Speed up pruning of ratelimiter (#19129)

I noticed this in some profiling. Basically, we prune the ratelimiters
by copying and iterating over every entry every 60 seconds. Instead,
let's use a wheel timer to track when we should potentially prune a
given key, and then we a) check fewer keys, and b) can run more
frequently. Hopefully this should mean we don't have a large pause
everytime we prune a ratelimiter with lots of keys.

Also fixes a bug where we didn't prune entries that were added via
`record_action` and never subsequently updated. This affected the media
and joins-per-room ratelimiter.

tests/api/test_ratelimiting.py

@@ -228,6 +228,21 @@ class TestRatelimiter(unittest.HomeserverTestCase):
 
         self.assertNotIn("test_id_1", limiter.actions)
 
+    def test_pruning_record_action(self) -> None:
+        """Test that entries added by record_action also get pruned."""
+        limiter = Ratelimiter(
+            store=self.hs.get_datastores().main,
+            clock=self.clock,
+            cfg=RatelimitSettings(key="", per_second=0.1, burst_count=1),
+        )
+        limiter.record_action(None, key="test_id_1", n_actions=1, _time_now_s=0)
+
+        self.assertIn("test_id_1", limiter.actions)
+
+        self.reactor.advance(60)
+
+        self.assertNotIn("test_id_1", limiter.actions)
+
     def test_db_user_override(self) -> None:
         """Test that users that have ratelimiting disabled in the DB aren't
         ratelimited.

tests/federation/test_federation_server.py

@@ -462,7 +462,7 @@ class SendJoinFederationTests(unittest.FederatingHomeserverTestCase):
         )
         self.assertEqual(r[("m.room.member", joining_user)].membership, "join")
 
-    @override_config({"rc_joins_per_room": {"per_second": 0, "burst_count": 3}})
+    @override_config({"rc_joins_per_room": {"per_second": 0.1, "burst_count": 3}})
     def test_make_join_respects_room_join_rate_limit(self) -> None:
         # In the test setup, two users join the room. Since the rate limiter burst
         # count is 3, a new make_join request to the room should be accepted.
@@ -484,7 +484,7 @@ class SendJoinFederationTests(unittest.FederatingHomeserverTestCase):
         )
         self.assertEqual(channel.code, HTTPStatus.TOO_MANY_REQUESTS, channel.json_body)
 
-    @override_config({"rc_joins_per_room": {"per_second": 0, "burst_count": 3}})
+    @override_config({"rc_joins_per_room": {"per_second": 0.1, "burst_count": 3}})
     def test_send_join_contributes_to_room_join_rate_limit_and_is_limited(self) -> None:
         # Make two make_join requests up front. (These are rate limited, but do not
         # contribute to the rate limit.)

tests/handlers/test_room_member.py

@@ -50,7 +50,7 @@ class TestJoinsLimitedByPerRoomRateLimiter(FederatingHomeserverTestCase):
 
         self.intially_unjoined_room_id = f"!example:{self.OTHER_SERVER_NAME}"
 
-    @override_config({"rc_joins_per_room": {"per_second": 0, "burst_count": 2}})
+    @override_config({"rc_joins_per_room": {"per_second": 0.1, "burst_count": 2}})
     def test_local_user_local_joins_contribute_to_limit_and_are_limited(self) -> None:
         # The rate limiter has accumulated one token from Alice's join after the create
         # event.
@@ -76,7 +76,7 @@ class TestJoinsLimitedByPerRoomRateLimiter(FederatingHomeserverTestCase):
             by=0.5,
         )
 
-    @override_config({"rc_joins_per_room": {"per_second": 0, "burst_count": 2}})
+    @override_config({"rc_joins_per_room": {"per_second": 0.1, "burst_count": 2}})
     def test_local_user_profile_edits_dont_contribute_to_limit(self) -> None:
         # The rate limiter has accumulated one token from Alice's join after the create
         # event. Alice should still be able to change her displayname.
@@ -100,7 +100,7 @@ class TestJoinsLimitedByPerRoomRateLimiter(FederatingHomeserverTestCase):
             )
         )
 
-    @override_config({"rc_joins_per_room": {"per_second": 0, "burst_count": 1}})
+    @override_config({"rc_joins_per_room": {"per_second": 0.1, "burst_count": 1}})
     def test_remote_joins_contribute_to_rate_limit(self) -> None:
         # Join once, to fill the rate limiter bucket.
         #
@@ -248,7 +248,7 @@ class TestReplicatedJoinsLimitedByPerRoomRateLimiter(BaseMultiWorkerStreamTestCa
         self.room_id = self.helper.create_room_as(self.alice, tok=self.alice_token)
         self.intially_unjoined_room_id = "!example:otherhs"
 
-    @override_config({"rc_joins_per_room": {"per_second": 0, "burst_count": 2}})
+    @override_config({"rc_joins_per_room": {"per_second": 0.01, "burst_count": 2}})
     def test_local_users_joining_on_another_worker_contribute_to_rate_limit(
         self,
     ) -> None: