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/*
* Copyright (C) 2016 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.
*/
#pragma once
#include <limits>
#include <wtf/Assertions.h>
#include <wtf/Condition.h>
#include <wtf/Deque.h>
#include <wtf/Lock.h>
#include <wtf/Noncopyable.h>
namespace WTF {
template<typename DataType>
class CrossThreadQueue final {
WTF_MAKE_FAST_ALLOCATED;
WTF_MAKE_NONCOPYABLE(CrossThreadQueue);
public:
CrossThreadQueue() = default;
void append(DataType&&);
DataType waitForMessage();
std::optional<DataType> tryGetMessage();
void kill();
bool isKilled() const;
bool isEmpty() const;
private:
mutable Lock m_lock;
Deque<DataType> m_queue WTF_GUARDED_BY_LOCK(m_lock);
Condition m_condition;
bool m_killed WTF_GUARDED_BY_LOCK(m_lock) { false };
};
template<typename DataType>
void CrossThreadQueue<DataType>::append(DataType&& message)
{
Locker locker { m_lock };
ASSERT(!m_killed);
m_queue.append(WTFMove(message));
m_condition.notifyOne();
}
template<typename DataType>
DataType CrossThreadQueue<DataType>::waitForMessage()
{
Locker locker { m_lock };
auto found = m_queue.end();
while (!m_killed && found == m_queue.end()) {
found = m_queue.begin();
if (found != m_queue.end())
break;
m_condition.wait(m_lock);
}
if (m_killed)
return { };
return m_queue.takeFirst();
}
template<typename DataType>
std::optional<DataType> CrossThreadQueue<DataType>::tryGetMessage()
{
Locker locker { m_lock };
if (m_queue.isEmpty())
return { };
return m_queue.takeFirst();
}
template<typename DataType>
void CrossThreadQueue<DataType>::kill()
{
Locker locker { m_lock };
m_killed = true;
m_condition.notifyAll();
}
template<typename DataType>
bool CrossThreadQueue<DataType>::isKilled() const
{
Locker locker { m_lock };
return m_killed;
}
template<typename DataType>
bool CrossThreadQueue<DataType>::isEmpty() const
{
Locker locker { m_lock };
return m_queue.isEmpty();
}
} // namespace WTF
using WTF::CrossThreadQueue;
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