Look up client descriptors by handler_id.

Previously, client descriptors were referenced directly from the
handler object.  Once we split the Tornado process into separate queue
and connection servers, these will no longer be in the same process,
so we need to reference them by ID instead.

zerver/lib/event_queue.py

@@ -148,8 +148,7 @@ class ClientDescriptor(object):
 
     def connect_handler(self, handler_id):
         self.current_handler_id = handler_id
-        handler = get_handler_by_id(self.current_handler_id)
-        handler.client_descriptor = self
+        set_descriptor_by_handler_id(handler_id, self)
         self.last_connection_time = time.time()
         def timeout_callback():
             self._timeout_handle = None
@@ -164,7 +163,7 @@ class ClientDescriptor(object):
         if self.current_handler_id:
             handler = get_handler_by_id(self.current_handler_id)
             request = handler._request
-            handler.client_descriptor = None
+            delete_descriptor_by_handler_id(self.current_handler_id, None)
             if client_closed:
                 logging.info("Client disconnected for queue %s (%s via %s)" %
                              (self.event_queue.id, self.user_profile_email,
@@ -179,6 +178,17 @@ class ClientDescriptor(object):
         do_gc_event_queues([self.event_queue.id], [self.user_profile_id],
                            [self.realm_id])
 
+descriptors_by_handler_id = {}
+
+def get_descriptor_by_handler_id(handler_id):
+    return descriptors_by_handler_id.get(handler_id)
+
+def set_descriptor_by_handler_id(handler_id, client_descriptor):
+    descriptors_by_handler_id[handler_id] = client_descriptor
+
+def delete_descriptor_by_handler_id(handler_id, client_descriptor):
+    del descriptors_by_handler_id[handler_id]
+
 def compute_full_event_type(event):
     if event["type"] == "update_message_flags":
         if event["all"]:

zerver/management/commands/runtornado.py

@@ -21,7 +21,8 @@ from tornado import ioloop
 from zerver.lib.debug import interactive_debug_listen
 from zerver.lib.response import json_response
 from zerver.lib.event_queue import process_notification, missedmessage_hook
-from zerver.lib.event_queue import setup_event_queue, add_client_gc_hook
+from zerver.lib.event_queue import setup_event_queue, add_client_gc_hook, \
+    get_descriptor_by_handler_id
 from zerver.lib.handlers import allocate_handler_id
 from zerver.lib.queue import setup_tornado_rabbitmq
 from zerver.lib.socket import get_sockjs_router, respond_send_message
@@ -187,8 +188,9 @@ class AsyncDjangoHandler(tornado.web.RequestHandler, base.BaseHandler):
         self.get()
 
     def on_connection_close(self):
-        if self.client_descriptor is not None:
-            self.client_descriptor.disconnect_handler(client_closed=True)
+        client_descriptor = get_descriptor_by_handler_id(self.handler_id)
+        if client_descriptor is not None:
+            client_descriptor.disconnect_handler(client_closed=True)
 
     # Based on django.core.handlers.base: get_response
     def get_response(self, request):