如何在c ++中同步getter和setter方法

Question

If 2 following methods in same class.

  bool CSettings::GetDelayTimer()
  {     
     return m_iTimerDelay;     
  }

  void CSettings::SetDelayTimer(int iTimerdelay)
  {
    m_iTimerDelay = iTimerdelay;
  }

In order to synchronize above methods I created following lock/unlock methods.

  void CSettings::Lock()
  {
    DWORD dwRet = WaitForSingleObject(m_hSettingsLock, INFINITE);
    if( dwRet == WAIT_OBJECT_0)
      return;
  }

  void CSettings::UnLock()
  {
    ReleaseMutex(m_hSettingsLock);
  }

how do I synchronize these getter/setter methods using lock/unlock. If I use lock in getter method I don't get chance to unlock as it will return before unlocking. I mean to say : Lock(); return m_iTimerDelay; UnLock(); Is it gonna work? Applying Lock/UnLock to setter is not a problem.

Any Idea to synchronize these methods?

Regards, Khurram.

Answer 1

Use RAII . Make an object whose constructor acquires the lock and whose destructor releases it. Then you can just do:

{
    ScopedLock f(m_hSettingsLock);
    return m_iTimerDelay;
}

Let ScopedLock::~ScopedLock release the lock.

Alternatively, the most likely inferior:

{
    Lock();
    bool ret = m_iTimerDelay;
    Unlock();
    return ret;
}

Note that in both cases the returned value can be stale.