thread_pool.h

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#pragma once
#include "engine_sys.h"
#include "logging_sys.h"
 
class ThreadManager final: public EngineManager {
public:
    explicit ThreadManager(size_t threads);
    ~ThreadManager() override;
 
    template <class F, class... Args>
    auto enqueue(F&& f, Args&&... args) -> std::future<decltype(f(args...))>;
 
    bool initialize() override;
 
    void update(double delta_time) override;
 
    void shutdown() override;
 
private:
    std::vector<std::thread> _workers;
    std::queue<std::function<void()>> tasks;
 
    std::mutex _queue_mutex;
    std::condition_variable condition;
    bool is_running = false;
};
 
 
template <class F, class... Args>
auto ThreadManager::enqueue(F&& f, Args&&... args) -> std::future<decltype(f(args...))> {
#if defined(SDL_PLATFORM_EMSCRIPTEN)
    LOG_INFO("ThreadPool not supported on Web builds.");
#else
 
    using return_type = decltype(f(args...));
 
    auto task = std::make_shared<std::packaged_task<return_type()>>(
        std::bind(std::forward<F>(f), std::forward<Args>(args)...)
    );
 
    std::future<return_type> res = task->get_future();
 
    {
        std::unique_lock lock(_queue_mutex);
        if (!is_running) {
            throw std::runtime_error("ThreadPool isn't running, cannot enqueue new tasks.");
        }
 
        tasks.emplace([task]() { (*task)(); });
    }
 
    condition.notify_one();
    return res;
#endif
 
}