#!/bin/bash
# -*- sh -*-

: << =cut

=head1 NAME

dm_cache_statistics_ - Wildcard-plugin to dm-cache statistics.

=head1 CONFIGURATION

This plugin does not normally require configuration.

The plugin may need to run as root to determine dm-cache status.
This is configured like this:

  [dm_cache_*]
	  user root

This is a wildcard plugin. To monitor a cached device-mapper volume,
link volume to this file. For example,

  ln -s /usr/share/munin/plugins/dm_cache_statistics_ \
        /etc/munin/plugins/dm_cache_statistics_vg_1122____lv_home

will monitor vg_1122-lv_home.

Please note that ____ (4 underscores) is replaced by - (dash) symbol.
This is workaround for http://munin-monitoring.org/ticket/1236

Cached volumes found in dmsetup status can be monitored.

=head1 AUTHOR

Original idea: Steinar H. Gunderson <sgunderson@bigfoot.com>
Found in Google by keywords "munin dm-cache"

Copyright (C) 2014 Vladimir Stackov <amigo.elite@gmail.com>

=head1 LICENSE

GPLv2

=head1 MAGIC MARKERS

 #%# family=auto
 #%# capabilities=autoconf suggest

=cut

CVOL=${0##*dm_cache_statistics_}
#workaround for http://munin-monitoring.org/ticket/1236
CVOL=${CVOL/____/-}

case $1 in
	autoconf)
		env dmsetup status > /dev/null 2>&1
		if [[ $? -eq 0 ]]; then
			echo yes
			exit 0
		else
			echo "no (env dmsetup returned value > 0)"
			exit 0
		fi
		;;
	suggest)
		dmsetup status | grep ' cache ' | awk -F: '{print $1}'
		exit $?
		;;
	config)
		echo "graph_title $CVOL dm-cache cache statistics"
		echo 'graph_args --base 1000'
		echo 'graph_vlabel blocks/sec'
		echo 'graph_category disk'
		echo "graph_info This graph shows the dm-cache cache statistics of the $CVOL cached voulme."

		echo 'cache_read_hits.type DERIVE'
		echo 'cache_read_hits.label Read hits'
		echo 'cache_read_hits.info Read hits for cache'

		echo 'cache_read_misses.type DERIVE'
		echo 'cache_read_misses.label Read misses'
		echo 'cache_read_misses.info Read misses for cache'

		echo 'cache_write_hits.type DERIVE'
		echo 'cache_write_hits.label Write hits'
		echo 'cache_write_hits.info Write hits for cache'

		echo 'cache_write_misses.type DERIVE'
		echo 'cache_write_misses.label Write misses'
		echo 'cache_write_misses.info Write misses for cache'

		echo 'cache_demotions.type DERIVE'
		echo 'cache_demotions.label Demotions'
		echo 'cache_demotions.info Demotions for cache'

		echo 'cache_promotions.type DERIVE'
		echo 'cache_promotions.label Promotions'
		echo 'cache_promotions.info Promotions for cache'

		exit 0
		;;
esac

dmstatus=$(dmsetup status $CVOL)

echo "cache_read_hits.value $(echo $dmstatus | awk '{print $8}')"
echo "cache_read_misses.value $(echo $dmstatus | awk '{print $9}')"
echo "cache_write_hits.value $(echo $dmstatus | awk '{print $10}')"
echo "cache_write_misses.value $(echo $dmstatus | awk '{print $11}')"
echo "cache_demotions.value $(echo $dmstatus | awk '{print $12}')"
echo "cache_promotions.value $(echo $dmstatus | awk '{print $13}')"