* lib/thread.rb (Queue::pop): get rid of race condition.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@2527 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 7 insertions, 15 deletions

diff --git a/lib/thread.rb b/lib/thread.rb
index a398317461..7666bccecf 100644
--- a/lib/thread.rb
+++ b/lib/thread.rb
@@ -173,22 +173,14 @@ class Queue
   alias enq push
 
   def pop(non_block=false)
-    Thread.critical = true
-    begin
-      loop do
-       if @que.empty?
-	  if non_block
-	    raise ThreadError, "queue empty"
-	  end
-	  @waiting.push Thread.current
-	  Thread.stop
-	else
-	  return @que.shift
-	end
-      end
-    ensure
-      Thread.critical = false
+    while (Thread.critical = true; @que.empty?)
+      raise ThreadError, "queue empty" if non_block
+      @waiting.push Thread.current
+      Thread.stop
     end
+    @que.shift
+  ensure
+    Thread.critical = false
   end
   alias shift pop
   alias deq pop