#!/usr/bin/env ruby

=begin

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 privilege 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

=end

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}"
  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
#
case ARGV[0]
when '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
#
when 'config'
  puts 'graph_args --base 1024k -r --lower-limit 0'
  puts "graph_title Oracle SGA from #{dbname}"
  puts 'graph_category db'
  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