Merge pull request #415 from Eta0/eta/synchronization

Fix a few synchronization-related crashes

Author: Iridium-IO

CompactGUI/Application.xaml.vb

@@ -7,32 +7,47 @@ Class Application
 
     Public Shared ReadOnly mutex As New Mutex(False, "Global\CompactGUI")
 
+    Private pipeServerCancellation As New CancellationTokenSource()
+    Private pipeServerTask As Task
+
     Private mainWindow As MainWindow
 
     Private Async Sub Application_Startup(sender As Object, e As StartupEventArgs)
 
         SettingsHandler.InitialiseSettings()
 
+        Dim acquiredMutex As Boolean
+
+        Try
+            acquiredMutex = mutex.WaitOne(0, False)
+        Catch ex As AbandonedMutexException
+            ' This means the mutex was acquired successfully,
+            ' but its last owner exited abruptly, without releasing it.
+            ' acquiredMutex should still be True here, but further error checking
+            ' on shared program state could be added here as well.
+            acquiredMutex = True
+        End Try
 
-        If Not SettingsHandler.AppSettings.AllowMultiInstance AndAlso Not mutex.WaitOne(0, False) Then
+        If Not SettingsHandler.AppSettings.AllowMultiInstance AndAlso Not acquiredMutex Then
 
             If e.Args.Length <> 0 AndAlso e.Args(0) = "-tray" Then
                 MessageBox.Show("An instance of CompactGUI is already running")
                 Application.Current.Shutdown()
 
             End If
 
-            Using client = New NamedPipeClientStream("CompactGUI")
+            Using client = New NamedPipeClientStream(".", "CompactGUI", PipeDirection.Out)
                 client.Connect()
                 Using writer = New StreamWriter(client)
-                    writer.WriteLine(e.Args(0))
+                    If e.Args.Length > 0 Then
+                        writer.WriteLine(e.Args(0))
+                    End If
                 End Using
             End Using
 
             Application.Current.Shutdown()
         ElseIf Not SettingsHandler.AppSettings.AllowMultiInstance Then
-
-            ProcessNextInstanceMessage()
+            pipeServerTask = ProcessNextInstanceMessage()
         End If
 
 
@@ -56,31 +71,40 @@ Class Application
     ' can be handled in this file.
 
 
-    Private Async Sub ProcessNextInstanceMessage()
-
-        Await Task.Run(Sub()
-                           While True
-
-                               Using server = New NamedPipeServerStream("CompactGUI")
-                                   server.WaitForConnection()
-                                   Using reader = New StreamReader(server)
-                                       Dim message = reader.ReadLine()
-                                       mainWindow.Dispatcher.Invoke(Sub()
-                                                                        mainWindow.Show()
-                                                                        mainWindow.WindowState = WindowState.Normal
-                                                                        mainWindow.Topmost = True
-                                                                        mainWindow.Activate()
-                                                                        mainWindow.Topmost = False
-                                                                        If message IsNot Nothing Then
-                                                                            mainWindow.ViewModel.SelectFolder(message)
-
-                                                                        End If
-                                                                    End Sub)
-
-                                   End Using
-                               End Using
-                           End While
-                       End Sub)
-    End Sub
+    Private Async Function ProcessNextInstanceMessage() As Task
+        Using server = New NamedPipeServerStream("CompactGUI",
+                                                 PipeDirection.In,
+                                                 1,
+                                                 PipeTransmissionMode.Byte,
+                                                 PipeOptions.Asynchronous)
+            While Not pipeServerCancellation.IsCancellationRequested
+                Try
+                    Await server.WaitForConnectionAsync(pipeServerCancellation.Token)
+                Catch ex As OperationCanceledException
+                    Return
+                End Try
+                Using reader = New StreamReader(server)
+                    Dim message = Await reader.ReadLineAsync()
+                    mainWindow.Dispatcher.Invoke(Sub()
+                                                     mainWindow.Show()
+                                                     mainWindow.WindowState = WindowState.Normal
+                                                     mainWindow.Topmost = True
+                                                     mainWindow.Activate()
+                                                     mainWindow.Topmost = False
+                                                     If message IsNot Nothing Then
+                                                         mainWindow.ViewModel.SelectFolder(message)
+                                                     End If
+                                                 End Sub)
+                End Using
+            End While
+        End Using
+    End Function
+
+    Public Async Function ShutdownPipeServer() As Task
+        If pipeServerTask IsNot Nothing Then
+            pipeServerCancellation.Cancel()
+            Await pipeServerTask
+        End If
+    End Function
 
 End Class

CompactGUI/ViewModels/MainViewModel.vb

@@ -258,10 +258,19 @@ Public Class MainViewModel : Inherits ObservableObject
                 .Arguments = $"""{ActiveFolder.FolderName}""",
                 .Verb = "runas"}
         }
-        Application.mutex.Dispose()
-        myproc.Start()
-        Application.Current.Shutdown()
-
+        Dim app As Application = Application.Current
+        app.ShutdownPipeServer().ContinueWith(
+            Sub()
+                app.Dispatcher.Invoke(
+                    Sub()
+                        Application.mutex.ReleaseMutex()
+                        Application.mutex.Dispose()
+                    End Sub
+                )
+                myproc.Start()
+                app.Dispatcher.Invoke(Sub() app.Shutdown())
+            End Sub
+        )
     End Sub