
{
JS_ASSERT(obj);
return IsCrossCompartmentWrapper(obj) && !IsDeadProxyObject(obj);
}
const unsigned JSSLOT_GC_GRAY_LINK = JSSLOT_PROXY_EXTRA + 1;
static unsigned
GrayLinkSlot(JSObject *obj)
{
JS_ASSERT(IsGrayListObject(obj));
return JSSLOT_GC_GRAY_LINK;
}
#ifdef DEBUG
static void
AssertNotOnGrayList(JSObject *obj)
{
JS_ASSERT_IF(IsGrayListObject(obj), obj->getReservedSlot(GrayLinkSlot(obj)).isUndefined());
}
#endif
static JSObject *
CrossCompartmentPointerReferent(JSObject *obj)
{
JS_ASSERT(IsGrayListObject(obj));
return &GetProxyPrivate(obj).toObject();
}
static JSObject *
NextIncomingCrossCompartmentPointer(JSObject *prev, bool unlink)
{
unsigned slot = GrayLinkSlot(prev);
JSObject *next = prev->getReservedSlot(slot).toObjectOrNull();
JS_ASSERT_IF(next, IsGrayListObject(next));
if (unlink)
prev->setSlot(slot, UndefinedValue());
return next;
}
void
js::DelayCrossCompartmentGrayMarking(JSObject *src)
{
JS_ASSERT(IsGrayListObject(src));
/* Called from MarkCrossCompartmentXXX functions. */
unsigned slot = GrayLinkSlot(src);
JSObject *dest = CrossCompartmentPointerReferent(src);
JSCompartment *comp = dest->compartment();
if (src->getReservedSlot(slot).isUndefined()) {
src->setCrossCompartmentSlot(slot, ObjectOrNullValue(comp->gcIncomingGrayPointers));
comp->gcIncomingGrayPointers = src;
} else {
JS_ASSERT(src->getReservedSlot(slot).isObjectOrNull());
}
#ifdef DEBUG
/*
* Assert that the object is in our list, also walking the list to check its
* integrity.
*/
JSObject *obj = comp->gcIncomingGrayPointers;
bool found = false;
while (obj) {
if (obj == src)
found = true;
obj = NextIncomingCrossCompartmentPointer(obj, false);
}
JS_ASSERT(found);
#endif
}
static void
MarkIncomingCrossCompartmentPointers(JSRuntime *rt, const uint32_t color)
{
JS_ASSERT(color == BLACK || color == GRAY);
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_SWEEP_MARK);
static const gcstats::Phase statsPhases[] = {
gcstats::PHASE_SWEEP_MARK_INCOMING_BLACK,
gcstats::PHASE_SWEEP_MARK_INCOMING_GRAY
};
gcstats::AutoPhase ap1(rt->gcStats, statsPhases[color]);
bool unlinkList = color == GRAY;
for (GCCompartmentGroupIter c(rt); !c.done(); c.next()) {
JS_ASSERT_IF(color == GRAY, c->zone()->isGCMarkingGray());
JS_ASSERT_IF(color == BLACK, c->zone()->isGCMarkingBlack());
JS_ASSERT_IF(c->gcIncomingGrayPointers, IsGrayListObject(c->gcIncomingGrayPointers));
for (JSObject *src = c->gcIncomingGrayPointers;
src;
src = NextIncomingCrossCompartmentPointer(src, unlinkList))
{
JSObject *dst = CrossCompartmentPointerReferent(src);
JS_ASSERT(dst->compartment() == c);
if (color == GRAY) {
if (IsObjectMarked(&src) && src->isMarked(GRAY))
MarkGCThingUnbarriered(&rt->gcMarker, (void**)&dst,
"cross-compartment gray pointer");
} else {
if (IsObjectMarked(&src) && !src->isMarked(GRAY))
MarkGCThingUnbarriered(&rt->gcMarker, (void**)&dst,
"cross-compartment black pointer");
}
}
if (unlinkList)
c->gcIncomingGrayPointers = NULL;
}
SliceBudget budget;
rt->gcMarker.drainMarkStack(budget);
}
static bool
RemoveFromGrayList(JSObject *wrapper)
{
if (!IsGrayListObject(wrapper))
return false;
unsigned slot = GrayLinkSlot(wrapper);
if (wrapper->getReservedSlot(slot).isUndefined())
return false; /* Not on our list. */
JSObject *tail = wrapper->getReservedSlot(slot).toObjectOrNull();
wrapper->setReservedSlot(slot, UndefinedValue());
JSCompartment *comp = CrossCompartmentPointerReferent(wrapper)->compartment();
JSObject *obj = comp->gcIncomingGrayPointers;
if (obj == wrapper) {
comp->gcIncomingGrayPointers = tail;
return true;
}
while (obj) {
unsigned slot = GrayLinkSlot(obj);
JSObject *next = obj->getReservedSlot(slot).toObjectOrNull();
if (next == wrapper) {
obj->setCrossCompartmentSlot(slot, ObjectOrNullValue(tail));
return true;
}
obj = next;
}
JS_NOT_REACHED("object not found in gray link list");
return false;
}
static void
ResetGrayList(JSCompartment *comp)
{
JSObject *src = comp->gcIncomingGrayPointers;
while (src)
src = NextIncomingCrossCompartmentPointer(src, true);
comp->gcIncomingGrayPointers = NULL;
}
void
js::NotifyGCNukeWrapper(JSObject *obj)
{
/*
* References to target of wrapper are being removed, we no longer have to
* remember to mark it.
*/
RemoveFromGrayList(obj);
}
enum {
JS_GC_SWAP_OBJECT_A_REMOVED = 1 << 0,
JS_GC_SWAP_OBJECT_B_REMOVED = 1 << 1
};
unsigned
js::NotifyGCPreSwap(JSObject *a, JSObject *b)
{
/*
* Two objects in the same compartment are about to have had their contents
* swapped. If either of them are in our gray pointer list, then we remove
* them from the lists, returning a bitset indicating what happened.
*/
return (RemoveFromGrayList(a) ? JS_GC_SWAP_OBJECT_A_REMOVED : 0) |
(RemoveFromGrayList(b) ? JS_GC_SWAP_OBJECT_B_REMOVED : 0);
}
void
js::NotifyGCPostSwap(JSObject *a, JSObject *b, unsigned removedFlags)
{
/*
* Two objects in the same compartment have had their contents swapped. If
* either of them were in our gray pointer list, we re-add them again.
*/
if (removedFlags & JS_GC_SWAP_OBJECT_A_REMOVED)
DelayCrossCompartmentGrayMarking(b);
if (removedFlags & JS_GC_SWAP_OBJECT_B_REMOVED)
DelayCrossCompartmentGrayMarking(a);
}
static void
EndMarkingZoneGroup(JSRuntime *rt)
{
/*
* Mark any incoming black pointers from previously swept compartments
* whose referents are not marked. This can occur when gray cells become
* black by the action of UnmarkGray.
