diff --git a/tests/util/caches/test_deferred_cache.py b/tests/util/caches/test_deferred_cache.py
index 68d26128c1..dadfabd46d 100644
--- a/tests/util/caches/test_deferred_cache.py
+++ b/tests/util/caches/test_deferred_cache.py
@@ -39,6 +39,101 @@ class DeferredCacheTestCase(TestCase):
self.assertEquals(self.successResultOf(cache.get("foo")), 123)
+ def test_hit_deferred(self):
+ cache = DeferredCache("test")
+ origin_d = defer.Deferred()
+ set_d = cache.set("k1", origin_d)
+
+ # get should return an incomplete deferred
+ get_d = cache.get("k1")
+ self.assertFalse(get_d.called)
+
+ # add a callback that will make sure that the set_d gets called before the get_d
+ def check1(r):
+ self.assertTrue(set_d.called)
+ return r
+
+ # TODO: Actually ObservableDeferred *doesn't* run its tests in order on py3.8.
+ # maybe we should fix that?
+ # get_d.addCallback(check1)
+
+ # now fire off all the deferreds
+ origin_d.callback(99)
+ self.assertEqual(self.successResultOf(origin_d), 99)
+ self.assertEqual(self.successResultOf(set_d), 99)
+ self.assertEqual(self.successResultOf(get_d), 99)
+
+ def test_callbacks(self):
+ """Invalidation callbacks are called at the right time"""
+ cache = DeferredCache("test")
+ callbacks = set()
+
+ # start with an entry, with a callback
+ cache.prefill("k1", 10, callback=lambda: callbacks.add("prefill"))
+
+ # now replace that entry with a pending result
+ origin_d = defer.Deferred()
+ set_d = cache.set("k1", origin_d, callback=lambda: callbacks.add("set"))
+
+ # ... and also make a get request
+ get_d = cache.get("k1", callback=lambda: callbacks.add("get"))
+
+ # we don't expect the invalidation callback for the original value to have
+ # been called yet, even though get() will now return a different result.
+ # I'm not sure if that is by design or not.
+ self.assertEqual(callbacks, set())
+
+ # now fire off all the deferreds
+ origin_d.callback(20)
+ self.assertEqual(self.successResultOf(set_d), 20)
+ self.assertEqual(self.successResultOf(get_d), 20)
+
+ # now the original invalidation callback should have been called, but none of
+ # the others
+ self.assertEqual(callbacks, {"prefill"})
+ callbacks.clear()
+
+ # another update should invalidate both the previous results
+ cache.prefill("k1", 30)
+ self.assertEqual(callbacks, {"set", "get"})
+
+ def test_set_fail(self):
+ cache = DeferredCache("test")
+ callbacks = set()
+
+ # start with an entry, with a callback
+ cache.prefill("k1", 10, callback=lambda: callbacks.add("prefill"))
+
+ # now replace that entry with a pending result
+ origin_d = defer.Deferred()
+ set_d = cache.set("k1", origin_d, callback=lambda: callbacks.add("set"))
+
+ # ... and also make a get request
+ get_d = cache.get("k1", callback=lambda: callbacks.add("get"))
+
+ # none of the callbacks should have been called yet
+ self.assertEqual(callbacks, set())
+
+ # oh noes! fails!
+ e = Exception("oops")
+ origin_d.errback(e)
+ self.assertIs(self.failureResultOf(set_d, Exception).value, e)
+ self.assertIs(self.failureResultOf(get_d, Exception).value, e)
+
+ # the callbacks for the failed requests should have been called.
+ # I'm not sure if this is deliberate or not.
+ self.assertEqual(callbacks, {"get", "set"})
+ callbacks.clear()
+
+ # the old value should still be returned now?
+ get_d2 = cache.get("k1", callback=lambda: callbacks.add("get2"))
+ self.assertEqual(self.successResultOf(get_d2), 10)
+
+ # replacing the value now should run the callbacks for those requests
+ # which got the original result
+ cache.prefill("k1", 30)
+ self.assertEqual(callbacks, {"prefill", "get2"})
+
def test_get_immediate(self):
cache = DeferredCache("test")
d1 = defer.Deferred()
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