Crafter.Thread/interfaces/Crafter.Thread-ThreadPool.cppm

//SPDX-License-Identifier: LGPL-3.0-only
//SPDX-FileCopyrightText: Copyright (C) 2026 Catcrafts®

export module Crafter.Thread:ThreadPool;
import std;

namespace Crafter {
	struct ThreadStorage {
		std::vector<std::function<void(void)>> tasks;
		std::vector<std::function<void(void)>> buffer;
		std::condition_variable cv;
		std::mutex mutex;
		std::atomic<unsigned int> taskCount;
		std::thread thread;
	};

	export class ThreadPool {
	public:
		static inline std::atomic<bool> stopped;
		static void Start(int maxThreads = -1);
		// Stops the workers, each once it has run what it was given, and ends
		// a JoinPool; a task enqueued once Stop has begun may not run. From
		// one thread at a time, not the pool's own: a task can't stop the
		// pool it runs in. Again, or before Start, it does nothing. JoinPool
		// can return before Stop has: Start a new pool once Stop returned.
		static void Stop();
		static void Enqueue(std::function<void(void)> task);
		static void Enqueue(std::vector<std::function<void(void)>> tasks);
		static void JoinPool();
		static inline unsigned int threadCount;
		static inline std::atomic<unsigned int> activeThreads;
	private:
		static inline std::unordered_map<std::thread::id, ThreadStorage*> threadIdMap;
		static inline ThreadStorage* threadStorage;
		static void WaitAndExecuteTask(ThreadStorage* threadStorage);
	};
}