Feodor2
/
Mypal
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
Mypal/js/src/gc/Nursery.cpp

932 lines
26 KiB
C++
Raw Blame History

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=8 sw=4 et tw=78:
*
* 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/. */
#include "gc/Nursery-inl.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/IntegerPrintfMacros.h"
#include "mozilla/Move.h"
#include "mozilla/Unused.h"
#include "jscompartment.h"
#include "jsfriendapi.h"
#include "jsgc.h"
#include "jsutil.h"
#include "gc/GCInternals.h"
#include "gc/Memory.h"
#include "jit/JitFrames.h"
#include "vm/ArrayObject.h"
#include "vm/Debugger.h"
#if defined(DEBUG)
#include "vm/EnvironmentObject.h"
#endif
#include "vm/Time.h"
#include "vm/TypedArrayObject.h"
#include "vm/TypeInference.h"
#include "jsobjinlines.h"
#include "vm/NativeObject-inl.h"
using namespace js;
using namespace gc;
using mozilla::ArrayLength;
using mozilla::DebugOnly;
using mozilla::PodCopy;
using mozilla::PodZero;
static const uintptr_t CanaryMagicValue = 0xDEADB15D;
struct js::Nursery::FreeMallocedBuffersTask : public GCParallelTaskHelper<FreeMallocedBuffersTask>
{
explicit FreeMallocedBuffersTask(FreeOp* fop) : fop_(fop) {}
bool init() { return buffers_.init(); }
void transferBuffersToFree(MallocedBuffersSet& buffersToFree,
const AutoLockHelperThreadState& lock);
~FreeMallocedBuffersTask() { join(); }
void run();
private:
FreeOp* fop_;
MallocedBuffersSet buffers_;
};
struct js::Nursery::SweepAction
{
SweepAction(SweepThunk thunk, void* data, SweepAction* next)
: thunk(thunk), data(data), next(next)
{}
SweepThunk thunk;
void* data;
SweepAction* next;
#if JS_BITS_PER_WORD == 32
protected:
uint32_t padding;
#endif
};
inline void
js::Nursery::NurseryChunk::poisonAndInit(JSRuntime* rt, uint8_t poison)
{
JS_POISON(this, poison, ChunkSize);
init(rt);
}
inline void
js::Nursery::NurseryChunk::init(JSRuntime* rt)
{
new (&trailer) gc::ChunkTrailer(rt, &rt->gc.storeBuffer);
}
/* static */ inline js::Nursery::NurseryChunk*
js::Nursery::NurseryChunk::fromChunk(Chunk* chunk)
{
return reinterpret_cast<NurseryChunk*>(chunk);
}
inline Chunk*
js::Nursery::NurseryChunk::toChunk(JSRuntime* rt)
{
auto chunk = reinterpret_cast<Chunk*>(this);
chunk->init(rt);
return chunk;
}
js::Nursery::Nursery(JSRuntime* rt)
: runtime_(rt)
, position_(0)
, currentStartChunk_(0)
, currentStartPosition_(0)
, currentEnd_(0)
, currentChunk_(0)
, maxNurseryChunks_(0)
, previousPromotionRate_(0)
, profileThreshold_(0)
, enableProfiling_(false)
, reportTenurings_(0)
, minorGcCount_(0)
, freeMallocedBuffersTask(nullptr)
, sweepActions_(nullptr)
{}
bool
js::Nursery::init(uint32_t maxNurseryBytes, AutoLockGC& lock)
{
if (!mallocedBuffers.init())
return false;
freeMallocedBuffersTask = js_new<FreeMallocedBuffersTask>(runtime()->defaultFreeOp());
if (!freeMallocedBuffersTask || !freeMallocedBuffersTask->init())
return false;
/* maxNurseryBytes parameter is rounded down to a multiple of chunk size. */
maxNurseryChunks_ = maxNurseryBytes >> ChunkShift;
/* If no chunks are specified then the nursery is permenantly disabled. */
if (maxNurseryChunks_ == 0)
return true;
if (!cellsWithUid_.init())
return false;
AutoMaybeStartBackgroundAllocation maybeBgAlloc;
updateNumChunksLocked(1, maybeBgAlloc, lock);
if (numChunks() == 0)
return false;
setCurrentChunk(0);
setStartPosition();
char* env = getenv("JS_GC_PROFILE_NURSERY");
if (env) {
if (0 == strcmp(env, "help")) {
fprintf(stderr, "JS_GC_PROFILE_NURSERY=N\n"
"\tReport minor GC's taking at least N microseconds.\n");
exit(0);
}
enableProfiling_ = true;
profileThreshold_ = atoi(env);
}
env = getenv("JS_GC_REPORT_TENURING");
if (env) {
if (0 == strcmp(env, "help")) {
fprintf(stderr, "JS_GC_REPORT_TENURING=N\n"
"\tAfter a minor GC, report any ObjectGroups with at least N instances tenured.\n");
exit(0);
}
reportTenurings_ = atoi(env);
}
PodZero(&startTimes_);
PodZero(&profileTimes_);
PodZero(&totalTimes_);
if (!runtime()->gc.storeBuffer.enable())
return false;
MOZ_ASSERT(isEnabled());
return true;
}
js::Nursery::~Nursery()
{
disable();
js_delete(freeMallocedBuffersTask);
}
void
js::Nursery::enable()
{
MOZ_ASSERT(isEmpty());
if (isEnabled())
return;
updateNumChunks(1);
if (numChunks() == 0)
return;
setCurrentChunk(0);
setStartPosition();
MOZ_ALWAYS_TRUE(runtime()->gc.storeBuffer.enable());
return;
}
void
js::Nursery::disable()
{
MOZ_ASSERT(isEmpty());
if (!isEnabled())
return;
updateNumChunks(0);
currentEnd_ = 0;
position_ = 0;
runtime()->gc.storeBuffer.disable();
}
bool
js::Nursery::isEmpty() const
{
MOZ_ASSERT(runtime_);
if (!isEnabled())
return true;
MOZ_ASSERT(currentStartChunk_ == 0);
MOZ_ASSERT(currentStartPosition_ == chunk(0).start());
return position() == currentStartPosition_;
}
JSObject*
js::Nursery::allocateObject(JSContext* cx, size_t size, size_t numDynamic, const js::Class* clasp)
{
/* Ensure there's enough space to replace the contents with a RelocationOverlay. */
MOZ_ASSERT(size >= sizeof(RelocationOverlay));
/* Sanity check the finalizer. */
MOZ_ASSERT_IF(clasp->hasFinalize(), CanNurseryAllocateFinalizedClass(clasp) ||
clasp->isProxy());
/* Make the object allocation. */
JSObject* obj = static_cast<JSObject*>(allocate(size));
if (!obj)
return nullptr;
/* If we want external slots, add them. */
HeapSlot* slots = nullptr;
if (numDynamic) {
MOZ_ASSERT(clasp->isNative() || clasp->isProxy());
slots = static_cast<HeapSlot*>(allocateBuffer(cx->zone(), numDynamic * sizeof(HeapSlot)));
if (!slots) {
/*
* It is safe to leave the allocated object uninitialized, since we
* do not visit unallocated things in the nursery.
*/
return nullptr;
}
}
/* Always initialize the slots field to match the JIT behavior. */
obj->setInitialSlotsMaybeNonNative(slots);
TraceNurseryAlloc(obj, size);
return obj;
}
void*
js::Nursery::allocate(size_t size)
{
MOZ_ASSERT(isEnabled());
MOZ_ASSERT(!runtime()->isHeapBusy());
MOZ_ASSERT_IF(currentChunk_ == currentStartChunk_, position() >= currentStartPosition_);
MOZ_ASSERT(position() % gc::CellSize == 0);
MOZ_ASSERT(size % gc::CellSize == 0);
if (currentEnd() < position() + size) {
if (currentChunk_ + 1 == numChunks())
return nullptr;
setCurrentChunk(currentChunk_ + 1);
}
void* thing = (void*)position();
position_ = position() + size;
JS_EXTRA_POISON(thing, JS_ALLOCATED_NURSERY_PATTERN, size);
MemProfiler::SampleNursery(reinterpret_cast<void*>(thing), size);
return thing;
}
void*
