用C++11實現一個有界的阻塞隊列

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對於一個無界的阻塞隊列而言，其實現非常簡單，即用一個鎖（鎖隊列）+ 一個條件變數（判空）即可。那麼對於一個有界阻塞隊列而言，其隊列的容量有上限，其實只要再加一個條件變數用來判斷是否滿即可。
綜上，我們需要

• mutex: 保護隊列的讀寫操作
• notEmptyCV: 條件變數，在take時wait, 在put之後notify
• notFullCV: 條件變數， 在put時wait, 在take之後notify.

C++11提供了豐富的多線程編程庫，包括加鎖解鎖、同步原語等封裝。我的實現如下：

#pragma once// Must use it higher than C++11#include <condition_variable>#include <mutex>#include <queue>#include <vector>#include <assert.h>#include <iostream>#include <thread>using namespace std::chrono_literals;template<typename T>class BoundedBlockingQueue {public:    // make class non-copyable    BoundedBlockingQueue(const BoundedBlockingQueue<T>&) = delete;    BoundedBlockingQueue& operator=(const BoundedBlockingQueue<T>&) = delete;    explicit BoundedBlockingQueue<T>(size_t maxSize)        : mtx_(),        maxSize_(maxSize)    {    }    void put(const T& x) {    //  std::cout << std::this_thread::get_id() << " puting" << x << std::endl;        std::unique_lock<std::mutex> locker(mtx_);        notFullCV_.wait(locker, [this]() {return queue_.size() < maxSize_; });                  assert(locker.owns_lock());        assert(queue_.size() < maxSize_);        queue_.push(x);        notEmptyCV_.notify_one();    }    T take() {    //  std::cout << std::this_thread::get_id() << " taking" << std::endl;        std::unique_lock<std::mutex> locker(mtx_);        notEmptyCV_.wait(locker, [this]() {return !queue_.empty(); });        assert(locker.owns_lock());        assert(!queue_.empty());        T front(queue_.front());        queue_.pop();        notFullCV_.notify_one();        return front;    }    // with time out    // @param timeout: max wait time, ms    // @param outRes: reference result if take successfully    // @return take successfully or not    bool take(int timeout, T& outRes) {        std::unique_lock<std::mutex> locker(mtx_);        notEmptyCV_.wait_for(locker, timeout*1ms, [this]() {return !queue_.empty(); });        assert(locker.owns_lock());        if(queue_.empty()) return false;                outRes = queue_.front(); queue_.pop();        notFullCV_.notify_one();        return true;    }    // Checking BlockingQueue status from outside    // DO NOT use it as internal call, which will cause DEADLOCK    bool empty() const {        std::unique_lock<std::mutex> locker(mtx_);        return queue_.empty();    }    size_t size() const {        std::unique_lock<std::mutex> locker(mtx_);        return queue_.size();    }    size_t maxSize() const {        return maxSize_;    }private:    mutable std::mutex mtx_;    std::condition_variable notEmptyCV_;    std::condition_variable notFullCV_;    size_t maxSize_;    std::queue<T> queue_;};

用C++11實現一個有界的阻塞隊列