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/*
* (C) 2019 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#ifndef BOTAN_THREAD_POOL_H_
#define BOTAN_THREAD_POOL_H_
#include <botan/types.h>
#include <functional>
#include <deque>
#include <vector>
#include <memory>
#include <utility>
#include <type_traits>
#include <mutex>
#include <thread>
#include <future>
#include <condition_variable>
namespace Botan {
class BOTAN_TEST_API Thread_Pool
{
public:
/**
* Return an instance to a shared thread pool
*/
static Thread_Pool& global_instance();
/**
* Initialize a thread pool with some number of threads
* @param pool_size number of threads in the pool, if 0
* then some default value is chosen
*/
Thread_Pool(size_t pool_size = 0);
~Thread_Pool() { shutdown(); }
void shutdown();
size_t worker_count() const { return m_workers.size(); }
Thread_Pool(const Thread_Pool&) = delete;
Thread_Pool& operator=(const Thread_Pool&) = delete;
Thread_Pool(Thread_Pool&&) = delete;
Thread_Pool& operator=(Thread_Pool&&) = delete;
/*
* Enqueue some work
*/
void queue_thunk(std::function<void ()>);
template<class F, class... Args>
auto run(F&& f, Args&&... args) -> std::future<typename std::result_of<F(Args...)>::type>
{
typedef typename std::result_of<F(Args...)>::type return_type;
auto future_work = std::bind(std::forward<F>(f), std::forward<Args>(args)...);
auto task = std::make_shared<std::packaged_task<return_type ()>>(future_work);
auto future_result = task->get_future();
queue_thunk([task]() { (*task)(); });
return future_result;
}
private:
void worker_thread();
// Only touched in constructor and destructor
std::vector<std::thread> m_workers;
std::mutex m_mutex;
std::condition_variable m_more_tasks;
std::deque<std::function<void ()>> m_tasks;
bool m_shutdown;
};
}
#endif
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