# frozen_string_literal: false
require_relative 'drb'
require 'monitor'
module DRb
# Timer id conversion keeps objects alive for a certain amount of time after
# their last access. The default time period is 600 seconds and can be
# changed upon initialization.
#
# To use TimerIdConv:
#
# DRb.install_id_conv TimerIdConv.new 60 # one minute
class TimerIdConv < DRbIdConv
class TimerHolder2 # :nodoc:
include MonitorMixin
class InvalidIndexError < RuntimeError; end
def initialize(keeping=600)
super()
@sentinel = Object.new
@gc = {}
@renew = {}
@keeping = keeping
@expires = nil
end
def add(obj)
synchronize do
rotate
key = obj.__id__
@renew[key] = obj
invoke_keeper
return key
end
end
def fetch(key)
synchronize do
rotate
obj = peek(key)
raise InvalidIndexError if obj == @sentinel
@renew[key] = obj # KeepIt
return obj
end
end
private
def peek(key)
return @renew.fetch(key) { @gc.fetch(key, @sentinel) }
end
def invoke_keeper
return if @expires
@expires = Time.now + @keeping
on_gc
end
def on_gc
return unless Thread.main.alive?
return if @expires.nil?
Thread.new { rotate } if @expires < Time.now
ObjectSpace.define_finalizer(Object.new) {on_gc}
end
def rotate
synchronize do
if @expires &.< Time.now
@gc = @renew # GCed
@renew = {}
@expires = @gc.empty? ? nil : Time.now + @keeping
end
end
end
end
# Creates a new TimerIdConv which will hold objects for +keeping+ seconds.
def initialize(keeping=600)
@holder = TimerHolder2.new(keeping)
end
def to_obj(ref) # :nodoc:
return super if ref.nil?
@holder.fetch(ref)
rescue TimerHolder2::InvalidIndexError
raise "invalid reference"
end
def to_id(obj) # :nodoc:
return @holder.add(obj)
end
end
end
# DRb.install_id_conv(TimerIdConv.new)
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