*/
MarkIncomingCrossCompartmentPointers(rt, BLACK);
MarkWeakReferencesInCurrentGroup(rt, gcstats::PHASE_SWEEP_MARK_WEAK);
/*
* Change state of current group to MarkGray to restrict marking to this
* group. Note that there may be pointers to the atoms compartment, and
* these will be marked through, as they are not marked with
* MarkCrossCompartmentXXX.
*/
for (GCZoneGroupIter zone(rt); !zone.done(); zone.next()) {
JS_ASSERT(zone->isGCMarkingBlack());
zone->setGCState(Zone::MarkGray);
}
/* Mark incoming gray pointers from previously swept compartments. */
rt->gcMarker.setMarkColorGray();
MarkIncomingCrossCompartmentPointers(rt, GRAY);
rt->gcMarker.setMarkColorBlack();
/* Mark gray roots and mark transitively inside the current compartment group. */
MarkGrayReferencesInCurrentGroup(rt);
/* Restore marking state. */
for (GCZoneGroupIter zone(rt); !zone.done(); zone.next()) {
JS_ASSERT(zone->isGCMarkingGray());
zone->setGCState(Zone::Mark);
}
JS_ASSERT(rt->gcMarker.isDrained());
}
static void
BeginSweepingZoneGroup(JSRuntime *rt)
{
/*
* Begin sweeping the group of zones in gcCurrentZoneGroup,
* performing actions that must be done before yielding to caller.
*/
bool sweepingAtoms = false;
for (GCZoneGroupIter zone(rt); !zone.done(); zone.next()) {
/* Set the GC state to sweeping. */
JS_ASSERT(zone->isGCMarking());
zone->setGCState(Zone::Sweep);
/* Purge the ArenaLists before sweeping. */
zone->allocator.arenas.purge();
if (zone == rt->atomsCompartment->zone())
sweepingAtoms = true;
}
ValidateIncrementalMarking(rt);
FreeOp fop(rt, rt->gcSweepOnBackgroundThread);
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_FINALIZE_START);
if (rt->gcFinalizeCallback)
rt->gcFinalizeCallback(&fop, JSFINALIZE_GROUP_START, !rt->gcIsFull /* unused */);
}
if (sweepingAtoms) {
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_SWEEP_ATOMS);
SweepAtoms(rt);
}
/* Prune out dead views from ArrayBuffer's view lists. */
for (GCCompartmentGroupIter c(rt); !c.done(); c.next())
ArrayBufferObject::sweep(c);
/* Collect watch points associated with unreachable objects. */
WatchpointMap::sweepAll(rt);
/* Detach unreachable debuggers and global objects from each other. */
Debugger::sweepAll(&fop);
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_SWEEP_COMPARTMENTS);
for (GCZoneGroupIter zone(rt); !zone.done(); zone.next()) {
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_SWEEP_DISCARD_CODE);
zone->discardJitCode(&fop, !zone->isPreservingCode());
}
bool releaseTypes = ReleaseObservedTypes(rt);
for (GCCompartmentGroupIter c(rt); !c.done(); c.next()) {
gcstats::AutoSCC scc(rt->gcStats, rt->gcZoneGroupIndex);
c->sweep(&fop, releaseTypes);
}
for (GCZoneGroupIter zone(rt); !zone.done(); zone.next()) {
gcstats::AutoSCC scc(rt->gcStats, rt->gcZoneGroupIndex);
zone->sweep(&fop, releaseTypes);
}
}
/*
* Queue all GC things in all zones for sweeping, either in the
* foreground or on the background thread.
*
* Note that order is important here for the background case.
*
* Objects are finalized immediately but this may change in the future.
*/
for (GCZoneGroupIter zone(rt); !zone.done(); zone.next()) {
gcstats::AutoSCC scc(rt->gcStats, rt->gcZoneGroupIndex);
zone->allocator.arenas.queueObjectsForSweep(&fop);
}
for (GCZoneGroupIter zone(rt); !zone.done(); zone.next()) {
gcstats::AutoSCC scc(rt->gcStats, rt->gcZoneGroupIndex);
zone->allocator.arenas.queueStringsForSweep(&fop);
}
for (GCZoneGroupIter zone(rt); !zone.done(); zone.next()) {
gcstats::AutoSCC scc(rt->gcStats, rt->gcZoneGroupIndex);
zone->allocator.arenas.queueScriptsForSweep(&fop);
}
#ifdef JS_ION
for (GCZoneGroupIter zone(rt); !zone.done(); zone.next()) {
gcstats::AutoSCC scc(rt->gcStats, rt->gcZoneGroupIndex);
zone->allocator.arenas.queueIonCodeForSweep(&fop);
}
#endif
for (GCZoneGroupIter zone(rt); !zone.done(); zone.next()) {
gcstats::AutoSCC scc(rt->gcStats, rt->gcZoneGroupIndex);
zone->allocator.arenas.queueShapesForSweep(&fop);
zone->allocator.arenas.gcShapeArenasToSweep =
zone->allocator.arenas.arenaListsToSweep[FINALIZE_SHAPE];
}
rt->gcSweepPhase = 0;
rt->gcSweepZone = rt->gcCurrentZoneGroup;
rt->gcSweepKindIndex = 0;
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_FINALIZE_END);
if (rt->gcFinalizeCallback)
rt->gcFinalizeCallback(&fop, JSFINALIZE_GROUP_END, !rt->gcIsFull /* unused */);
}
}
static void
EndSweepingZoneGroup(JSRuntime *rt)
{
/* Update the GC state for zones we have swept and unlink the list. */
for (GCZoneGroupIter zone(rt); !zone.done(); zone.next()) {
JS_ASSERT(zone->isGCSweeping());
zone->setGCState(Zone::Finished);
}
/* Reset the list of arenas marked as being allocated during sweep phase. */
while (ArenaHeader *arena = rt->gcArenasAllocatedDuringSweep) {
rt->gcArenasAllocatedDuringSweep = arena->getNextAllocDuringSweep();
arena->unsetAllocDuringSweep();
}
}
static void
BeginSweepPhase(JSRuntime *rt)
{
/*
* Sweep phase.
