/*
* Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
* Copyright (C) 2007 Eric Seidel <eric@webkit.org>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#include "config.h"
#include "Heap.h"
#include "CodeBlock.h"
#include "ConservativeRoots.h"
#include "GCActivityCallback.h"
#include "Interpreter.h"
#include "JSGlobalData.h"
#include "JSGlobalObject.h"
#include "JSLock.h"
#include "JSONObject.h"
#include "Tracing.h"
#include <algorithm>
#define COLLECT_ON_EVERY_SLOW_ALLOCATION 0
using namespace std;
namespace JSC {
const size_t minBytesPerCycle = 512 * 1024;
Heap::Heap(JSGlobalData* globalData)
: m_operationInProgress(NoOperation)
, m_markedSpace(globalData)
, m_markListSet(0)
, m_activityCallback(DefaultGCActivityCallback::create(this))
, m_globalData(globalData)
, m_machineThreads(this)
, m_markStack(globalData->jsArrayVPtr)
, m_handleHeap(globalData)
, m_extraCost(0)
{
m_markedSpace.setHighWaterMark(minBytesPerCycle);
(*m_activityCallback)();
}
Heap::~Heap()
{
// The destroy function must already have been called, so assert this.
ASSERT(!m_globalData);
}
void Heap::destroy()
{
JSLock lock(SilenceAssertionsOnly);
if (!m_globalData)
return;
ASSERT(!m_globalData->dynamicGlobalObject);
ASSERT(m_operationInProgress == NoOperation);
// The global object is not GC protected at this point, so sweeping may delete it
// (and thus the global data) before other objects that may use the global data.
RefPtr<JSGlobalData> protect(m_globalData);
#if ENABLE(JIT)
m_globalData->jitStubs->clearHostFunctionStubs();
#endif
delete m_markListSet;
m_markListSet = 0;
m_markedSpace.clearMarks();
m_handleHeap.finalizeWeakHandles();
m_markedSpace.destroy();
m_globalData = 0;
}
void Heap::reportExtraMemoryCostSlowCase(size_t cost)
{
// Our frequency of garbage collection tries to balance memory use against speed
// by collecting based on the number of newly created values. However, for values
// that hold on to a great deal of memory that's not in the form of other JS values,
// that is not good enough - in some cases a lot of those objects can pile up and
// use crazy amounts of memory without a GC happening. So we track these extra
// memory costs. Only unusually large objects are noted, and we only keep track
// of this extra cost until the next GC. In garbage collected languages, most values
// are either very short lived temporaries, or have extremely long lifetimes. So
// if a large value survives one garbage collection, there is not much point to
// collecting more frequently as long as it stays alive.
if (m_extraCost > maxExtraCost && m_extraCost > m_markedSpace.highWaterMark() / 2)
collectAllGarbage();
m_extraCost += cost;
}
void* Heap::allocateSlowCase(size_t bytes)
{
ASSERT(globalData()->identifierTable == wtfThreadData().currentIdentifierTable());
ASSERT(JSLock::lockCount() > 0);
ASSERT(JSLock::currentThreadIsHoldingLock());
ASSERT(bytes <= MarkedSpace::maxCellSize);
ASSERT(m_operationInProgress == NoOperation);
#if COLLECT_ON_EVERY_SLOW_ALLOCATION
collectAllGarbage();
ASSERT(m_operationInProgress == NoOperation);
#endif
reset(DoNotSweep);
m_operationInProgress = Allocation;
void* result = m_markedSpace.allocate(bytes);
m_operationInProgress = NoOperation;
ASSERT(result);
return result;
}
void Heap::protect(JSValue k)
{
ASSERT(k);
ASSERT(JSLock::currentThreadIsHoldingLock() || !m_globalData->isSharedInstance());
if (!k.isCell())
return;
m_protectedValues.add(k.asCell());
