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* lib/monitor.rb: Improve documentation. Patch by Sandor Szucs.

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[Ruby 1.9 - Bug #4823]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@32119 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
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drbrain 2011-06-16 06:09:57 +00:00
parent 09b830c4b2
commit 14d0f7aa48
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5
ChangeLog
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@ -1,3 +1,8 @@
Thu Jun 16 15:09:29 2011 Eric Hodel <drbrain@segment7.net>
* lib/monitor.rb: Improve documentation. Patch by Sandor Szucs.
[Ruby 1.9 - Bug #4823]
Thu Jun 16 14:54:09 2011 Eric Hodel <drbrain@segment7.net>
* lib/webrick/utils.rb: Document WEBrick::Utils. Patch by Olivier

167
lib/monitor.rb
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@ -1,81 +1,91 @@
=begin
= monitor.rb
Copyright (C) 2001 Shugo Maeda <shugo@ruby-lang.org>
This library is distributed under the terms of the Ruby license.
You can freely distribute/modify this library.
== example
This is a simple example.
require 'monitor.rb'
buf = []
buf.extend(MonitorMixin)
empty_cond = buf.new_cond
# consumer
Thread.start do
loop do
buf.synchronize do
empty_cond.wait_while { buf.empty? }
print buf.shift
end
end
end
# producer
while line = ARGF.gets
buf.synchronize do
buf.push(line)
empty_cond.signal
end
end
The consumer thread waits for the producer thread to push a line
to buf while buf.empty?, and the producer thread (main thread)
reads a line from ARGF and push it to buf, then call
empty_cond.signal.
=end
# = monitor.rb
#
# Copyright (C) 2001 Shugo Maeda <shugo@ruby-lang.org>
#
# This library is distributed under the terms of the Ruby license.
# You can freely distribute/modify this library.
#
require 'thread'
#
# In concurrent programming, a monitor is an object or module intended to be
# used safely by more than one thread. The defining characteristic of a
# monitor is that its methods are executed with mutual exclusion. That is, at
# each point in time, at most one thread may be executing any of its methods.
# This mutual exclusion greatly simplifies reasoning about the implementation
# of monitors compared to reasoning about parallel code that updates a data
# structure.
#
# Adds monitor functionality to an arbitrary object by mixing the module with
# +include+. For example:
# You can read more about the general principles on the Wikipedia page for
# Monitors[http://en.wikipedia.org/wiki/Monitor_%28synchronization%29]
#
# == Examples
#
# === Simple object.extend
#
# require 'monitor.rb'
#
# buf = []
# buf.extend(MonitorMixin)
# empty_cond = buf.new_cond
#
# # consumer
# Thread.start do
# loop do
# buf.synchronize do
# empty_cond.wait_while { buf.empty? }
# print buf.shift
# end
# end
# end
#
# # producer
# while line = ARGF.gets
# buf.synchronize do
# buf.push(line)
# empty_cond.signal
# end
# end
#
# The consumer thread waits for the producer thread to push a line to buf
# while <tt>buf.empty?</tt>. The producer thread (main thread) reads a
# line from ARGF and pushes it into buf then calls <tt>empty_cond.signal</tt>
# to notify the consumer thread of new data.
#
# === Simple Class include
#
# require 'monitor'
# require 'monitor'
#
# class SynchronizedArray < Array
#
# buf = []
# buf.extend(MonitorMixin)
# empty_cond = buf.new_cond
# include MonitorMixin
#
# # consumer
# Thread.start do
# loop do
# buf.synchronize do
# empty_cond.wait_while { buf.empty? }
# print buf.shift
# end
# end
# end
# def initialize(*args)
# super(*args)
# end
#
# alias :old_shift :shift
# alias :old_unshift :unshift
#
# def shift(n=1)
# self.synchronize do
# self.old_shift(n)
# end
# end
#
# def unshift(item)
# self.synchronize do
# self.old_unshift(item)
# end
# end
#
# # other methods ...
# end
#
# # producer
# while line = ARGF.gets
# buf.synchronize do
# buf.push(line)
# empty_cond.signal
# end
# end
#
# The consumer thread waits for the producer thread to push a line
# to buf while buf.empty?, and the producer thread (main thread)
# reads a line from ARGF and push it to buf, then call
# empty_cond.signal.
# +SynchronizedArray+ implements an Array with synchronized access to items.
# This Class is implemented as subclass of Array which includes the
# MonitorMixin module.
#
module MonitorMixin
#
@ -215,11 +225,16 @@ module MonitorMixin
private
# Use <tt>extend MonitorMixin</tt> or <tt>include MonitorMixin</tt> instead
# of this constructor. Have look at the examples above to understand how to
# use this module.
def initialize(*args)
super
mon_initialize
end
# Initializes the MonitorMixin after being included in a class or when an
# object has been extended with the MonitorMixin
def mon_initialize
@mon_owner = nil
@mon_count = 0
@ -245,6 +260,16 @@ module MonitorMixin
end
end
# Use the Monitor class when you want to have a lock object for blocks with
# mutual exclusion.
#
# require 'monitor'
#
# lock = Monitor.new
# lock.synchronize do
# # exclusive access
# end
#
class Monitor
include MonitorMixin
alias try_enter try_mon_enter
@ -260,8 +285,6 @@ end
# - All the internals (internal modules Accessible and Initializable, class
# ConditionVariable) appear in RDoc. It might be good to hide them, by
# making them private, or marking them :nodoc:, etc.
# - The entire example from the RD section at the top is replicated in the RDoc
# comment for MonitorMixin. Does the RD section need to remain?
# - RDoc doesn't recognise aliases, so we have mon_synchronize documented, but
# not synchronize.
# - mon_owner is in Nutshell, but appears as an accessor in a separate module