/**
	This file is a part of rexy's general purpose library
	Copyright (C) 2020 rexy712

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "rexy/threadpool.hpp"

#include <utility> //move, forward

namespace rexy{

	threadpool::threadpool(int numthreads){
		for(int i = 0;i < numthreads;++i){
			m_workers.emplace_back(&threadpool::worker_loop, this);
		}
	}
	void threadpool::worker_loop(void){
		while(m_valid){
			write_lock_t lk(m_qlk);
			//wait for wakeup, continue if the threadpool is dead or there is a job to run
			m_qcv.wait(lk, [this]{return !m_valid || !m_jobs.empty();});

			//if the threadpool is dead, kill ourself
			if(!m_valid){
				return;
			}

			//steal job from queue
			auto job = std::move(m_jobs.front());
			m_jobs.pop();

			lk.unlock();
			job();
		}
	}
	threadpool::threadpool(const threadpool& other):
		m_ctor_lock(other.m_qlk),
		m_jobs(other.m_jobs),
		m_valid(true)
	{
		m_ctor_lock.unlock();
		for(size_t i = 0;i < other.m_workers.size();++i){
			m_workers.emplace_back(&threadpool::worker_loop, this);
		}
		m_qcv.notify_all();
	}
	threadpool::threadpool(threadpool&& other):
		m_ctor_lock(other.m_qlk),
		m_workers(std::move(other.m_workers)),
		m_jobs(std::move(other.m_jobs)),
		m_valid(other.m_valid.exchange(false))
	{
		m_ctor_lock.unlock();
	}
	threadpool::~threadpool(void){
		invalidate();
		for(auto& thread : m_workers){
			thread.join();
		}
	}

	void threadpool::invalidate(void){
		m_valid = false;
		//wakeup all workers and end them
		m_qcv.notify_all();
	}

}