131 lines
4.1 KiB
C++
131 lines
4.1 KiB
C++
/*
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* Copyright (C) 2021 Apple Inc. All Rights Reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "config.h"
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#include <wtf/SuspendableWorkQueue.h>
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namespace WTF {
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Ref<SuspendableWorkQueue> SuspendableWorkQueue::create(const char* name, WorkQueue::QOS qos)
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{
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return adoptRef(*new SuspendableWorkQueue(name, qos));
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}
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SuspendableWorkQueue::SuspendableWorkQueue(const char* name, QOS qos)
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: WorkQueue(name, Type::Serial, qos)
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{
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ASSERT(isMainThread());
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}
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void SuspendableWorkQueue::suspend(Function<void()>&& suspendFunction, CompletionHandler<void()>&& completionHandler)
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{
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ASSERT(isMainThread());
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Locker suspensionLocker { m_suspensionLock };
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// Last suspend function will be the one that is used.
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m_suspendFunction = WTFMove(suspendFunction);
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m_suspensionCompletionHandlers.append(WTFMove(completionHandler));
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if (m_isOrWillBeSuspended)
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return;
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m_isOrWillBeSuspended = true;
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// Make sure queue will be suspended when there is no task scheduled on the queue.
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WorkQueue::dispatch([this] {
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suspendIfNeeded();
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});
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}
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void SuspendableWorkQueue::resume()
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{
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ASSERT(isMainThread());
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Locker suspensionLocker { m_suspensionLock };
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if (!m_isOrWillBeSuspended)
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return;
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m_isOrWillBeSuspended = false;
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m_suspensionCondition.notifyOne();
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}
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void SuspendableWorkQueue::dispatch(Function<void()>&& function)
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{
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// WorkQueue will protect this in dispatch().
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WorkQueue::dispatch([this, function = WTFMove(function)] {
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suspendIfNeeded();
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function();
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});
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}
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void SuspendableWorkQueue::dispatchAfter(Seconds seconds, Function<void()>&& function)
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{
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WorkQueue::dispatchAfter(seconds, [this, function = WTFMove(function)] {
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suspendIfNeeded();
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function();
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});
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}
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void SuspendableWorkQueue::dispatchSync(Function<void()>&& function)
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{
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// This function should be called only when queue is not about to be suspended,
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// otherwise thread may be blocked.
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if (isMainThread()) {
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Locker suspensionLocker { m_suspensionLock };
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RELEASE_ASSERT(!m_isOrWillBeSuspended);
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}
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WorkQueue::dispatchSync(WTFMove(function));
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}
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void SuspendableWorkQueue::invokeAllSuspensionCompletionHandlers()
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{
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ASSERT(!isMainThread());
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if (m_suspensionCompletionHandlers.isEmpty())
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return;
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callOnMainThread([completionHandlers = std::exchange(m_suspensionCompletionHandlers, { })]() mutable {
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for (auto& completionHandler : completionHandlers) {
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if (completionHandler)
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completionHandler();
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}
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});
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}
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void SuspendableWorkQueue::suspendIfNeeded()
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{
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ASSERT(!isMainThread());
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Locker suspensionLocker { m_suspensionLock };
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auto suspendFunction = std::exchange(m_suspendFunction, { });
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if (m_isOrWillBeSuspended)
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suspendFunction();
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invokeAllSuspensionCompletionHandlers();
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while (m_isOrWillBeSuspended)
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m_suspensionCondition.wait(m_suspensionLock);
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}
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} // namespace WTF
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