Generalized EventRelatedCache to ObjectRelatedCache

src/pretix/base/cache.py

@@ -2,29 +2,14 @@ import hashlib
 import time
 
 from django.core.cache import caches
-
-from pretix.base.models import Event
+from django.db.models import Model
 
 
-class EventRelatedCache:
-    """
-    This object behaves exactly like the cache implementations by Django
-    but with one important difference: It stores all keys related to a
-    certain event, so you pass an event when creating this object and if
-    you store data in this cache, it is only stored for this event. The
-    main purpose of this is to be able to flush all cached data related
-    to this event at once.
+class NamespacedCache:
 
-    The EventRelatedCache instance itself is stateless, all state is
-    stored in the cache backend, so you can instantiate this class as many
-    times as you want.
-    """
-
-    def __init__(self, event: Event, cache: str='default'):
-        assert isinstance(event, Event)
+    def __init__(self, prefixkey, cache: str='default'):
         self.cache = caches[cache]
-        self.event = event
-        self.prefixkey = 'event:%s' % self.event.pk
+        self.prefixkey = prefixkey
 
     def _prefix_key(self, original_key: str) -> str:
         # Race conditions can happen here, but should be very very rare.
@@ -36,15 +21,14 @@ class EventRelatedCache:
         if prefix is None:
             prefix = int(time.time())
             self.cache.set(self.prefixkey, prefix)
-        key = 'event:%s:%d:%s' % (self.event.pk, prefix, original_key)
+        key = '%s:%d:%s' % (self.prefixkey, prefix, original_key)
         if len(key) > 200:  # Hash long keys, as memcached has a length limit
             # TODO: Use a more efficient, non-cryptographic hash algorithm
             key = hashlib.sha256(key.encode("UTF-8")).hexdigest()
         return key
 
-    @staticmethod
-    def _strip_prefix(key: str) -> str:
-        return key.split(":", 3)[-1] if 'event:' in key else key
+    def _strip_prefix(self, key: str) -> str:
+        return key.split(":", 2 + self.prefixkey.count(":"))[-1]
 
     def clear(self):
         try:
@@ -86,3 +70,22 @@ class EventRelatedCache:
 
     def close(self):  # NOQA
         pass
+
+
+class ObjectRelatedCache(NamespacedCache):
+    """
+    This object behaves exactly like the cache implementations by Django
+    but with one important difference: It stores all keys related to a
+    certain object, so you pass an object when creating this object and if
+    you store data in this cache, it is only stored for this object. The
+    main purpose of this is to be able to flush all cached data related
+    to this object at once.
+
+    The ObjectRelatedCache instance itself is stateless, all state is
+    stored in the cache backend, so you can instantiate this class as many
+    times as you want.
+    """
+
+    def __init__(self, obj, cache: str='default'):
+        assert isinstance(obj, Model)
+        super().__init__('%s:%s' % (obj._meta.object_name, obj.pk), cache)

src/pretix/base/models.py

@@ -260,6 +260,11 @@ class Organizer(Versionable):
     def __str__(self):
         return self.name
 
+    def save(self, *args, **kwargs):
+        obj = super().save(*args, **kwargs)
+        self.get_cache().clear()
+        return obj
+
     @cached_property
     def settings(self) -> SettingsProxy:
         """
@@ -267,6 +272,17 @@ class Organizer(Versionable):
         """
         return SettingsProxy(self, type=OrganizerSetting)
 
+    def get_cache(self) -> "pretix.base.cache.ObjectRelatedCache":
+        """
+        Returns an :py:class:`ObjectRelatedCache` object. This behaves equivalent to
+        Django's built-in cache backends, but puts you into an isolated environment for
+        this organizer, so you don't have to prefix your cache keys. In addition, the cache
+        is being cleared every time the organizer changes.
+        """
+        from pretix.base.cache import ObjectRelatedCache
+
+        return ObjectRelatedCache(self)
+
 
 class OrganizerPermission(Versionable):
     """
@@ -414,16 +430,16 @@ class Event(Versionable):
             "DATETIME_FORMAT" if self.settings.show_times else "DATE_FORMAT"
         )
 
-    def get_cache(self) -> "pretix.base.cache.EventRelatedCache":
+    def get_cache(self) -> "pretix.base.cache.ObjectRelatedCache":
         """
-        Returns an :py:class:`EventRelatedCache` object. This behaves equivalent to
+        Returns an :py:class:`ObjectRelatedCache` object. This behaves equivalent to
         Django's built-in cache backends, but puts you into an isolated environment for
         this event, so you don't have to prefix your cache keys. In addition, the cache
         is being cleared every time the event or one of its related objects change.
         """
-        from pretix.base.cache import EventRelatedCache
+        from pretix.base.cache import ObjectRelatedCache
 
-        return EventRelatedCache(self)
+        return ObjectRelatedCache(self)
 
     @cached_property
     def settings(self) -> SettingsProxy: