source: extensions/gsdl-video/trunk/installed/cmdline/lib/ruby/1.8/drb/timeridconv.rb@ 18425

require 'drb/drb'
require 'monitor'

module DRb
  class TimerIdConv < DRbIdConv
    class TimerHolder2
      include MonitorMixin

      class InvalidIndexError < RuntimeError; end

      def initialize(timeout=600)
    super()
    @sentinel = Object.new
    @gc = {}
    @curr = {}
    @renew = {}
    @timeout = timeout
    @keeper = keeper
      end

      def add(obj)
    synchronize do 
      key = obj.__id__
      @curr[key] = obj
      return key
    end
      end

      def fetch(key, dv=@sentinel)
    synchronize do 
      obj = peek(key)
      if obj == @sentinel
        return dv unless dv == @sentinel
        raise InvalidIndexError
      end
      @renew[key] = obj # KeepIt
      return obj
    end
      end

      def include?(key)
    synchronize do 
      obj = peek(key)
      return false if obj == @sentinel
      true
    end
      end

      def peek(key)
    synchronize do 
      return @curr.fetch(key, @renew.fetch(key, @gc.fetch(key, @sentinel)))
    end
      end

      private
      def alternate
    synchronize do
      @gc = @curr       # GCed
      @curr = @renew
      @renew = {}
    end
      end

      def keeper
    Thread.new do
      loop do
        size = alternate
        sleep(@timeout)
      end
    end
      end
    end

    def initialize(timeout=600)
      @holder = TimerHolder2.new(timeout)
    end

    def to_obj(ref)
      return super if ref.nil?
      @holder.fetch(ref)
    rescue TimerHolder2::InvalidIndexError
      raise "invalid reference"
    end

    def to_id(obj)
      return @holder.add(obj)
    end
  end
end

# DRb.install_id_conv(TimerIdConv.new)