68 lines
1.5 KiB
C++
68 lines
1.5 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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#include <condition_variable>
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#include <mutex>
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#include <queue>
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#include <utility>
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#pragma once
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namespace rocksdb {
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template <class T>
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class channel {
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public:
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explicit channel() : eof_(false) {}
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channel(const channel&) = delete;
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void operator=(const channel&) = delete;
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void sendEof() {
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std::lock_guard<std::mutex> lk(lock_);
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eof_ = true;
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cv_.notify_all();
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}
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bool eof() {
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std::lock_guard<std::mutex> lk(lock_);
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return buffer_.empty() && eof_;
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}
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size_t size() const {
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std::lock_guard<std::mutex> lk(lock_);
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return buffer_.size();
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}
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// writes elem to the queue
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void write(T&& elem) {
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std::unique_lock<std::mutex> lk(lock_);
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buffer_.emplace(std::forward<T>(elem));
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cv_.notify_one();
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}
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/// Moves a dequeued element onto elem, blocking until an element
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/// is available.
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// returns false if EOF
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bool read(T& elem) {
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std::unique_lock<std::mutex> lk(lock_);
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cv_.wait(lk, [&] { return eof_ || !buffer_.empty(); });
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if (eof_ && buffer_.empty()) {
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return false;
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}
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elem = std::move(buffer_.front());
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buffer_.pop();
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cv_.notify_one();
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return true;
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}
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private:
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std::condition_variable cv_;
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std::mutex lock_;
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std::queue<T> buffer_;
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bool eof_;
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};
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} // namespace rocksdb
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