【C++11】条件变量

实现一个同步队列

并且多线程竞争读写。
实例如下：

template<typename T>
class SyncQueue
{
public:
    SyncQueue(int maxSize) : m_maxSize(maxSize) {}
    void put(const T& value)
    {
        std::lock_guard<std::mutex> locker(m_mutex);
        while (isFull())
        {
            cout << "queue full! waiting..." << endl;
            m_notFull.wait(m_mutex);
        }
        m_queue.push_back(value);
        std::this_thread::sleep_for(std::chrono::seconds(1));

        m_notEmpty.notify_one();
    }

    T take()
    {
        std::lock_guard<std::mutex> locker(m_mutex);
        while (isEmpty())
        {
            cout << "queue empty! waiting..." << endl;
            m_notEmpty.wait(m_mutex);
        }
        T temp = m_queue.front();
        m_queue.pop_front();
        std::this_thread::sleep_for(std::chrono::seconds(1));

        m_notFull.notify_one();     //队列不空
        return temp;
    }

    bool empty()
    {
        std::lock_guard<std::mutex> locker(m_mutex);
        return m_queue.empty();
    }

    bool full()
    {
        std::lock_guard<std::mutex> locker(m_mutex);
        return m_queue.size() == m_maxSize;
    }

    size_t size()
    {
        std::lock_guard<std::mutex> locker(m_mutex);
        return m_queue.size();
    }

private:
    bool isFull() const
    {
        return m_queue.size() == m_maxSize;
    }
    bool isEmpty()
    {
        return m_queue.empty();
    }

private:
    std::list    m_queue;
    std::mutex      m_mutex;
    std::condition_variable_any m_notEmpty;
    std::condition_variable_any m_notFull;
    int             m_maxSize;
};
SyncQueue<int> Queue(3);
static int gValue = 0;

void add()
{
    while (true)
    {
        int value = gValue++;
        Queue.put(value);
        cout << "thread :" << std::this_thread::get_id() << "   put :" << value << " curr size:"<void sub()
{
    while (true)
    {
        int value = Queue.take();
        cout << "thread :" << std::this_thread::get_id() << "   take:"<" curr size:" << Queue.size() << endl;
    }
}

int main()
{
    std::thread t1(add);
    std::thread t2(add);

    std::thread t3(sub);
    t1.join();
    t2.join();
    t3.join();
    return 0;
}

运行解决如下：

这里量个线程add操作，一个线程sub操作。

条件变量的另一种用法

m_notFull.wait(m_mutex, [this] 
{
    cout << "queue full! waiting..." << endl;
    return !isFull(); 
});