Carla: Show error when a plugin-bridge crashes

c++/carla-backend/carla_backend.h

@@ -499,10 +499,15 @@ enum CallbackType {
      */
     CALLBACK_NSM_SAVE = 18,
 
+    /*!
+     * An error occurred, show last error to user.
+     */
+    CALLBACK_ERROR = 19,
+
     /*!
      * The engine has crashed or malfunctioned and will no longer work.
      */
-    CALLBACK_QUIT = 19
+    CALLBACK_QUIT = 20
 };
 
 /*!

c++/carla-backend/carla_threads.cpp

@@ -287,8 +287,17 @@ void CarlaPluginThread::run()
         m_process->waitForFinished(-1);
 
         if (m_process->exitCode() != 0)
+        {
             qWarning("CarlaPluginThread::run() - bridge crashed");
 
+            QString errorString = QString("Plugin '%1' has crashed!\n"
+                                          "Saving now will lose its current settings.\n"
+                                          "Please remove this plugin, and not rely on it from this point.").arg(plugin->name());
+            CarlaBackend::setLastError(errorString.toUtf8().constData());
+
+            engine->callback(CarlaBackend::CALLBACK_ERROR, plugin->id(), 0, 0, 0.0);
+        }
+
         break;
     }
 }

src/carla.py

@@ -1220,6 +1220,7 @@ class CarlaMainW(QMainWindow, ui_carla.Ui_CarlaMainW):
         self.connect(self, SIGNAL("NSM_Open1Callback()"), SLOT("slot_handleNSM_Open1Callback()"))
         self.connect(self, SIGNAL("NSM_Open2Callback()"), SLOT("slot_handleNSM_Open2Callback()"))
         self.connect(self, SIGNAL("NSM_SaveCallback()"), SLOT("slot_handleNSM_SaveCallback()"))
+        self.connect(self, SIGNAL("ErrorCallback(QString)"), SLOT("slot_handleErrorCallback(QString)"))
         self.connect(self, SIGNAL("QuitCallback()"), SLOT("slot_handleQuitCallback()"))
 
         self.TIMER_GUI_STUFF  = self.startTimer(self.m_savedSettings["Main/RefreshInterval"])     # Peaks
@@ -1503,6 +1504,10 @@ class CarlaMainW(QMainWindow, ui_carla.Ui_CarlaMainW):
         self.save_project()
         Carla.Host.nsm_reply_save()
 
+    @pyqtSlot(str)
+    def slot_handleErrorCallback(self, error):
+        QMessageBox.critical(self, self.tr("Error"), error)
+
     @pyqtSlot()
     def slot_handleQuitCallback(self):
         CustomMessageBox(self, QMessageBox.Warning, self.tr("Warning"),
@@ -2071,6 +2076,8 @@ def callback_function(ptr, action, pluginId, value1, value2, value3):
         Carla.gui.emit(SIGNAL("NSM_Open2Callback()"))
     elif action == CALLBACK_NSM_SAVE:
         Carla.gui.emit(SIGNAL("NSM_SaveCallback()"))
+    elif action == CALLBACK_ERROR:
+        Carla.gui.emit(SIGNAL("ErrorCallback(QString)"), cString(Carla.Host.get_last_error()))
     elif action == CALLBACK_QUIT:
         Carla.gui.emit(SIGNAL("QuitCallback()"))
 

src/shared_carla.py

@@ -193,7 +193,8 @@ CALLBACK_NSM_ANNOUNCE      = 15
 CALLBACK_NSM_OPEN1         = 16
 CALLBACK_NSM_OPEN2         = 17
 CALLBACK_NSM_SAVE          = 18
-CALLBACK_QUIT              = 19
+CALLBACK_ERROR             = 19
+CALLBACK_QUIT              = 20
 
 # enum ProcessModeType
 PROCESS_MODE_SINGLE_CLIENT    = 0