axmol/cocos/base/CCAsyncTaskPool.h

/****************************************************************************
Copyright (c) 2010      cocos2d-x.org
Copyright (c) 2013-2014 Chukong Technologies Inc.

http://www.cocos2d-x.org

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****************************************************************************/

#ifndef __CCSYNC_TASK_POOL_H_
#define __CCSYNC_TASK_POOL_H_

#include "platform/CCPlatformMacros.h"
#include <vector>
#include <queue>
#include <memory>
#include <thread>
#include <mutex>
#include <condition_variable>
#include <future>
#include <functional>
#include <stdexcept>

NS_CC_BEGIN
/////////////////////////////////////////////////////////////////////////////

class AsyncTaskPool
{
public:
    enum class TaskType
    {
        TASK_IO,
        TASK_NETWORK,
        TASK_MAX_TYPE,
    };
    static AsyncTaskPool* getInstance();
    
    static void destoryInstance();
    
    template<class F, class... Args>
    auto enqueue(TaskType type, F&& f, Args&&... args)
    -> std::future<typename std::result_of<F(Args...)>::type>;
    
CC_CONSTRUCTOR_ACCESS:
    AsyncTaskPool();
    ~AsyncTaskPool();
    
protected:
    // thread tasks internally used
    class ThreadTasks {
        friend class AsyncTaskPool;
    public:
        ThreadTasks()
        : _stop(false)
        {
            _thread = std::thread(
                                  [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();
                                          }
                                          
                                          task();
                                      }
                                  }
                                  );
        }
        ~ThreadTasks()
        {
            std::unique_lock<std::mutex> lock(_queue_mutex);
            _stop = true;
            _condition.notify_all();
            _thread.join();
        }
    private:
        // need to keep track of thread so we can join them
        std::thread _thread;
        // the task queue
        std::queue< std::function<void()> > _tasks;
        
        // synchronization
        std::mutex _queue_mutex;
        std::condition_variable _condition;
        bool _stop;
    };
    
    //tasks
    ThreadTasks _threadTasks[int(TaskType::TASK_MAX_TYPE)];
    static AsyncTaskPool* s_asyncTaskPool;
};



NS_CC_END
#endif //__CCSYNC_TASK_POOL_H_