[C++]C++11, condition_variable 샘플 정리

intro

• CreateEvent 사용하는거랑 비슷. 단순 예제닌깐 leak 있는건 알아서 잘~

sample

• 샘플

  char* get_time_for_test()
  {
    struct tm *newtime;
    __time64_t long_time;
    _time64(&long_time);
    newtime = _localtime64(&long_time);
    char* temp = new char[255];
    memset(temp, 0, 255);
    sprintf(temp, "%02d:%02d:%02d", newtime->tm_hour, newtime->tm_min, newtime->tm_sec);
    return temp;
  }
  #include <condition_variable>
  std::mutex mtx_lock1;
  std::mutex mtx_lock2;
  std::mutex mtx_lock3;
  std::condition_variable cond1;
  std::condition_variable cond2;
  void test_condition_variable()
  {
    //wait_for, wait_until 이런것도 있긴함.
    std::thread thread1([](){
        printf("%s: thread1 start\n", get_time_for_test());
        Sleep(3000);
        //해당 조건변수를 기다리고 있는 thread 중 하나를 깨운다.
        cond1.notify_one();
        printf("thread1 notify_one\n");
   
        printf("%s: thread1 end\n", get_time_for_test());
    });
    std::thread thread2([](){
        printf("%s: thread2 start\n", get_time_for_test());
        std::unique_lock<std::mutex> unique_lock(mtx_lock1);
        cond1.wait(unique_lock);
        printf("%s: thread2 wake up\n", get_time_for_test());
        Sleep(3000);
        //해당 조건변수를 기다리고 있는 thread 를 전부 깨운다.
        cond2.notify_all();
        printf("thread2 notify_all\n");
   
        printf("%s: thread2 end\n", get_time_for_test());
    });
    std::thread thread3([](){
        printf("%s: thread3 start\n", get_time_for_test());
        std::unique_lock<std::mutex> unique_lock(mtx_lock2);
        cond2.wait(unique_lock);
        printf("%s: thread3 end\n", get_time_for_test());
    });
    std::thread thread4([](){
        printf("%s: thread4 start\n", get_time_for_test());
        std::unique_lock<std::mutex> unique_lock(mtx_lock3);
        cond2.wait(unique_lock);
        printf("%s: thread4 end\n", get_time_for_test());
    });
    thread1.join();
    thread2.join();
    thread3.join();
    thread4.join();
  }
  

• 결과는 이런식. 점점 편해지는 세상.

  13:54:15: thread1 start
  13:54:15: thread4 start
  13:54:15: thread2 start
  13:54:15: thread3 start
  threadl notify_one
  13:54:18: thread2 wake up
  13:54:18: thread1 end
  thread2 notify_all
  13:54:21: thread3 end
  13:54:21: thread4 end
  13:54:21: thread2 end