Reactor/lib/EventLoopThread.hpp

#pragma once

#include "Core.hpp"
#include "Utilities.hpp"
#include <thread>
#include <string>
#include <vector>
#include <memory>
#include <atomic>
#include <latch>

namespace reactor
{

class EventLoopThread : public NonCopyable
{
private:
	std::jthread thread_;
	EventLoop* loop_;
	std::latch readyLatch_;
	std::string name_;

	/*
	*	The function executed by the internal thread.
	*	It creates the EventLoop, signals readiness, and runs the loop.
	*/
	void threadFunc()
	{
		EventLoop loop;
		loop_ = &loop;
		readyLatch_.count_down();
		loop.loop();
	}

public:
	/*
	*	Constructs an EventLoopThread.
	*	Starts a new thread and creates an EventLoop within it,
	*	waiting until the loop is fully initialized.
	*/
	explicit EventLoopThread(const std::string& name = "EventLoopThread")
		: loop_(nullptr), readyLatch_(1), name_(name)
	{
		thread_ = std::jthread(&EventLoopThread::threadFunc, this);
		readyLatch_.wait();
		LOG_INFO << "EventLoopThread '" << name_ << "' initialized";
	}

	/*
	*	Destructs the EventLoopThread.
	*	Quits the event loop. The underlying jthread automatically joins.
	*/
	~EventLoopThread()
	{
		if (loop_) {
			loop_->quit();
		}
		LOG_INFO << "EventLoopThread '" << name_ << "' destroyed";
	}

	/*
	*	Returns the EventLoop associated with this thread.
	*	The pointer is valid for the lifetime of the thread.
	*/
	EventLoop* getLoop()
	{
		return loop_;
	}

	/*
	*	Returns the name of the thread.
	*/
	const std::string& name() const
	{
		return name_;
	}
};

class EventLoopThreadPool : public NonCopyable
{
private:
	std::vector<std::unique_ptr<EventLoopThread>> threads_;
	std::vector<EventLoop*> loops_;
	std::atomic<size_t> next_;
	std::string baseThreadName_;

public:
	/*
	*	Constructs an EventLoopThreadPool.
	*	Creates a pool of threads, each running an EventLoop.
	*/
	explicit EventLoopThreadPool(size_t numThreads, const std::string& baseName = "EventLoopThread")
		: next_(0), baseThreadName_(baseName)
	{
		LOG_INFO << "Creating EventLoopThreadPool with " << numThreads << " threads";

		for (size_t i = 0; i < numThreads; ++i) {
			std::string threadName = baseThreadName_ + "-" + std::to_string(i);
			auto thread = std::make_unique<EventLoopThread>(threadName);
			loops_.push_back(thread->getLoop());
			threads_.push_back(std::move(thread));
		}

		LOG_INFO << "EventLoopThreadPool created with " << numThreads << " threads";
	}

	/*
	*	Destructs the thread pool.
	*	The threads will be quit and joined automatically via their destructors.
	*/
	~EventLoopThreadPool()
	{
		LOG_INFO << "EventLoopThreadPool destroying " << threads_.size() << " threads";
	}

	/*
	*	Gets the next EventLoop from the pool in a round-robin fashion.
	*	This method is thread-safe.
	*/
	EventLoop* getNextLoop()
	{
		if (loops_.empty()) {
			LOG_WARN << "EventLoopThreadPool has no loops available";
			return nullptr;
		}

		size_t index = next_.fetch_add(1, std::memory_order_relaxed) % loops_.size();
		LOG_TRACE << "EventLoopThreadPool returning loop " << index;
		return loops_[index];
	}

	/*
	*	Returns pointers to all EventLoops in the pool.
	*/
	std::vector<EventLoop*> getAllLoops() const
	{
		return loops_;
	}

	/*
	*	Returns the number of threads in the pool.
	*/
	size_t size() const
	{
		return loops_.size();
	}

	/*
	*	Returns the base name for threads in the pool.
	*/
	const std::string& getBaseName() const
	{
		return baseThreadName_;
	}
};

}