thread.rb in rubysl-thread-2.1

- old
+ new
@@ -1,341 +1,682 @@
-require "rubysl/thread"
+#
+#		thread.rb - thread support classes
+#			$Date: 2006-12-31 07:02:22 -0800 (Sun, 31 Dec 2006) $
+#			by Yukihiro Matsumoto <matz@netlab.co.jp>
+#
+# Copyright (C) 2001  Yukihiro Matsumoto
+# Copyright (C) 2000  Network Applied Communication Laboratory, Inc.
+# Copyright (C) 2000  Information-technology Promotion Agency, Japan
+#
+
+if $DEBUG
+  Thread.abort_on_exception = true
+end
+
+#
+# ConditionVariable objects augment class Mutex. Using condition variables,
+# it is possible to suspend while in the middle of a critical section until a
+# resource becomes available.
+#
+# Example:
+#
+#   require 'thread'
+#
+#   mutex = Mutex.new
+#   resource = ConditionVariable.new
+#
+#   a = Thread.new {
+#     mutex.synchronize {
+#       # Thread 'a' now needs the resource
+#       resource.wait(mutex)
+#       # 'a' can now have the resource
+#     }
+#   }
+#
+#   b = Thread.new {
+#     mutex.synchronize {
+#       # Thread 'b' has finished using the resource
+#       resource.signal
+#     }
+#   }
+#
+class ConditionVariable
+  #
+  # Creates a new ConditionVariable
+  #
+  def initialize
+    @waiters = []
+  end
+
+  #
+  # Releases the lock held in +mutex+ and waits; reacquires the lock on wakeup.
+  #
+  def wait(mutex, timeout=nil)
+    Rubinius.lock(self)
+
+    begin
+      wchan = Rubinius::Channel.new
+
+      begin
+        mutex.unlock
+        @waiters.push wchan
+        Rubinius.unlock(self)
+        signaled = wchan.receive_timeout timeout
+      ensure
+        mutex.lock
+        Rubinius.lock(self)
+
+        unless signaled or @waiters.delete(wchan)
+          # we timed out, but got signaled afterwards (e.g. while waiting to
+          # acquire @lock), so pass that signal on to the next waiter
+          @waiters.shift << true unless @waiters.empty?
+        end
+      end
+
+      if timeout
+        !!signaled
+      else
+        self
+      end
+    ensure
+      Rubinius.unlock(self)
+    end
+  end
+
+  #
+  # Wakes up the first thread in line waiting for this lock.
+  #
+  def signal
+    Rubinius.lock(self)
+    begin
+      @waiters.shift << true unless @waiters.empty?
+    ensure
+      Rubinius.unlock(self)
+    end
+    self
+  end
+
+  #
+  # Wakes up all threads waiting for this lock.
+  #
+  def broadcast
+    Rubinius.lock(self)
+    begin
+      @waiters.shift << true until @waiters.empty?
+    ensure
+      Rubinius.unlock(self)
+    end
+    self
+  end
+end
+
+#
+# This class provides a way to synchronize communication between threads.
+#
+# Example:
+#
+#   require 'thread'
+#
+#   queue = Queue.new
+#
+#   producer = Thread.new do
+#     5.times do |i|
+#       sleep rand(i) # simulate expense
+#       queue << i
+#       puts "#{i} produced"
+#     end
+#   end
+#
+#   consumer = Thread.new do
+#     5.times do |i|
+#       value = queue.pop
+#       sleep rand(i/2) # simulate expense
+#       puts "consumed #{value}"
+#     end
+#   end
+#
+#   consumer.join
+#
+class Queue
+  #
+  # Creates a new queue.
+  #
+  def initialize
+    @que = []
+    @que.taint		# enable tainted comunication
+    self.taint
+    @waiting = []
+    @waiting.taint
+    @mutex = Mutex.new
+    @resource = ConditionVariable.new
+  end
+
+  #
+  # Pushes +obj+ to the queue.
