fair-but-slow-queue-for-1.9.diff

Index: lib/thread.rb
===================================================================
--- lib/thread.rb	(リビジョン 28689)
+++ lib/thread.rb	(作業コピー)
@@ -148,6 +148,7 @@
     @waiting.taint
     self.taint
     @mutex = Mutex.new
+    @relocked = ConditionVariable.new
   end
 
   #
@@ -158,7 +159,10 @@
       @que.push obj
       begin
         t = @waiting.shift
-        t.wakeup if t
+        if t
+          t.wakeup
+          @relocked.wait(@mutex)
+        end
       rescue ThreadError
         retry
       end
@@ -187,6 +191,7 @@
           raise ThreadError, "queue empty" if non_block
           @waiting.push Thread.current
           @mutex.sleep
+          @relocked.signal
         else
           return @que.shift
         end

gistfile1.rb

# Test for Queue fairness
# just testing - the fairness is not a spec at present.

create_waiter = lambda { |name, command|
  t = Thread.new {
    p [command.pop, name]
  }
  Thread.pass until t.status == 'sleep'
  t
}

50.times do
  command = Queue.new
  # create 3 waiters, and...
  create_waiter.call(:first, command)
  create_waiter.call(:second, command)
  create_waiter.call(:third, command)
  # and pushes a command.
  command.push(:go)
  # then try to consume the command by a subsequent thread
  Thread.new {
    p [command.pop, :LATER]
  }
end