CLock same-thread double-access problem.

"Ricardo Vazquez" <>
Mon, 24 Sep 2007 11:09:54 +0200
Hello everybody!

This is my scenario:

My application has one instance of:
   class CMapDevices : public CMap <long, long&, CDevice*, CDevice*&>

Several threads can access this CMap; but they must not access it at the
same time.
So I added these member variables to CMapDevices:
   CSemaphore* m_sem;
   CSingleLock* m_lock;
CMapDevices ::CMapDevices ()
 CString sSemaphoreName;
 sSemaphoreName.Format("devs-%f",(double)(DATE)COleDateTime::GetCurrentTime()); m_sem = new CSemaphore (1, 1, sSemaphoreName); m_lock = new CSingleLock(m_sem);}So that wherever my code accesses the map I call m_lock->Lock(3000) beforethe access, and then m_lock->Unlock() after the access.My problem is this:Under certain circumstances, within the same thread, this is the code flow Iget:[within the same thread]-Access to map (lock)||--2nd. access to map (lock -again- for the same thread)||--2nd. access finishes (unlock)|-1st. access finishes (the map was already unlocked... but it shouldn't!)As you can see, when the 2nd. access finishes the map is unlocked for thisthread, so that any other thread could access it: but the map should be keptlocked until the first access finishes!So my question is:What synchronization objects and access-control mechanisms should I use tomanage this possible situation and how should I use them?Any other hints or clues?Any helpful code I could find over the Internet?Thank you!Ricardo V?zquez.Madrid, Spain.

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