1999-08-13 01:45:20 -04:00
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=begin
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2001-03-06 04:03:59 -05:00
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= monitor.rb
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1999-08-13 01:45:20 -04:00
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2001-03-06 04:03:59 -05:00
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Copyright (C) 2001 Shugo Maeda <shugo@ruby-lang.org>
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1999-08-13 01:45:20 -04:00
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2001-03-06 04:03:59 -05:00
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This library is distributed under the terms of the Ruby license.
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You can freely distribute/modify this library.
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1999-08-13 01:45:20 -04:00
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2001-03-06 04:03:59 -05:00
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== example
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1999-08-13 01:45:20 -04:00
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2001-03-06 04:03:59 -05:00
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This is a simple example.
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require 'monitor.rb'
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buf = []
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buf.extend(MonitorMixin)
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empty_cond = buf.new_cond
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# consumer
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Thread.start do
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loop do
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buf.synchronize do
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empty_cond.wait_while { buf.empty? }
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print buf.shift
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end
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end
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end
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# producer
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while line = ARGF.gets
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buf.synchronize do
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buf.push(line)
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empty_cond.signal
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end
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end
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The consumer thread waits for the producer thread to push a line
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to buf while buf.empty?, and the producer thread (main thread)
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reads a line from ARGF and push it to buf, then call
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empty_cond.signal.
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1999-08-13 01:45:20 -04:00
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=end
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module MonitorMixin
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module Accessible
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protected
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attr_accessor :mon_owner, :mon_count
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attr_reader :mon_entering_queue, :mon_waiting_queue
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end
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module Initializable
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protected
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def mon_initialize
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@mon_owner = nil
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@mon_count = 0
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@mon_entering_queue = []
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@mon_waiting_queue = []
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end
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end
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class ConditionVariable
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class Timeout < Exception; end
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include Accessible
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def wait(timeout = nil)
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if @monitor.mon_owner != Thread.current
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raise ThreadError, "current thread not owner"
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end
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Thread.critical = true
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count = @monitor.mon_count
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@monitor.mon_count = 0
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@monitor.mon_owner = nil
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if @monitor.mon_waiting_queue.empty?
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t = @monitor.mon_entering_queue.shift
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else
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t = @monitor.mon_waiting_queue.shift
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end
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t.wakeup if t
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@waiters.push(Thread.current)
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if timeout
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t = Thread.current
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timeout_thread = Thread.start {
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sleep(timeout)
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t.raise(Timeout.new)
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}
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end
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begin
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Thread.stop
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rescue Timeout
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@waiters.delete(Thread.current)
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ensure
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if timeout && timeout_thread.alive?
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Thread.kill(timeout_thread)
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end
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end
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Thread.critical = true
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while @monitor.mon_owner &&
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@monitor.mon_owner != Thread.current
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@monitor.mon_waiting_queue.push(Thread.current)
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Thread.stop
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Thread.critical = true
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end
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@monitor.mon_owner = Thread.current
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@monitor.mon_count = count
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Thread.critical = false
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end
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def wait_while
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while yield
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wait
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end
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end
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def wait_until
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until yield
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wait
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end
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end
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def signal
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if @monitor.mon_owner != Thread.current
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raise ThreadError, "current thread not owner"
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end
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Thread.critical = true
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t = @waiters.shift
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t.wakeup if t
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Thread.critical = false
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Thread.pass
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end
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def broadcast
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if @monitor.mon_owner != Thread.current
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raise ThreadError, "current thread not owner"
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end
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Thread.critical = true
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for t in @waiters
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t.wakeup
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end
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@waiters.clear
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Thread.critical = false
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Thread.pass
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end
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def count_waiters
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return @waiters.length
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end
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private
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def initialize(monitor)
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@monitor = monitor
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@waiters = []
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end
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end
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include Accessible
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include Initializable
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extend Initializable
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def self.extend_object(obj)
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super(obj)
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obj.mon_initialize
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end
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def try_mon_enter
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result = false
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Thread.critical = true
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if mon_owner.nil?
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self.mon_owner = Thread.current
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end
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if mon_owner == Thread.current
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self.mon_count += 1
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result = true
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end
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Thread.critical = false
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return result
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end
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def mon_enter
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Thread.critical = true
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while mon_owner != nil && mon_owner != Thread.current
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mon_entering_queue.push(Thread.current)
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Thread.stop
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Thread.critical = true
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end
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self.mon_owner = Thread.current
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self.mon_count += 1
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Thread.critical = false
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end
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def mon_exit
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if mon_owner != Thread.current
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raise ThreadError, "current thread not owner"
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end
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Thread.critical = true
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self.mon_count -= 1
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if mon_count == 0
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self.mon_owner = nil
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if mon_waiting_queue.empty?
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t = mon_entering_queue.shift
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else
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t = mon_waiting_queue.shift
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end
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end
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t.wakeup if t
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Thread.critical = false
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Thread.pass
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end
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def mon_synchronize
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mon_enter
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begin
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yield
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ensure
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mon_exit
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end
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end
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alias synchronize mon_synchronize
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def new_cond
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return ConditionVariable.new(self)
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end
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private
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def initialize(*args)
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super
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mon_initialize
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end
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end
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class Monitor
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include MonitorMixin
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alias try_enter try_mon_enter
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alias enter mon_enter
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alias exit mon_exit
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alias owner mon_owner
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end
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# Local variables:
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# mode: Ruby
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# tab-width: 8
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# End:
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