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

[Russ Cox <rsc@swtch.com>]

> 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?

Yes.

>  - 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?

Yes!  Otherwise you can't kill a process that is blocked
reading the log file.

>  - 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

Tough for them.

> I found inspiration in /sys/src/9/ip/netlog.c and
> /sys/src/cmd/ssh/sshnet.c

See also /sys/src/9/port/log.c.  Sshnet is a good example
of getting the flushes right.

Russ