optimize cache logic

scrape.py

@@ -125,7 +125,6 @@ async def main():
     # use this event type to store our url cache
     cache_event_type = 'de.lubiland.snowstorm-matrix.cache'
 
-    cache = {}
     while True:
         # do sync first to e.g. accept an admin room invite
         sync = await matrix.sync(timeout=30000, sync_filter=sync_filter)
@@ -137,22 +136,22 @@ async def main():
 
         if next_update < datetime.now():
             # refresh url cache
-            old_cache = cache
             cache = {}
             for category in category_list:
                 cache_state = await matrix.room_get_state_event(room_id=admin_room,
                                                                 event_type=cache_event_type,
                                                                 state_key=category)
+                if not hasattr(cache, category):
+                    cache[category] = []
                 if hasattr(cache_state, 'content') and 'url_list' in cache_state.content:
-                    if not hasattr(cache, category):
-                        cache[category] = []
                     cache[category] += cache_state.content['url_list']
+            old_cache = cache
 
             # scrape all blog posts and process them
             blog = get_blog()
             for post in blog:
                 # check if post url is in cache and matches our category
-                if post['category'] in category_list and hasattr(cache, post['category']) and post['url'] not in cache[post['category']]:
+                if post['category'] in category_list and post['url'] not in cache[post['category']]:
                     # post url not found in cache
                     # announce new post to matrix rooms
                     print('new post: '+post['url'])
@@ -185,7 +184,7 @@ async def main():
                     cache[category].remove(cache[category][0])
 
                 # set new cache event
-                if hasattr(old_cache, 'category') and old_cache[category] != cache[category]:
+                if old_cache[category] != cache[category]:
                     await matrix.room_put_state(room_id=admin_room,
                                                 event_type=cache_event_type,
                                                 state_key=category,