ThreadSafeQueue.hpp

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#ifndef ECHOMAP_THREADSAFEQUEUE_HPP
#define ECHOMAP_THREADSAFEQUEUE_HPP
 
#include <condition_variable>
#include <deque>
#include <mutex>
#include <optional>
 
namespace echomap
{

template <class ValueT>
    requires std::move_constructible<ValueT>
class ThreadSafeQueue
{
public:
    void produce(
            ValueT value
    )
    {
        std::scoped_lock lock(mutex);
        queue.push_back(std::move(value));
        cv.notify_one();
    }

    std::optional<ValueT> try_consume()
    {
        std::scoped_lock lock(mutex);
 
        if (!queue.empty()) {
            auto value = std::move(queue.front());
            queue.pop_front();
            return value;
        }
 
        return std::nullopt;
    }

    std::optional<ValueT> wait_consume(
            std::stop_token stop_token
    )
    {
        std::unique_lock lock(mutex);
        cv.wait(lock, stop_token, [this] {
            return !queue.empty();
        });
 
        if (queue.empty())
            return std::nullopt;
 
        auto value = std::move(queue.front());
        queue.pop_front();
        return value;
    }

    [[nodiscard]] bool empty() const
    {
        std::scoped_lock lock(mutex);
        return queue.empty();
    }

    void clear()
    {
        std::scoped_lock lock(mutex);
        queue.clear();
    }
 
private:
    mutable std::mutex mutex;
    std::condition_variable_any cv;
    std::deque<ValueT> queue;
};
 
} // namespace echomap
 
#endif // ECHOMAP_THREADSAFEQUEUE_HPP