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Diffstat (limited to 'ruby_1_8_6/lib/monitor.rb')
| -rw-r--r-- | ruby_1_8_6/lib/monitor.rb | 352 |
1 files changed, 0 insertions, 352 deletions
diff --git a/ruby_1_8_6/lib/monitor.rb b/ruby_1_8_6/lib/monitor.rb deleted file mode 100644 index 4c146c8086..0000000000 --- a/ruby_1_8_6/lib/monitor.rb +++ /dev/null @@ -1,352 +0,0 @@ -=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 - - -# -# Adds monitor functionality to an arbitrary object by mixing the module with -# +include+. For 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. -# -module MonitorMixin - # - # FIXME: This isn't documented in Nutshell. - # - # Since MonitorMixin.new_cond returns a ConditionVariable, and the example - # above calls while_wait and signal, this class should be documented. - # - class ConditionVariable - class Timeout < Exception; end - - # Create a new timer with the argument timeout, and add the - # current thread to the list of waiters. Then the thread is - # stopped. It will be resumed when a corresponding #signal - # occurs. - def wait(timeout = nil) - @monitor.instance_eval {mon_check_owner()} - timer = create_timer(timeout) - - Thread.critical = true - count = @monitor.instance_eval {mon_exit_for_cond()} - @waiters.push(Thread.current) - - begin - Thread.stop - return true - rescue Timeout - return false - ensure - Thread.critical = true - begin - if timer && timer.alive? - Thread.kill(timer) - end - if @waiters.include?(Thread.current) # interrupted? - @waiters.delete(Thread.current) - end - @monitor.instance_eval {mon_enter_for_cond(count)} - ensure - Thread.critical = false - end - end - end - - - # call #wait while the supplied block returns +true+. - def wait_while - while yield - wait - end - end - - # call #wait until the supplied block returns +true+. - def wait_until - until yield - wait - end - end - - # Wake up and run the next waiter - def signal - @monitor.instance_eval {mon_check_owner()} - Thread.critical = true - t = @waiters.shift - t.wakeup if t - Thread.critical = false - Thread.pass - end - - # Wake up all the waiters. - def broadcast - @monitor.instance_eval {mon_check_owner()} - Thread.critical = true - for t in @waiters - t.wakeup - end - @waiters.clear - Thread.critical = false - Thread.pass - end - - def count_waiters - return @waiters.length - end - - private - - def initialize(monitor) - @monitor = monitor - @waiters = [] - end - - def create_timer(timeout) - if timeout - waiter = Thread.current - return Thread.start { - Thread.pass - sleep(timeout) - Thread.critical = true - waiter.raise(Timeout.new) - } - else - return nil - end - end - end - - def self.extend_object(obj) - super(obj) - obj.instance_eval {mon_initialize()} - end - - # - # Attempts to enter exclusive section. Returns +false+ if lock fails. - # - def mon_try_enter - result = false - Thread.critical = true - if @mon_owner.nil? - @mon_owner = Thread.current - end - if @mon_owner == Thread.current - @mon_count += 1 - result = true - end - Thread.critical = false - return result - end - # For backward compatibility - alias try_mon_enter mon_try_enter - - # - # Enters exclusive section. - # - def mon_enter - Thread.critical = true - mon_acquire(@mon_entering_queue) - @mon_count += 1 - ensure - Thread.critical = false - end - - # - # Leaves exclusive section. - # - def mon_exit - mon_check_owner - Thread.critical = true - @mon_count -= 1 - if @mon_count == 0 - mon_release - end - Thread.critical = false - Thread.pass - end - - # - # Enters exclusive section and executes the block. Leaves the exclusive - # section automatically when the block exits. See example under - # +MonitorMixin+. - # - def mon_synchronize - mon_enter - begin - yield - ensure - mon_exit - end - end - alias synchronize mon_synchronize - - # - # FIXME: This isn't documented in Nutshell. - # - # Create a new condition variable for this monitor. - # This facilitates control of the monitor with #signal and #wait. - # - def new_cond - return ConditionVariable.new(self) - end - - private - - def initialize(*args) - super - mon_initialize - end - - # called by initialize method to set defaults for instance variables. - def mon_initialize - @mon_owner = nil - @mon_count = 0 - @mon_entering_queue = [] - @mon_waiting_queue = [] - end - - # Throw a ThreadError exception if the current thread - # does't own the monitor - def mon_check_owner - if @mon_owner != Thread.current - raise ThreadError, "current thread not owner" - end - end - - def mon_acquire(queue) - while @mon_owner && @mon_owner != Thread.current - queue.push(Thread.current) - Thread.stop - Thread.critical = true - end - @mon_owner = Thread.current - end - - def mon_release - @mon_owner = nil - t = @mon_waiting_queue.shift - t = @mon_entering_queue.shift unless t - t.wakeup if t - end - - def mon_enter_for_cond(count) - mon_acquire(@mon_waiting_queue) - @mon_count = count - end - - def mon_exit_for_cond - count = @mon_count - @mon_count = 0 - return count - ensure - mon_release - end -end - -# Monitors provide means of mutual exclusion for Thread programming. -# A critical region is created by means of the synchronize method, -# which takes a block. -# The condition variables (created with #new_cond) may be used -# to control the execution of a monitor with #signal and #wait. -# -# the Monitor class wraps MonitorMixin, and provides aliases -# alias try_enter try_mon_enter -# alias enter mon_enter -# alias exit mon_exit -# to access its methods more concisely. -class Monitor - include MonitorMixin - alias try_enter try_mon_enter - alias enter mon_enter - alias exit mon_exit -end - - -# Documentation comments: -# - All documentation comes from Nutshell. -# - MonitorMixin.new_cond appears in the example, but is not documented in -# Nutshell. -# - 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 -# here, so is hard/impossible to RDoc. Some other useful accessors -# (mon_count and some queue stuff) are also in this module, and don't appear -# directly in the RDoc output. -# - in short, it may be worth changing the code layout in this file to make the -# documentation easier - -# Local variables: -# mode: Ruby -# tab-width: 8 -# End: |