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Copy pathBlockAllocator.cpp
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173 lines (151 loc) · 5.71 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.
*/
#include "config.h"
#include "BlockAllocator.h"
#include "CopiedBlock.h"
#include "CopyWorkList.h"
#include "MarkedBlock.h"
#include "JSCInlines.h"
#include "WeakBlock.h"
#include <wtf/CurrentTime.h>
namespace JSC {
inline ThreadIdentifier createBlockFreeingThread(BlockAllocator* allocator)
{
if (!GCActivityCallback::s_shouldCreateGCTimer)
return 0; // No block freeing thread.
ThreadIdentifier identifier = createThread(allocator->blockFreeingThreadStartFunc, allocator, "JavaScriptCore::BlockFree");
RELEASE_ASSERT(identifier);
return identifier;
}
BlockAllocator::BlockAllocator()
: m_superRegion()
, m_copiedRegionSet(CopiedBlock::blockSize)
, m_markedRegionSet(MarkedBlock::blockSize)
, m_fourKBBlockRegionSet(WeakBlock::blockSize)
, m_workListRegionSet(CopyWorkListSegment::blockSize)
, m_numberOfEmptyRegions(0)
, m_isCurrentlyAllocating(false)
, m_blockFreeingThreadShouldQuit(false)
, m_blockFreeingThread(createBlockFreeingThread(this))
{
m_regionLock.Init();
}
BlockAllocator::~BlockAllocator()
{
releaseFreeRegions();
{
std::lock_guard<std::mutex> lock(m_emptyRegionConditionMutex);
m_blockFreeingThreadShouldQuit = true;
m_emptyRegionCondition.notify_all();
}
if (m_blockFreeingThread)
waitForThreadCompletion(m_blockFreeingThread);
ASSERT(allRegionSetsAreEmpty());
ASSERT(m_emptyRegions.isEmpty());
}
bool BlockAllocator::allRegionSetsAreEmpty() const
{
return m_copiedRegionSet.isEmpty()
&& m_markedRegionSet.isEmpty()
&& m_fourKBBlockRegionSet.isEmpty()
&& m_workListRegionSet.isEmpty();
}
void BlockAllocator::releaseFreeRegions()
{
while (true) {
Region* region;
{
SpinLockHolder locker(&m_regionLock);
if (!m_numberOfEmptyRegions)
region = 0;
else {
region = m_emptyRegions.removeHead();
RELEASE_ASSERT(region);
m_numberOfEmptyRegions--;
}
}
if (!region)
break;
region->destroy();
}
}
void BlockAllocator::waitForDuration(std::chrono::milliseconds duration)
{
std::unique_lock<std::mutex> lock(m_emptyRegionConditionMutex);
// If this returns early, that's fine, so long as it doesn't do it too
// frequently. It would only be a bug if this function failed to return
// when it was asked to do so.
if (m_blockFreeingThreadShouldQuit)
return;
m_emptyRegionCondition.wait_for(lock, duration);
}
void BlockAllocator::blockFreeingThreadStartFunc(void* blockAllocator)
{
static_cast<BlockAllocator*>(blockAllocator)->blockFreeingThreadMain();
}
void BlockAllocator::blockFreeingThreadMain()
{
size_t currentNumberOfEmptyRegions;
while (!m_blockFreeingThreadShouldQuit) {
// Generally wait for one second before scavenging free blocks. This
// may return early, particularly when we're being asked to quit.
waitForDuration(std::chrono::seconds(1));
if (m_blockFreeingThreadShouldQuit)
break;
if (m_isCurrentlyAllocating) {
m_isCurrentlyAllocating = false;
continue;
}
// Sleep until there is actually work to do rather than waking up every second to check.
{
std::unique_lock<std::mutex> lock(m_emptyRegionConditionMutex);
SpinLockHolder regionLocker(&m_regionLock);
while (!m_numberOfEmptyRegions && !m_blockFreeingThreadShouldQuit) {
m_regionLock.Unlock();
m_emptyRegionCondition.wait(lock);
m_regionLock.Lock();
}
currentNumberOfEmptyRegions = m_numberOfEmptyRegions;
}
size_t desiredNumberOfEmptyRegions = currentNumberOfEmptyRegions / 2;
while (!m_blockFreeingThreadShouldQuit) {
Region* region;
{
SpinLockHolder locker(&m_regionLock);
if (m_numberOfEmptyRegions <= desiredNumberOfEmptyRegions)
region = 0;
else {
region = m_emptyRegions.removeHead();
RELEASE_ASSERT(region);
m_numberOfEmptyRegions--;
}
}
if (!region)
break;
region->destroy();
}
}
}
} // namespace JSC