From: Jérémie Laval <jeremie.laval@gmail.com>
Date: Fri, 30 May 2014 18:50:35 +0000 (-0400)
Subject: Merge pull request #1068 from esdrubal/bug18421
X-Git-Url: http://wien.tomnetworks.com/gitweb/?a=commitdiff_plain;h=610d1e7aaff5bb0d98875ecaba32581e360b805c;hp=103fd26cbb781ecf436924b2a49b214d0d7470c1;p=mono.git

Merge pull request #1068 from esdrubal/bug18421

Changed ConcurrentQueue to remove last ref/value. Fixes 18421
---

diff --git a/mcs/class/corlib/System.Collections.Concurrent/ConcurrentQueue.cs b/mcs/class/corlib/System.Collections.Concurrent/ConcurrentQueue.cs
index d19cc4cec7d..aff2492e021 100644
--- a/mcs/class/corlib/System.Collections.Concurrent/ConcurrentQueue.cs
+++ b/mcs/class/corlib/System.Collections.Concurrent/ConcurrentQueue.cs
@@ -97,12 +97,13 @@ namespace System.Collections.Concurrent
 		public bool TryDequeue (out T result)
 		{
 			result = default (T);
+			Node oldNext = null;
 			bool advanced = false;
 
 			while (!advanced) {
 				Node oldHead = head;
 				Node oldTail = tail;
-				Node oldNext = oldHead.Next;
+				oldNext = oldHead.Next;
 				
 				if (oldHead == head) {
 					// Empty case ?
@@ -122,6 +123,8 @@ namespace System.Collections.Concurrent
 				}
 			}
 
+			oldNext.Value = default (T);
+
 			Interlocked.Decrement (ref count);
 
 			return true;
diff --git a/mcs/class/corlib/Test/System.Collections.Concurrent/ConcurrentQueueTests.cs b/mcs/class/corlib/Test/System.Collections.Concurrent/ConcurrentQueueTests.cs
index b0006440afa..80313356fe2 100644
--- a/mcs/class/corlib/Test/System.Collections.Concurrent/ConcurrentQueueTests.cs
+++ b/mcs/class/corlib/Test/System.Collections.Concurrent/ConcurrentQueueTests.cs
@@ -215,6 +215,28 @@ namespace MonoTests.System.Collections.Concurrent
 		{
 			queue.CopyTo (new int[3], 0);
 		}
+		
+		static WeakReference CreateWeakReference (object obj)
+		{
+			return new WeakReference (obj);
+		}
+		
+		[Test]
+		public void TryDequeueReferenceTest ()
+		{
+			var obj = new Object ();
+			var weakReference = CreateWeakReference(obj);
+			var queue = new ConcurrentQueue<object> ();
+
+			queue.Enqueue (obj);
+			queue.TryDequeue (out obj);
+			obj = null;
+
+			GC.Collect ();
+			GC.WaitForPendingFinalizers ();
+
+			Assert.IsFalse (weakReference.IsAlive);
+		}
 	}
 }
 #endif