js::Nursery::allocateBuffer(Zone* zone, size_t nbytes)
{
MOZ_ASSERT(nbytes > 0);
if (nbytes <= MaxNurseryBufferSize) {
void* buffer = allocate(nbytes);
if (buffer)
return buffer;
}
void* buffer = zone->pod_malloc<uint8_t>(nbytes);
if (buffer && !mallocedBuffers.putNew(buffer)) {
js_free(buffer);
return nullptr;
}
return buffer;
}
void*
js::Nursery::allocateBuffer(JSObject* obj, size_t nbytes)
{
MOZ_ASSERT(obj);
MOZ_ASSERT(nbytes > 0);
if (!IsInsideNursery(obj))
return obj->zone()->pod_malloc<uint8_t>(nbytes);
return allocateBuffer(obj->zone(), nbytes);
}
void*
js::Nursery::reallocateBuffer(JSObject* obj, void* oldBuffer,
size_t oldBytes, size_t newBytes)
{
if (!IsInsideNursery(obj))
return obj->zone()->pod_realloc<uint8_t>((uint8_t*)oldBuffer, oldBytes, newBytes);
if (!isInside(oldBuffer)) {
void* newBuffer = obj->zone()->pod_realloc<uint8_t>((uint8_t*)oldBuffer, oldBytes, newBytes);
if (newBuffer && oldBuffer != newBuffer)
MOZ_ALWAYS_TRUE(mallocedBuffers.rekeyAs(oldBuffer, newBuffer, newBuffer));
return newBuffer;
}
/* The nursery cannot make use of the returned slots data. */
if (newBytes < oldBytes)
return oldBuffer;
void* newBuffer = allocateBuffer(obj->zone(), newBytes);
if (newBuffer)
PodCopy((uint8_t*)newBuffer, (uint8_t*)oldBuffer, oldBytes);
return newBuffer;
}
void
js::Nursery::freeBuffer(void* buffer)
{
if (!isInside(buffer)) {
removeMallocedBuffer(buffer);
js_free(buffer);
}
}
void
Nursery::setForwardingPointer(void* oldData, void* newData, bool direct)
{
MOZ_ASSERT(isInside(oldData));
// Bug 1196210: If a zero-capacity header lands in the last 2 words of a
// jemalloc chunk abutting the start of a nursery chunk, the (invalid)
// newData pointer will appear to be "inside" the nursery.
MOZ_ASSERT(!isInside(newData) || (uintptr_t(newData) & ChunkMask) == 0);
if (direct) {
*reinterpret_cast<void**>(oldData) = newData;
} else {
AutoEnterOOMUnsafeRegion oomUnsafe;
if (!forwardedBuffers.initialized() && !forwardedBuffers.init())
oomUnsafe.crash("Nursery::setForwardingPointer");
#ifdef DEBUG
if (ForwardedBufferMap::Ptr p = forwardedBuffers.lookup(oldData))
MOZ_ASSERT(p->value() == newData);
#endif
if (!forwardedBuffers.put(oldData, newData))
oomUnsafe.crash("Nursery::setForwardingPointer");
}
}
void
Nursery::setSlotsForwardingPointer(HeapSlot* oldSlots, HeapSlot* newSlots, uint32_t nslots)
{
// Slot arrays always have enough space for a forwarding pointer, since the
// number of slots is never zero.
MOZ_ASSERT(nslots > 0);
setForwardingPointer(oldSlots, newSlots, /* direct = */ true);
}
void
Nursery::setElementsForwardingPointer(ObjectElements* oldHeader, ObjectElements* newHeader,
uint32_t nelems)
{
// Only use a direct forwarding pointer if there is enough space for one.
setForwardingPointer(oldHeader->elements(), newHeader->elements(),
nelems > ObjectElements::VALUES_PER_HEADER);
}
#ifdef DEBUG
static bool IsWriteableAddress(void* ptr)
{
volatile uint64_t* vPtr = reinterpret_cast<volatile uint64_t*>(ptr);
*vPtr = *vPtr;
return true;
}
#endif
void
js::Nursery::forwardBufferPointer(HeapSlot** pSlotsElems)
{
HeapSlot* old = *pSlotsElems;
if (!isInside(old))
return;
// The new location for this buffer is either stored inline with it or in
// the forwardedBuffers table.
