nginx-devel Digest, Vol 38, Issue 2

[Maxim Dounin]

Hello!

On Tue, Dec 04, 2012 at 04:57:32PM +1100, Lawrence Pit wrote:

> >>After I finished this patch I checked the 1.3 branch, and noticed it
> >>already has an $msec http variable defined. But it's output is with a
> >>dot character before the milliseconds part. Why is that?
> >
> >http {
> > map $msec $s {
> >	~(?<x>.*)\. $x;
> > }
> >
> > map $msec $ms {
> >	~\.(?<x>.*) $x;
> > }
> >
> > server {
> >	return 200 "msec=$msec usec=${s}${ms}000\n";
> > }
> >}
> >
> >$ curl http://localhost:8000/
> >msec=1354471012.591 usec=1354471012591000
> 
> That's cool, impressive. Though ugly ;)  If it needs to do that for
> every request it's relatively expensive compared to what I'd rather
> do:
> 
>    proxy_set_header X-Queue-Start "${msec}000";
> 
> Is there any objection to not output the dot character starting from
> the 1.3 release?
> 
> My reason for not using the dot character is that it seems like an
> arbitrary view concern to me and when the value is not used for
> logging purposes it's most likely to be used for calculations or
> conversions; in which case not having to parse out the dot character
> makes things simpler.

I consider dot character very valuable here, as it simplifies both 
reading such numbers and calculations with them, as well as 
eliminates measurment units confusion (much like what Time::HiRes 
does with time() in Perl).  The format also matches all other time 
variables nginx exports, like $request_time, 
$upstream_response_time and so on.

In any case, the $msec variable appeared in nginx 0.3.8, 7 years ago 
(log_format only at that time), and there are no plans to change it's 
semantics.

-- 
Maxim Dounin
http://nginx.com/support.html