*
* Finalize as we sweep, outside of rt->gcLock but with rt->isHeapBusy()
* true 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_ASSERT(!rt->gcAbortSweepAfterCurrentGroup);
ComputeNonIncrementalMarkingForValidation(rt);
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_SWEEP);
#ifdef JS_THREADSAFE
rt->gcSweepOnBackgroundThread = rt->hasContexts() && rt->useHelperThreads();
#endif
#ifdef DEBUG
for (CompartmentsIter c(rt); !c.done(); c.next()) {
JS_ASSERT(!c->gcIncomingGrayPointers);
for (JSCompartment::WrapperEnum e(c); !e.empty(); e.popFront()) {
if (e.front().key.kind != CrossCompartmentKey::StringWrapper)
AssertNotOnGrayList(&e.front().value.get().toObject());
}
}
#endif
DropStringWrappers(rt);
FindZoneGroups(rt);
EndMarkingZoneGroup(rt);
BeginSweepingZoneGroup(rt);
}
bool
ArenaLists::foregroundFinalize(FreeOp *fop, AllocKind thingKind, SliceBudget &sliceBudget)
{
if (!arenaListsToSweep[thingKind])
return true;
ArenaList &dest = arenaLists[thingKind];
return FinalizeArenas(fop, &arenaListsToSweep[thingKind], dest, thingKind, sliceBudget);
}
static bool
DrainMarkStack(JSRuntime *rt, SliceBudget &sliceBudget, gcstats::Phase phase)
{
/* Run a marking slice and return whether the stack is now empty. */
gcstats::AutoPhase ap(rt->gcStats, phase);
return rt->gcMarker.drainMarkStack(sliceBudget);
}
static bool
SweepPhase(JSRuntime *rt, SliceBudget &sliceBudget)
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_SWEEP);
FreeOp fop(rt, rt->gcSweepOnBackgroundThread);
bool finished = DrainMarkStack(rt, sliceBudget, gcstats::PHASE_SWEEP_MARK);
if (!finished)
return false;
for (;;) {
/* Finalize foreground finalized things. */
for (; rt->gcSweepPhase < FinalizePhaseCount ; ++rt->gcSweepPhase) {
gcstats::AutoPhase ap(rt->gcStats, FinalizePhaseStatsPhase[rt->gcSweepPhase]);
for (; rt->gcSweepZone; rt->gcSweepZone = rt->gcSweepZone->nextNodeInGroup()) {
Zone *zone = rt->gcSweepZone;
while (rt->gcSweepKindIndex < FinalizePhaseLength[rt->gcSweepPhase]) {
AllocKind kind = FinalizePhases[rt->gcSweepPhase][rt->gcSweepKindIndex];
if (!zone->allocator.arenas.foregroundFinalize(&fop, kind, sliceBudget))
return false; /* Yield to the mutator. */
++rt->gcSweepKindIndex;
}
rt->gcSweepKindIndex = 0;
}
rt->gcSweepZone = rt->gcCurrentZoneGroup;
}
/* Remove dead shapes from the shape tree, but don't finalize them yet. */
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_SWEEP_SHAPE);
for (; rt->gcSweepZone; rt->gcSweepZone = rt->gcSweepZone->nextNodeInGroup()) {
Zone *zone = rt->gcSweepZone;
while (ArenaHeader *arena = zone->allocator.arenas.gcShapeArenasToSweep) {
for (CellIterUnderGC i(arena); !i.done(); i.next()) {
Shape *shape = i.get<Shape>();
if (!shape->isMarked())
shape->sweep();
}
zone->allocator.arenas.gcShapeArenasToSweep = arena->next;
sliceBudget.step(Arena::thingsPerArena(Arena::thingSize(FINALIZE_SHAPE)));
if (sliceBudget.isOverBudget())
return false; /* Yield to the mutator. */
}
}
}
EndSweepingZoneGroup(rt);
GetNextZoneGroup(rt);
if (!rt->gcCurrentZoneGroup)
return true; /* We're finished. */
EndMarkingZoneGroup(rt);
BeginSweepingZoneGroup(rt);
}
}
static void
EndSweepPhase(JSRuntime *rt, JSGCInvocationKind gckind, bool lastGC)
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_SWEEP);
FreeOp fop(rt, rt->gcSweepOnBackgroundThread);
JS_ASSERT_IF(lastGC, !rt->gcSweepOnBackgroundThread);
JS_ASSERT(rt->gcMarker.isDrained());
rt->gcMarker.stop();
/*
* Recalculate whether GC was full or not as this may have changed due to
* newly created zones. Can only change from full to not full.
*/
if (rt->gcIsFull) {
for (ZonesIter zone(rt); !zone.done(); zone.next()) {
if (!zone->isCollecting()) {
rt->gcIsFull = false;
break;
}
}
}
/*
* If we found any black->gray edges during marking, we completely clear the
* mark bits of all uncollected zones, or if a reset has occured, zones that
* will no longer be collected. This is safe, although it may
* prevent the cycle collector from collecting some dead objects.
*/
if (rt->gcFoundBlackGrayEdges) {
for (ZonesIter zone(rt); !zone.done(); zone.next()) {
if (!zone->isCollecting())
zone->allocator.arenas.unmarkAll();
}
}
#ifdef DEBUG
PropertyTree::dumpShapes(rt);
#endif
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_DESTROY);
/*
* Sweep script filenames after sweeping functions in the generic loop
* above. In this way when a scripted function's finalizer destroys the
* script and calls rt->destroyScriptHook, the hook can still access the
* script's filename. See bug 323267.
*/
if (rt->gcIsFull)
SweepScriptData(rt);
/* Clear out any small pools that we're hanging on to. */
if (JSC::ExecutableAllocator *execAlloc = rt->maybeExecAlloc())
execAlloc->purge();
/*
* This removes compartments from rt->compartment, so we do it last to make
* sure we don't miss sweeping any compartments.
*/
if (!lastGC)
SweepZones(&fop, lastGC);
if (!rt->gcSweepOnBackgroundThread) {
/*
* Destroy arenas after we finished the sweeping so finalizers can
* safely use IsAboutToBeFinalized(). This is done on the
* GCHelperThread if possible. We acquire the lock only because
* Expire needs to unlock it for other callers.
