зеркало из https://github.com/github/ruby.git
322 строки
6.6 KiB
Ruby
322 строки
6.6 KiB
Ruby
=begin
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= monitor.rb
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Copyright (C) 2001 Shugo Maeda <shugo@ruby-lang.org>
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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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== example
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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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=end
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#
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# Adds monitor functionality to an arbitrary object by mixing the module with
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# +include+. For example:
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#
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# require 'monitor.rb'
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#
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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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#
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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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#
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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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#
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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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#
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module MonitorMixin
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#
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# FIXME: This isn't documented in Nutshell.
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#
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# Since MonitorMixin.new_cond returns a ConditionVariable, and the example
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# above calls while_wait and signal, this class should be documented.
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#
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class ConditionVariable
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class Timeout < Exception; end
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def wait(timeout = nil)
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@monitor.funcall(:mon_check_owner)
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timer = create_timer(timeout)
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Thread.critical = true
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count = @monitor.funcall(:mon_exit_for_cond)
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@waiters.push(Thread.current)
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begin
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Thread.stop
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return true
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rescue Timeout
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return false
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ensure
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Thread.critical = true
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if timer && timer.alive?
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Thread.kill(timer)
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end
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if @waiters.include?(Thread.current) # interrupted?
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@waiters.delete(Thread.current)
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end
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@monitor.funcall(:mon_enter_for_cond, count)
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Thread.critical = false
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end
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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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@monitor.funcall(:mon_check_owner)
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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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@monitor.funcall(:mon_check_owner)
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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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def create_timer(timeout)
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if timeout
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waiter = Thread.current
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return Thread.start {
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Thread.pass
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sleep(timeout)
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Thread.critical = true
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waiter.raise(Timeout.new)
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}
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else
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return nil
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end
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end
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end
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def self.extend_object(obj)
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super(obj)
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obj.funcall(:mon_initialize)
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end
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#
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# Attempts to enter exclusive section. Returns +false+ if lock fails.
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#
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def mon_try_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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@mon_owner = Thread.current
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end
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if @mon_owner == Thread.current
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@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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# For backward compatibility
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alias try_mon_enter mon_try_enter
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#
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# Enters exclusive section.
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#
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def mon_enter
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Thread.critical = true
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mon_acquire(@mon_entering_queue)
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@mon_count += 1
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Thread.critical = false
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end
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#
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# Leaves exclusive section.
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#
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def mon_exit
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mon_check_owner
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Thread.critical = true
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@mon_count -= 1
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if @mon_count == 0
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mon_release
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end
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Thread.critical = false
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Thread.pass
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end
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#
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# Enters exclusive section and executes the block. Leaves the exclusive
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# section automatically when the block exits. See example under
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# +MonitorMixin+.
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#
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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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#
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# FIXME: This isn't documented in Nutshell.
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#
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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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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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def mon_check_owner
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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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end
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def mon_acquire(queue)
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while @mon_owner && @mon_owner != Thread.current
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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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@mon_owner = Thread.current
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end
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def mon_release
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@mon_owner = nil
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t = @mon_waiting_queue.shift
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t = @mon_entering_queue.shift unless t
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t.wakeup if t
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end
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def mon_enter_for_cond(count)
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mon_acquire(@mon_waiting_queue)
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@mon_count = count
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end
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def mon_exit_for_cond
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count = @mon_count
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@mon_count = 0
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mon_release
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return count
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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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end
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# Documentation comments:
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# - All documentation comes from Nutshell.
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# - MonitorMixin.new_cond appears in the example, but is not documented in
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# Nutshell.
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# - All the internals (internal modules Accessible and Initializable, class
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# ConditionVariable) appear in RDoc. It might be good to hide them, by
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# making them private, or marking them :nodoc:, etc.
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# - The entire example from the RD section at the top is replicated in the RDoc
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# comment for MonitorMixin. Does the RD section need to remain?
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# - RDoc doesn't recognise aliases, so we have mon_synchronize documented, but
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# not synchronize.
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# - mon_owner is in Nutshell, but appears as an accessor in a separate module
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# here, so is hard/impossible to RDoc. Some other useful accessors
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# (mon_count and some queue stuff) are also in this module, and don't appear
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# directly in the RDoc output.
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# - in short, it may be worth changing the code layout in this file to make the
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# documentation easier
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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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