[hobbit] wildcards or regex with SPLITNCV

[Graham Nayler]

Shawn,

Sorry, I obviously overinterpreted your earlier posts about patching and 
getting your snapshot working.

I can't really comment about your application, other than to say I think 
you'll have a major problem getting different numbers of traces on different 
graphs within a single test. Running multiple tests, with some having 
individual traces/graph and some having multiple, is probably the only way 
you'll be able to manage that.

But back to your SPLITNCV problem, I finally had a bit of a closer look at 
it, as it's so closely related to what I've been doing myself. Yes it will 
allow adding datasources within a test without restarting hobbit (or more 
accurately, and seriously, having to delete and reinitialise the RRD files, 
so losing previous history). Don't know about it's support in 4.2, but it is 
supported in 4.3 - but it is broken.

Here's my reply to someone else today on the subject, which describes the 
usage and the fix
http://www.hswn.dk/hobbiton/2008/10/msg00423.html

Regarding the python script, essentially it skips the first two header 
lines, then parses any lines it sees of the format
<any old junk> {space} <datasource_name> {space} :: <signed floating point 
value> <more junk>

and writes for each line found the following three lines to stdout
DS:<datasource_name>:GAUGE:600:U:U
<testname>.<datasource_name>.rrd
<value>

As it receives each <value> the script host (hobbitd_rrd) updates (or 
generates if required) the named RRD file.

Subsequently, I've now changed it to output a DS line equivalent to what the 
SPLITNCV mechanism does
DS:lambda:GAUGE:600:U:U
partly as I had some very long datasource names, and RRD throws an error 
(and fails to create the file) if it sees datasources longer than 19 
characters.

FYI, as I see it, the overheads of using external script mechanism 
additional to the SPLITNCV methods are:
one process fork per test report
write the body of the test report to a temporary diskfile
run the script
delete the temporary diskfile

Graham Nayler

----- Original Message ----- 
From: "Shawn Heisey" <elyograg at elyograg.org>
To: <hobbit at hswn.dk>; <apalmer at mainstreamdata.com>
Sent: Monday, October 20, 2008 7:38 PM
Subject: Re: [hobbit] wildcards or regex with SPLITNCV

{snip}

> I finally got around to looking at this.  I think I'm even more confused. 
> Not sure where you got the idea I'm comfortable with the source ... I've 
> looked at the 4.3 sources trying to get rid of warnings and get it 
> working, but the only thing that did was remind me just how many years 
> it's been since I did any C programming.  My eyes glazed over a bit with 
> your python too, I haven't invested any time in that language yet.
>
{snip}