*/
AutoLockGC lock(rt);
ExpireChunksAndArenas(rt, gckind == GC_SHRINK);
}
}
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_FINALIZE_END);
if (rt->gcFinalizeCallback)
rt->gcFinalizeCallback(&fop, JSFINALIZE_COLLECTION_END, !rt->gcIsFull);
/* If we finished a full GC, then the gray bits are correct. */
if (rt->gcIsFull)
rt->gcGrayBitsValid = true;
}
/* Set up list of zones for sweeping of background things. */
JS_ASSERT(!rt->gcSweepingZones);
for (GCZonesIter zone(rt); !zone.done(); zone.next()) {
zone->gcNextGraphNode = rt->gcSweepingZones;
rt->gcSweepingZones = zone;
}
/* If not sweeping on background thread then we must do it here. */
if (!rt->gcSweepOnBackgroundThread) {
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_DESTROY);
SweepBackgroundThings(rt, false);
rt->freeLifoAlloc.freeAll();
/* Ensure the compartments get swept if it's the last GC. */
if (lastGC)
SweepZones(&fop, lastGC);
}
for (ZonesIter zone(rt); !zone.done(); zone.next()) {
zone->setGCLastBytes(zone->gcBytes, gckind);
if (zone->isCollecting()) {
JS_ASSERT(zone->isGCFinished());
zone->setGCState(Zone::NoGC);
}
#ifdef DEBUG
JS_ASSERT(!zone->isCollecting());
JS_ASSERT(!zone->wasGCStarted());
for (unsigned i = 0 ; i < FINALIZE_LIMIT ; ++i) {
JS_ASSERT_IF(!IsBackgroundFinalized(AllocKind(i)) ||
!rt->gcSweepOnBackgroundThread,
!zone->allocator.arenas.arenaListsToSweep[i]);
}
#endif
}
#ifdef DEBUG
for (CompartmentsIter c(rt); !c.done(); c.next()) {
JS_ASSERT(!c->gcIncomingGrayPointers);
JS_ASSERT(!c->gcLiveArrayBuffers);
for (JSCompartment::WrapperEnum e(c); !e.empty(); e.popFront()) {
if (e.front().key.kind != CrossCompartmentKey::StringWrapper)
AssertNotOnGrayList(&e.front().value.get().toObject());
}
}
#endif
FinishMarkingValidation(rt);
rt->gcLastGCTime = PRMJ_Now();
}
/* ...while this class is to be used only for garbage collection. */
class AutoGCSession : AutoTraceSession {
public:
explicit AutoGCSession(JSRuntime *rt);
~AutoGCSession();
};
/* Start a new heap session. */
AutoTraceSession::AutoTraceSession(JSRuntime *rt, js::HeapState heapState)
: runtime(rt),
prevState(rt->heapState)
{
JS_ASSERT(!rt->noGCOrAllocationCheck);
JS_ASSERT(!rt->isHeapBusy());
JS_ASSERT(heapState != Idle);
rt->heapState = heapState;
}
AutoTraceSession::~AutoTraceSession()
{
JS_ASSERT(runtime->isHeapBusy());
runtime->heapState = prevState;
}
AutoGCSession::AutoGCSession(JSRuntime *rt)
: AutoTraceSession(rt, MajorCollecting)
{
runtime->gcIsNeeded = false;
runtime->gcInterFrameGC = true;
runtime->gcNumber++;
}
AutoGCSession::~AutoGCSession()
{
#ifndef JS_MORE_DETERMINISTIC
runtime->gcNextFullGCTime = PRMJ_Now() + GC_IDLE_FULL_SPAN;
#endif
runtime->gcChunkAllocationSinceLastGC = false;
#ifdef JS_GC_ZEAL
/* Keeping these around after a GC is dangerous. */
runtime->gcSelectedForMarking.clearAndFree();
#endif
/* Clear gcMallocBytes for all compartments */
for (ZonesIter zone(runtime); !zone.done(); zone.next()) {
zone->resetGCMallocBytes();
zone->unscheduleGC();
}
runtime->resetGCMallocBytes();
}
AutoCopyFreeListToArenas::AutoCopyFreeListToArenas(JSRuntime *rt)
: runtime(rt)
{
for (ZonesIter zone(rt); !zone.done(); zone.next())
zone->allocator.arenas.copyFreeListsToArenas();
}
AutoCopyFreeListToArenas::~AutoCopyFreeListToArenas()
{
for (ZonesIter zone(runtime); !zone.done(); zone.next())
zone->allocator.arenas.clearFreeListsInArenas();
}
static void
IncrementalCollectSlice(JSRuntime *rt,
int64_t budget,
JS::gcreason::Reason gcReason,
JSGCInvocationKind gcKind);
static void
ResetIncrementalGC(JSRuntime *rt, const char *reason)
{
switch (rt->gcIncrementalState) {
case NO_INCREMENTAL:
return;
case MARK: {
/* Cancel any ongoing marking. */
AutoCopyFreeListToArenas copy(rt);
rt->gcMarker.reset();
rt->gcMarker.stop();
for (GCCompartmentsIter c(rt); !c.done(); c.next()) {
ArrayBufferObject::resetArrayBufferList(c);
ResetGrayList(c);
}
for (GCZonesIter zone(rt); !zone.done(); zone.next()) {
JS_ASSERT(zone->isGCMarking());
zone->setNeedsBarrier(false, Zone::UpdateIon);
zone->setGCState(Zone::NoGC);
}
rt->setNeedsBarrier(false);
AssertNeedsBarrierFlagsConsistent(rt);
rt->gcIncrementalState = NO_INCREMENTAL;
JS_ASSERT(!rt->gcStrictCompartmentChecking);
break;
}
case SWEEP:
rt->gcMarker.reset();
for (ZonesIter zone(rt); !zone.done(); zone.next())
zone->scheduledForDestruction = false;
/* Finish sweeping the current zone group, then abort. */
rt->gcAbortSweepAfterCurrentGroup = true;
IncrementalCollectSlice(rt, SliceBudget::Unlimited, JS::gcreason::RESET, GC_NORMAL);
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_WAIT_BACKGROUND_THREAD);
rt->gcHelperThread.waitBackgroundSweepOrAllocEnd();
}
break;
default:
JS_NOT_REACHED("Invalid incremental GC state");
}
rt->gcStats.reset(reason);
#ifdef DEBUG
for (CompartmentsIter c(rt); !c.done(); c.next())
JS_ASSERT(!c->gcLiveArrayBuffers);
for (ZonesIter zone(rt); !zone.done(); zone.next()) {
JS_ASSERT(!zone->needsBarrier());
for (unsigned i = 0; i < FINALIZE_LIMIT; ++i)
JS_ASSERT(!zone->allocator.arenas.arenaListsToSweep[i]);
}
#endif
}
class AutoGCSlice {
public:
AutoGCSlice(JSRuntime *rt);
~AutoGCSlice();
private:
JSRuntime *runtime;
};
AutoGCSlice::AutoGCSlice(JSRuntime *rt)
: runtime(rt)
{
/*
* During incremental GC, the compartment's active flag determines whether
* there are stack frames active for any of its scripts. Normally this flag
* is set at the beginning of the mark phase. During incremental GC, we also
* set it at the start of every phase.
*/
rt->stackSpace.markActiveCompartments();
for (GCZonesIter zone(rt); !zone.done(); zone.next()) {
/*
* Clear needsBarrier early so we don't do any write barriers during
* GC. We don't need to update the Ion barriers (which is expensive)
* because Ion code doesn't run during GC. If need be, we'll update the
* Ion barriers in ~AutoGCSlice.
