/*
* Copyright (C) 2010 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 "WorkQueue.h"
#include <WebCore/NotImplemented.h>
#include <wtf/Threading.h>
inline WorkQueue::WorkItemWin::WorkItemWin(PassOwnPtr<WorkItem> item, WorkQueue* queue)
: m_item(item)
, m_queue(queue)
{
}
PassRefPtr<WorkQueue::WorkItemWin> WorkQueue::WorkItemWin::create(PassOwnPtr<WorkItem> item, WorkQueue* queue)
{
return adoptRef(new WorkItemWin(item, queue));
}
WorkQueue::WorkItemWin::~WorkItemWin()
{
}
inline WorkQueue::HandleWorkItem::HandleWorkItem(HANDLE handle, PassOwnPtr<WorkItem> item, WorkQueue* queue)
: WorkItemWin(item, queue)
, m_handle(handle)
, m_waitHandle(0)
{
ASSERT_ARG(handle, handle);
}
PassRefPtr<WorkQueue::HandleWorkItem> WorkQueue::HandleWorkItem::createByAdoptingHandle(HANDLE handle, PassOwnPtr<WorkItem> item, WorkQueue* queue)
{
return adoptRef(new HandleWorkItem(handle, item, queue));
}
WorkQueue::HandleWorkItem::~HandleWorkItem()
{
::CloseHandle(m_handle);
}
void WorkQueue::handleCallback(void* context, BOOLEAN timerOrWaitFired)
{
ASSERT_ARG(context, context);
ASSERT_ARG(timerOrWaitFired, !timerOrWaitFired);
WorkItemWin* item = static_cast<WorkItemWin*>(context);
WorkQueue* queue = item->queue();
{
MutexLocker lock(queue->m_workItemQueueLock);
queue->m_workItemQueue.append(item);
// If no other thread is performing work, we can do it on this thread.
if (!queue->tryRegisterAsWorkThread()) {
// Some other thread is performing work. Since we hold the queue lock, we can be sure
// that the work thread is not exiting due to an empty queue and will process the work
// item we just added to it. If we weren't holding the lock we'd have to signal
// m_performWorkEvent to make sure the work item got picked up.
return;
}
}
queue->performWorkOnRegisteredWorkThread();
}
void WorkQueue::registerHandle(HANDLE handle, PassOwnPtr<WorkItem> item)
{
RefPtr<HandleWorkItem> handleItem = HandleWorkItem::createByAdoptingHandle(handle, item, this);
{
MutexLocker lock(m_handlesLock);
ASSERT_ARG(handle, !m_handles.contains(handle));
m_handles.set(handle, handleItem);
}
HANDLE waitHandle;
if (!::RegisterWaitForSingleObject(&waitHandle, handle, handleCallback, handleItem.get(), INFINITE, WT_EXECUTEDEFAULT)) {
DWORD error = ::GetLastError();
ASSERT_NOT_REACHED();
}
handleItem->setWaitHandle(waitHandle);
}
void WorkQueue::unregisterAndCloseHandle(HANDLE handle)
{
RefPtr<HandleWorkItem> item;
{
MutexLocker locker(m_handlesLock);
ASSERT_ARG(handle, m_handles.contains(handle));
item = m_handles.take(handle);
}
unregisterWaitAndDestroyItemSoon(item.release());
}
DWORD WorkQueue::workThreadCallback(void* context)
{
ASSERT_ARG(context, context);
WorkQueue* queue = static_cast<WorkQueue*>(context);
if (!queue->tryRegisterAsWorkThread())
return 0;
queue->performWorkOnRegisteredWorkThread();
return 0;
}
void WorkQueue::performWorkOnRegisteredWorkThread()
{
ASSERT(m_isWorkThreadRegistered);
bool isValid = true;
m_workItemQueueLock.lock();
while (isValid && !m_workItemQueue.isEmpty()) {
Vector<RefPtr<WorkItemWin> > workItemQueue;
m_workItemQueue.swap(workItemQueue);
// Allow more work to be scheduled while we're not using the queue directly.
m_workItemQueueLock.unlock();
for (size_t i = 0; i < workItemQueue.size(); ++i) {
MutexLocker locker(m_isValidMutex);
isValid = m_isValid;
if (!isValid)
break;
workItemQueue[i]->item()->execute();
}
m_workItemQueueLock.lock();
}
// One invariant we maintain is that any work scheduled while a work thread is registered will
// be handled by that work thread. Unregister as the work thread while the queue lock is still
// held so that no work can be scheduled while we're still registered.
