Subj : Re: waitformultipleobjects() on several semaphores ?
To   : comp.programming.threads
From : mandatory
Date : Fri Feb 04 2005 07:34 pm

"Neill Clift [MSFT]" <neillc@microsoft.com> skrev i en meddelelse 
news:4203a87c$1@news.microsoft.com...
>> wrote:
>>
>> The bWaitAll parameter must be set to FALSE so that the wait will return
>> if any of the wait objects have been signaled.  You'll have the check the
>> return code to correctly identify which semaphore got signaled.  If
>> Microsoft's WaitForMultipleObjects implementation allows for more than
>> one semaphore signal to get consumed on a wait any option then you'll 
>> have
>> to find another solution.  I don't think it would allow that.  That
>> would be pretty stupid, even for Microsoft.
>>
>
> The API will only create one side effect in the list of objects for a wait
> any call. So you would own one mutex or consume one semaphore
> release etc.


Im not sure i understand you here.

I have this array "semaphores" which contains 4 valid handles for 4 
sempahores:

    HANDLE semaphores[4];


In ThreadA i have a wait:

dwStatus = WaitForMultipleObjects (4, semaphores, FALSE, INFINITE);

If one semaphore is signalled, then it is ok - i get the dwStatus value of 
the semphore which was signalled.

The problem i think im experiencing, is what if 2 semaphores are signalled 
at the same time ?



If it was events, i normally would do like this:

dwStatus = WaitForMultipleObjects (numberofevents, eventarray, FALSE, 
INFINITE);

if (dStatus!= WAIT_TIMEOUT)
   {
    for (int i=0;i<numberofevents;i++)
        {
         dwStatus = WaitForSingleObject (eventarray[i], 0);
         if (dwStatus == WAIT_OBJECT_0 )
          {
            // the event was signalled
           ..
           ....
          }
        }
  }


But am i right that this approach doesnt work on semaphores ?

.