*/
if (zone->isGCMarking()) {
JS_ASSERT(zone->needsBarrier());
zone->setNeedsBarrier(false, Zone::DontUpdateIon);
} else {
JS_ASSERT(!zone->needsBarrier());
}
}
rt->setNeedsBarrier(false);
AssertNeedsBarrierFlagsConsistent(rt);
}
AutoGCSlice::~AutoGCSlice()
{
/* We can't use GCZonesIter if this is the end of the last slice. */
bool haveBarriers = false;
for (ZonesIter zone(runtime); !zone.done(); zone.next()) {
if (zone->isGCMarking()) {
zone->setNeedsBarrier(true, Zone::UpdateIon);
zone->allocator.arenas.prepareForIncrementalGC(runtime);
haveBarriers = true;
} else {
zone->setNeedsBarrier(false, Zone::UpdateIon);
}
}
runtime->setNeedsBarrier(haveBarriers);
AssertNeedsBarrierFlagsConsistent(runtime);
}
static void
PushZealSelectedObjects(JSRuntime *rt)
{
#ifdef JS_GC_ZEAL
/* Push selected objects onto the mark stack and clear the list. */
for (JSObject **obj = rt->gcSelectedForMarking.begin();
obj != rt->gcSelectedForMarking.end(); obj++)
{
MarkObjectUnbarriered(&rt->gcMarker, obj, "selected obj");
}
#endif
}
static void
IncrementalCollectSlice(JSRuntime *rt,
int64_t budget,
JS::gcreason::Reason reason,
JSGCInvocationKind gckind)
{
AutoCopyFreeListToArenas copy(rt);
AutoGCSlice slice(rt);
gc::State initialState = rt->gcIncrementalState;
int zeal = 0;
#ifdef JS_GC_ZEAL
if (reason == JS::gcreason::DEBUG_GC && budget != SliceBudget::Unlimited) {
/*
* Do the incremental collection type specified by zeal mode if the
* collection was triggered by RunDebugGC() and incremental GC has not
* been cancelled by ResetIncrementalGC.
*/
zeal = rt->gcZeal();
}
#endif
JS_ASSERT_IF(rt->gcIncrementalState != NO_INCREMENTAL, rt->gcIsIncremental);
rt->gcIsIncremental = budget != SliceBudget::Unlimited;
if (zeal == ZealIncrementalRootsThenFinish || zeal == ZealIncrementalMarkAllThenFinish) {
/*
* Yields between slices occurs at predetermined points in these modes;
* the budget is not used.
*/
budget = SliceBudget::Unlimited;
}
SliceBudget sliceBudget(budget);
if (rt->gcIncrementalState == NO_INCREMENTAL) {
rt->gcIncrementalState = MARK_ROOTS;
rt->gcLastMarkSlice = false;
}
if (rt->gcIncrementalState == MARK)
AutoGCRooter::traceAllWrappers(&rt->gcMarker);
switch (rt->gcIncrementalState) {
case MARK_ROOTS:
if (!BeginMarkPhase(rt)) {
rt->gcIncrementalState = NO_INCREMENTAL;
return;
}
if (rt->hasContexts())
PushZealSelectedObjects(rt);
rt->gcIncrementalState = MARK;
if (zeal == ZealIncrementalRootsThenFinish)
break;
/* fall through */
case MARK: {
/* If we needed delayed marking for gray roots, then collect until done. */
if (!rt->gcMarker.hasBufferedGrayRoots())
sliceBudget.reset();
bool finished = DrainMarkStack(rt, sliceBudget, gcstats::PHASE_MARK);
if (!finished)
break;
JS_ASSERT(rt->gcMarker.isDrained());
if (!rt->gcLastMarkSlice &&
((initialState == MARK && budget != SliceBudget::Unlimited) ||
zeal == ZealIncrementalMarkAllThenFinish))
{
/*
* Yield with the aim of starting the sweep in the next
* slice. We will need to mark anything new on the stack
* when we resume, so we stay in MARK state.
*/
rt->gcLastMarkSlice = true;
break;
}
rt->gcIncrementalState = SWEEP;
/*
* This runs to completion, but we don't continue if the budget is
* now exhasted.
*/
BeginSweepPhase(rt);
if (sliceBudget.isOverBudget())
break;
/*
* Always yield here when running in incremental multi-slice zeal
* mode, so RunDebugGC can reset the slice buget.
*/
if (zeal == ZealIncrementalMultipleSlices)
break;
/* fall through */
}
case SWEEP: {
bool finished = SweepPhase(rt, sliceBudget);
if (!finished)
break;
EndSweepPhase(rt, gckind, reason == JS::gcreason::LAST_CONTEXT);
if (rt->gcSweepOnBackgroundThread)
rt->gcHelperThread.startBackgroundSweep(gckind == GC_SHRINK);
rt->gcIncrementalState = NO_INCREMENTAL;
break;
}
default:
JS_ASSERT(false);
}
}
IncrementalSafety
gc::IsIncrementalGCSafe(JSRuntime *rt)
{
JS_ASSERT(!rt->mainThread.suppressGC);
if (rt->gcKeepAtoms)
return IncrementalSafety::Unsafe("gcKeepAtoms set");
if (!rt->gcIncrementalEnabled)
return IncrementalSafety::Unsafe("incremental permanently disabled");
return IncrementalSafety::Safe();
}
static void
BudgetIncrementalGC(JSRuntime *rt, int64_t *budget)
{
IncrementalSafety safe = IsIncrementalGCSafe(rt);
if (!safe) {
ResetIncrementalGC(rt, safe.reason());
*budget = SliceBudget::Unlimited;
rt->gcStats.nonincremental(safe.reason());
return;
}
if (rt->gcMode != JSGC_MODE_INCREMENTAL) {
ResetIncrementalGC(rt, "GC mode change");
*budget = SliceBudget::Unlimited;
rt->gcStats.nonincremental("GC mode");
return;
}
if (rt->isTooMuchMalloc()) {
*budget = SliceBudget::Unlimited;
rt->gcStats.nonincremental("malloc bytes trigger");
}
bool reset = false;
for (ZonesIter zone(rt); !zone.done(); zone.next()) {
if (zone->gcBytes >= zone->gcTriggerBytes) {
*budget = SliceBudget::Unlimited;
rt->gcStats.nonincremental("allocation trigger");
}
if (rt->gcIncrementalState != NO_INCREMENTAL &&
zone->isGCScheduled() != zone->wasGCStarted())
{
reset = true;
}
if (zone->isTooMuchMalloc()) {
*budget = SliceBudget::Unlimited;
rt->gcStats.nonincremental("malloc bytes trigger");
}
}
if (reset)
ResetIncrementalGC(rt, "zone change");
}
/*
* GC, repeatedly if necessary, until we think we have not created any new
* garbage. We disable inlining to ensure that the bottom of the stack with
* possible GC roots recorded in MarkRuntime excludes any pointers we use during
* the marking implementation.
*/
static JS_NEVER_INLINE void
GCCycle(JSRuntime *rt, bool incremental, int64_t budget, JSGCInvocationKind gckind, JS::gcreason::Reason reason)
{
/* If we attempt to invoke the GC while we are running in the GC, assert. */
JS_ASSERT(!rt->isHeapBusy());
#ifdef DEBUG
for (ZonesIter zone(rt); !zone.done(); zone.next())
JS_ASSERT_IF(rt->gcMode == JSGC_MODE_GLOBAL, zone->isGCScheduled());
#endif
AutoGCSession gcsession(rt);
/*
* As we about to purge caches and clear the mark bits we must wait for
* any background finalization to finish. We must also wait for the
* background allocation to finish so we can avoid taking the GC lock
* when manipulating the chunks during the GC.