unregisterAsWorkThread();
m_workItemQueueLock.unlock();
}
void WorkQueue::platformInitialize(const char* name)
{
m_isWorkThreadRegistered = 0;
m_timerQueue = ::CreateTimerQueue();
ASSERT_WITH_MESSAGE(m_timerQueue, "::CreateTimerQueue failed with error %lu", ::GetLastError());
}
bool WorkQueue::tryRegisterAsWorkThread()
{
LONG result = ::InterlockedCompareExchange(&m_isWorkThreadRegistered, 1, 0);
ASSERT(!result || result == 1);
return !result;
}
void WorkQueue::unregisterAsWorkThread()
{
LONG result = ::InterlockedCompareExchange(&m_isWorkThreadRegistered, 0, 1);
ASSERT_UNUSED(result, result == 1);
}
void WorkQueue::platformInvalidate()
{
#if !ASSERT_DISABLED
MutexLocker lock(m_handlesLock);
ASSERT(m_handles.isEmpty());
#endif
// FIXME: We need to ensure that any timer-queue timers that fire after this point don't try to
// access this WorkQueue <http://webkit.org/b/44690>.
::DeleteTimerQueueEx(m_timerQueue, 0);
}
void WorkQueue::scheduleWork(PassOwnPtr<WorkItem> item)
{
MutexLocker locker(m_workItemQueueLock);
m_workItemQueue.append(WorkItemWin::create(item, this));
// Spawn a work thread to perform the work we just added. As an optimization, we avoid
// spawning the thread if a work thread is already registered. This prevents multiple work
// threads from being spawned in most cases. (Note that when a work thread has been spawned but
// hasn't registered itself yet, m_isWorkThreadRegistered will be false and we'll end up
// spawning a second work thread here. But work thread registration process will ensure that
// only one thread actually ends up performing work.)
if (!m_isWorkThreadRegistered)
::QueueUserWorkItem(workThreadCallback, this, WT_EXECUTEDEFAULT);
}
struct TimerContext : public ThreadSafeRefCounted<TimerContext> {
static PassRefPtr<TimerContext> create() { return adoptRef(new TimerContext); }
WorkQueue* queue;
OwnPtr<WorkItem> item;
Mutex timerMutex;
HANDLE timer;
private:
TimerContext() : queue(0), timer(0) { }
};
void WorkQueue::timerCallback(void* context, BOOLEAN timerOrWaitFired)
{
ASSERT_ARG(context, context);
ASSERT_UNUSED(timerOrWaitFired, timerOrWaitFired);
// Balanced by leakRef in scheduleWorkAfterDelay.
RefPtr<TimerContext> timerContext = adoptRef(static_cast<TimerContext*>(context));
timerContext->queue->scheduleWork(timerContext->item.release());
MutexLocker lock(timerContext->timerMutex);
ASSERT(timerContext->timer);
ASSERT(timerContext->queue->m_timerQueue);
if (!::DeleteTimerQueueTimer(timerContext->queue->m_timerQueue, timerContext->timer, 0))
ASSERT_WITH_MESSAGE(false, "::DeleteTimerQueueTimer failed with error %lu", ::GetLastError());
}
void WorkQueue::scheduleWorkAfterDelay(PassOwnPtr<WorkItem> item, double delay)
{
ASSERT(m_timerQueue);
RefPtr<TimerContext> context = TimerContext::create();
context->queue = this;
context->item = item;
{
// The timer callback could fire before ::CreateTimerQueueTimer even returns, so we protect
// context->timer with a mutex to ensure the timer callback doesn't access it before the
// timer handle has been stored in it.
MutexLocker lock(context->timerMutex);
// Since our timer callback is quick, we can execute in the timer thread itself and avoid
// an extra thread switch over to a worker thread.
if (!::CreateTimerQueueTimer(&context->timer, m_timerQueue, timerCallback, context.get(), delay * 1000, 0, WT_EXECUTEINTIMERTHREAD)) {
ASSERT_WITH_MESSAGE(false, "::CreateTimerQueueTimer failed with error %lu", ::GetLastError());
return;
}
}
// The timer callback will handle destroying context.
context.release().leakRef();
}
void WorkQueue::unregisterWaitAndDestroyItemSoon(PassRefPtr<HandleWorkItem> item)
{
// We're going to make a blocking call to ::UnregisterWaitEx before closing the handle. (The
// blocking version of ::UnregisterWaitEx is much simpler than the non-blocking version.) If we
// do this on the current thread, we'll deadlock if we're currently in a callback function for
// the wait we're unregistering. So instead we do it asynchronously on some other worker thread.
::QueueUserWorkItem(unregisterWaitAndDestroyItemCallback, item.leakRef(), WT_EXECUTEDEFAULT);
}
DWORD WINAPI WorkQueue::unregisterWaitAndDestroyItemCallback(void* context)
{
ASSERT_ARG(context, context);
RefPtr<HandleWorkItem> item = adoptRef(static_cast<HandleWorkItem*>(context));
// Now that we know we're not in a callback function for the wait we're unregistering, we can
// make a blocking call to ::UnregisterWaitEx.
if (!::UnregisterWaitEx(item->waitHandle(), INVALID_HANDLE_VALUE)) {
DWORD error = ::GetLastError();
ASSERT_NOT_REACHED();
}
return 0;
}