do {
if (forwardedBuffers.initialized()) {
if (ForwardedBufferMap::Ptr p = forwardedBuffers.lookup(old)) {
*pSlotsElems = reinterpret_cast<HeapSlot*>(p->value());
break;
}
}
*pSlotsElems = *reinterpret_cast<HeapSlot**>(old);
} while (false);
MOZ_ASSERT(!isInside(*pSlotsElems));
MOZ_ASSERT(IsWriteableAddress(*pSlotsElems));
}
js::TenuringTracer::TenuringTracer(JSRuntime* rt, Nursery* nursery)
: JSTracer(rt, JSTracer::TracerKindTag::Tenuring, TraceWeakMapKeysValues)
, nursery_(*nursery)
, tenuredSize(0)
, head(nullptr)
, tail(&head)
{
}
/* static */ void
js::Nursery::printProfileHeader()
{
#define PRINT_HEADER(name, text) \
fprintf(stderr, " %6s", text);
FOR_EACH_NURSERY_PROFILE_TIME(PRINT_HEADER)
#undef PRINT_HEADER
fprintf(stderr, "\n");
}
/* static */ void
js::Nursery::printProfileTimes(const ProfileTimes& times)
{
for (auto time : times)
fprintf(stderr, " %6" PRIi64, time);
fprintf(stderr, "\n");
}
void
js::Nursery::printTotalProfileTimes()
{
if (enableProfiling_) {
fprintf(stderr, "MinorGC TOTALS: %7" PRIu64 " collections: ", minorGcCount_);
printProfileTimes(totalTimes_);
}
}
inline void
js::Nursery::startProfile(ProfileKey key)
{
startTimes_[key] = PRMJ_Now();
}
inline void
js::Nursery::endProfile(ProfileKey key)
{
profileTimes_[key] = PRMJ_Now() - startTimes_[key];
totalTimes_[key] += profileTimes_[key];
}
inline void
js::Nursery::maybeStartProfile(ProfileKey key)
{
if (enableProfiling_)
startProfile(key);
}
inline void
js::Nursery::maybeEndProfile(ProfileKey key)
{
if (enableProfiling_)
endProfile(key);
}
void
js::Nursery::collect(JSRuntime* rt, JS::gcreason::Reason reason)
{
MOZ_ASSERT(!rt->mainThread.suppressGC);
MOZ_RELEASE_ASSERT(CurrentThreadCanAccessRuntime(rt));
if (!isEnabled() || isEmpty()) {
// Our barriers are not always exact, and there may be entries in the
// storebuffer even when the nursery is disabled or empty. It's not safe
// to keep these entries as they may refer to tenured cells which may be
// freed after this point.
rt->gc.storeBuffer.clear();
}
if (!isEnabled())
return;
rt->gc.incMinorGcNumber();
rt->gc.stats.beginNurseryCollection(reason);
TraceMinorGCStart();
startProfile(ProfileKey::Total);
// The hazard analysis thinks doCollection can invalidate pointers in
// tenureCounts below.
JS::AutoSuppressGCAnalysis nogc;
TenureCountCache tenureCounts;
double promotionRate = 0;
if (!isEmpty())
promotionRate = doCollection(rt, reason, tenureCounts);
// Resize the nursery.
maybeStartProfile(ProfileKey::Resize);
maybeResizeNursery(reason, promotionRate);
maybeEndProfile(ProfileKey::Resize);
// If we are promoting the nursery, or exhausted the store buffer with
// pointers to nursery things, which will force a collection well before
// the nursery is full, look for object groups that are getting promoted
// excessively and try to pretenure them.
maybeStartProfile(ProfileKey::Pretenure);
if (promotionRate > 0.8 || reason == JS::gcreason::FULL_STORE_BUFFER) {
JSContext* cx = rt->contextFromMainThread();
for (auto& entry : tenureCounts.entries) {
if (entry.count >= 3000) {
ObjectGroup* group = entry.group;
if (group->canPreTenure()) {
AutoCompartment ac(cx, group->compartment());
group->setShouldPreTenure(cx);
}
}
}
}
maybeEndProfile(ProfileKey::Pretenure);
// We ignore gcMaxBytes when allocating for minor collection. However, if we
// overflowed, we disable the nursery. The next time we allocate, we'll fail
// because gcBytes >= gcMaxBytes.