*/
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_WAIT_BACKGROUND_THREAD);
rt->gcHelperThread.waitBackgroundSweepOrAllocEnd();
}
{
if (!incremental) {
/* If non-incremental GC was requested, reset incremental GC. */
ResetIncrementalGC(rt, "requested");
rt->gcStats.nonincremental("requested");
budget = SliceBudget::Unlimited;
} else {
BudgetIncrementalGC(rt, &budget);
}
IncrementalCollectSlice(rt, budget, reason, gckind);
}
}
#ifdef JS_GC_ZEAL
static bool
IsDeterministicGCReason(JS::gcreason::Reason reason)
{
if (reason > JS::gcreason::DEBUG_GC &&
reason != JS::gcreason::CC_FORCED && reason != JS::gcreason::SHUTDOWN_CC)
{
return false;
}
if (reason == JS::gcreason::MAYBEGC)
return false;
return true;
}
#endif
static bool
ShouldCleanUpEverything(JSRuntime *rt, JS::gcreason::Reason reason, JSGCInvocationKind gckind)
{
// During shutdown, we must clean everything up, for the sake of leak
// detection. When a runtime has no contexts, or we're doing a GC before a
// shutdown CC, those are strong indications that we're shutting down.
//
// DEBUG_MODE_GC indicates we're discarding code because the debug mode
// has changed; debug mode affects the results of bytecode analysis, so
// we need to clear everything away.
return !rt->hasContexts() ||
reason == JS::gcreason::SHUTDOWN_CC ||
reason == JS::gcreason::DEBUG_MODE_GC ||
gckind == GC_SHRINK;
}
#ifdef JSGC_GENERATIONAL
class AutoDisableStoreBuffer
{
JSRuntime *runtime;
bool prior;
public:
AutoDisableStoreBuffer(JSRuntime *rt) : runtime(rt) {
prior = rt->gcStoreBuffer.isEnabled();
rt->gcStoreBuffer.disable();
}
~AutoDisableStoreBuffer() {
if (prior)
runtime->gcStoreBuffer.enable();
}
};
#else
struct AutoDisableStoreBuffer
{
AutoDisableStoreBuffer(JSRuntime *) {}
};
#endif
static void
Collect(JSRuntime *rt, bool incremental, int64_t budget,
JSGCInvocationKind gckind, JS::gcreason::Reason reason)
{
/* GC shouldn't be running in parallel execution mode */
JS_ASSERT(!InParallelSection());
JS_AbortIfWrongThread(rt);
if (rt->mainThread.suppressGC)
return;
#if JS_TRACE_LOGGING
AutoTraceLog logger(TraceLogging::defaultLogger(),
TraceLogging::GC_START,
TraceLogging::GC_STOP);
#endif
ContextIter cx(rt);
if (!cx.done())
MaybeCheckStackRoots(cx);
#ifdef JS_GC_ZEAL
if (rt->gcDeterministicOnly && !IsDeterministicGCReason(reason))
return;
#endif
JS_ASSERT_IF(!incremental || budget != SliceBudget::Unlimited, JSGC_INCREMENTAL);
#ifdef JS_GC_ZEAL
bool isShutdown = reason == JS::gcreason::SHUTDOWN_CC || !rt->hasContexts();
struct AutoVerifyBarriers {
JSRuntime *runtime;
bool restartPreVerifier;
bool restartPostVerifier;
AutoVerifyBarriers(JSRuntime *rt, bool isShutdown)
: runtime(rt)
{
restartPreVerifier = !isShutdown && rt->gcVerifyPreData;
restartPostVerifier = !isShutdown && rt->gcVerifyPostData;
if (rt->gcVerifyPreData)
EndVerifyPreBarriers(rt);
if (rt->gcVerifyPostData)
EndVerifyPostBarriers(rt);
}
~AutoVerifyBarriers() {
if (restartPreVerifier)
StartVerifyPreBarriers(runtime);
if (restartPostVerifier)
StartVerifyPostBarriers(runtime);
}
} av(rt, isShutdown);
#endif
MinorGC(rt, reason);
/*
* Marking can trigger many incidental post barriers, some of them for
* objects which are not going to be live after the GC.
*/
AutoDisableStoreBuffer adsb(rt);
RecordNativeStackTopForGC(rt);
int zoneCount = 0;
int compartmentCount = 0;
int collectedCount = 0;
for (ZonesIter zone(rt); !zone.done(); zone.next()) {
if (rt->gcMode == JSGC_MODE_GLOBAL)
zone->scheduleGC();
/* This is a heuristic to avoid resets. */
if (rt->gcIncrementalState != NO_INCREMENTAL && zone->needsBarrier())
zone->scheduleGC();
zoneCount++;
if (zone->isGCScheduled())
collectedCount++;
}
for (CompartmentsIter c(rt); !c.done(); c.next())
compartmentCount++;
rt->gcShouldCleanUpEverything = ShouldCleanUpEverything(rt, reason, gckind);
gcstats::AutoGCSlice agc(rt->gcStats, collectedCount, zoneCount, compartmentCount, reason);
do {
/*
* 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->gcIncrementalState == NO_INCREMENTAL) {
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_GC_BEGIN);
if (JSGCCallback callback = rt->gcCallback)
callback(rt, JSGC_BEGIN);
}
rt->gcPoke = false;
GCCycle(rt, incremental, budget, gckind, reason);
if (rt->gcIncrementalState == NO_INCREMENTAL) {
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_GC_END);
if (JSGCCallback callback = rt->gcCallback)
callback(rt, JSGC_END);
}
/* Need to re-schedule all zones for GC. */
if (rt->gcPoke && rt->gcShouldCleanUpEverything)
JS::PrepareForFullGC(rt);
/*
* On shutdown, iterate until finalizers or the JSGC_END callback
* stop creating garbage.
