Use cache.pop() instead of a separate membership test + del []

synapse/storage/_base.py

@@ -75,8 +75,7 @@ def cached(max_entries=1000):
             defer.returnValue(ret)
 
         def invalidate(key):
-            if key in cache:
-                del cache[key]
+            cache.pop(key, None)
 
         wrapped.invalidate = invalidate
         wrapped.prefill = prefill

tests/storage/test__base.py

@@ -66,6 +66,13 @@ class CacheDecoratorTestCase(unittest.TestCase):
 
         self.assertEquals(callcount[0], 2)
 
+    def test_invalidate_missing(self):
+        @cached()
+        def func(self, key):
+            return key
+
+        func.invalidate("what")
+
     @defer.inlineCallbacks
     def test_max_entries(self):
         callcount = [0]