if (rt->gc.usage.gcBytes() >= rt->gc.tunables.gcMaxBytes())
disable();
endProfile(ProfileKey::Total);
minorGcCount_++;
int64_t totalTime = profileTimes_[ProfileKey::Total];
rt->gc.stats.endNurseryCollection(reason);
TraceMinorGCEnd();
if (enableProfiling_ && totalTime >= profileThreshold_) {
static int printedHeader = 0;
if ((printedHeader++ % 200) == 0) {
fprintf(stderr, "MinorGC: Reason PRate Size ");
printProfileHeader();
}
fprintf(stderr, "MinorGC: %20s %5.1f%% %4u ",
JS::gcreason::ExplainReason(reason),
promotionRate * 100,
numChunks());
printProfileTimes(profileTimes_);
if (reportTenurings_) {
for (auto& entry : tenureCounts.entries) {
if (entry.count >= reportTenurings_) {
fprintf(stderr, "%d x ", entry.count);
entry.group->print();
}
}
}
}
}
double
js::Nursery::doCollection(JSRuntime* rt, JS::gcreason::Reason reason,
TenureCountCache& tenureCounts)
{
AutoTraceSession session(rt, JS::HeapState::MinorCollecting);
AutoSetThreadIsPerformingGC performingGC;
AutoDisableProxyCheck disableStrictProxyChecking(rt);
mozilla::DebugOnly<AutoEnterOOMUnsafeRegion> oomUnsafeRegion;
size_t initialNurserySize = spaceToEnd();
// Move objects pointed to by roots from the nursery to the major heap.
TenuringTracer mover(rt, this);
// Mark the store buffer. This must happen first.
StoreBuffer& sb = rt->gc.storeBuffer;
// The MIR graph only contains nursery pointers if cancelIonCompilations()
// is set on the store buffer, in which case we cancel all compilations.
maybeStartProfile(ProfileKey::CancelIonCompilations);
if (sb.cancelIonCompilations())
js::CancelOffThreadIonCompile(rt);
maybeEndProfile(ProfileKey::CancelIonCompilations);
maybeStartProfile(ProfileKey::TraceValues);
sb.traceValues(mover);
maybeEndProfile(ProfileKey::TraceValues);
maybeStartProfile(ProfileKey::TraceCells);
sb.traceCells(mover);
maybeEndProfile(ProfileKey::TraceCells);
maybeStartProfile(ProfileKey::TraceSlots);
sb.traceSlots(mover);
maybeEndProfile(ProfileKey::TraceSlots);
maybeStartProfile(ProfileKey::TraceWholeCells);
sb.traceWholeCells(mover);
maybeEndProfile(ProfileKey::TraceWholeCells);
maybeStartProfile(ProfileKey::TraceGenericEntries);
sb.traceGenericEntries(&mover);
maybeEndProfile(ProfileKey::TraceGenericEntries);
maybeStartProfile(ProfileKey::MarkRuntime);
rt->gc.traceRuntimeForMinorGC(&mover, session.lock);
maybeEndProfile(ProfileKey::MarkRuntime);
maybeStartProfile(ProfileKey::MarkDebugger);
{
gcstats::AutoPhase ap(rt->gc.stats, gcstats::PHASE_MARK_ROOTS);
Debugger::markAll(&mover);
}
maybeEndProfile(ProfileKey::MarkDebugger);
maybeStartProfile(ProfileKey::ClearNewObjectCache);
rt->contextFromMainThread()->caches.newObjectCache.clearNurseryObjects(rt);
maybeEndProfile(ProfileKey::ClearNewObjectCache);
// Most of the work is done here. This loop iterates over objects that have
// been moved to the major heap. If these objects have any outgoing pointers
// to the nursery, then those nursery objects get moved as well, until no
// objects are left to move. That is, we iterate to a fixed point.
maybeStartProfile(ProfileKey::CollectToFP);
collectToFixedPoint(mover, tenureCounts);
maybeEndProfile(ProfileKey::CollectToFP);
// Sweep compartments to update the array buffer object's view lists.
maybeStartProfile(ProfileKey::SweepArrayBufferViewList);
for (CompartmentsIter c(rt, SkipAtoms); !c.done(); c.next())
c->sweepAfterMinorGC(&mover);
maybeEndProfile(ProfileKey::SweepArrayBufferViewList);
// Update any slot or element pointers whose destination has been tenured.
