113 lines
3.5 KiB
C++
113 lines
3.5 KiB
C++
#pragma once
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// blocking_queue:
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// A blocking multi-consumer/multi-producer thread safe queue.
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// Has max capacity and supports timeout on push or pop operations.
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#include <cstddef>
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#include <chrono>
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#include <memory>
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#include <queue>
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#include <mutex>
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#include <condition_variable>
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namespace c11log {
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namespace details
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{
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template<typename T>
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class blocking_queue {
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public:
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using queue_t = std::queue<T>;
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using size_type = typename queue_t::size_type;
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using clock = std::chrono::system_clock;
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explicit blocking_queue(size_type max_size) :max_size_(max_size), q_()
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{}
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blocking_queue(const blocking_queue&) = delete;
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blocking_queue& operator=(const blocking_queue&) = delete;
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~blocking_queue() = default;
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size_type size()
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{
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std::lock_guard<std::mutex> lock(mutex_);
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return q_.size();
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}
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// Push copy of item into the back of the queue.
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// If the queue is full, block the calling thread util there is room or timeout have passed.
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// Return: false on timeout, true on successful push.
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template<class Duration_Rep, class Duration_Period>
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bool push(const T& item, const std::chrono::duration<Duration_Rep, Duration_Period>& timeout)
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{
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std::unique_lock<std::mutex> ul(mutex_);
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if (q_.size() >= max_size_)
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{
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if (!item_popped_cond_.wait_until(ul, clock::now() + timeout, [this]() { return this->q_.size() < this->max_size_; }))
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return false;
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}
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q_.push(item);
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if (q_.size() <= 1)
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{
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ul.unlock(); //So the notified thread will have better chance to accuire the lock immediatly..
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item_pushed_cond_.notify_one();
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}
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return true;
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}
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// Push copy of item into the back of the queue.
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// If the queue is full, block the calling thread until there is room.
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void push(const T& item)
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{
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while (!push(item, one_hour));
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}
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// Pop a copy of the front item in the queue into the given item ref.
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// If the queue is empty, block the calling thread util there is item to pop or timeout have passed.
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// Return: false on timeout , true on successful pop/
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template<class Duration_Rep, class Duration_Period>
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bool pop(T& item, const std::chrono::duration<Duration_Rep, Duration_Period>& timeout)
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{
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std::unique_lock<std::mutex> ul(mutex_);
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if (q_.empty())
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{
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if (!item_pushed_cond_.wait_until(ul, clock::now() + timeout, [this]() { return !this->q_.empty(); }))
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return false;
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}
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item = q_.front();
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q_.pop();
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if (q_.size() >= max_size_ - 1)
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{
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ul.unlock(); //So the notified thread will have better chance to accuire the lock immediatly..
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item_popped_cond_.notify_one();
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}
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return true;
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}
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// Pop a copy of the front item in the queue into the given item ref.
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// If the queue is empty, block the calling thread util there is item to pop.
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void pop(T& item)
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{
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while (!pop(item, one_hour));
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}
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// Clear the queue
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void clear()
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{
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T item;
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while (pop(item, std::chrono::milliseconds(0)));
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}
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private:
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size_type max_size_;
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std::queue<T> q_;
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std::mutex mutex_;
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std::condition_variable item_pushed_cond_;
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std::condition_variable item_popped_cond_;
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static constexpr auto one_hour = std::chrono::seconds(3);
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};
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}
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}
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