[9fans] userspace netlog style log file in fs?

[Axel Belinfante <Axel.Belinfante@cs.utwente.nl>]

I'm turning my 802.1x thingy into an fs, using 9p(2),
and I'm now looking into adding a netlog-style
log file such that you can just 'cat /net/8021x/log'
and it will hang there in read until stuff is
added to the log. multiple readers should see
the same stuff.

I guess this amounts to
 - keeping a ring buffer of log messages (a la netlog)
 - keeping a queue of 'pending' read's --
   read is the only thing for which completion
   may have to be delayed, right?
 - pending reads should 'complete' when stuff
   is logged (i.e. something to read appears)
 - pending reads should be cleaned away
   when the fid is clunked
 - deal with flushes?
 - deal with slow readers that read slower
   than the log gets updated, i.e. at a certain
   moment they may ask for data that already has
   been overwritten

I found inspiration in /sys/src/9/ip/netlog.c and
/sys/src/cmd/ssh/sshnet.c
(and other places mentioned in 9p(2))
Are there other things I might want to look at?
Are there particular traps I might want to avoid,
things to think of?

Sorry for these a bit vague, 'open' questions -
I'm sure I'll succeed to figure things out myself,
but if people have been there already I'd rather
not reinvent the wheel.
Also, I could imagine that such logging stuff might
be useful for other programs, if it could be
integrated easily.

Axel.