Make sure Subscription does not double-cancel its consumer

In a case when the consumer is already cancelled.

Author: michaelklishin

projects/client/RabbitMQ.Client/src/client/api/QueueingBasicConsumer.cs

@@ -38,6 +38,8 @@
 //  Copyright (c) 2007-2014 GoPivotal, Inc.  All rights reserved.
 //---------------------------------------------------------------------------
 
+using System;
+
 using RabbitMQ.Client;
 using RabbitMQ.Client.Events;
 using RabbitMQ.Util;
@@ -153,8 +155,8 @@ public override void HandleBasicDeliver(string consumerTag,
         /// </summary>
         public override void OnCancel()
         {
-            Queue.Close();
             base.OnCancel();
+            Queue.Close();
         }
     }
 }

projects/client/RabbitMQ.Client/src/client/messagepatterns/Subscription.cs

@@ -89,6 +89,7 @@ public Subscription(IModel model, string queueName, bool noAck)
             NoAck = noAck;
             m_consumer = new QueueingBasicConsumer(Model);
             ConsumerTag = Model.BasicConsume(QueueName, NoAck, m_consumer);
+            m_consumer.ConsumerCancelled += HandleConsumerCancelled;
             LatestEvent = null;
         }
 
@@ -100,6 +101,7 @@ public Subscription(IModel model, string queueName, bool noAck, string consumerT
             QueueName = queueName;
             NoAck = noAck;
             m_consumer = new QueueingBasicConsumer(Model);
+            m_consumer.ConsumerCancelled += HandleConsumerCancelled;
             ConsumerTag = Model.BasicConsume(QueueName, NoAck, consumerTag, m_consumer);
             LatestEvent = null;
         }
@@ -206,10 +208,9 @@ public void Close()
             try
             {
                 bool shouldCancelConsumer = false;
-
                 if (m_consumer != null)
                 {
-                    shouldCancelConsumer = true;
+                    shouldCancelConsumer = m_consumer.IsRunning;
                     m_consumer = null;
                 }
 
@@ -439,5 +440,14 @@ protected void MutateLatestEvent(BasicDeliverEventArgs value)
                 LatestEvent = value;
             }
         }
+
+        private void HandleConsumerCancelled(object sender, ConsumerEventArgs e)
+        {
+            lock (m_eventLock)
+            {
+                m_consumer = null;
+                MutateLatestEvent(null);
+            }
+        }
     }
 }

projects/client/Unit/RabbitMQ.Client.Unit.csproj

@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <!-- Warning! This file contains important customizations. Using Visual Studio to edit project's properties might break things. -->
   <!-- Props file -->
@@ -124,6 +124,7 @@
     <Compile Include="src\unit\TestSharedQueue.cs" />
     <Compile Include="src\unit\TestSsl.cs" />
     <Compile Include="src\unit\TestStreamWireFormatting.cs" />
+    <Compile Include="src\unit\TestSubscription.cs" />
     <Compile Include="src\unit\WireFormattingFixture.cs" />
   </ItemGroup>
   <ItemGroup>
@@ -143,4 +144,4 @@
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
   <!-- Custom BeforeClean -->
   <Target Name="BeforeClean" DependsOnTargets="CleanTestResults" />
-</Project>
+</Project>

projects/client/Unit/src/unit/TestSubscription.cs

@@ -0,0 +1,76 @@
+// This source code is dual-licensed under the Apache License, version
+// 2.0, and the Mozilla Public License, version 1.1.
+//
+// The APL v2.0:
+//
+//---------------------------------------------------------------------------
+//   Copyright (C) 2007-2014 GoPivotal, Inc.
+//
+//   Licensed under the Apache License, Version 2.0 (the "License");
+//   you may not use this file except in compliance with the License.
+//   You may obtain a copy of the License at
+//
+//       http://www.apache.org/licenses/LICENSE-2.0
+//
+//   Unless required by applicable law or agreed to in writing, software
+//   distributed under the License is distributed on an "AS IS" BASIS,
+//   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//   See the License for the specific language governing permissions and
+//   limitations under the License.
+//---------------------------------------------------------------------------
+//
+// The MPL v1.1:
+//
+//---------------------------------------------------------------------------
+//  The contents of this file are subject to the Mozilla Public License
+//  Version 1.1 (the "License"); you may not use this file except in
+//  compliance with the License. You may obtain a copy of the License
+//  at http://www.mozilla.org/MPL/
+//
+//  Software distributed under the License is distributed on an "AS IS"
+//  basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+//  the License for the specific language governing rights and
+//  limitations under the License.
+//
+//  The Original Code is RabbitMQ.
+//
+//  The Initial Developer of the Original Code is GoPivotal, Inc.
+//  Copyright (c) 2007-2014 GoPivotal, Inc.  All rights reserved.
+//---------------------------------------------------------------------------
+
+using System;
+using System.Threading;
+using NUnit.Framework;
+
+using RabbitMQ.Client.MessagePatterns;
+
+namespace RabbitMQ.Client.Unit
+{
+    [TestFixture]
+    class TestSubscription : IntegrationFixture
+    {
+        [SetUp]
+        public override void Init()
+        {
+            var connFactory = new ConnectionFactory()
+            {
+                AutomaticRecoveryEnabled = false
+            };
+            Conn = connFactory.CreateConnection();
+            Model = Conn.CreateModel();
+        }
+
+        [Test, Timeout(5000)]
+        public void TestConsumerCancellationNotification()
+        {
+            var q = Guid.NewGuid().ToString();
+            this.Model.QueueDeclare(queue: q, durable: false, exclusive: false, autoDelete: false, arguments: null);
+            var sub = new Subscription(this.Model, q);
+            this.Model.QueueDelete(q);
+            sub.Consumer.ConsumerCancelled += (_sender, _args) =>
+            {
+                sub.Close();
+            };
+        }
+    }
+}