51 lines
1.5 KiB
C++
51 lines
1.5 KiB
C++
/*
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* This file is open source software, licensed to you under the terms
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* of the Apache License, Version 2.0 (the "License"). See the NOTICE file
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* distributed with this work for additional information regarding copyright
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* ownership. You may not use this file except in compliance with the License.
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*
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing,
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* software distributed under the License is distributed on an
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* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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* KIND, either express or implied. See the License for the
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* specific language governing permissions and limitations
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* under the License.
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*/
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/*
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* Copyright (C) 2015 Cloudius Systems, Ltd.
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*/
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#pragma once
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#include <mutex>
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#include <condition_variable>
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#include <experimental/optional>
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// Single-element blocking queue
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template <typename T>
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class exchanger {
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private:
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std::mutex _mutex;
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std::condition_variable _cv;
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std::experimental::optional<T> _element;
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public:
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void give(T value) {
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std::unique_lock<std::mutex> lock(_mutex);
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_cv.wait(lock, [this] { return !_element; });
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_element = value;
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_cv.notify_one();
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}
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T take() {
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std::unique_lock<std::mutex> lock(_mutex);
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_cv.wait(lock, [this] { return bool(_element); });
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auto v = *_element;
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_element = {};
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_cv.notify_one();
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return v;
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}
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};
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