Return a special value to initiate longpolling

Fixes #261.

(imported from commit dd0312c3574c9ca924ab76edcb2fb6c03085be32)

zephyr/decorator.py

@@ -8,17 +8,18 @@ from django.conf import settings
 
 from functools import wraps
 
-import types
+class _RespondAsynchronously(object):
+    pass
 
-class TornadoAsyncException(Exception): pass
+# Return RespondAsynchronously from an @asynchronous view if the
+# response will be provided later by calling handler.finish(), or has
+# already been provided this way. We use this for longpolling mode.
+RespondAsynchronously = _RespondAsynchronously()
 
 def asynchronous(method):
     @wraps(method)
     def wrapper(request, *args, **kwargs):
-        v = method(request, handler=request._tornado_handler, *args, **kwargs)
-        if v == None or type(v) == types.GeneratorType:
-            raise TornadoAsyncException
-        return v
+        return method(request, handler=request._tornado_handler, *args, **kwargs)
     if getattr(method, 'csrf_exempt', False):
         wrapper.csrf_exempt = True
     return wrapper

zephyr/management/commands/runtornado.py

@@ -190,13 +190,12 @@ class AsyncDjangoHandler(tornado.web.RequestHandler, base.BaseHandler):
                             break
 
                 if response is None:
-                    from ...decorator import TornadoAsyncException
+                    from ...decorator import RespondAsynchronously
 
                     try:
                         response = callback(request, *callback_args, **callback_kwargs)
-                    except TornadoAsyncException, e:
-                        # TODO: Maybe add debugging output here
-                        return
+                        if response is RespondAsynchronously:
+                            return
                     except Exception, e:
                         # If the view raised an exception, run it through exception
                         # middleware, and if the exception middleware returns a

zephyr/tests.py

@@ -7,7 +7,7 @@ from django.db.models import Q
 from zephyr.models import Message, UserProfile, Stream, Recipient, Subscription, \
     filter_by_subscriptions, Realm, do_send_message, Client
 from zephyr.views import json_get_updates, api_get_messages
-from zephyr.decorator import TornadoAsyncException
+from zephyr.decorator import RespondAsynchronously
 from zephyr.lib.initial_password import initial_password, initial_api_key
 
 import simplejson
@@ -457,10 +457,7 @@ class GetUpdatesTest(AuthedTestCase):
         post_data = {"last": str(1), "first": str(1)}
         post_data.update(extra_post_data)
         request = POSTRequestMock(post_data, user, callback)
-        # json_get_updates returns None, which raises an exception in the
-        # @asynchronous decorator, which raises a TornadoAsyncException. So this
-        # is expected, but should probably change.
-        self.assertRaises(TornadoAsyncException, view_func, request)
+        self.assertEquals(view_func(request), RespondAsynchronously)
 
     def test_json_get_updates(self):
         """
@@ -497,7 +494,7 @@ class GetUpdatesTest(AuthedTestCase):
             messages.extend(data)
 
         request = POSTRequestMock({"last": str(last_received), "first": "1"}, user, callback)
-        self.assertRaises(TornadoAsyncException, json_get_updates, request)
+        self.assertEquals(json_get_updates(request), RespondAsynchronously)
         self.assertEquals(len(messages), 0)
 
     def test_missing_last_received(self):
@@ -514,7 +511,7 @@ class GetUpdatesTest(AuthedTestCase):
                 self.assertTrue(message.id > 1)
 
         request = POSTRequestMock({}, user, callback)
-        self.assertRaises(TornadoAsyncException, json_get_updates, request)
+        self.assertEquals(json_get_updates(request), RespondAsynchronously)
 
 class Runner(DjangoTestSuiteRunner):
     option_list = (

zephyr/views.py

@@ -22,7 +22,7 @@ from django.views.decorators.csrf import csrf_exempt
 
 from zephyr.decorator import asynchronous, require_post, \
     authenticated_api_view, authenticated_json_view, \
-    internal_notify_view, \
+    internal_notify_view, RespondAsynchronously, \
     has_request_variables, POST
 from zephyr.lib.query import last_n
 from zephyr.lib.avatar import gravatar_hash
@@ -447,7 +447,12 @@ def get_updates_backend(request, user_profile, handler, client_id,
                                        dont_block, **kwargs)
     if resp is not None:
         send_with_safety_check(resp, handler, **kwargs)
-        return
+
+        # We have already invoked handler.finish(), so we bypass the usual view
+        # response path.  We are "responding asynchronously" except that it
+        # already happened.  This is slightly weird, but lets us share
+        # send_with_safety_check with the code below.
+        return RespondAsynchronously
 
     # Enter long-polling mode.
     #
@@ -472,6 +477,9 @@ def get_updates_backend(request, user_profile, handler, client_id,
     user_profile.add_receive_callback(handler.async_callback(cb))
     user_profile.add_pointer_update_callback(handler.async_callback(cb))
 
+    # runtornado recognizes this special return value.
+    return RespondAsynchronously
+
 def generate_client_id():
     return base64.b16encode(os.urandom(16)).lower()