}
bool Heap::unprotect(JSValue k)
{
ASSERT(k);
ASSERT(JSLock::currentThreadIsHoldingLock() || !m_globalData->isSharedInstance());
if (!k.isCell())
return false;
return m_protectedValues.remove(k.asCell());
}
void Heap::markProtectedObjects(HeapRootMarker& heapRootMarker)
{
ProtectCountSet::iterator end = m_protectedValues.end();
for (ProtectCountSet::iterator it = m_protectedValues.begin(); it != end; ++it)
heapRootMarker.mark(&it->first);
}
void Heap::pushTempSortVector(Vector<ValueStringPair>* tempVector)
{
m_tempSortingVectors.append(tempVector);
}
void Heap::popTempSortVector(Vector<ValueStringPair>* tempVector)
{
ASSERT_UNUSED(tempVector, tempVector == m_tempSortingVectors.last());
m_tempSortingVectors.removeLast();
}
void Heap::markTempSortVectors(HeapRootMarker& heapRootMarker)
{
typedef Vector<Vector<ValueStringPair>* > VectorOfValueStringVectors;
VectorOfValueStringVectors::iterator end = m_tempSortingVectors.end();
for (VectorOfValueStringVectors::iterator it = m_tempSortingVectors.begin(); it != end; ++it) {
Vector<ValueStringPair>* tempSortingVector = *it;
Vector<ValueStringPair>::iterator vectorEnd = tempSortingVector->end();
for (Vector<ValueStringPair>::iterator vectorIt = tempSortingVector->begin(); vectorIt != vectorEnd; ++vectorIt) {
if (vectorIt->first)
heapRootMarker.mark(&vectorIt->first);
}
}
}
inline RegisterFile& Heap::registerFile()
{
return m_globalData->interpreter->registerFile();
}
void Heap::markRoots()
{
#ifndef NDEBUG
if (m_globalData->isSharedInstance()) {
ASSERT(JSLock::lockCount() > 0);
ASSERT(JSLock::currentThreadIsHoldingLock());
}
#endif
void* dummy;
ASSERT(m_operationInProgress == NoOperation);
if (m_operationInProgress != NoOperation)
CRASH();
m_operationInProgress = Collection;
MarkStack& markStack = m_markStack;
HeapRootMarker heapRootMarker(markStack);
// We gather conservative roots before clearing mark bits because
// conservative gathering uses the mark bits from our last mark pass to
// determine whether a reference is valid.
ConservativeRoots machineThreadRoots(this);
m_machineThreads.gatherConservativeRoots(machineThreadRoots, &dummy);
ConservativeRoots registerFileRoots(this);
registerFile().gatherConservativeRoots(registerFileRoots);
m_markedSpace.clearMarks();
markStack.append(machineThreadRoots);
markStack.drain();
markStack.append(registerFileRoots);
markStack.drain();
markProtectedObjects(heapRootMarker);
markStack.drain();
markTempSortVectors(heapRootMarker);
markStack.drain();
if (m_markListSet && m_markListSet->size())
MarkedArgumentBuffer::markLists(heapRootMarker, *m_markListSet);
if (m_globalData->exception)
heapRootMarker.mark(&m_globalData->exception);
markStack.drain();
m_handleHeap.markStrongHandles(heapRootMarker);
markStack.drain();
m_handleStack.mark(heapRootMarker);
markStack.drain();
// Mark the small strings cache as late as possible, since it will clear
// itself if nothing else has marked it.
// FIXME: Change the small strings cache to use Weak<T>.
m_globalData->smallStrings.markChildren(heapRootMarker);
markStack.drain();
// Weak handles must be marked last, because their owners use the set of
// opaque roots to determine reachability.
int lastOpaqueRootCount;
do {
lastOpaqueRootCount = markStack.opaqueRootCount();
m_handleHeap.markWeakHandles(heapRootMarker);
markStack.drain();
// If the set of opaque roots has grown, more weak handles may have become reachable.
