[collectd] Tail plugin and DSType gauge

[Toni Ylenius]

Hi,

how do you use the Tail plugin with DSType gauge? I'm trying to read 
cfengine promise_summary.log file with following configuration

<Plugin tail>
    <File "/var/cfengine/promise_summary.log">
        Instance "cfengine"
        <Match>
            Regex "kept ([0-9]+)%"
            DSType "GaugeMin"
            Type "gauge"
            Instance "promises-kept"
        </Match>
    </File>
</Plugin>

and a graph looks like this
http://www.iki.fi/~yleniust/comp/collectd/tail-gauge.png

I found out that a value is reset to Nan in the function 
simple_submit_match (src/utils_tail_match.c) on each submit. I don't 
understand why is this, to me it makes more sense to retain the old 
value until the file is updated.

Thanks
Toni Ylenius