1 #ifndef THREAD_POOL_H_

2 #define THREAD_POOL_H_

3

4 #include <list>

5 #include <functional>

6 #include <thread>

7 #include <mutex>

8 #include <condition_variable>

9

10 class ThreadPool {

11 private:

12 int num_threads;

13 std::thread *thread; // array of threads

14

15 struct WorkItem {

16 std::function<void ()> work;

17 std::function<void ()> done;

18 };

19

20 int qsize;

21 std::list<WorkItem> workq;

22 mutable std::mutex workq_mutex;

23 std::condition_variable workq_condvar;

24

25 int nactive; // number of active workers (not sleeping)

26

27 // condvar used by wait

28 std::condition_variable done_condvar;

29

30 bool quit;

31

32 void thread_func();

33

34 public:

35 // passing num_threads == -1 auto-detects based on number of processors

36 explicit ThreadPool(int num_threads = -1);

37 ~ThreadPool();

38

39 void add_work(std::function<void ()> func);

40 void add_work(std::function<void ()> work_func, std::function<void ()> done_func);

41 void clear_work();

42

43 // returns the number of queued work items

44 int queued() const;

45 // returns the number of active threads

46 int active() const;

47 // returns number of pending work items (both in the queue and active)

48 int pending() const;

49

50 // waits for all work to be completed

51 long wait();

52 long wait(long timeout);

53 };

54

55 #endif // THREAD_POOL_H_