maybeStartProfile(ProfileKey::UpdateJitActivations);
js::jit::UpdateJitActivationsForMinorGC(rt, &mover);
forwardedBuffers.finish();
maybeEndProfile(ProfileKey::UpdateJitActivations);
maybeStartProfile(ProfileKey::ObjectsTenuredCallback);
rt->gc.callObjectsTenuredCallback();
maybeEndProfile(ProfileKey::ObjectsTenuredCallback);
// Sweep.
maybeStartProfile(ProfileKey::FreeMallocedBuffers);
freeMallocedBuffers();
maybeEndProfile(ProfileKey::FreeMallocedBuffers);
maybeStartProfile(ProfileKey::Sweep);
sweep();
maybeEndProfile(ProfileKey::Sweep);
maybeStartProfile(ProfileKey::ClearStoreBuffer);
rt->gc.storeBuffer.clear();
maybeEndProfile(ProfileKey::ClearStoreBuffer);
// Make sure hashtables have been updated after the collection.
maybeStartProfile(ProfileKey::CheckHashTables);
maybeEndProfile(ProfileKey::CheckHashTables);
// Calculate and return the promotion rate.
return mover.tenuredSize / double(initialNurserySize);
}
void
js::Nursery::FreeMallocedBuffersTask::transferBuffersToFree(MallocedBuffersSet& buffersToFree,
const AutoLockHelperThreadState& lock)
{
// Transfer the contents of the source set to the task's buffers_ member by
// swapping the sets, which also clears the source.
MOZ_ASSERT(!isRunningWithLockHeld(lock));
MOZ_ASSERT(buffers_.empty());
mozilla::Swap(buffers_, buffersToFree);
}
void
js::Nursery::FreeMallocedBuffersTask::run()
{
for (MallocedBuffersSet::Range r = buffers_.all(); !r.empty(); r.popFront())
fop_->free_(r.front());
buffers_.clear();
}
void
js::Nursery::freeMallocedBuffers()
{
if (mallocedBuffers.empty())
return;
bool started;
{
AutoLockHelperThreadState lock;
freeMallocedBuffersTask->joinWithLockHeld(lock);
freeMallocedBuffersTask->transferBuffersToFree(mallocedBuffers, lock);
started = freeMallocedBuffersTask->startWithLockHeld(lock);
}
if (!started)
freeMallocedBuffersTask->runFromMainThread(runtime());
MOZ_ASSERT(mallocedBuffers.empty());
}
void
js::Nursery::waitBackgroundFreeEnd()
{
// We may finishRoots before nursery init if runtime init fails.
if (!isEnabled())
return;
MOZ_ASSERT(freeMallocedBuffersTask);
freeMallocedBuffersTask->join();
}
void
js::Nursery::sweep()
{
/* Sweep unique id's in all in-use chunks. */
for (CellsWithUniqueIdSet::Enum e(cellsWithUid_); !e.empty(); e.popFront()) {
JSObject* obj = static_cast<JSObject*>(e.front());
if (!IsForwarded(obj))
obj->zone()->removeUniqueId(obj);
else
MOZ_ASSERT(Forwarded(obj)->zone()->hasUniqueId(Forwarded(obj)));
}
cellsWithUid_.clear();
runSweepActions();
sweepDictionaryModeObjects();
{
#ifdef JS_CRASH_DIAGNOSTICS
for (unsigned i = 0; i < numChunks(); ++i)
chunk(i).poisonAndInit(runtime(), JS_SWEPT_NURSERY_PATTERN);
#endif
setCurrentChunk(0);
}
/* Set current start position for isEmpty checks. */
setStartPosition();
MemProfiler::SweepNursery(runtime());
}
size_t
js::Nursery::spaceToEnd() const
{
unsigned lastChunk = numChunks() - 1;
MOZ_ASSERT(lastChunk >= currentStartChunk_);
MOZ_ASSERT(currentStartPosition_ - chunk(currentStartChunk_).start() <= NurseryChunkUsableSize);
size_t bytes = (chunk(currentStartChunk_).end() - currentStartPosition_) +
((lastChunk - currentStartChunk_) * NurseryChunkUsableSize);
MOZ_ASSERT(bytes <= numChunks() * NurseryChunkUsableSize);
return bytes;
}
MOZ_ALWAYS_INLINE void
js::Nursery::setCurrentChunk(unsigned chunkno)
{
MOZ_ASSERT(chunkno < maxChunks());
MOZ_ASSERT(chunkno < numChunks());
currentChunk_ = chunkno;
position_ = chunk(chunkno).start();
currentEnd_ = chunk(chunkno).end();
chunk(chunkno).poisonAndInit(runtime(), JS_FRESH_NURSERY_PATTERN);
}
MOZ_ALWAYS_INLINE void
js::Nursery::setStartPosition()
{
currentStartChunk_ = currentChunk_;
currentStartPosition_ = position();
}
void
js::Nursery::maybeResizeNursery(JS::gcreason::Reason reason, double promotionRate)
{
static const double GrowThreshold = 0.05;
static const double ShrinkThreshold = 0.01;
// Shrink the nursery to its minimum size of we ran out of memory or
// received a memory pressure event.
