#!/usr/bin/env ruby
#
# Munin Plugin for MSSQL - Buffer cache hit ratio monitoring
#
# Author: Wilfred Chau <openapp.developer@gmail.com>
# Date: 2011-05-19
# Version: 1.0
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2
# as published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#
#
# Prerequistes:
#	1) /etc/odbc.ini and /etc/freetds.conf
#	2) rubygems
#	3) ruby-dbi
#
# Usage:
#	1) copy this script to the munin install plugins directory (e.g. /usr/share/munin/plugins)
#	2) chmod to allow executable to others
#	3) create symbolic link in /etc/munin/plugins
#          ln -s /usr/share/munin/plugins/mssql_buffercachehitratio.rb /etc/munin/plugins/mssql_buffercachehitratio.rb
#
# Parameters:
#	autoconf
#	config (required)
#
# Config variables:
#	sqluser : mssql user who has view server state privilege
#	sqlpass : password for the mssql user
#	dsn     : datasource name as defined in /etc/odbc.ini
#
#%# family=auto
#%# capabilities=autoconf

require 'rubygems'
require 'dbi'

sqluser  = 'rubyuser'
sqlpass  = 'rubyuser'
dsn      = 'TESTSQL'

#
# Queries
#
#
dbh = DBI.connect("DBI:ODBC:#{dsn}",sqluser,sqlpass)

buffercachehitratio_query = "select (a.cntr_value * 1.0 / b.cntr_value) * 100.0
                            from sys.dm_os_performance_counters a
                            join (select cntr_value, object_name
                                  from sys.dm_os_performance_counters
                                  where counter_name = 'Buffer cache hit ratio base'
                                  and object_name = 'SQLServer:Buffer Manager') b
                            on a.object_name = b.object_name
                            where a.counter_name = 'Buffer cache hit ratio'
                            and a.object_name = 'SQLServer:Buffer Manager'"

#
# autoconf
#
if ARGV[0] == "autoconf"
	if all_instance_names.length > 1 && sqluser.length > 1 && sqlpass.length > 1
		puts "yes"
	else
		puts "no"
		puts "Usage: #{__FILE__} autoconf|conf"
	end
	exit 0
#
# config definition
#
elsif ARGV[0] == "config"
	puts "graph_args --base 1000 -r --lower-limit 0"
	puts "graph_title MSSQL Buffer Cache Hit Ratio "
	puts "graph_category db"
	puts "graph_info This graph shows Buffer Cache Hit Ratio"
	puts "graph_vlabel %"
	puts "graph_scale no"
	puts "graph_period second"

	puts "bc_hitratio.label BufferCacheHitRatio"
	puts "bc_hitratio.info BufferCacheHitRatio"
	puts "bc_hitratio.type GAUGE"
	puts "bc_hitratio.draw LINE1"

	exit 0
end

sth = dbh.execute(buffercachehitratio_query)
sth.fetch do |row|
	puts "bc_hitratio.value #{row[0].strip.to_s}"
end
sth.finish
dbh.disconnect
