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