Re: [9fans] rio snarf

[Russ Cox <russcox@gmail.com>]

> Well. We just found that removing snarf from rio fsys makes things
> work great wrt sharing the snarf buffer across machines.

If that's all you want to do, just create a /dev/snarf 
before rio runs -- if it sees one already there, it won't
provide one.

> At first, we thought that if was enough to call open(OTRUNC) while
> copying to the snarf buffer, then we noticed the deadlock with the
> open("/dev/snarf") in rio, then we tried removing snarf from rio, and,
> voila.

This I still don't fully understand.  The reason the snarf buffer doesn't
change until close is probably lost to history, but one nice effect
is that updating the snarf buffer is atomic -- you'll never see a 
partially written one.

> Either I'm crazy because of the lots of coffee I have been drinking, or
> there is something I'm missing regarding why rio has snarf builtin instead
> of using a regular file for that.

Rio used to provide a separate snarf buffer for each instance of rio.
It's only recently that there has been this push toward having one
snarf buffer for the whole system.

Russ