concurrent_queue.hpp

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#pragma once
 
#include <cstdint>
#include <condition_variable>
#include <mutex>
#include <queue>
 
 
namespace vulkan_display_detail{
 
constexpr size_t unlimited_size = SIZE_MAX;
 
template<typename T, size_t max_size = unlimited_size>
class ConcurrentQueue{
        std::queue<T> queue;
        mutable std::mutex mutex{};
        std::condition_variable queue_decremented_cv{};
        std::condition_variable queue_incremented_cv{};
 
        void push_and_unlock(std::unique_lock<std::mutex>& lock, T&& item){
                queue.push(std::move(item));
                lock.unlock();
                queue_incremented_cv.notify_one();
        }
 
        T pop(bool nonblocking = false)
        {
                std::unique_lock<std::mutex> lock{mutex};
                if (queue.size() == 0 && nonblocking) {
                        return T();
                }
 
                queue_incremented_cv.wait(lock, [this]{return queue.size() > 0;});
                T result = std::move(queue.front());
                queue.pop();
 
                lock.unlock();
                queue_decremented_cv.notify_one();
                return result;
        }
public:
        T try_pop(){
                return pop(true);
        }
 
        T wait_pop(){
                return pop(false);
        }
 
        template<typename Rep, typename Period>
        T timed_pop(std::chrono::duration<Rep, Period> timeout){
                std::unique_lock<std::mutex> lock{mutex};
 
                queue_incremented_cv.wait_for(lock, timeout, [this]{return queue.size() > 0;});
                if (queue.empty()){
                        return T{};
                }
                T result = std::move(queue.front());
                queue.pop();
 
                lock.unlock();
                queue_decremented_cv.notify_one();
                return result;
        }
 
        T force_push(T item){
                std::unique_lock lock{mutex};
                T result = {};
                if (queue.size() >= max_size) {
                        result = std::move(queue.front());
                        queue.pop();
                }
                push_and_unlock(lock, std::move(item));
                return result;
        }
 
        bool try_push(T item){
                std::unique_lock lock{mutex};
                if (queue.size() >= max_size) {
                        return false;
                }
                push_and_unlock(lock, std::move(item));
                return true;
        }
 
        void wait_push(T item){
                std::unique_lock lock{mutex};
                if (max_size != unlimited_size) {
                        queue_decremented_cv.wait(lock, [this]{return queue.size() < max_size;});
                }
                push_and_unlock(lock, std::move(item));
        }
};
 
} //namespace vulkan_display_detail