On Oct 10, 2009, at 1:50 AM, Jordan Brown wrote:
> Back on that topic of how to log...
>
> I find myself adding a bunch of debug/log type messages to my
> application, which makes me want to reconsider the best, or at least
> easy and not horrible, way to get them written to a file somewhere.
>
> The three obvious answers are:
>
> 1) Just printf them, and rely on SMF's output redirection.
> Problem: doesn't play nice with log rotation.
>
> 2) syslog(). Problems: Heavyweight, mixes them in with other
> application output, very verbose format makes reading difficult.
>
> 3) Write to some application-unique log file. Problem: no
> standardization, must roll your own log rotation.
>
> But how about something like this?
>
> void
> log(char *fmt, ...)
> {
> static char *logfile = NULL;
> va_list va;
> FILE *f;
>
> if (logfile == NULL) {
> logfile = get_smf_string("restarter/logfile");
> }
>
> f = fopen(logfile, "a");
> if (f == NULL)
> f = stdout;
>
> va_start(va, fmt);
> vfprintf(f, fmt, va);
> va_end(va);
>
> if (f != stdout)
> fclose(f);
> }
>
> ... where get_smf_string() is left as an exercise for the reader.
>
> Heavier than just printf, but (I believe) lighter than syslog, and
> neatly goes into the service-specific log file. Can't be rerouted
> using syslog.conf, but then again for debug/trace type output it's
> not clear that's desirable anyway... and it's heavy.
>
> We should probably have a more structured logging facility (e.g. to
> facilitate data mining), but that's pretty heavyweight, both from
> the standpoint of designing and implementing such a thing and from
> the standpoint of using it to add debugging output to an application.
>
> Thoughts?
That isn't any better than just (1), because smf already gives each
thing
a log, and I'm not sure what you meant above by "doesn't play nice w/
log
rotation" but those logs *are* rotated. There is a single entry in
logadm that triggers a script that rotates all smf logs.
That said, I personally think we should extend the SMF schema with
a <logfile> XML element to declare other logfiles associated with a
service,
since many have more than one, and also could indicate the format,
result
in automatic rotation of those, change their location paths, etc etc.
-Mike
---
Mike Shapiro, Sun Microsystems Open Storage / Fishworks. blogs.sun.com/mws/
