fix: Make cachetools caches thread-safe (#155)

Author: sveneberth

src/viur/shop/modules/discount.py

@@ -1,4 +1,5 @@
 import io
+import threading
 import typing as t  # noqa
 
 import cachetools
@@ -15,6 +16,9 @@
 
 logger = SHOP_LOGGER.getChild(__name__)
 
+lock_current_automatically_discounts = threading.Lock()
+"""Lock to make the current_automatically_discounts cache thread-safe"""
+
 
 class Discount(ShopModuleAbstract, List):
     moduleName = "discount"
@@ -236,7 +240,7 @@ def can_apply(
         return dv.is_fulfilled, dv
 
     @property
-    @cachetools.cached(cache=cachetools.TTLCache(maxsize=1024, ttl=3600))
+    @cachetools.cached(cache=cachetools.TTLCache(maxsize=1024, ttl=3600), lock=lock_current_automatically_discounts)
     def current_automatically_discounts(self) -> list[SkeletonInstance_T[DiscountSkel]]:
         query = self.viewSkel().all().filter("activate_automatically =", True)
         discounts = []

src/viur/shop/modules/discount_condition.py

@@ -1,5 +1,6 @@
 import random
 import string
+import threading
 import typing as t
 
 import cachetools
@@ -22,6 +23,9 @@
 CODE_LENGTH = 8
 SUFFIX_LENGTH = 6
 
+lock_get_skel = threading.Lock()
+"""Lock to make the get_skel cache thread-safe"""
+
 
 class DiscountCondition(ShopModuleAbstract, List):
     moduleName = "discount_condition"
@@ -158,7 +162,7 @@ def generate_subcodes(self, parent_key: db.Key, prefix: str, amount: int):
     # --- Helpers  ------------------------------------------------------------
 
     @classmethod
-    @cachetools.cached(cache=cachetools.TTLCache(maxsize=1024, ttl=3600))
+    @cachetools.cached(cache=cachetools.TTLCache(maxsize=1024, ttl=3600), lock=lock_get_skel)
     def get_skel(cls, key: db.Key) -> SkeletonInstance_T["DiscountConditionSkel"] | None:
         # logger.debug(f"get_skel({key=})")
         skel = SHOP_INSTANCE.get().discount_condition.viewSkel()