#!/usr/bin/env ruby
# thin_peak_memory - 
#     A munin plugin for Linux to monitor the maximum memory size
#     that an each individual thin process has reached
# 
# For Linux ONLY !
# DOES NOT WORK on OSX, Solaris or BSD.
# only linux, because this script relies on proc filesystem
#
# Author: 
#   Frederico de Souza Araujo - fred.the.master@gmail.com
#   http://www.frederico-araujo.com
#
# Based on:
#   thin_process_memory - 
#       A munin plugin to monitor memory size of 
#       each individual thin process
#   by Ben VandenBos and Avvo, Inc.
#
# 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.
#
#
#%# family=auto
#%# capabilities=autoconf

module Munin
  class ThinPeakMemory
    
    def run
      instances = get_pids()
      instances.each do |instance|
        pid, port = instance.split("|")
        hwm = (pid_hwm(pid).to_i)/1024
        puts "thin_#{port}.value #{hwm}"
      end
    end
    
    # only get VmHWM count for each pid
    #  (Virtual Memory High Water Mark)
    # Using Proc filesystem
    # ONLY LINUX! because relies on proc filesystem
    # TODO: make this work on OSX and Solaris,
    #      so the whole unix gang is happy ;)
    def pid_hwm(pid)
      res = `grep "VmHWM" /proc/#{pid}/status`.split[1]
      if res.match("cannot access")
        return nil
      else
        return res
      end
    end
    
    # fetch all pids that match thin
    def get_pids
      pids = `pgrep -f 'thin' -l | awk -F " " '{ if (substr( $4, 10, 4)>=1) print $1"|"substr( $4, 10, 4)}' | sort -t'|' -nk 2`.split(/\r?\n/)
    end

    def autoconf
      get_pids().length > 0
    end
    
  end
end

mpm = Munin::ThinPeakMemory.new

case ARGV[0]
when "config"
  puts "graph_title Thin Peak Memory (High Water Mark)"
  puts "graph_vlabel HWM"
  puts "graph_category webserver"
  puts "graph_args -l 0"
  puts "graph_scale yes"
  puts "graph_info Tracks the peak memory of thin processes, aka High Water Mark."
  mpm.get_pids.each do |instance|
    pid, port = instance.split("|")    
    puts "thin_#{port}.label thin_#{port}"
    puts "thin_#{port}.info Peak Memory"
    puts "thin_#{port}.type GAUGE"
    puts "thin_#{port}.min 0"
  end
when "autoconf"
  if mpm.autoconf
    puts "yes"
    exit 0
  end
  puts "no"
  exit 1
else
  mpm.run
end