*/
} while (rt->gcPoke && rt->gcShouldCleanUpEverything);
}
void
js::GC(JSRuntime *rt, JSGCInvocationKind gckind, JS::gcreason::Reason reason)
{
Collect(rt, false, SliceBudget::Unlimited, gckind, reason);
}
void
js::GCSlice(JSRuntime *rt, JSGCInvocationKind gckind, JS::gcreason::Reason reason, int64_t millis)
{
int64_t sliceBudget;
if (millis)
sliceBudget = SliceBudget::TimeBudget(millis);
else if (rt->gcHighFrequencyGC && rt->gcDynamicMarkSlice)
sliceBudget = rt->gcSliceBudget * IGC_MARK_SLICE_MULTIPLIER;
else
sliceBudget = rt->gcSliceBudget;
Collect(rt, true, sliceBudget, gckind, reason);
}
void
js::GCFinalSlice(JSRuntime *rt, JSGCInvocationKind gckind, JS::gcreason::Reason reason)
{
Collect(rt, true, SliceBudget::Unlimited, gckind, reason);
}
static bool
ZonesSelected(JSRuntime *rt)
{
for (ZonesIter zone(rt); !zone.done(); zone.next()) {
if (zone->isGCScheduled())
return true;
}
return false;
}
void
js::GCDebugSlice(JSRuntime *rt, bool limit, int64_t objCount)
{
int64_t budget = limit ? SliceBudget::WorkBudget(objCount) : SliceBudget::Unlimited;
if (!ZonesSelected(rt)) {
if (JS::IsIncrementalGCInProgress(rt))
JS::PrepareForIncrementalGC(rt);
else
JS::PrepareForFullGC(rt);
}
Collect(rt, true, budget, GC_NORMAL, JS::gcreason::DEBUG_GC);
}
/* Schedule a full GC unless a zone will already be collected. */
void
js::PrepareForDebugGC(JSRuntime *rt)
{
if (!ZonesSelected(rt))
JS::PrepareForFullGC(rt);
}
JS_FRIEND_API(void)
JS::ShrinkGCBuffers(JSRuntime *rt)
{
AutoLockGC lock(rt);
JS_ASSERT(!rt->isHeapBusy());
if (!rt->useHelperThreads())
ExpireChunksAndArenas(rt, true);
else
rt->gcHelperThread.startBackgroundShrink();
}
void
js::MinorGC(JSRuntime *rt, JS::gcreason::Reason reason)
{
#ifdef JSGC_GENERATIONAL
rt->gcNursery.collect(rt, reason);
#endif
}
void
js::gc::FinishBackgroundFinalize(JSRuntime *rt)
{
rt->gcHelperThread.waitBackgroundSweepEnd();
}
AutoFinishGC::AutoFinishGC(JSRuntime *rt)
{
if (JS::IsIncrementalGCInProgress(rt)) {
JS::PrepareForIncrementalGC(rt);
JS::FinishIncrementalGC(rt, JS::gcreason::API);
}
gc::FinishBackgroundFinalize(rt);
}
AutoPrepareForTracing::AutoPrepareForTracing(JSRuntime *rt)
: finish(rt),
session(rt),
copy(rt)
{
RecordNativeStackTopForGC(rt);
}
JSCompartment *
js::NewCompartment(JSContext *cx, Zone *zone, JSPrincipals *principals)
{
JSRuntime *rt = cx->runtime();
JS_AbortIfWrongThread(rt);
ScopedJSDeletePtr<Zone> zoneHolder;
if (!zone) {
zone = cx->new_<Zone>(rt);
if (!zone)
return NULL;
zoneHolder.reset(zone);
if (!zone->init(cx))
return NULL;
zone->setGCLastBytes(8192, GC_NORMAL);
JSPrincipals *trusted = rt->trustedPrincipals();
zone->isSystem = principals && principals == trusted;
}
ScopedJSDeletePtr<JSCompartment> compartment(cx->new_<JSCompartment>(zone));
if (!compartment || !compartment->init(cx))
return NULL;
// Set up the principals.
JS_SetCompartmentPrincipals(compartment, principals);
AutoLockGC lock(rt);
if (!zone->compartments.append(compartment.get())) {
js_ReportOutOfMemory(cx);
return NULL;
}
if (zoneHolder && !rt->zones.append(zone)) {
js_ReportOutOfMemory(cx);
return NULL;
}
zoneHolder.forget();
return compartment.forget();
}
void
gc::RunDebugGC(JSContext *cx)
{
#ifdef JS_GC_ZEAL
JSRuntime *rt = cx->runtime();
if (rt->mainThread.suppressGC)
return;
PrepareForDebugGC(cx->runtime());
int type = rt->gcZeal();
if (type == ZealIncrementalRootsThenFinish ||
type == ZealIncrementalMarkAllThenFinish ||
type == ZealIncrementalMultipleSlices)
{
js::gc::State initialState = rt->gcIncrementalState;
int64_t budget;
if (type == ZealIncrementalMultipleSlices) {
/*
* Start with a small slice limit and double it every slice. This
* ensure that we get multiple slices, and collection runs to
* completion.
*/
if (initialState == NO_INCREMENTAL)
rt->gcIncrementalLimit = rt->gcZealFrequency / 2;
else
rt->gcIncrementalLimit *= 2;
budget = SliceBudget::WorkBudget(rt->gcIncrementalLimit);
} else {
// This triggers incremental GC but is actually ignored by IncrementalMarkSlice.
budget = SliceBudget::WorkBudget(1);
}
Collect(rt, true, budget, GC_NORMAL, JS::gcreason::DEBUG_GC);
/*
* For multi-slice zeal, reset the slice size when we get to the sweep
* phase.
*/
if (type == ZealIncrementalMultipleSlices &&
initialState == MARK && rt->gcIncrementalState == SWEEP)
{
rt->gcIncrementalLimit = rt->gcZealFrequency / 2;
}
} else if (type == ZealPurgeAnalysisValue) {
cx->compartment()->types.maybePurgeAnalysis(cx, /* force = */ true);
} else {
Collect(rt, false, SliceBudget::Unlimited, GC_NORMAL, JS::gcreason::DEBUG_GC);
}
#endif
}
void
gc::SetDeterministicGC(JSContext *cx, bool enabled)
{
#ifdef JS_GC_ZEAL
JSRuntime *rt = cx->runtime();
rt->gcDeterministicOnly = enabled;
#endif
}
void
gc::SetValidateGC(JSContext *cx, bool enabled)
{
JSRuntime *rt = cx->runtime();
rt->gcValidate = enabled;
}
void
gc::SetFullCompartmentChecks(JSContext *cx, bool enabled)
{
JSRuntime *rt = cx->runtime();
rt->gcFullCompartmentChecks = enabled;
}
#ifdef DEBUG
/* Should only be called manually under gdb */
void PreventGCDuringInteractiveDebug()
{
TlsPerThreadData.get()->suppressGC++;
}
#endif
void
js::ReleaseAllJITCode(FreeOp *fop)
{
#ifdef JS_ION
for (ZonesIter zone(fop->runtime()); !zone.done(); zone.next()) {
# ifdef DEBUG
/* Assert no baseline scripts are marked as active. */
for (CellIter i(zone, FINALIZE_SCRIPT); !i.done(); i.next()) {
JSScript *script = i.get<JSScript>();
JS_ASSERT_IF(script->hasBaselineScript(), !script->baselineScript()->active());
}
# endif
/* Mark baseline scripts on the stack as active. */
ion::MarkActiveBaselineScripts(zone);
ion::InvalidateAll(fop, zone);
for (CellIter i(zone, FINALIZE_SCRIPT); !i.done(); i.next()) {
JSScript *script = i.get<JSScript>();
ion::FinishInvalidation(fop, script);
/*
* Discard baseline script if it's not marked as active. Note that
* this also resets the active flag.
