#! /usr/bin/ruby
#
# Munin Plugin for SGA memory components monitoring
#
# Author: Wilfred Chau <openapp.developer@gmail.com>
# Date: 2011-05-12
# 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) env.ORACLE_HOME set in munin-node
#	2) rubygems
#	3) oci8 - DBI gem for connecting to Oracle
#	   * instruction of installing oci8 is available here:
#	     http://ruby-oci8.rubyforge.org/en/InstallBinaryPackage.html
#
# 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/oracle_orcl_sga.rb /etc/munin/plugins/oracle_orcl_sga.rb
#
# Parameters:
#	autoconf
#	config (required)
#
# Configurable variables:
#	orauser : oracle user who has select priviledge to query v$sgastat view
#	orapass : password for the oracle user
#	dbport  : port used by the monitored instance (notice: numeric value)
#	dbname  : database to be monitored
#	dbhost  : host or ip address of db instance
#	
#
#%# family=auto
#%# capabilities=autoconf

require 'rubygems'
require 'oci8'

orauser  = 'munin'
orapass  = 'munin'
dbport   = 1522
dbname   = 'orcl'
dbhost   = 'localhost'

tnsname  = "(DESCRIPTION =
            (ADDRESS = (PROTOCOL = TCP)(HOST = #{dbhost})(PORT = #{dbport}))
            (CONNECT_DATA = (SID = #{dbname})))"

def runQuery (name,query)
	rows = $conn.exec(query)
	puts "#{name}.value #{rows.fetch().to_s}"
        rows.close
end


#
# Queries
#
shared_pool_query = "SELECT TO_CHAR(ROUND(SUM(decode(pool, 'shared pool', 
                    decode(name, 'library cache',0,
                                 'dictionary chace',0,
                                 'free memory',0,
                                 'sql area',0,
                                 (bytes)/(1024*1024)),0)),2)) pool_misc
                    from V$SGASTAT"

buffer_cache_query = "SELECT TO_CHAR(ROUND(SUM(decode(pool,NULL,
                     decode(name, 'db_block_buffers', (bytes)/(1024/1024),
                            'buffer_cache',(bytes)/(1024*1024),0),0)),2)) sga_bufcache
                     from V$SGASTAT"

fixed_area_query = "SELECT TO_CHAR(ROUND(SUM(decode(pool,NULL,
                   decode(name, 'fixed_sga', (bytes)/(1024*1024),0),0)),2)) sga_fixed
                   from V$SGASTAT"

java_pool_query = "SELECT TO_CHAR(ROUND(SUM(decode(pool, 'java pool', (bytes)/(1024*1024),0)),2)) sga_jpool
                   from V$SGASTAT"

large_pool_query = "SELECT TO_CHAR(ROUND(SUM(decode(pool, 'large pool', (bytes)/(1024*1024),0)),2)) sga_lpool
                   from V$SGASTAT"

log_buffer_query = "SELECT TO_CHAR(ROUND(SUM(decode(pool, NULL,
                   decode(name, 'log_buffer', (bytes)/(1024*1024),0),0)),2)) sga_lbuffer
                   from V$SGASTAT" 


memory_components = { "fixed_area"   => fixed_area_query,
                      "buffer_cache" => buffer_cache_query,
                      "java_pool"    => java_pool_query,
                      "large_pool"   => large_pool_query,
                      "log_buffer"   => log_buffer_query,
                      "shared_pool"  => shared_pool_query
                     }

#
# autoconf
#
if ARGV[0] == "autoconf"
	if tnsname.length > 1 && orauser.length > 1 && orapass.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 1024k -r --lower-limit 0"	
	puts "graph_title Oracle SGA from #{dbname}"
	puts "graph_category Oracle"
	puts "graph_info This graph shows the SGA memory usage (in MB)"
	puts "graph_vlabel MB"
	puts "graph_scale no"
	puts "graph_period second"

	memory_components.keys.each do |m|
		puts "#{m}.label #{m}"
		puts "#{m}.info SGA: #{m}"
		puts "#{m}.type GAUGE"

		# make sure fixed_area is at the bottom of the stack
		if ( m ==  'fixed_area' )
	        	puts "#{m}.draw AREA"
		else	
                	puts "#{m}.draw STACK"
		end
	end

	exit 0
end

$conn = OCI8.new(orauser, orapass, tnsname)
memory_components.each do |mc, query|
	runQuery(mc, query)
end
$conn.logoff