webchat: use class instead of global variables

examples/webchat/chat/views.py

@@ -6,50 +6,56 @@ from django.http import HttpResponse
 from gevent.event import Event
 from webchat import settings
 
-messages = []
-MESSAGES_SIZE = 200
-new_message_event = Event()
 
-
-def new_message(from_, body):
+class ChatRoom(object):
+    cache_size = 200
+
+    def __init__(self):
+        self.cache = []
+        self.new_message_event = Event()
+
+    def main(self, request):
+        if self.cache:
+            request.session['cursor'] = self.cache[-1]['id']
+        return render_to_response('index.html', {'MEDIA_URL': settings.MEDIA_URL, 'messages': self.cache})
+
+    def message_new(self, request):
+        name = request.META.get('REMOTE_ADDR') or 'Anonymous'
+        msg = create_message(name, request.POST['body'])
+        self.cache.append(msg)
+        if len(self.cache) > self.cache_size:
+            self.cache = self.cache[-self.cache_size:]
+        self.new_message_event.set()
+        self.new_message_event.clear()
+        return json_response(msg)
+
+    def message_updates(self, request):
+        cursor = request.session.get('cursor')
+        if not self.cache or cursor == self.cache[-1]['id']:
+            self.new_message_event.wait()
+        assert cursor != self.cache[-1]['id'], cursor
+        try:
+            for index, m in enumerate(self.cache):
+                if m['id'] == cursor:
+                    return json_response({'messages': self.cache[index+1:]})
+            return json_response({'messages': self.cache})
+        finally:
+            if self.cache:
+                request.session['cursor'] = self.cache[-1]['id']
+            else:
+                request.session.pop('cursor', None)
+
+room = ChatRoom()
+main = room.main
+message_new = room.message_new
+message_updates = room.message_updates
+
+
+def create_message(from_, body):
     data = {'id': str(uuid.uuid4()), 'from': from_, 'body': body}
     data['html'] = render_to_string('message.html', dictionary={'message': data})
     return data
 
-def last_message_id():
-    if messages:
-        return messages[-1]['id']
-
-def main(request):
-    if messages:
-        request.session['cursor'] = messages[-1]['id']
-    return render_to_response('index.html', {'MEDIA_URL': settings.MEDIA_URL, 'messages': messages})
-
-def message_new(request):
-    name = request.META.get('REMOTE_ADDR') or 'Anonymous'
-    msg = new_message(name, request.POST['body'])
-    messages.append(msg)
-    if len(messages) > MESSAGES_SIZE:
-        del messages[0]
-    new_message_event.set()
-    new_message_event.clear()
-    return json_response(msg)
-
-def message_updates(request):
-    cursor = request.session.get('cursor')
-    if cursor == last_message_id():
-        new_message_event.wait()
-    assert cursor != last_message_id(), cursor
-    try:
-        for index, m in enumerate(messages):
-            if m['id'] == cursor:
-                return json_response({'messages': messages[index+1:]})
-        return json_response({'messages': messages})
-    finally:
-        if messages:
-            request.session['cursor'] = messages[-1]['id']
-        else:
-            request.session.pop('cursor', None)
 
 def json_response(value, **kwargs):
     kwargs.setdefault('content_type', 'text/javascript; charset=UTF-8')