Add client_gratavar support to GET /messages.

Clients fetching messages can now specify that they are able
to compute their avatar, and if they set client_gratavar to
True in the request (w/our normal encoding scheme), then the
backend will not compute it, and the payload will be smaller.

The fix starts with get_messages_backend.  The flag gets
passed down through these functions:

    * MessageDict.post_process_dicts.
    * MessageDict.set_sender_avatar.

We also fix up the callers for post_process_dicts to explicitly
pass in the client_gravatar path, but for now they all just hard
code the value to False.

zerver/lib/message.py

@@ -78,7 +78,17 @@ def message_to_dict(message, apply_markdown):
     # type: (Message, bool) -> Dict[str, Any]
     json = message_to_dict_json(message, apply_markdown)
     obj = extract_message_dict(json)
-    MessageDict.post_process_dicts([obj])
+
+    '''
+    In this codepath we do net yet optimize for clients
+    that can compute their own gravatar URLs.
+    '''
+    client_gravatar = False
+
+    MessageDict.post_process_dicts(
+        [obj],
+        client_gravatar=client_gravatar,
+    )
     return obj
 
 @cache_with_key(to_dict_cache_key, timeout=3600*24)
@@ -88,13 +98,13 @@ def message_to_dict_json(message, apply_markdown):
 
 class MessageDict(object):
     @staticmethod
-    def post_process_dicts(objs):
-        # type: (List[Dict[str, Any]]) -> None
+    def post_process_dicts(objs, client_gravatar):
+        # type: (List[Dict[str, Any]], bool) -> None
         MessageDict.bulk_hydrate_sender_info(objs)
 
         for obj in objs:
             MessageDict.hydrate_recipient_info(obj)
-            MessageDict.set_sender_avatar(obj)
+            MessageDict.set_sender_avatar(obj, client_gravatar)
 
             del obj['sender_realm_id']
             del obj['sender_avatar_source']
@@ -366,17 +376,14 @@ class MessageDict(object):
             obj['stream_id'] = recipient_type_id
 
     @staticmethod
-    def set_sender_avatar(obj):
-        # type: (Dict[str, Any]) -> None
+    def set_sender_avatar(obj, client_gravatar):
+        # type: (Dict[str, Any], bool) -> None
         sender_id = obj['sender_id']
         sender_realm_id = obj['sender_realm_id']
         sender_email = obj['sender_email']
         sender_avatar_source = obj['sender_avatar_source']
         sender_avatar_version = obj['sender_avatar_version']
 
-        # TODO: Make client_gravatar configurable.
-        client_gravatar = False
-
         obj['avatar_url'] = get_avatar_field(
             user_id=sender_id,
             realm_id=sender_realm_id,

zerver/tests/test_messages.py

@@ -576,7 +576,7 @@ class StreamMessagesTest(ZulipTestCase):
         message = most_recent_message(user_profile)
         row = MessageDict.get_raw_db_rows([message.id])[0]
         dct = MessageDict.build_dict_from_raw_db_row(row, apply_markdown=True)
-        MessageDict.post_process_dicts([dct])
+        MessageDict.post_process_dicts([dct], client_gravatar=False)
         self.assertEqual(dct['display_recipient'], 'Denmark')
 
         stream = get_stream('Denmark', user_profile.realm)
@@ -699,7 +699,7 @@ class MessageDictTest(ZulipTestCase):
                 MessageDict.build_dict_from_raw_db_row(row, False)
                 for row in rows
             ]
-            MessageDict.post_process_dicts(objs)
+            MessageDict.post_process_dicts(objs, client_gravatar=False)
 
         delay = time.time() - t
         # Make sure we don't take longer than 1.5ms per message to
@@ -1268,7 +1268,7 @@ class EditMessageTest(ZulipTestCase):
         msg = Message.objects.get(id=msg_id)
         cached = message_to_dict(msg, False)
         uncached = MessageDict.to_dict_uncached_helper(msg, False)
-        MessageDict.post_process_dicts([uncached])
+        MessageDict.post_process_dicts([uncached], client_gravatar=False)
         self.assertEqual(cached, uncached)
         if subject:
             self.assertEqual(msg.topic_name(), subject)

zerver/tests/test_narrow.py

@@ -518,6 +518,24 @@ class GetOldMessagesTest(ZulipTestCase):
 
         self.get_and_check_messages(dict(narrow=ujson.dumps([dict(operator='pm-with', operand=self.example_email("othello"))])))
 
+    def test_client_avatar(self):
+        # type: () -> None
+        """
+        The client_gravatar flag determines whether we send avatar_url.
+        """
+        hamlet = self.example_user('hamlet')
+        self.login(hamlet.email)
+
+        self.send_message(hamlet.email, self.example_email("iago"), Recipient.PERSONAL)
+
+        result = self.get_and_check_messages({})
+        message = result['messages'][0]
+        self.assertIn('gravatar.com', message['avatar_url'])
+
+        result = self.get_and_check_messages(dict(client_gravatar=ujson.dumps(True)))
+        message = result['messages'][0]
+        self.assertEqual(message['avatar_url'], None)
+
     def test_get_messages_with_narrow_pm_with(self):
         # type: () -> None
         """

zerver/views/messages.py

@@ -563,9 +563,11 @@ def get_messages_backend(request, user_profile,
                          num_after = REQ(converter=to_non_negative_int),
                          narrow = REQ('narrow', converter=narrow_parameter, default=None),
                          use_first_unread_anchor = REQ(default=False, converter=ujson.loads),
+                         client_gravatar=REQ(default=False,
+                                             converter=ujson.loads),
                          apply_markdown=REQ(default=True,
                                             converter=ujson.loads)):
-    # type: (HttpRequest, UserProfile, int, int, int, Optional[List[Dict[str, Any]]], bool, bool) -> HttpResponse
+    # type: (HttpRequest, UserProfile, int, int, int, Optional[List[Dict[str, Any]]], bool, bool, bool) -> HttpResponse
     include_history = ok_to_include_history(narrow, user_profile.realm)
 
     if include_history and not use_first_unread_anchor:
@@ -760,7 +762,7 @@ def get_messages_backend(request, user_profile,
             del msg_dict["edit_history"]
         message_list.append(msg_dict)
 
-    MessageDict.post_process_dicts(message_list)
+    MessageDict.post_process_dicts(message_list, client_gravatar)
 
     statsd.incr('loaded_old_messages', len(message_list))
     ret = {'messages': message_list,