封装 C++11 chrono

```c++class TimerCounter {public:  TimerCounter(const std::string& flag, bool enable_cout = true, long threshlod = -1) :      _enable_cout(enable_cout), _threshlod(threshlod)    {        _start = get_current_us();        this->_flag = flag;    }        ~TimerCounter() {        if(_enable_cout)         {          long delta = get_time_ms_elapsed();            if(delta > _threshold)             {                std::cout << _flag << " Timer elasped:" << delta << "ms" << std::endl;            }        }    }        int64_t get_current_us() {        auto now = std::chrono::system_clock::now();        auto duration = std::chrono::duration_cast<std::chrono::microseconds>(now.time_since_epoch());        return duration.count();    }        long get_time_ms_elapsed() {        long end = get_current_us();        long n = (end - start) / 1000;        return n;    }
private:    bool _enable_cout;    std::string _flag;    long _threshold;    long _start;};```

int main() {  std::cout << "###############" << std::endl;      // 出括号 TimerCounter 析构，  {    TimerCounter time;    std::this_thread::sleep_for(std::chrono::minutes(10));      }  std::cout << "********" << std::endl;  return 0;}