if (gc::IsOOMReason(reason)) {
minimizeAllocableSpace();
return;
}
if (promotionRate > GrowThreshold)
growAllocableSpace();
else if (promotionRate < ShrinkThreshold && previousPromotionRate_ < ShrinkThreshold)
shrinkAllocableSpace();
previousPromotionRate_ = promotionRate;
}
void
js::Nursery::growAllocableSpace()
{
updateNumChunks(Min(numChunks() * 2, maxNurseryChunks_));
}
void
js::Nursery::shrinkAllocableSpace()
{
updateNumChunks(Max(numChunks() - 1, 1u));
}
void
js::Nursery::minimizeAllocableSpace()
{
updateNumChunks(1);
}
void
js::Nursery::updateNumChunks(unsigned newCount)
{
if (numChunks() != newCount) {
AutoMaybeStartBackgroundAllocation maybeBgAlloc;
AutoLockGC lock(runtime());
updateNumChunksLocked(newCount, maybeBgAlloc, lock);
}
}
void
js::Nursery::updateNumChunksLocked(unsigned newCount,
AutoMaybeStartBackgroundAllocation& maybeBgAlloc,
AutoLockGC& lock)
{
// The GC nursery is an optimization and so if we fail to allocate nursery
// chunks we do not report an error.
unsigned priorCount = numChunks();
MOZ_ASSERT(priorCount != newCount);
if (newCount < priorCount) {
// Shrink the nursery and free unused chunks.
for (unsigned i = newCount; i < priorCount; i++)
runtime()->gc.recycleChunk(chunk(i).toChunk(runtime()), lock);
chunks_.shrinkTo(newCount);
return;
}
// Grow the nursery and allocate new chunks.
if (!chunks_.resize(newCount))
return;
for (unsigned i = priorCount; i < newCount; i++) {
auto newChunk = runtime()->gc.getOrAllocChunk(lock, maybeBgAlloc);
if (!newChunk) {
chunks_.shrinkTo(i);
return;
}
chunks_[i] = NurseryChunk::fromChunk(newChunk);
chunk(i).poisonAndInit(runtime(), JS_FRESH_NURSERY_PATTERN);
}
}
void
js::Nursery::queueSweepAction(SweepThunk thunk, void* data)
{
static_assert(sizeof(SweepAction) % CellSize == 0,
"SweepAction size must be a multiple of cell size");
MOZ_ASSERT(isEnabled());
AutoEnterOOMUnsafeRegion oomUnsafe;
auto action = reinterpret_cast<SweepAction*>(allocate(sizeof(SweepAction)));
if (!action)
oomUnsafe.crash("Nursery::queueSweepAction");
new (action) SweepAction(thunk, data, sweepActions_);
sweepActions_ = action;
}
void
js::Nursery::runSweepActions()
{
// The hazard analysis doesn't know whether the thunks can GC.
JS::AutoSuppressGCAnalysis nogc;
AutoSetThreadIsSweeping threadIsSweeping;
for (auto action = sweepActions_; action; action = action->next)
action->thunk(action->data);
sweepActions_ = nullptr;
}
bool
js::Nursery::queueDictionaryModeObjectToSweep(NativeObject* obj)
{
MOZ_ASSERT(IsInsideNursery(obj));
return dictionaryModeObjects_.append(obj);
}
void
js::Nursery::sweepDictionaryModeObjects()
{
for (auto obj : dictionaryModeObjects_) {
if (!IsForwarded(obj))
obj->sweepDictionaryListPointer();
}
dictionaryModeObjects_.clear();
}
Reference in New Issue View Git Blame Copy Permalink