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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 "GCThread.h"
#include "CopyVisitor.h"
#include "CopyVisitorInlineMethods.h"
#include "GCThreadSharedData.h"
#include "SlotVisitor.h"
#include <wtf/MainThread.h>
#include <wtf/PassOwnPtr.h>
namespace JSC {
GCThread::GCThread(GCThreadSharedData& shared, SlotVisitor* slotVisitor, CopyVisitor* copyVisitor)
: m_threadID(0)
, m_shared(shared)
, m_slotVisitor(WTF::adoptPtr(slotVisitor))
, m_copyVisitor(WTF::adoptPtr(copyVisitor))
{
}
ThreadIdentifier GCThread::threadID()
{
ASSERT(m_threadID);
return m_threadID;
}
void GCThread::initializeThreadID(ThreadIdentifier threadID)
{
ASSERT(!m_threadID);
m_threadID = threadID;
}
SlotVisitor* GCThread::slotVisitor()
{
ASSERT(m_slotVisitor);
return m_slotVisitor.get();
}
CopyVisitor* GCThread::copyVisitor()
{
ASSERT(m_copyVisitor);
return m_copyVisitor.get();
}
GCPhase GCThread::waitForNextPhase()
{
MutexLocker locker(m_shared.m_phaseLock);
while (m_shared.m_gcThreadsShouldWait)
m_shared.m_phaseCondition.wait(m_shared.m_phaseLock);
m_shared.m_numberOfActiveGCThreads--;
if (!m_shared.m_numberOfActiveGCThreads)
m_shared.m_activityCondition.signal();
while (m_shared.m_currentPhase == NoPhase)
m_shared.m_phaseCondition.wait(m_shared.m_phaseLock);
m_shared.m_numberOfActiveGCThreads++;
return m_shared.m_currentPhase;
}
void GCThread::gcThreadMain()
{
GCPhase currentPhase;
#if ENABLE(PARALLEL_GC)
WTF::registerGCThread();
#endif
// Wait for the main thread to finish creating and initializing us. The main thread grabs this lock before
// creating this thread. We aren't guaranteed to have a valid threadID until the main thread releases this lock.
{
MutexLocker locker(m_shared.m_phaseLock);
}
{
ParallelModeEnabler enabler(*m_slotVisitor);
while ((currentPhase = waitForNextPhase()) != Exit) {
// Note: Each phase is responsible for its own termination conditions. The comments below describe
// how each phase reaches termination.
switch (currentPhase) {
case Mark:
m_slotVisitor->drainFromShared(SlotVisitor::SlaveDrain);
// GCThreads only return from drainFromShared() if the main thread sets the m_parallelMarkersShouldExit
// flag in the GCThreadSharedData. The only way the main thread sets that flag is if it realizes
// that all of the various subphases in Heap::markRoots() have been fully finished and there is
// no more marking work to do and all of the GCThreads are idle, meaning no more work can be generated.
break;
case Copy:
// We don't have to call startCopying() because it's called for us on the main thread to avoid a
// race condition.
m_copyVisitor->copyFromShared();
// We know we're done copying when we return from copyFromShared() because we would
// only do so if there were no more chunks of copying work left to do. When there is no
// more copying work to do, the main thread will wait in CopiedSpace::doneCopying() until
// all of the blocks that the GCThreads borrowed have been returned. doneCopying()
// returns our borrowed CopiedBlock, allowing the copying phase to finish.
m_copyVisitor->doneCopying();
break;
case NoPhase:
ASSERT_NOT_REACHED();
break;
case Exit:
ASSERT_NOT_REACHED();
break;
}
}
}
}
void GCThread::gcThreadStartFunc(void* data)
{
GCThread* thread = static_cast<GCThread*>(data);
thread->gcThreadMain();
}
} // namespace JSC
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