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253 lines (213 loc) · 7.82 KB
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/*
* Copyright (C) 2012 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef BlockAllocator_h
#define BlockAllocator_h
#include "GCActivityCallback.h"
#include "HeapBlock.h"
#include "Region.h"
#include <condition_variable>
#include <wtf/DoublyLinkedList.h>
#include <wtf/Forward.h>
#include <wtf/PageAllocationAligned.h>
#include <wtf/TCSpinLock.h>
#include <wtf/Threading.h>
namespace JSC {
class BlockAllocator;
class CodeBlock;
class CopiedBlock;
class CopyWorkListSegment;
template <typename T> class GCArraySegment;
class HandleBlock;
class JSCell;
class VM;
class MarkedBlock;
class WeakBlock;
// Simple allocator to reduce VM cost by holding onto blocks of memory for
// short periods of time and then freeing them on a secondary thread.
class BlockAllocator {
public:
BlockAllocator();
~BlockAllocator();
template <typename T> DeadBlock* allocate();
DeadBlock* allocateCustomSize(size_t blockSize, size_t blockAlignment);
template <typename T> void deallocate(T*);
template <typename T> void deallocateCustomSize(T*);
JS_EXPORT_PRIVATE void releaseFreeRegions();
private:
void waitForDuration(std::chrono::milliseconds);
friend ThreadIdentifier createBlockFreeingThread(BlockAllocator*);
void blockFreeingThreadMain();
static void blockFreeingThreadStartFunc(void* heap);
struct RegionSet {
RegionSet(size_t blockSize)
: m_numberOfPartialRegions(0)
, m_blockSize(blockSize)
{
}
bool isEmpty() const
{
return m_fullRegions.isEmpty() && m_partialRegions.isEmpty();
}
DoublyLinkedList<Region> m_fullRegions;
DoublyLinkedList<Region> m_partialRegions;
size_t m_numberOfPartialRegions;
size_t m_blockSize;
};
DeadBlock* tryAllocateFromRegion(RegionSet&, DoublyLinkedList<Region>&, size_t&);
bool allRegionSetsAreEmpty() const;
template <typename T> RegionSet& regionSetFor();
SuperRegion m_superRegion;
RegionSet m_copiedRegionSet;
RegionSet m_markedRegionSet;
// WeakBlocks and GCArraySegments use the same RegionSet since they're the same size.
RegionSet m_fourKBBlockRegionSet;
RegionSet m_workListRegionSet;
DoublyLinkedList<Region> m_emptyRegions;
size_t m_numberOfEmptyRegions;
bool m_isCurrentlyAllocating;
bool m_blockFreeingThreadShouldQuit;
SpinLock m_regionLock;
std::mutex m_emptyRegionConditionMutex;
std::condition_variable m_emptyRegionCondition;
ThreadIdentifier m_blockFreeingThread;
};
inline DeadBlock* BlockAllocator::tryAllocateFromRegion(RegionSet& set, DoublyLinkedList<Region>& regions, size_t& numberOfRegions)
{
if (numberOfRegions) {
ASSERT(!regions.isEmpty());
Region* region = regions.head();
ASSERT(!region->isFull());
if (region->isEmpty()) {
ASSERT(region == m_emptyRegions.head());
m_numberOfEmptyRegions--;
set.m_numberOfPartialRegions++;
region = m_emptyRegions.removeHead()->reset(set.m_blockSize);
set.m_partialRegions.push(region);
}
DeadBlock* block = region->allocate();
if (region->isFull()) {
set.m_numberOfPartialRegions--;
set.m_fullRegions.push(set.m_partialRegions.removeHead());
}
return block;
}
return 0;
}
template<typename T>
inline DeadBlock* BlockAllocator::allocate()
{
RegionSet& set = regionSetFor<T>();
DeadBlock* block;
m_isCurrentlyAllocating = true;
{
SpinLockHolder locker(&m_regionLock);
if ((block = tryAllocateFromRegion(set, set.m_partialRegions, set.m_numberOfPartialRegions)))
return block;
if ((block = tryAllocateFromRegion(set, m_emptyRegions, m_numberOfEmptyRegions)))
return block;
}
Region* newRegion = Region::create(&m_superRegion, T::blockSize);
SpinLockHolder locker(&m_regionLock);
m_emptyRegions.push(newRegion);
m_numberOfEmptyRegions++;
block = tryAllocateFromRegion(set, m_emptyRegions, m_numberOfEmptyRegions);
ASSERT(block);
return block;
}
inline DeadBlock* BlockAllocator::allocateCustomSize(size_t blockSize, size_t blockAlignment)
{
size_t realSize = WTF::roundUpToMultipleOf(blockAlignment, blockSize);
Region* newRegion = Region::createCustomSize(&m_superRegion, realSize, blockAlignment);
DeadBlock* block = newRegion->allocate();
ASSERT(block);
return block;
}
template<typename T>
inline void BlockAllocator::deallocate(T* block)
{
RegionSet& set = regionSetFor<T>();
bool shouldWakeBlockFreeingThread = false;
{
SpinLockHolder locker(&m_regionLock);
Region* region = block->region();
ASSERT(!region->isEmpty());
if (region->isFull())
set.m_fullRegions.remove(region);
else {
set.m_partialRegions.remove(region);
set.m_numberOfPartialRegions--;
}
region->deallocate(block);
if (region->isEmpty()) {
m_emptyRegions.push(region);
shouldWakeBlockFreeingThread = !m_numberOfEmptyRegions;
m_numberOfEmptyRegions++;
} else {
set.m_partialRegions.push(region);
set.m_numberOfPartialRegions++;
}
}
if (shouldWakeBlockFreeingThread) {
std::lock_guard<std::mutex> lock(m_emptyRegionConditionMutex);
m_emptyRegionCondition.notify_one();
}
if (!m_blockFreeingThread)
releaseFreeRegions();
}
template<typename T>
inline void BlockAllocator::deallocateCustomSize(T* block)
{
Region* region = block->region();
ASSERT(region->isCustomSize());
region->deallocate(block);
region->destroy();
}
#define REGION_SET_FOR(blockType, set) \
template <> \
inline BlockAllocator::RegionSet& BlockAllocator::regionSetFor<blockType>() \
{ \
return set; \
} \
template <> \
inline BlockAllocator::RegionSet& BlockAllocator::regionSetFor<HeapBlock<blockType>>() \
{ \
return set; \
} \
REGION_SET_FOR(MarkedBlock, m_markedRegionSet);
REGION_SET_FOR(CopiedBlock, m_copiedRegionSet);
REGION_SET_FOR(WeakBlock, m_fourKBBlockRegionSet);
REGION_SET_FOR(GCArraySegment<const JSCell*>, m_fourKBBlockRegionSet);
REGION_SET_FOR(GCArraySegment<CodeBlock*>, m_fourKBBlockRegionSet);
REGION_SET_FOR(CopyWorkListSegment, m_workListRegionSet);
REGION_SET_FOR(HandleBlock, m_fourKBBlockRegionSet);
#undef REGION_SET_FOR
template <typename T>
inline BlockAllocator::RegionSet& BlockAllocator::regionSetFor()
{
RELEASE_ASSERT_NOT_REACHED();
return *(RegionSet*)0;
}
} // namespace JSC
#endif // BlockAllocator_h