Class: Eventr::SupervisedObject

Inherits:
Object
  • Object
show all
Defined in:
lib/eventr/actors.rb

Direct Known Subclasses

Consumer, Publisher

Instance Method Summary collapse

Instance Method Details

#application ⇒ Object 



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# File 'lib/eventr/actors.rb', line 34

def application() threads[:application]; end

#on_exception ⇒ Object 



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# File 'lib/eventr/actors.rb', line 37

def on_exception
  @on_exception
end

#on_exception=(&block) ⇒ Object 



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# File 'lib/eventr/actors.rb', line 41

def on_exception=(&block)
  @on_exception = block
end

#sleep_time_from_backoff ⇒ Object 



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# File 'lib/eventr/actors.rb', line 45

def sleep_time_from_backoff
  backoff = Thread.current[:backoff] || 0
  (0..backoff).inject([1,0]) { |(a,b), _| [b, a+b] }[0]
end

#start ⇒ Object 



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# File 'lib/eventr/actors.rb', line 28

def start
  start_application_thread
  start_supervisor_thread
end

#start_application_thread ⇒ Object 



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# File 'lib/eventr/actors.rb', line 50

def start_application_thread
  threads[:application] ||= Thread.new {
    begin
      main()
    rescue StandardError => e
      on_exception.call(e) if on_exception.respond_to? :call
      warn "#{e.class.name}: #{e.message}\n\t#{e.backtrace.join("\n\t")}"
      raise e
    ensure
      threads[:supervisor].wakeup # wakeup the supervisor to help us recover
    end
  }
end

#start_supervisor_thread ⇒ Object 



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# File 'lib/eventr/actors.rb', line 64

def start_supervisor_thread
  threads[:supervisor] ||= Thread.new {
    Thread.current[:backoff] = 1

    begin
      runs = 5
      loop {
        unless (application && application.alive?)
          puts "#{self.class.name}::Supervisor: cleaning up app thread and restarting it."
          threads[:application] = nil
          start_application_thread

          # stop when we've successfully cleaned something up
          runs = 0

          # and make sure to reset backoff
          Thread.current[:backoff] = 1
        end

        # check for required cleanup 5 times over as many seconds
        if (runs -= 1) <= 0
          Thread.stop
          runs = 5
        end

        sleep 1
      }

    rescue StandardError => e
      warn "#{e.class.name}: #{e.message}\n\t#{e.backtrace.join("\n\t")}"

      if Thread.current[:backoff] <= 15
        Thread.current[:backoff] += 1
        sleep_time = sleep_time_from_backoff
        warn "sleeping for #{sleep_time} before restarting supervisor"
        sleep sleep_Time
        retry
      end

      # if the supervisor goes away, take the whole thing down.
      threads[:application].raise SupervisorDown, "supervisor went away due to: #{e.class.name}: #{e.message} -> #{e.backtrace.first}"

      raise e
    end
  }
end

#stop ⇒ Object 



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# File 'lib/eventr/actors.rb', line 24

def stop
  threads.values.each { |t| t.send :kill }
end

#supervisor ⇒ Object 



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# File 'lib/eventr/actors.rb', line 35

def supervisor() threads[:supervisor]; end

#threads ⇒ Object 



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# File 'lib/eventr/actors.rb', line 33

def threads() @threads ||= {}; end