+  #
+  def push(obj)
+    @mutex.synchronize do
+      @que.push obj
+      @resource.signal
+    end
+  end
+
+  #
+  # Alias of push
+  #
+  alias << push
+
+  #
+  # Alias of push
+  #
+  alias enq push
+
+  #
+  # Retrieves data from the queue.  If the queue is empty, the calling thread is
+  # suspended until data is pushed onto the queue.  If +non_block+ is true, the
+  # thread isn't suspended, and an exception is raised.
+  #
+  def pop(non_block=false)
+    while true
+      @mutex.synchronize do
+        #FIXME: some code in net or somewhere violates encapsulation
+        #and demands that a waiting queue exist for Queue, as a result
+        #we have to do a linear search here to remove the current Thread.
+        @waiting.delete(Thread.current)
+        if @que.empty?
+          raise ThreadError, "queue empty" if non_block
+          @waiting.push Thread.current
+          @resource.wait(@mutex)
+        else
+          retval = @que.shift
+          @resource.signal
+          return retval
+        end
+      end
+    end
+  end
+
+  #
+  # Alias of pop
+  #
+  alias shift pop
+
+  #
+  # Alias of pop
+  #
+  alias deq pop
+
+  #
+  # Returns +true+ if the queue is empty.
+  #
+  def empty?
+    @que.empty?
+  end
+
+  #
+  # Removes all objects from the queue.
+  #
+  def clear
+    @que.clear
+  end
+
+  #
+  # Returns the length of the queue.
+  #
+  def length
+    @que.length
+  end
+
+  #
+  # Alias of length.
+  #
+  alias size length
+
+  #
+  # Returns the number of threads waiting on the queue.
+  #
+  def num_waiting
+    @waiting.size
+  end
+end
+
+#
+# This class represents queues of specified size capacity.  The push operation
+# may be blocked if the capacity is full.
+#
+# See Queue for an example of how a SizedQueue works.
+#
+class SizedQueue < Queue
+  #
+  # Creates a fixed-length queue with a maximum size of +max+.
+  #
+  def initialize(max)
+    raise ArgumentError, "queue size must be positive" unless max > 0
+    @max = max
+    @queue_wait = []
+    @queue_wait.taint		# enable tainted comunication
+    @size_mutex = Mutex.new
+    @sem = ConditionVariable.new
+    super()
+  end
+
+  #
+  # Returns the maximum size of the queue.
+  #
+  def max
+    @max
+  end
+
+  #
+  # Sets the maximum size of the queue.
+  #
+  def max=(max)
+    @size_mutex.synchronize do
+      @max = max
+      @sem.broadcast
+    end
+    max
+  end
+
+  #
+  # Pushes +obj+ to the queue.  If there is no space left in the queue, waits
+  # until space becomes available.
+  #
+  def push(obj)
+    while true
+      @size_mutex.synchronize do
+        @queue_wait.delete(Thread.current)
+        if @que.size >= @max
+          @queue_wait.push Thread.current
+          @sem.wait(@size_mutex)
+        else
+          return super(obj)
+        end
+      end
+    end
+  end
+
+  #
+  # Alias of push
+  #
+  alias << push
+
+  #
+  # Alias of push
+  #
+  alias enq push
+
+  #
+  # Retrieves data from the queue and runs a waiting thread, if any.
+  #
+  def pop(*args)
+    retval = super
+
+    @size_mutex.synchronize do
+      if @que.size < @max
+        @sem.broadcast
+      end
+    end
+
+    return retval
+  end
+
+  #
+  # Alias of pop
+  #
+  alias shift pop
+
+  #
+  # Alias of pop
+  #
+  alias deq pop
+
+  #
+  # Returns the number of threads waiting on the queue.
+  #
+  def num_waiting
+    @waiting.size + @queue_wait.size
+  end
+end
+
+# Documentation comments:
+#  - How do you make RDoc inherit documentation from superclass?