Make closing/crashing much more reliable.

qutebrowser/app.py

@@ -70,6 +70,7 @@ class QuteBrowser(QApplication):
     keyparser = None
     args = None  # ArgumentParser
     timer = None  # QTimer for python hacks
+    shutting_down = False
 
     def __init__(self):
         super().__init__(sys.argv)
@@ -94,7 +95,8 @@ class QuteBrowser(QApplication):
         self._init_cmds()
         self.mainwindow = MainWindow()
 
-        self.aboutToQuit.connect(self._shutdown)
+        self.setQuitOnLastWindowClosed(False)
+        self.lastWindowClosed.connect(self.shutdown)
         self.mainwindow.tabs.keypress.connect(self.keyparser.handle)
         self.keyparser.set_cmd_text.connect(
             self.mainwindow.status.cmd.on_set_cmd_text)
@@ -171,6 +173,15 @@ class QuteBrowser(QApplication):
         except Exception:
             history = []
 
+        # Try to shutdown gracefully
+        try:
+            self.shutdown(do_quit=False)
+        except Exception:
+            pass
+        try:
+            self.lastWindowClosed.disconnect(self.shutdown)
+        except TypeError:
+            logging.exception("Preventing shutdown failed.")
         QApplication.closeAllWindows()
         dlg = CrashDialog(pages, history, exc)
         ret = dlg.exec_()
@@ -182,7 +193,10 @@ class QuteBrowser(QApplication):
             logging.debug('Running {} with args {}'.format(sys.executable,
                                                            argv))
             subprocess.Popen(argv)
-        sys.exit(1)
+        try:
+            self.quit()
+        except Exception:
+            sys.exit(1)
 
     def _python_hacks(self):
         """Get around some PyQt-oddities by evil hacks.
@@ -246,10 +260,24 @@ class QuteBrowser(QApplication):
             pass
 
     @pyqtSlot()
-    def _shutdown(self):
+    def shutdown(self, do_quit=True):
-        """Try to shutdown everything cleanly."""
+        """Try to shutdown everything cleanly.
+
+        For some reason lastWindowClosing sometimes seem to get emitted twice,
+        so we make sure we only run once here.
+
+        quit -- Whether to quit after shutting down.
+
+        """
+        if self.shutting_down:
+            return
+        self.shutting_down = True
+        logging.debug("Shutting down...")
         config.config.save()
+        self.mainwindow.tabs.shutdown_complete.connect(self.quit)
         self.mainwindow.tabs.shutdown()
+        if do_quit:
+            self.quit()
 
     @pyqtSlot(tuple)
     def cmd_handler(self, tpl):
@@ -272,7 +300,7 @@ class QuteBrowser(QApplication):
             'opencur':       self.mainwindow.tabs.opencur,
             'tabopen':       self.mainwindow.tabs.tabopen,
             'tabopencur':    self.mainwindow.tabs.tabopencur,
-            'quit':          self.quit,
+            'quit':          self.shutdown,
             'tabclose':      self.mainwindow.tabs.cur_close,
             'tabprev':       self.mainwindow.tabs.switch_prev,
             'tabnext':       self.mainwindow.tabs.switch_next,

qutebrowser/widgets/browser.py

@@ -67,6 +67,7 @@ class TabbedBrowser(TabWidget):
     cur_scroll_perc_changed = pyqtSignal(int, int)
     set_cmd_text = pyqtSignal(str)  # Set commandline to a given text
     keypress = pyqtSignal('QKeyEvent')
+    shutdown_complete = pyqtSignal()  # All tabs have been shut down.
     _url_stack = []  # Stack of URLs of closed tabs
     _space = None  # Space QShortcut
     _tabs = None
@@ -154,15 +155,22 @@ class TabbedBrowser(TabWidget):
                 # FIXME maybe we actually should store the webview objects here
                 self._url_stack.append(tab.url())
                 self.removeTab(idx)
-                try:
+                tab.shutdown(callback=functools.partial(self._cb_tab_shutdown,
-                    self._tabs.remove(tab)
+                                                        tab))
-                except ValueError:
-                    pass
-                tab.shutdown()
         else:
             # FIXME
             pass
 
+    def _cb_tab_shutdown(self, tab):
+        """Called after a tab has been shut down completely."""
+        try:
+            self._tabs.remove(tab)
+        except ValueError:
+            logging.error("tab {} could not be removed from tabs {}.".format(
+                tab, self._tabs))
+        if not self._tabs:  # all tabs shut down
+            self.shutdown_complete.emit()
+
     def cur_reload(self, count=None):
         """Reload the current/[count]th tab.
 
@@ -433,9 +441,14 @@ class TabbedBrowser(TabWidget):
 
     def shutdown(self):
         """Try to shut down all tabs cleanly."""
-        self.currentChanged.disconnect()
+        try:
+            self.currentChanged.disconnect()
+        except TypeError:
+            pass
         for tabidx in range(self.count()):
-            self.widget(tabidx).shutdown()
+            tab = self.widget(tabidx)
+            tab.shutdown(callback=functools.partial(self._cb_tab_shutdown,
+                                                    tab))
 
 
 class BrowserTab(QWebView):
@@ -451,12 +464,15 @@ class BrowserTab(QWebView):
     open_tab = pyqtSignal('QUrl')
     linkHovered = pyqtSignal(str, str, str)
     _scroll_pos = (-1, -1)
+    _shutdown_callback = None  # callback to be called after shutdown
     _open_new_tab = False  # open new tab for the next action
+    _destroyed = None  # Dict of all items to be destroyed.
     # dict of tab specific signals, and the values we last got from them.
     signal_cache = None
 
     def __init__(self, parent=None):
         super().__init__(parent)
+        self._destroyed = {}
         self.setPage(BrowserPage())
         self.signal_cache = SignalCache(uncached=['linkHovered'])
         self.loadProgress.connect(self.on_load_progress)
@@ -513,7 +529,7 @@ class BrowserTab(QWebView):
         """
         self.progress = prog
 
-    def shutdown(self):
+    def shutdown(self, callback=None):
         """Shut down the tab cleanly and remove it.
 
         Inspired by [1].
@@ -521,13 +537,37 @@ class BrowserTab(QWebView):
         [1] https://github.com/integricho/path-of-a-pyqter/tree/master/qttut08
 
         """
+        page = self.page()
+        netman = page.networkAccessManager()
+        self._shutdown_callback = callback
+        try:
+            # Avoid loading finished signal when stopping
+            self.loadFinished.disconnect()
+        except TypeError:
+            logging.exception("This should never happen.")
         self.stop()
         self.close()
         self.settings().setAttribute(QWebSettings.JavascriptEnabled, False)
-        self.page().deleteLater()
+
+        self._destroyed[page] = False
+        page.destroyed.connect(functools.partial(self.on_destroyed, page))
+        page.deleteLater()
+
+        self._destroyed[self] = False
+        self.destroyed.connect(functools.partial(self.on_destroyed, self))
         self.deleteLater()
-        self.page().networkAccessManager().abort_requests()
+
-        self.page().networkAccessManager().deleteLater()
+        self._destroyed[netman] = False
+        netman.abort_requests()
+        netman.destroyed.connect(functools.partial(self.on_destroyed, netman))
+        netman.deleteLater()
+
+    def on_destroyed(self, sender):
+        """Called when a subsystem has been destroyed during shutdown."""
+        self._destroyed[sender] = True
+        if all(self._destroyed.values()):
+            if self._shutdown_callback is not None:
+                self._shutdown_callback()
 
     def eventFilter(self, watched, e):
         """Dirty hack to emit a signal if the scroll position changed.