From 5aa8f6193ee23c32da940c483d55e3b5327c966a Mon Sep 17 00:00:00 2001
From: Oskar Hahn <mail@oshahn.de>
Date: Sat, 24 Feb 2018 17:54:59 +0100
Subject: [PATCH] Add methods to delete the restricted_data_cache

---
 openslides/users/models.py     |  1 -
 openslides/utils/autoupdate.py |  2 +-
 openslides/utils/cache.py      | 28 ++++++++++++++++++++++++++++
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/openslides/users/models.py b/openslides/users/models.py
index a28f33719..f9e173f35 100644
--- a/openslides/users/models.py
+++ b/openslides/users/models.py
@@ -1,5 +1,4 @@
 import smtplib
-
 from random import choice
 
 from django.contrib.auth.hashers import make_password
diff --git a/openslides/utils/autoupdate.py b/openslides/utils/autoupdate.py
index 06aaa8b7a..65aed3244 100644
--- a/openslides/utils/autoupdate.py
+++ b/openslides/utils/autoupdate.py
@@ -3,7 +3,7 @@ import threading
 import time
 import warnings
 from collections import OrderedDict, defaultdict
-from typing import Any, Dict, Generator, Iterable, List, Tuple, Union, Optional
+from typing import Any, Dict, Generator, Iterable, List, Optional, Tuple, Union
 
 from channels import Channel, Group
 from channels.asgi import get_channel_layer
diff --git a/openslides/utils/cache.py b/openslides/utils/cache.py
index 1cb16d31f..9e2e6ebc4 100644
--- a/openslides/utils/cache.py
+++ b/openslides/utils/cache.py
@@ -396,6 +396,34 @@ class RestrictedDataCache:
             self.get_cache_key(user_id),
             "{}/{}".format(collection_string, id))
 
+    def del_user(self, user_id: int) -> None:
+        """
+        Removes all elements for one user from the cache.
+        """
+        redis = get_redis_connection()
+        redis.delete(self.get_cache_key(user_id))
+
+    def del_all(self) -> None:
+        """
+        Deletes all elements from the cache.
+
+        This method uses the redis command SCAN. See
+        https://redis.io/commands/scan#scan-guarantees for its limitations. If
+        an element is added to the cache while del_all() is in process, it is
+        possible, that it is not deleted.
+        """
+        redis = get_redis_connection()
+
+        # Get all keys that start with self.base_cache_key and delete them
+        match = cache.make_key('{}:*'.format(self.base_cache_key))
+        cursor = 0
+        while True:
+            cursor, keys = redis.scan(cursor, match)
+            for key in keys:
+                redis.delete(key)
+            if cursor == 0:
+                return
+
     def exists_for_user(self, user_id: int) -> bool:
         """
         Returns True if the cache for the user exists, else False.