Double lock on wxMutex(wxMUTEX_DEFAULT) allowed?

[Alexander Steffens]

Hello,

shouldn't it be possible to workaround that like following sketchcode
within wxMutex::TryLock in the non recursive case on MSW?
Or are I absolutely naive?


//----------------
wxMutexError
wxMutexMSW::TryLock() {

    //first do MSW-stuff as before
    wxMutexError error = TryLock_old();

   if(wxMUTEX_NO_ERROR != error)
       return error;

      //now we are sure that no other thread than current thread
      //is inside this part.
      //because we are the current thread we can not be here twice.
      //therefore we are alone even if TryLock_old is recursive.

      //now we check if we *was* here with the current thread
      //for an unlocked lock before. If yes would have a dead_lock
      //if we think in the non-recursive way.

      unsigned long thread_id = wxThread::GetCurrentId();

      if(m_hmpLockedByThread.find( thread_id ) == m_hmpLockedByThread.end() {
         //ok we are here for the first lock with this thread
         m_hmpLockedByThread.insert(thread_id);
         return wxMUTEX_NO_ERROR;
      }
      else {
         return wxMUTEX_DEAD_LOCK;
      }
}
//----------------

and in the header

//----------------
class wxMutexMSW {

   //symbolically
   wxHashSet<unsigned long> m_hmpLockedByThread;
   ...
}
//----------------

and in Unlock we haveto remove the current thread id.


I think it would be fine do something like that within wxMutex, else most users
have to handle the incompatible behaviour between some unixes and windows
in their app.

Alexander