fix #1720 -- don't wait for the daemon eventhread to terminate but count on it to eventually die

python/src/deltachat/account.py

@@ -609,10 +609,14 @@ class Account(object):
         self.log("remove dc_context references")
         # the dc_context_unref triggers get_next_event to return ffi.NULL
         # which in turns makes the event thread finish execution
+        self._event_thread.mark_shutdown()
         self._dc_context = None
 
-        self.log("wait for event thread to finish")
-        self._event_thread.wait()
+        # the following wait is left out for now because it can fail if
+        # a) python code holds an extra self._dc_context reference
+        # b) the core does not manage to send a NULL through get_next_event()
+        # self.log("wait for event thread to finish")
+        # self._event_thread.wait()
 
         self._shutdown_event.set()
 

python/src/deltachat/direct_imap.py

@@ -162,6 +162,10 @@ class DirectImap:
             requested = [b'BODY.PEEK[HEADER]', FLAGS]
             for uid, data in self.conn.fetch(messages, requested).items():
                 body_bytes = data[b'BODY[HEADER]']
+                if not body_bytes:
+                    log("Message", uid, "has empty body")
+                    continue
+
                 flags = data[FLAGS]
                 path = pathlib.Path(str(dir)).joinpath("IMAP", self.logid, imapfolder)
                 path.mkdir(parents=True, exist_ok=True)

python/src/deltachat/events.py

@@ -139,6 +139,7 @@ class EventThread(threading.Thread):
         self.account = account
         super(EventThread, self).__init__(name="events")
         self.setDaemon(True)
+        self._marked_for_shutdown = False
         self.start()
 
     @contextmanager
@@ -147,6 +148,9 @@ class EventThread(threading.Thread):
         yield
         self.account.log(message + " FINISHED")
 
+    def mark_shutdown(self):
+        self._marked_for_shutdown = True
+
     def wait(self):
         if self == threading.current_thread():
             # we are in the callback thread and thus cannot
@@ -164,10 +168,12 @@ class EventThread(threading.Thread):
             lib.dc_get_event_emitter(self.account._dc_context),
             lib.dc_event_emitter_unref,
         )
-        while 1:
+        while not self._marked_for_shutdown:
             event = lib.dc_get_next_event(event_emitter)
             if event == ffi.NULL:
                 break
+            if self._marked_for_shutdown:
+                break
             evt = lib.dc_event_get_id(event)
             data1 = lib.dc_event_get_data1_int(event)
             # the following code relates to the deltachat/_build.py's helper