} while (lastOpaqueRootCount != markStack.opaqueRootCount());
markStack.reset();
m_operationInProgress = NoOperation;
}
size_t Heap::objectCount() const
{
return m_markedSpace.objectCount();
}
size_t Heap::size() const
{
return m_markedSpace.size();
}
size_t Heap::capacity() const
{
return m_markedSpace.capacity();
}
size_t Heap::globalObjectCount()
{
return m_globalData->globalObjectCount;
}
size_t Heap::protectedGlobalObjectCount()
{
size_t count = m_handleHeap.protectedGlobalObjectCount();
ProtectCountSet::iterator end = m_protectedValues.end();
for (ProtectCountSet::iterator it = m_protectedValues.begin(); it != end; ++it) {
if (it->first->isObject() && asObject(it->first)->isGlobalObject())
count++;
}
return count;
}
size_t Heap::protectedObjectCount()
{
return m_protectedValues.size();
}
class TypeCounter {
public:
TypeCounter();
void operator()(JSCell*);
PassOwnPtr<TypeCountSet> take();
private:
const char* typeName(JSCell*);
OwnPtr<TypeCountSet> m_typeCountSet;
};
inline TypeCounter::TypeCounter()
: m_typeCountSet(new TypeCountSet)
{
}
inline const char* TypeCounter::typeName(JSCell* cell)
{
if (cell->isString())
return "string";
if (cell->isGetterSetter())
return "Getter-Setter";
if (cell->isAPIValueWrapper())
return "API wrapper";
if (cell->isPropertyNameIterator())
return "For-in iterator";
if (const ClassInfo* info = cell->classInfo())
return info->className;
if (!cell->isObject())
return "[empty cell]";
return "Object";
}
inline void TypeCounter::operator()(JSCell* cell)
{
m_typeCountSet->add(typeName(cell));
}
inline PassOwnPtr<TypeCountSet> TypeCounter::take()
{
return m_typeCountSet.release();
}
PassOwnPtr<TypeCountSet> Heap::protectedObjectTypeCounts()
{
TypeCounter typeCounter;
ProtectCountSet::iterator end = m_protectedValues.end();
for (ProtectCountSet::iterator it = m_protectedValues.begin(); it != end; ++it)
typeCounter(it->first);
m_handleHeap.protectedObjectTypeCounts(typeCounter);
return typeCounter.take();
}
void HandleHeap::protectedObjectTypeCounts(TypeCounter& typeCounter)
{
Node* end = m_strongList.end();
for (Node* node = m_strongList.begin(); node != end; node = node->next()) {
JSValue value = *node->slot();
if (value && value.isCell())
typeCounter(value.asCell());
}
}
PassOwnPtr<TypeCountSet> Heap::objectTypeCounts()
{
TypeCounter typeCounter;
forEach(typeCounter);
return typeCounter.take();
}
bool Heap::isBusy()
{
return m_operationInProgress != NoOperation;
}
void Heap::collectAllGarbage()
{
reset(DoSweep);
}
void Heap::reset(SweepToggle sweepToggle)
{
ASSERT(globalData()->identifierTable == wtfThreadData().currentIdentifierTable());
JAVASCRIPTCORE_GC_BEGIN();
markRoots();
m_handleHeap.finalizeWeakHandles();
JAVASCRIPTCORE_GC_MARKED();
m_markedSpace.reset();
m_extraCost = 0;
#if ENABLE(JSC_ZOMBIES)
sweepToggle = DoSweep;
#endif
if (sweepToggle == DoSweep) {
m_markedSpace.sweep();
m_markedSpace.shrink();
}
// To avoid pathological GC churn in large heaps, we set the allocation high
// water mark to be proportional to the current size of the heap. The exact
// proportion is a bit arbitrary. A 2X multiplier gives a 1:1 (heap size :
// new bytes allocated) proportion, and seems to work well in benchmarks.
size_t proportionalBytes = 2 * m_markedSpace.size();
m_markedSpace.setHighWaterMark(max(proportionalBytes, minBytesPerCycle));
JAVASCRIPTCORE_GC_END();
(*m_activityCallback)();
}
void Heap::setActivityCallback(PassOwnPtr<GCActivityCallback> activityCallback)
{
m_activityCallback = activityCallback;
}
GCActivityCallback* Heap::activityCallback()
{
return m_activityCallback.get();
}
} // namespace JSC