Re: [boost] [thread] condition suffering from lost wakup bug?

From: Roland Schwarz (roland.schwarz_at_[hidden])
Date: 2005-09-15 09:07:44

Roland Schwarz wrote:

>4) a signal arrives, while gate still is closed
>    Now is 0 < nWaitersToUnblock < N, correct?
>    But 0 == nWaitersBlocked
>    the signal results in a NO-OP and consequently the
>    waiter from 3) will never get it to see - hence it is lost ??
>
>  
>
Replacing the seuence on entry to wait:
sem_Wait (semBlockLock);
nWaitersBlocked++;
sem_post(semBlockLock);

by

atomic_increment(nWaitersBlocked);
sem_Wait (semBlockLock);
sem_Wait (semBlockLock);

would avoid loosing this signal, since the signal(bAll) function would
increment nWaitersToUnblock then.

Roland