From be1498768f54eb6f36781894a22a9aad6e51b90f Mon Sep 17 00:00:00 2001
From: Andrew Godwin <andrew@aeracode.org>
Date: Sun, 14 Feb 2016 19:22:46 +0000
Subject: [PATCH] HTTP Long Poll finishing off

---
 channels/handler.py | 39 +++++++++++++++++++++++++++++++--------
 channels/worker.py  |  1 -
 docs/asgi.rst       | 15 +++++++++++++++
 3 files changed, 46 insertions(+), 9 deletions(-)

diff --git a/channels/handler.py b/channels/handler.py
index 85cacf1..9cb5036 100644
--- a/channels/handler.py
+++ b/channels/handler.py
@@ -23,10 +23,13 @@ class AsgiRequest(http.HttpRequest):
     dict, and wraps request body handling.
     """
 
-    # Exception that will cause any handler to skip around response
-    # transmission and presume something else will do it later.
     class ResponseLater(Exception):
-        pass
+        """
+        Exception that will cause any handler to skip around response
+        transmission and presume something else will do it later.
+        """
+        def __init__(self):
+            Exception.__init__(self, "Response later")
 
     def __init__(self, message):
         self.message = message
@@ -171,17 +174,37 @@ class AsgiHandler(base.BaseHandler):
                 }
             )
             response = http.HttpResponseBadRequest()
-        except AsgiRequest.ResponseLater:
-            # The view has promised something else
-            # will send a response at a later time
-            return
         else:
-            response = self.get_response(request)
+            try:
+                response = self.get_response(request)
+            except AsgiRequest.ResponseLater:
+                # The view has promised something else
+                # will send a response at a later time
+                return
         # Transform response into messages, which we yield back to caller
         for message in self.encode_response(response):
             # TODO: file_to_stream
             yield message
 
+    def process_exception_by_middleware(self, exception, request):
+        """
+        Catches ResponseLater and re-raises it, else tries to delegate
+        to middleware exception handling.
+        """
+        if isinstance(exception, AsgiRequest.ResponseLater):
+            raise
+        else:
+            return super(AsgiHandler, self).process_exception_by_middleware(exception, request)
+
+    def handle_uncaught_exception(self, request, resolver, exc_info):
+        """
+        Propagates ResponseLater up into the higher handler method,
+        processes everything else
+        """
+        if issubclass(exc_info[0], AsgiRequest.ResponseLater):
+            raise
+        return super(AsgiHandler, self).handle_uncaught_exception(request, resolver, exc_info)
+
     @classmethod
     def encode_response(cls, response):
         """
diff --git a/channels/worker.py b/channels/worker.py
index c9567dd..8e61d80 100644
--- a/channels/worker.py
+++ b/channels/worker.py
@@ -25,7 +25,6 @@ class Worker(object):
         """
         channels = self.channel_layer.registry.all_channel_names()
         while True:
-            logger.debug("Worker waiting for message")
             channel, content = self.channel_layer.receive_many(channels, block=True)
             logger.debug("Worker got message on %s: repl %s", channel, content.get("reply_channel", "none"))
             # If no message, stall a little to avoid busy-looping then continue
diff --git a/docs/asgi.rst b/docs/asgi.rst
index 019f7a3..fa92e31 100644
--- a/docs/asgi.rst
+++ b/docs/asgi.rst
@@ -565,6 +565,21 @@ Keys:
   server-pushed requests, and applications should not create reply channels.
 
 
+Disconnect
+''''''''''
+
+Sent when a HTTP connection is closed. This is mainly useful for long-polling,
+where you may have added the response channel to a Group or other set of
+channels you want to trigger a reply to when data arrives.
+
+Channel: ``http.disconnect``
+
+Keys:
+
+* ``reply_channel``: Channel name responses would have been sent on. No longer
+  valid after this message is sent; all messages to it will be dropped.
+
+
 WebSocket
 ---------