*/
ion::FinishDiscardBaselineScript(fop, script);
}
}
#endif
}
/*
* There are three possible PCCount profiling states:
*
* 1. None: Neither scripts nor the runtime have count information.
* 2. Profile: Active scripts have count information, the runtime does not.
* 3. Query: Scripts do not have count information, the runtime does.
*
* When starting to profile scripts, counting begins immediately, with all JIT
* code discarded and recompiled with counts as necessary. Active interpreter
* frames will not begin profiling until they begin executing another script
* (via a call or return).
*
* The below API functions manage transitions to new states, according
* to the table below.
*
* Old State
* -------------------------
* Function None Profile Query
* --------
* StartPCCountProfiling Profile Profile Profile
* StopPCCountProfiling None Query Query
* PurgePCCounts None None None
*/
static void
ReleaseScriptCounts(FreeOp *fop)
{
JSRuntime *rt = fop->runtime();
JS_ASSERT(rt->scriptAndCountsVector);
ScriptAndCountsVector &vec = *rt->scriptAndCountsVector;
for (size_t i = 0; i < vec.length(); i++)
vec[i].scriptCounts.destroy(fop);
fop->delete_(rt->scriptAndCountsVector);
rt->scriptAndCountsVector = NULL;
}
JS_FRIEND_API(void)
js::StartPCCountProfiling(JSContext *cx)
{
JSRuntime *rt = cx->runtime();
if (rt->profilingScripts)
return;
if (rt->scriptAndCountsVector)
ReleaseScriptCounts(rt->defaultFreeOp());
ReleaseAllJITCode(rt->defaultFreeOp());
rt->profilingScripts = true;
}
JS_FRIEND_API(void)
js::StopPCCountProfiling(JSContext *cx)
{
JSRuntime *rt = cx->runtime();
if (!rt->profilingScripts)
return;
JS_ASSERT(!rt->scriptAndCountsVector);
ReleaseAllJITCode(rt->defaultFreeOp());
ScriptAndCountsVector *vec = cx->new_<ScriptAndCountsVector>(SystemAllocPolicy());
if (!vec)
return;
for (ZonesIter zone(rt); !zone.done(); zone.next()) {
for (CellIter i(zone, FINALIZE_SCRIPT); !i.done(); i.next()) {
JSScript *script = i.get<JSScript>();
if (script->hasScriptCounts && script->types) {
ScriptAndCounts sac;
sac.script = script;
sac.scriptCounts.set(script->releaseScriptCounts());
if (!vec->append(sac))
sac.scriptCounts.destroy(rt->defaultFreeOp());
}
}
}
rt->profilingScripts = false;
rt->scriptAndCountsVector = vec;
}
JS_FRIEND_API(void)
js::PurgePCCounts(JSContext *cx)
{
JSRuntime *rt = cx->runtime();
if (!rt->scriptAndCountsVector)
return;
JS_ASSERT(!rt->profilingScripts);
ReleaseScriptCounts(rt->defaultFreeOp());
}
void
js::PurgeJITCaches(Zone *zone)
{
#ifdef JS_ION
for (CellIterUnderGC i(zone, FINALIZE_SCRIPT); !i.done(); i.next()) {
JSScript *script = i.get<JSScript>();
/* Discard Ion caches. */
ion::PurgeCaches(script, zone);
}
#endif
}
void
ArenaLists::adoptArenas(JSRuntime *rt, ArenaLists *fromArenaLists)
{
// The other parallel threads have all completed now, and GC
// should be inactive, but still take the lock as a kind of read
// fence.
AutoLockGC lock(rt);
fromArenaLists->purge();
for (size_t thingKind = 0; thingKind != FINALIZE_LIMIT; thingKind++) {
#ifdef JS_THREADSAFE
// When we enter a parallel section, we join the background
// thread, and we do not run GC while in the parallel section,
// so no finalizer should be active!
volatile uintptr_t *bfs = &backgroundFinalizeState[thingKind];
switch (*bfs) {
case BFS_DONE:
break;
case BFS_JUST_FINISHED:
// No allocations between end of last sweep and now.
// Transfering over arenas is a kind of allocation.
*bfs = BFS_DONE;
break;
default:
JS_ASSERT(!"Background finalization in progress, but it should not be.");
break;
}
#endif /* JS_THREADSAFE */
ArenaList *fromList = &fromArenaLists->arenaLists[thingKind];
ArenaList *toList = &arenaLists[thingKind];
while (fromList->head != NULL) {
ArenaHeader *fromHeader = fromList->head;
fromList->head = fromHeader->next;
fromHeader->next = NULL;
toList->insert(fromHeader);
}
}
}
bool
ArenaLists::containsArena(JSRuntime *rt, ArenaHeader *needle)
{
AutoLockGC lock(rt);
size_t allocKind = needle->getAllocKind();
for (ArenaHeader *aheader = arenaLists[allocKind].head;
aheader != NULL;
aheader = aheader->next)
{
if (aheader == needle)
return true;
}
return false;
}
AutoMaybeTouchDeadZones::AutoMaybeTouchDeadZones(JSContext *cx)
: runtime(cx->runtime()),
markCount(runtime->gcObjectsMarkedInDeadZones),
inIncremental(JS::IsIncrementalGCInProgress(runtime)),
manipulatingDeadZones(runtime->gcManipulatingDeadZones)
{
runtime->gcManipulatingDeadZones = true;
}
AutoMaybeTouchDeadZones::AutoMaybeTouchDeadZones(JSObject *obj)
: runtime(obj->compartment()->rt),
markCount(runtime->gcObjectsMarkedInDeadZones),
inIncremental(JS::IsIncrementalGCInProgress(runtime)),
manipulatingDeadZones(runtime->gcManipulatingDeadZones)
{
runtime->gcManipulatingDeadZones = true;
}
AutoMaybeTouchDeadZones::~AutoMaybeTouchDeadZones()
{
if (inIncremental && runtime->gcObjectsMarkedInDeadZones != markCount) {
JS::PrepareForFullGC(runtime);
js::GC(runtime, GC_NORMAL, JS::gcreason::TRANSPLANT);
}
runtime->gcManipulatingDeadZones = manipulatingDeadZones;
}
AutoSuppressGC::AutoSuppressGC(JSContext *cx)
: suppressGC_(cx->runtime()->mainThread.suppressGC)
{
suppressGC_++;
}
AutoSuppressGC::AutoSuppressGC(JSCompartment *comp)
: suppressGC_(comp->rt->mainThread.suppressGC)
{
suppressGC_++;
}
#ifdef DEBUG
AutoDisableProxyCheck::AutoDisableProxyCheck(JSRuntime *rt
MOZ_GUARD_OBJECT_NOTIFIER_PARAM_IN_IMPL)
: count(rt->gcDisableStrictProxyCheckingCount)
{
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
count++;
}
#endif