postfixのactiveとかincomingとかをinotifyでイベント監視

mail_queue_watcher.rb

#! /usr/bin/env ruby1.9.1
# coding: utf-8

require 'find'
require 'rb-inotify'

QUEUE_DIR = '/var/spool/postfix'
PID_FILE = "/tmp/#{File.basename(__FILE__)}.pid"
OUT_FILE = "/tmp/#{File.basename(__FILE__)}.out"

logger = ->(msg,*args){
  if $DEBUG
    t = Time.now
    if args.empty?
      puts "#{t.strftime('%Y-%m-%d %H:%M:%S.%3N')} : #{msg}"
    else
      puts "#{t.strftime('%Y-%m-%d %H:%M:%S.%3N')} : #{msg}" % args
    end
  end
}

notifier = INotify::Notifier.new

# 監視対象イベント
events = [:create, :delete, :moved_from, :moved_to]

# カウンタ（キー:イベント, 値:回数）
counter = Hash.new(0)

# ファイルへのイベント発生時のコールバック
countup = ->(ev){
  logger.call [ev.flags, ev.name, ev.absolute_name].inspect
  events.each do |e|
    counter[e]+=1 if ev.flags.include? e
  end
}

# ディレクトリで発生するイベントを再帰的に監視
watch = ->(fpath){
  case fpath2 = fpath.sub(QUEUE_DIR, '').sub(/^$/,'/')
  ## postfix の active, incoming ,... を監視する
  when '/', %r<^/(active|incoming|defer|deferred|corrupt|hold)/?>
    logger.call "watch: add %s", fpath2
    notifier.watch(fpath, *events) do |ev|
      case
      when ev.flags.include?(:isdir) && ev.flags.include?(:create)
        watch[ev.absolute_name]
      when !ev.flags.include?(:isdir) && ev.name =~ /\A[0-9a-fA-F]+\Z/
        countup[ev]
      end
    end
  else
    logger.call "watch: ignore %s", fpath
  end
}

# /var/spool/postfix 以下のディレクトリを探して watch
Find.find QUEUE_DIR do |fpath|
  watch[fpath] if File.directory? fpath
end

# PIDファイル（簡単にSIGUSR1を送れるように）
File.open(PID_FILE, 'w'){ |fh| fh << $$ }

# メインループ
begin
  Signal.trap :USR1, 'DEFAULT'
  notifier.run
rescue SignalException => e
  if e.message == 'SIGUSR1'
    Signal.trap :USR1, 'IGNORE'
    logger.call "SIGUSR1 received, writing %s...", OUT_FILE
    open(OUT_FILE, 'w') do |fh|
      events.each do |ev| fh << "%s = %d\n" % [ ev, counter[ev] ] end
    end
    #sleep 1
    logger.call "resume inotify event loop"
    retry
  else
    raise e
  end
ensure
  File.unlink PID_FILE
end