132 lines
3.7 KiB
C++
132 lines
3.7 KiB
C++
/*
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* Copyright (C) 2016 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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#pragma once
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#include <wtf/Condition.h>
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#include <wtf/Deque.h>
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#include <wtf/Lock.h>
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#include <wtf/ThreadSafeRefCounted.h>
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namespace WTF {
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template<typename T, size_t BufferSize>
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class SynchronizedFixedQueue final : public ThreadSafeRefCounted<SynchronizedFixedQueue<T, BufferSize>> {
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public:
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static Ref<SynchronizedFixedQueue> create()
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{
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return adoptRef(*new SynchronizedFixedQueue());
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}
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void open()
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{
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Locker locker { m_lock };
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if (m_open)
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return;
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// Restore the queue to its original state.
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m_open = true;
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m_queue.clear();
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}
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void close()
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{
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Locker locker { m_lock };
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if (!m_open)
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return;
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// Wake all the sleeping threads up with a closing state.
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m_open = false;
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m_condition.notifyAll();
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}
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bool isOpen()
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{
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Locker locker { m_lock };
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return m_open;
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}
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bool enqueue(const T& value)
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{
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Locker locker { m_lock };
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// Wait for an empty place to be available in the queue.
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m_condition.wait(m_lock, [this] {
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assertIsHeld(m_lock);
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return !m_open || m_queue.size() < BufferSize;
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});
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// The queue is closing, exit immediately.
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if (!m_open)
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return false;
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// Add the item in the queue.
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m_queue.append(value);
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// Notify the other threads that an item was added to the queue.
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m_condition.notifyAll();
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return true;
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}
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bool dequeue(T& value)
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{
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Locker locker { m_lock };
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// Wait for an item to be added.
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m_condition.wait(m_lock, [this] {
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assertIsHeld(m_lock);
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return !m_open || m_queue.size();
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});
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// The queue is closing, exit immediately.
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if (!m_open)
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return false;
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// Get a copy from m_queue.first and then remove it.
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value = m_queue.first();
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m_queue.removeFirst();
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// Notify the other threads that an item was removed from the queue.
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m_condition.notifyAll();
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return true;
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}
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private:
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SynchronizedFixedQueue()
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{
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static_assert(!((BufferSize - 1) & BufferSize), "BufferSize must be power of 2.");
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}
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Lock m_lock;
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Condition m_condition;
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bool m_open WTF_GUARDED_BY_LOCK(m_lock) { true };
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Deque<T, BufferSize> m_queue WTF_GUARDED_BY_LOCK(m_lock);
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};
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}
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using WTF::SynchronizedFixedQueue;
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