Re: Process-Shared Mutex (futex) - What is it good for ?

[Vladimir Zidar <vladimir@mindnever.org>]

On Tue, 2002-06-11 at 15:19, Peter Wächtler wrote:

> 
> A-prog:               B-prog:
> 
> gets write lock
> write some data
>                         block on read lock
> write some data
> crashes
>                         wants an error indication to repair data magically

 B-Prog unblocks, but gets -1, with errno=EPIPE.

> 
> 
> So a crashing A-prog is OK for you, but B should get an indication.
> Could catch a signal (SIGLOST?) returning -1 with errno=LOCKBROKEN
> That would be possible with futex.

 Nice if that *would* be possible. But that IS how nutexes are working
already.

> That is a case for writing data to a file - what about linked lists
> in memory?

 Exactly the same. Nutexes are not related to files in any way (other
than /dev/nutex descriptor, but that's completly different thing).


-- 
Bye,

 and have a very nice day !