#46: fix deadlock in RosterTree

Author: ForNeVeR

src/JabberNet.Muzzle/ControlExtensions.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Linq;
+using System.Threading.Tasks;
 using System.Windows.Forms;
 
 namespace JabberNet.Muzzle
@@ -23,6 +24,38 @@ public static void InvokeAction(this Control control, Action action)
             });
         }
 
+        /// <summary>
+        /// Asynchronously invokes the action in the control owning thread if invocation is required.
+        /// </summary>
+        /// <param name="control">Control on which the action should be invoked.</param>
+        /// <param name="action">The invocable action.</param>
+        public static Task BeginInvokeAction(this Control control, Action action)
+        {
+            var source = new TaskCompletionSource<object>();
+            if (control.InvokeRequired)
+            {
+                control.BeginInvoke((Action)(() =>
+                {
+                    try
+                    {
+                        action();
+                        source.SetResult(null);
+                    }
+                    catch (Exception exception)
+                    {
+                        source.SetException(exception);
+                    }
+                }));
+            }
+            else
+            {
+                action();
+                source.SetResult(null);
+            }
+
+            return source.Task;
+        }
+
         /// <summary>
         /// Invoke the function in the control owning thread if invocation is required.
         /// </summary>

src/JabberNet.Muzzle/RosterTree.cs

@@ -510,7 +510,7 @@ private void m_client_OnDisconnect(object sender)
 
         private void m_pres_OnPrimarySessionChange(object sender, JID bare)
         {
-            this.InvokeAction(() =>
+            this.BeginInvokeAction(() =>
             {
                 var pres = m_pres[bare];
                 var nodelist = (LinkedList)m_items[bare.ToString()];

tests/JabberNet.Test/Muzzle/ControlExtensionTests.cs

@@ -50,33 +50,39 @@ public void InvocationShouldBePerformedInAnotherThreadInCaseOfMultiThreading()
                 var form = new Form();
                 var handle = form.Handle;
 
-                Exception exception = null;
-                Task.Factory.StartNew(() =>
-                {
-                    try
+                RunApplicationWithParallelTask(
+                    form,
+                    () =>
                     {
                         Assert.IsTrue(form.InvokeRequired);
                         form.InvokeAction(() =>
                         {
                             Assert.AreEqual(threadId, Thread.CurrentThread.ManagedThreadId);
                         });
-                    }
-                    catch (Exception ex)
-                    {
-                        exception = ex;
-                    }
-                    finally
-                    {
-                        Application.Exit();
-                    }
-                });
+                    });
+            });
+        }
 
-                Application.Run(form);
-                if (exception != null)
-                {
-                    throw exception;
-                }
+        [Test]
+        public void BeginInvokeShouldReturnFinishedTask()
+        {
+            Task result = null;
+            ExecuteInStaThread(() =>
+            {
+                var form = new Form();
+                var handle = form.Handle;
+
+                RunApplicationWithParallelTask(
+                    form,
+                    () =>
+                    {
+                        Assert.IsTrue(form.InvokeRequired);
+                        result = form.BeginInvokeAction(Application.Exit);
+                    });
             });
+
+            Assert.IsNotNull(result);
+            Assert.IsTrue(result.IsCompleted);
         }
 
         [Test]
@@ -121,5 +127,36 @@ private static void ExecuteInStaThread(Action action)
                 throw exception;
             }
         }
+
+        private static void ExecuteInTask(Action action, Action<Exception> catchClause, Action finallyClause)
+        {
+            Task.Factory.StartNew(() =>
+            {
+                try
+                {
+                    action();
+                }
+                catch (Exception exception)
+                {
+                    catchClause(exception);
+                }
+                finally
+                {
+                    finallyClause();
+                }
+            });
+        }
+
+        private static void RunApplicationWithParallelTask(Form mainForm, Action task)
+        {
+            Exception exception = null;
+            ExecuteInTask(task, ex => exception = ex, Application.Exit);
+
+            Application.Run(mainForm);
+            if (exception != null)
+            {
+                throw exception;
+            }
+        }
     }
 }