Add 'failure_ts' column to 'destinations' table (#6016)

Track the time that a server started failing at, for general analysis purposes.

tests/util/test_retryutils.py

@@ -0,0 +1,127 @@
+# -*- coding: utf-8 -*-
+# Copyright 2019 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from synapse.util.retryutils import (
+    MIN_RETRY_INTERVAL,
+    RETRY_MULTIPLIER,
+    NotRetryingDestination,
+    get_retry_limiter,
+)
+
+from tests.unittest import HomeserverTestCase
+
+
+class RetryLimiterTestCase(HomeserverTestCase):
+    def test_new_destination(self):
+        """A happy-path case with a new destination and a successful operation"""
+        store = self.hs.get_datastore()
+        d = get_retry_limiter("test_dest", self.clock, store)
+        self.pump()
+        limiter = self.successResultOf(d)
+
+        # advance the clock a bit before making the request
+        self.pump(1)
+
+        with limiter:
+            pass
+
+        d = store.get_destination_retry_timings("test_dest")
+        self.pump()
+        new_timings = self.successResultOf(d)
+        self.assertIsNone(new_timings)
+
+    def test_limiter(self):
+        """General test case which walks through the process of a failing request"""
+        store = self.hs.get_datastore()
+
+        d = get_retry_limiter("test_dest", self.clock, store)
+        self.pump()
+        limiter = self.successResultOf(d)
+
+        self.pump(1)
+        try:
+            with limiter:
+                self.pump(1)
+                failure_ts = self.clock.time_msec()
+                raise AssertionError("argh")
+        except AssertionError:
+            pass
+
+        # wait for the update to land
+        self.pump()
+
+        d = store.get_destination_retry_timings("test_dest")
+        self.pump()
+        new_timings = self.successResultOf(d)
+        self.assertEqual(new_timings["failure_ts"], failure_ts)
+        self.assertEqual(new_timings["retry_last_ts"], failure_ts)
+        self.assertEqual(new_timings["retry_interval"], MIN_RETRY_INTERVAL)
+
+        # now if we try again we should get a failure
+        d = get_retry_limiter("test_dest", self.clock, store)
+        self.pump()
+        self.failureResultOf(d, NotRetryingDestination)
+
+        #
+        # advance the clock and try again
+        #
+
+        self.pump(MIN_RETRY_INTERVAL)
+        d = get_retry_limiter("test_dest", self.clock, store)
+        self.pump()
+        limiter = self.successResultOf(d)
+
+        self.pump(1)
+        try:
+            with limiter:
+                self.pump(1)
+                retry_ts = self.clock.time_msec()
+                raise AssertionError("argh")
+        except AssertionError:
+            pass
+
+        # wait for the update to land
+        self.pump()
+
+        d = store.get_destination_retry_timings("test_dest")
+        self.pump()
+        new_timings = self.successResultOf(d)
+        self.assertEqual(new_timings["failure_ts"], failure_ts)
+        self.assertEqual(new_timings["retry_last_ts"], retry_ts)
+        self.assertGreaterEqual(
+            new_timings["retry_interval"], MIN_RETRY_INTERVAL * RETRY_MULTIPLIER * 0.5
+        )
+        self.assertLessEqual(
+            new_timings["retry_interval"], MIN_RETRY_INTERVAL * RETRY_MULTIPLIER * 2.0
+        )
+
+        #
+        # one more go, with success
+        #
+        self.pump(MIN_RETRY_INTERVAL * RETRY_MULTIPLIER * 2.0)
+        d = get_retry_limiter("test_dest", self.clock, store)
+        self.pump()
+        limiter = self.successResultOf(d)
+
+        self.pump(1)
+        with limiter:
+            self.pump(1)
+
+        # wait for the update to land
+        self.pump()
+
+        d = store.get_destination_retry_timings("test_dest")
+        self.pump()
+        new_timings = self.successResultOf(d)
+        self.assertIsNone(new_timings)