Re: Directory-change notification (was Re: Desktop)

[Alan Cox <alan lxorguk ukuu org uk>]

> is that POSIX RT signals have a nasty API, and in fact, systems of
> messages from the kernel will inevitably have a nasty API, simply
> because you can't allocate an arbitrary-sized queue in the kernel and
> have to to deal with the possibility of overflow.
> 
> A possibility that occurs to me for dealing with that problem of
> message-queue overflows is to have a user-space daemon that is

We already handle queue overflows. You get a signal with no rt info. That
tells you 'something happened, your guess what'

> [ P.S. - if somebody figures out a decent way to do this and
>   gets a patch into the kernel, GUI folks will be in their debt
>   forever. ] 

fd=opendir("foo");
fcntl(fd, F_SETFL, FASYNC);
[and set owner of course]

The API seems reasonably easy to define, its just actually writing the code
for it that might take a bit longer to sort out. You'd then get a SIGIO with
the file handle number in the real time data.