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authorRichard van der Hoff <1389908+richvdh@users.noreply.github.com>2021-11-04 14:45:34 +0000
committerGitHub <noreply@github.com>2021-11-04 14:45:34 +0000
commitf36434590c1baafad4621afc9d2b583e9f89b6bb (patch)
tree09b237e7b8c66a013d76f4178fed78229acdf995 /tests/util
parentTrack ongoing event fetches correctly in the presence of failure (#11240) (diff)
downloadsynapse-f36434590c1baafad4621afc9d2b583e9f89b6bb.tar.xz
Additional test for `cachedList` (#11246)
I was trying to understand how `cachedList` works, and ended up writing this
extra test. I figure we may as well keep it.
Diffstat (limited to 'tests/util')
-rw-r--r--tests/util/caches/test_descriptors.py43
1 files changed, 43 insertions, 0 deletions
diff --git a/tests/util/caches/test_descriptors.py b/tests/util/caches/test_descriptors.py
index 39947a166b..ced3efd93f 100644
--- a/tests/util/caches/test_descriptors.py
+++ b/tests/util/caches/test_descriptors.py
@@ -17,6 +17,7 @@ from typing import Set
 from unittest import mock
 
 from twisted.internet import defer, reactor
+from twisted.internet.defer import Deferred
 
 from synapse.api.errors import SynapseError
 from synapse.logging.context import (
@@ -703,6 +704,48 @@ class CachedListDescriptorTestCase(unittest.TestCase):
             obj.mock.assert_called_once_with((40,), 2)
             self.assertEqual(r, {10: "fish", 40: "gravy"})
 
+    def test_concurrent_lookups(self):
+        """All concurrent lookups should get the same result"""
+
+        class Cls:
+            def __init__(self):
+                self.mock = mock.Mock()
+
+            @descriptors.cached()
+            def fn(self, arg1):
+                pass
+
+            @descriptors.cachedList("fn", "args1")
+            def list_fn(self, args1) -> "Deferred[dict]":
+                return self.mock(args1)
+
+        obj = Cls()
+        deferred_result = Deferred()
+        obj.mock.return_value = deferred_result
+
+        # start off several concurrent lookups of the same key
+        d1 = obj.list_fn([10])
+        d2 = obj.list_fn([10])
+        d3 = obj.list_fn([10])
+
+        # the mock should have been called exactly once
+        obj.mock.assert_called_once_with((10,))
+        obj.mock.reset_mock()
+
+        # ... and none of the calls should yet be complete
+        self.assertFalse(d1.called)
+        self.assertFalse(d2.called)
+        self.assertFalse(d3.called)
+
+        # complete the lookup. @cachedList functions need to complete with a map
+        # of input->result
+        deferred_result.callback({10: "peas"})
+
+        # ... which should give the right result to all the callers
+        self.assertEqual(self.successResultOf(d1), {10: "peas"})
+        self.assertEqual(self.successResultOf(d2), {10: "peas"})
+        self.assertEqual(self.successResultOf(d3), {10: "peas"})
+
     @defer.inlineCallbacks
     def test_invalidate(self):
         """Make sure that invalidation callbacks are called."""