Re: [boost] [thread] RFC standard proposed mutex, read-write mutex, condition

From: Howard Hinnant (hinnant_at_[hidden])
Date: 2007-08-22 09:59:31

On Aug 22, 2007, at 8:05 AM, Yuval Ronen wrote:

> Yuval Ronen wrote:
>> Howard Hinnant wrote:
>>
>>> Because of this, it is
>>> not possible (in the above use case) for there to be a set_mutex on
>>> the condition to change the facade, since both facades are
>>> simultaneously in use.
>>
>> Yes, I've realized that too late. My set_mutex() function is useless
>> because it has to be atomic with the wait().
>
> I've just thought that it might be not so useless after all.  
> 'set_mutex'
> is supposed to be called after the mutex was locked, and before  
> calling
> condition::wait. Because the mutex is locked, we are protected against
> simultaneous use. There can be a problem when multiple readers lock  
> for
> read, and simultaneously call set_mutex, but if we assume they all set
> the same mutex it shouldn't be a problem.

How would wake from wait be handled?  I.e. what mutex (facade) would  
it use to lock with?  The last one set may not correspond to the  
proper one on wake.

-Howard