You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
113 lines
3.1 KiB
113 lines
3.1 KiB
6 years ago
|
#pragma once
|
||
|
|
|
||
|
|
#include <vector>
|
||
|
|
#include <queue>
|
||
|
|
#include <memory>
|
||
|
|
#include <thread>
|
||
|
|
#include <mutex>
|
||
|
|
#include <condition_variable>
|
||
|
|
#include <future>
|
||
|
|
#include <functional>
|
||
|
|
#include <stdexcept>
|
||
|
|
|
||
|
|
class ThreadPool {
|
||
|
|
public:
|
||
|
|
ThreadPool(size_t);
|
||
|
|
template<class F, class... Args>
|
||
|
|
auto enqueue(F&& f, Args&&... args)
|
||
|
|
-> std::future<typename std::result_of<F(Args...)>::type>;
|
||
|
|
~ThreadPool();
|
||
|
|
|
||
|
|
bool has_running_tasks() {
|
||
|
|
std::unique_lock<std::mutex> lock(running_tasks_mutex);
|
||
|
|
return n_running_tasks > 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
private:
|
||
|
|
// need to keep track of threads so we can join them
|
||
|
|
std::vector< std::thread > workers;
|
||
|
|
// the task queue
|
||
|
|
std::queue< std::function<void()> > tasks;
|
||
|
|
|
||
|
|
int n_running_tasks;
|
||
|
|
|
||
|
|
// synchronization
|
||
|
|
std::mutex queue_mutex;
|
||
|
|
std::mutex running_tasks_mutex;
|
||
|
|
std::condition_variable condition;
|
||
|
|
bool stop;
|
||
|
|
};
|
||
|
|
|
||
|
|
// the constructor just launches some amount of workers
|
||
|
|
inline ThreadPool::ThreadPool(size_t threads)
|
||
|
|
: n_running_tasks(0), stop(false)
|
||
|
|
{
|
||
|
|
for(size_t i = 0;i<threads;++i)
|
||
|
|
workers.emplace_back(
|
||
|
|
[this]
|
||
|
|
{
|
||
|
|
for(;;)
|
||
|
|
{
|
||
|
|
std::function<void()> task;
|
||
|
|
|
||
|
|
{
|
||
|
|
std::unique_lock<std::mutex> lock(this->queue_mutex);
|
||
|
|
this->condition.wait(lock,
|
||
|
|
[this]{ return this->stop || !this->tasks.empty(); });
|
||
|
|
if(this->stop && this->tasks.empty())
|
||
|
|
return;
|
||
|
|
task = std::move(this->tasks.front());
|
||
|
|
this->tasks.pop();
|
||
|
|
}
|
||
|
|
|
||
|
|
{
|
||
|
|
std::unique_lock<std::mutex> lock(this->running_tasks_mutex);
|
||
|
|
n_running_tasks++;
|
||
|
|
}
|
||
|
|
task();
|
||
|
|
{
|
||
|
|
std::unique_lock<std::mutex> lock(this->running_tasks_mutex);
|
||
|
|
n_running_tasks--;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
);
|
||
|
|
}
|
||
|
|
|
||
|
|
// add new work item to the pool
|
||
|
|
template<class F, class... Args>
|
||
|
|
auto ThreadPool::enqueue(F&& f, Args&&... args)
|
||
|
|
-> std::future<typename std::result_of<F(Args...)>::type>
|
||
|
|
{
|
||
|
|
using return_type = typename std::result_of<F(Args...)>::type;
|
||
|
|
|
||
|
|
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<std::mutex> lock(queue_mutex);
|
||
|
|
|
||
|
|
// don't allow enqueueing after stopping the pool
|
||
|
|
if(stop)
|
||
|
|
throw std::runtime_error("enqueue on stopped ThreadPool");
|
||
|
|
|
||
|
|
tasks.emplace([task](){ (*task)(); });
|
||
|
|
}
|
||
|
|
condition.notify_one();
|
||
|
|
return res;
|
||
|
|
}
|
||
|
|
|
||
|
|
// the destructor joins all threads
|
||
|
|
inline ThreadPool::~ThreadPool()
|
||
|
|
{
|
||
|
|
{
|
||
|
|
std::unique_lock<std::mutex> lock(queue_mutex);
|
||
|
|
stop = true;
|
||
|
|
}
|
||
|
|
condition.notify_all();
|
||
|
|
for(std::thread &worker: workers)
|
||
|
|
worker.join();
|
||
|
|
}
|