Initial support for long-polling.

fear_tracker/routing.py

@@ -0,0 +1,16 @@
+from channels.http import AsgiHandler
+from channels.routing import ProtocolTypeRouter, URLRouter
+
+from django.conf.urls import url
+
+from . import views
+
+application = ProtocolTypeRouter({
+    "http": URLRouter([
+        url(r'^(?P<access_code>[a-zA-Z]{6})/', URLRouter([
+            url(r"status/(?P<hashcode>[a-z0-9]{64})/",
+                views.StatusLongPollConsumer, name='status'),
+        ])),
+        url(r"", AsgiHandler),
+    ]),
+})

fear_tracker/templates/game.html

@@ -360,7 +360,7 @@
         el.addEventListener("change", formElementChanged);
       }
 
-      setInterval(function() {
+      function checkStatus() {
         if(activeRequests.size != 0) return;
         fetch(new Request("{% url 'status' access_code=access_code %}"
                            + (statusObj.hash != ""
@@ -381,8 +381,13 @@
             } else {
               statusObj = data;
             }
+          })
+          .catch(() => {})
+          .then(() => {
+            checkStatus();
           });
-      }, 5000);
+      }
+      checkStatus();
     });
   </script>
 {% endif %}

fear_tracker/urls.py

@@ -27,7 +27,5 @@ urlpatterns = [
         path('update/', views.update_game, name='update_game'),
         path('qr/', views.qr_code, name='qr_code'),
         path('status/', views.status, name='status'),
-        url('^status/(?P<hashcode>[a-z0-9]{64})/',
-            views.status, name='status'),
-        ])),
+    ])),
 ]

fear_tracker/views.py

@@ -5,6 +5,11 @@ import hashlib
 import json
 import qrcode
 
+from asgiref.sync import async_to_sync
+
+from channels.generic.http import AsyncHttpConsumer
+from channels.layers import get_channel_layer
+
 from django.db import transaction
 from django.http import HttpResponse
 from django.shortcuts import get_object_or_404, redirect, render
@@ -278,6 +283,10 @@ def handle_game_request(request, game, update):
             for player in players.values():
                 player.ready = True
 
+        async_to_sync(get_channel_layer().group_send)(
+                "%s_status" % game.access_code,
+                {"type": "fear_tracker.invalidate_status"})
+
     if update:
         if errors:
             res = {
@@ -325,3 +334,33 @@ def status(request, game, hashcode=None):
     else:
         status_string = json.dumps(status_obj)
         return HttpResponse(status_string)
+
+
+class StatusLongPollConsumer(AsyncHttpConsumer):
+    async def handle(self, body):
+        self.access_code = self.scope["url_route"]["kwargs"]["access_code"]
+        self.hashcode = self.scope["url_route"]["kwargs"]["hashcode"]
+
+        await self.channel_layer.group_add("%s_status" % self.access_code,
+                                           self.channel_name)
+
+    async def http_request(self, message):
+        """
+        Async entrypoint - concatenates body fragments and hands off control
+        to ``self.handle`` when the body has been completely received.
+        """
+        if "body" in message:
+            self.body.append(message["body"])
+        if not message.get("more_body"):
+            await self.handle(b"".join(self.body))
+
+    async def disconnect(self):
+        await self.channel_layer.group_discard("%s_status" % self.access_code,
+                                               self.channel_name)
+
+    async def fear_tracker_invalidate_status(self, event):
+        no_hash_status = reverse('status',
+                                 kwargs={'access_code': self.access_code})
+        await self.send_response(302, b'', headers=[
+            (b"Location", no_hash_status.encode('utf-8'))
+        ])

fear_tracker_site/routing.py

@@ -1,4 +1,3 @@
-from channels.routing import ProtocolTypeRouter
+import fear_tracker.routing
 
-# No async routing currently; just default sync http.
-application = ProtocolTypeRouter({})
+application = fear_tracker.routing.application

fear_tracker_site/settings.py

@@ -31,6 +31,7 @@ ALLOWED_HOSTS = []
 # Application definition
 
 INSTALLED_APPS = [
+    'channels',
     'fear_tracker',
     'django.contrib.admin',
     'django.contrib.auth',
@@ -82,6 +83,12 @@ DATABASES = {
     }
 }
 
+CHANNEL_LAYERS = {
+    "default": {
+        "BACKEND": "channels.layers.InMemoryChannelLayer"
+    }
+}
+
 
 # Password validation
 # https://docs.djangoproject.com/en/2.2/ref/settings/#auth-password-validators