lib/god/event_handler.rb

   1 module God
   2   class EventHandler
   3     @@actions = {}
   4     @@handler = nil
   5     @@loaded = false
   6
   7     def self.loaded?
   8       @@loaded
   9     end
  10
  11     def self.event_system
  12       @@handler::EVENT_SYSTEM
  13     end
  14
  15     def self.load
  16       begin
  17         case RUBY_PLATFORM
  18         when /darwin/i, /bsd/i
  19           require 'god/event_handlers/kqueue_handler'
  20           @@handler = KQueueHandler
  21         when /linux/i
  22           require 'god/event_handlers/netlink_handler'
  23           @@handler = NetlinkHandler
  24         else
  25           raise NotImplementedError, "Platform not supported for EventHandler"
  26         end
  27         @@loaded = true
  28       rescue Exception
  29         require 'god/event_handlers/dummy_handler'
  30         @@handler = DummyHandler
  31         @@loaded = false
  32       end
  33     end
  34
  35     def self.register(pid, event, &block)
  36       @@actions[pid] ||= {}
  37       @@actions[pid][event] = block
  38       @@handler.register_process(pid, @@actions[pid].keys)
  39     end
  40
  41     def self.deregister(pid, event=nil)
  42       if watching_pid? pid
  43         if event.nil?
  44           @@actions.delete(pid)
  45           @@handler.register_process(pid, []) if system("kill -0 #{pid} &> /dev/null")
  46         else
  47           @@actions[pid].delete(event)
  48           @@handler.register_process(pid, @@actions[pid].keys) if system("kill -0 #{pid} &> /dev/null")
  49         end
  50       end
  51     end
  52
  53     def self.call(pid, event, extra_data = {})
  54       @@actions[pid][event].call(extra_data) if watching_pid?(pid) && @@actions[pid][event]
  55     end
  56
  57     def self.watching_pid?(pid)
  58       @@actions[pid]
  59     end
  60
  61     def self.start
  62       Thread.new do
  63         loop do
  64           begin
  65             @@handler.handle_events
  66           rescue Exception => e
  67             message = format("Unhandled exception (%s): %s\n%s",
  68                              e.class, e.message, e.backtrace.join("\n"))
  69             applog(nil, :fatal, message)
  70           end
  71         end
  72       end
  73     end
  74
  75   end
  76 end