lib/god/conditions/process_exits.rb

   1 module God
   2   module Conditions
   3
   4     # Condition Symbol :process_exits
   5     # Type: Event
   6     #
   7     # Trigger when a process exits.
   8     #
   9     # Paramaters
  10     #   Required
  11     #     +pid_file+ is the pid file of the process in question. Automatically
  12     #                populated for Watches.
  13     #
  14     # Examples
  15     #
  16     # Trigger if process exits (from a Watch):
  17     #
  18     #   on.condition(:process_exits)
  19     #
  20     # Trigger if process exits:
  21     #
  22     #   on.condition(:process_exits) do |c|
  23     #     c.pid_file = "/var/run/mongrel.3000.pid"
  24     #   end
  25     class ProcessExits < EventCondition
  26       def initialize
  27         self.info = "process exited"
  28       end
  29
  30       def valid?
  31         true
  32       end
  33
  34       def register
  35         pid = self.watch.pid
  36
  37         begin
  38           EventHandler.register(pid, :proc_exit) do |extra|
  39             formatted_extra = extra.size > 0 ? " #{extra.inspect}" : ""
  40             self.info = "process #{pid} exited#{formatted_extra}"
  41             Hub.trigger(self)
  42           end
  43
  44           msg = "#{self.watch.name} registered 'proc_exit' event for pid #{pid}"
  45           applog(self.watch, :info, msg)
  46         rescue StandardError
  47           raise EventRegistrationFailedError.new
  48         end
  49       end
  50
  51       def deregister
  52         pid = self.watch.pid
  53         if pid
  54           EventHandler.deregister(pid, :proc_exit)
  55
  56           msg = "#{self.watch.name} deregistered 'proc_exit' event for pid #{pid}"
  57           applog(self.watch, :info, msg)
  58         else
  59           applog(self.watch, :error, "#{self.watch.name} could not deregister: no cached PID or PID file #{self.watch.pid_file} (#{self.base_name})")
  60         end
  61       end
  62     end
  63
  64   end
  65 end