Make crash dialog available before Application starts

CURA-4895

cura/CrashHandler.py

@@ -1,7 +1,6 @@
 # Copyright (c) 2017 Ultimaker B.V.
 # Cura is released under the terms of the LGPLv3 or higher.
 
-import sys
 import platform
 import traceback
 import faulthandler
@@ -14,7 +13,7 @@ import ssl
 import urllib.request
 import urllib.error
 
-from PyQt5.QtCore import QT_VERSION_STR, PYQT_VERSION_STR, QCoreApplication
+from PyQt5.QtCore import QT_VERSION_STR, PYQT_VERSION_STR
 from PyQt5.QtWidgets import QDialog, QDialogButtonBox, QVBoxLayout, QLabel, QTextEdit, QGroupBox
 
 from UM.Application import Application
@@ -49,10 +48,11 @@ fatal_exception_types = [
 class CrashHandler:
     crash_url = "https://stats.ultimaker.com/api/cura"
 
-    def __init__(self, exception_type, value, tb):
+    def __init__(self, exception_type, value, tb, has_started = True):
         self.exception_type = exception_type
         self.value = value
         self.traceback = tb
+        self.has_started = has_started
         self.dialog = None # Don't create a QDialog before there is a QApplication
 
         # While we create the GUI, the information will be stored for sending afterwards
@@ -67,10 +67,6 @@ class CrashHandler:
         if not CuraDebugMode and exception_type not in fatal_exception_types:
             return
 
-        application = QCoreApplication.instance()
-        if not application:
-            sys.exit(1)
-
         self.dialog = QDialog()
         self._createDialog()
 
@@ -79,6 +75,7 @@ class CrashHandler:
         self.dialog.setMinimumWidth(640)
         self.dialog.setMinimumHeight(640)
         self.dialog.setWindowTitle(catalog.i18nc("@title:window", "Crash Report"))
+        self.dialog.finished.connect(self._close)
 
         layout = QVBoxLayout(self.dialog)
 
@@ -89,6 +86,9 @@ class CrashHandler:
         layout.addWidget(self._userDescriptionWidget())
         layout.addWidget(self._buttonsWidget())
 
+    def _close(self):
+        os._exit(1)
+
     def _messageWidget(self):
         label = QLabel()
         label.setText(catalog.i18nc("@label crash message", """<p><b>A fatal error has occurred. Please send us this Crash Report to fix the problem</p></b>

cura/CuraApplication.py

@@ -1,5 +1,4 @@
 # Copyright (c) 2017 Ultimaker B.V.
-# Copyright (c) 2017 Ultimaker B.V.
 # Cura is released under the terms of the LGPLv3 or higher.
 from PyQt5.QtNetwork import QLocalServer
 from PyQt5.QtNetwork import QLocalSocket
@@ -113,6 +112,8 @@ class CuraApplication(QtApplication):
     # changes of the settings.
     SettingVersion = 4
 
+    Created = False
+
     class ResourceTypes:
         QmlFiles = Resources.UserType + 1
         Firmware = Resources.UserType + 2
@@ -256,7 +257,7 @@ class CuraApplication(QtApplication):
         self._center_after_select = False
         self._camera_animation = None
         self._cura_actions = None
-        self._started = False
+        self.started = False
 
         self._message_box_callback = None
         self._message_box_callback_arguments = []
@@ -409,6 +410,8 @@ class CuraApplication(QtApplication):
 
         self.getCuraSceneController().setActiveBuildPlate(0)  # Initialize
 
+        CuraApplication.Created = True
+
     def _onEngineCreated(self):
         self._engine.addImageProvider("camera", CameraImageProvider.CameraImageProvider())
 
@@ -503,7 +506,7 @@ class CuraApplication(QtApplication):
     #
     #   Note that the AutoSave plugin also calls this method.
     def saveSettings(self):
-        if not self._started: # Do not do saving during application start
+        if not self.started: # Do not do saving during application start
             return
 
         ContainerRegistry.getInstance().saveDirtyContainers()
@@ -732,7 +735,7 @@ class CuraApplication(QtApplication):
             for file_name in self._open_file_queue: #Open all the files that were queued up while plug-ins were loading.
                 self._openFile(file_name)
 
-            self._started = True
+            self.started = True
 
             self.exec_()
 

cura_app.py

@@ -71,8 +71,40 @@ if "PYTHONPATH" in os.environ.keys():                       # If PYTHONPATH is u
 
 def exceptHook(hook_type, value, traceback):
     from cura.CrashHandler import CrashHandler
-    _crash_handler = CrashHandler(hook_type, value, traceback)
+    from cura.CuraApplication import CuraApplication
-    _crash_handler.show()
+    has_started = False
+    if CuraApplication.Created:
+        has_started = CuraApplication.getInstance().started
+
+    #
+    # When the exception hook is triggered, the QApplication may not have been initialized yet. In this case, we don't
+    # have an QApplication to handle the event loop, which is required by the Crash Dialog.
+    # The flag "CuraApplication.Created" is set to True when CuraApplication finishes its constructor call.
+    #
+    # Before the "started" flag is set to True, the Qt event loop has not started yet. The event loop is a blocking
+    # call to the QApplication.exec_(). In this case, we need to:
+    #   1. Remove all scheduled events so no more unnecessary events will be processed, such as loading the main dialog,
+    #      loading the machine, etc.
+    #   2. Start the Qt event loop with exec_() and show the Crash Dialog.
+    #
+    # If the application has finished its initialization and was running fine, and then something causes a crash,
+    # we run the old routine to show the Crash Dialog.
+    #
+    from PyQt5.Qt import QApplication
+    if CuraApplication.Created:
+        _crash_handler = CrashHandler(hook_type, value, traceback, has_started)
+        if not has_started:
+            CuraApplication.getInstance().removePostedEvents(None)
+            _crash_handler.show()
+            sys.exit(CuraApplication.getInstance().exec_())
+        else:
+            _crash_handler.show()
+            sys.exit(1)
+    else:
+        application = QApplication(sys.argv)
+        _crash_handler = CrashHandler(hook_type, value, traceback, has_started)
+        _crash_handler.dialog.show()
+        sys.exit(application.exec_())
 
 if not known_args["debug"]:
     sys.excepthook = exceptHook