Method push

include/csound_threaded.hpp:70–76

    std::condition_variable condition_variable_;
public:
    void push(Data const& data)
    {
        std::unique_lock<std::mutex> lock(mutex_);
        queue_.push(data);
        lock.unlock();
        condition_variable_.notify_one();
    }
    bool empty() const
    {
        std::unique_lock<std::mutex> lock(mutex_);