remove old cache

src/cache.py

@@ -13,6 +13,33 @@
 
 CACHE_TIME_SECONDS = 120
 cache_time_seconds = int(os.getenv("CACHE_TIME_SECONDS", CACHE_TIME_SECONDS))
+DELETE_CACHE_TIME_SECONDS = 240
+delete_cache_time_seconds = int(os.getenv("DELETE_CACHE_TIME_SECONDS", DELETE_CACHE_TIME_SECONDS))
+
+
+def remove_old_cache(
+    last_updated: dict, response: dict, remove_cache_time_seconds: float = delete_cache_time_seconds
+):
+    """
+    Remove old cache entries from the cache
+
+    :param last_updated: dict of last updated times
+    :param response: dict of responses, same keys as last_updated
+    :param remove_cache_time_seconds: the amount of time, after which the cache should be removed
+    """
+    now = datetime.now(tz=timezone.utc)
+    logger.info("Removing old cache entries")
+    keys_to_remove = []
+    for key, value in last_updated.items():
+        if now - timedelta(seconds=remove_cache_time_seconds) > value:
+            logger.debug(f"Removing {key} from cache, ({value})")
+            keys_to_remove.append(key)
+
+    for key in keys_to_remove:
+        last_updated.pop(key)
+        response.pop(key)
+
+    return last_updated, response
 
 
 def cache_response(func):
@@ -47,11 +74,16 @@ def wrapper(*args, **kwargs):  # noqa
         request = route_variables.get("request", None)
         save_api_call_to_db(session=session, user=user, request=request)
 
+        if 'background_tasks' in route_variables:
+            route_variables['background_tasks'].add_task(cache_response, last_updated)
+
         # drop session and user
         for var in ["session", "user", "request"]:
             if var in route_variables:
                 route_variables.pop(var)
 
+        last_updated, response = remove_old_cache(last_updated, response)
+
         # make route_variables into a string
         route_variables = json.dumps(route_variables)