From: Martin DeMello <martindemello@...>
Date: 2006-11-23T02:19:29+09:00
Subject: Re: inotify over nfs

On 11/22/06, ara.t.howard@noaa.gov <ara.t.howard@noaa.gov> wrote:
>
> how is this working for you?  i think when i looked into inotify i found that
> messages would get sent twice or not at all or out of order or something like
> that... i forget this exact issues.  have you seen any?  btw.  could i/we have
> a look at your code?

Code inlined (not sure how the usenet and forum sides handle actual
attachments) - one watcher.rb per node and one process-inotify sitting
on the server.

martin

--- watcher.rb ---
require 'inotify'
require 'find'
require 'drb'

DRb.start_service
$www = DRbObject.new(nil, 'druby://www:7777')

EVENTS = {
  Inotify::CREATE => "created",
  Inotify::DELETE => "deleted"
}

ACTIONS = {
  Inotify::CREATE => :from_inotify,
  Inotify::MOVED_TO => :from_inotify,
  Inotify::MOVED_FROM => :delete_from_inotify,
  Inotify::DELETE => :delete_from_inotify
}

HOME_WATCHES = {}
INOTIFY_WATCHES = {}

HOME = Inotify.new
INOTIFY = Inotify.new

def watch(user)
  dir = File.join('/home', user)
  begin
    wd = INOTIFY.add_watch(dir, Inotify::CREATE | Inotify::DELETE |
			   Inotify::MOVED_TO)
    INOTIFY_WATCHES[wd] = user
  rescue Exception => e
    puts "Skipping #{e}: #{$!}"
  end
end

# watch the home directory
HOME.add_watch("/home", Inotify::CREATE | Inotify::ISDIR)

Thread.new do
  HOME.each_event {|ev|
    p ["HOME", ev]
    if ev.mask == Inotify::CREATE | Inotify::ISDIR
      newusr = ev.name
      watch(newusr)
    end
  }
end

# watch all the user subdirectories
Dir['/home/*'].each {|dir|
  user = File.basename(dir)
  watch(user)
}

t = Thread.new do
  INOTIFY.each_event {|ev|
    # skip hidden files
    unless ev.name =~ /^\./
      user = INOTIFY_WATCHES[ev.wd]
      str = ev.name
      action = ACTIONS[ev.mask]
      if action
	begin
	  $www.incoming('resource', user, action, str)
	rescue Exception => e
	  puts "!! exception: #{e}"
	end
      end
    end
  }
end

t.join
-----------------------------------

--- process-inotify.rb ---
#!usr/bin/ruby

require 'rubygems'
require 'active_record'
require 'config/environment'
require 'app/models/user'
require 'app/models/resource'
require 'drb'
require 'inotify'
require 'find'
require 'thread'
require 'logger'

# queue incoming events

$incoming = Queue.new

class InotifyListener
  def incoming(*args)
    $incoming << args
  end
end

DRb.start_service("druby://:7777", InotifyListener.new)

LOG = Logger.new('log/inotify.log')

def log(msg)
  LOG.info(msg)
end

log "opening db connection..."
db_config = YAML::load(File.open("config/database.yml"))
ActiveRecord::Base.establish_connection(db_config['production'])
log "done!"

t = Thread.new do
  loop do
    if $incoming.empty?
      sleep 1
      next
    else
      begin
        signal = $incoming.shift
	log signal.inspect
        recv, username, action, file = signal
	user = User.find_by_login(username)
	unless user
          log "Unrecognized user #{username}: #{[recv, action, file].inspect}"
	  next
	end
	if action
	  begin
            Resource.send(action.to_sym, user, file)
	  rescue Exception => e
	    log "!! exception: #{e}"
	  end
	end
      rescue Exception => e1
        log "!! exception: #{e1}"
      end
    end
  end
end

DRb.thread.join
------------------------------