From 526f09b6e8b4179a70bb1840eb2a4dc6c9db9c94 Mon Sep 17 00:00:00 2001
From: Olivier 'reivilibre <oliverw@matrix.org>
Date: Thu, 6 Mar 2025 17:54:52 +0000
Subject: [PATCH 1/2] Docstring is a contradiction. Can we make it make sense?
---
synapse/storage/databases/state/store.py | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/synapse/storage/databases/state/store.py b/synapse/storage/databases/state/store.py
index 90d7beb92f..df82c77468 100644
--- a/synapse/storage/databases/state/store.py
+++ b/synapse/storage/databases/state/store.py
@@ -739,8 +739,8 @@ class StateGroupDataStore(StateBackgroundUpdateStore, SQLBaseStore):
room_id: str,
state_groups_to_sequence_numbers: Mapping[int, int],
) -> bool:
- """Deletes no longer referenced state groups and de-deltas any state
- groups that reference them.
+ """Deletes state groups that are no longer referenced by events <<<TODO confirm this is the intended meaning>>>
+ and de-deltas any state groups that reference them.
Args:
room_id: The room the state groups belong to (must all be in the
From 82a789f8c00fe90407e2727d02d9790c51a140ba Mon Sep 17 00:00:00 2001
From: Olivier 'reivilibre <oliverw@matrix.org>
Date: Thu, 6 Mar 2025 17:54:57 +0000
Subject: [PATCH 2/2] Demonstration of table explosion
---
tests/storage/test_state.py | 89 +++++++++++++++++++++++++++++++++++++
1 file changed, 89 insertions(+)
diff --git a/tests/storage/test_state.py b/tests/storage/test_state.py
index 48f8d1c340..07aea01067 100644
--- a/tests/storage/test_state.py
+++ b/tests/storage/test_state.py
@@ -643,3 +643,92 @@ class StateStoreTestCase(HomeserverTestCase):
),
)
self.assertEqual(context.state_group_before_event, groups[0][0])
+
+
+class StateGroupDataStoreTestCase(HomeserverTestCase):
+ """Tests for the StateGroupDataStore"""
+
+ def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
+ self.store = hs.get_datastores().main
+ self.storage = hs.get_storage_controllers()
+ self.state_datastore = self.storage.state.stores.state
+
+ def test_purge_unreferenced_state_groups__dedelta(self) -> None:
+ """
+ Tests the de-delta-ing behaviour of event-unreferenced state group purging.
+
+ Set up a state group DAG like:
+
+ 1 {m.room.member/@a:h} -> 2 {m.room.member/@b:h} -> 3 {m.room.member/@c:h}
+
+ Then delete state group 2, supposing it is no longer referenced by any events.
+
+ The end state group DAG should look like ...
+ """
+
+ self.get_success(
+ self.state_datastore.db_pool.simple_insert_many(
+ table="state_groups_state",
+ keys=("state_group", "room_id", "type", "state_key", "event_id"),
+ values=[
+ (1, "!r:h", "m.room.member", "@a:h", "$abc"),
+ (2, "!r:h", "m.room.member", "@b:h", "$def"),
+ (3, "!r:h", "m.room.member", "@c:h", "$ghi"),
+ ],
+ desc="_",
+ )
+ )
+
+ self.get_success(
+ self.state_datastore.db_pool.simple_insert_many(
+ table="state_group_edges",
+ keys=("state_group", "prev_state_group"),
+ values=[
+ (2, 1),
+ (3, 2),
+ ],
+ desc="_",
+ )
+ )
+
+ self.get_success(
+ self.state_datastore.db_pool.simple_insert_many(
+ table="state_groups_pending_deletion",
+ keys=("state_group", "sequence_number", "insertion_ts"),
+ values=[
+ (2, 1, -90000000),
+ ],
+ desc="_",
+ )
+ )
+ self.assertTrue(
+ self.get_success(
+ self.state_datastore.purge_unreferenced_state_groups("!r:h", {2: 1})
+ )
+ )
+
+ snapshot_rows = sorted(
+ self.get_success(
+ self.state_datastore.db_pool.simple_select_list(
+ "state_groups_state",
+ {},
+ ("state_group", "type", "state_key", "event_id"),
+ desc="_",
+ )
+ )
+ )
+
+ self.assertEqual(
+ snapshot_rows,
+ [
+ (1, "m.room.member", "@a:h", "$abc"),
+ (
+ 3,
+ "m.room.member",
+ "@a:h",
+ "$abc",
+ ), # <--- BOOM, table increased in size!!!
+ (3, "m.room.member", "@b:h", "$def"),
+ (3, "m.room.member", "@c:h", "$ghi"),
+ ],
+ )