f93d1c4790
Fixes https://github.com/matrix-org/dendrite/issues/3240 and potentially a root cause for state resets. While testing, I've had added some more debug logging: ``` time="2023-12-16T18:13:11.319458084Z" level=warning msg="already processed event" event_id="$qFYMl_F2vb1N0yxmvlFAMhqhGhLKq4kA-o_YCQKH7tQ" kind=KindNew times=2 time="2023-12-16T18:13:14.537389126Z" level=warning msg="already processed event" event_id="$EU-LTsKErT6Mt1k12-p_3xOHfiLaK6gtwVDlZ35lSuo" kind=KindNew times=5 time="2023-12-16T18:13:16.789551206Z" level=warning msg="already processed event" event_id="$dIPuAfTL5x0VyG873LKPslQeljCSxFT1WKxUtjIMUGE" kind=KindNew times=5 time="2023-12-16T18:13:17.383838767Z" level=warning msg="already processed event" event_id="$7noSZiCkzerpkz_UBO3iatpRnaOiPx-3IXc0GPDQVGE" kind=KindNew times=2 time="2023-12-16T18:13:22.091946597Z" level=warning msg="already processed event" event_id="$3Lvo3Wbi2ol9-nNbQ93N-E2MuGQCJZo5397KkFH-W6E" kind=KindNew times=1 time="2023-12-16T18:13:23.026417446Z" level=warning msg="already processed event" event_id="$lj1xS46zsLBCChhKOLJEG-bu7z-_pq9i_Y2DUIjzGy4" kind=KindNew times=4 ``` So we did receive the same event over and over again. Given they are `KindNew`, we don't short circuit if we already processed them, which potentially caused the state to be calculated with a now wrong state snapshot. Also fixes the back pressure metric. We now correctly increment the counter once we sent the message to NATS and decrement it once we actually processed an event. |
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.. | ||
acls | ||
api | ||
auth | ||
internal | ||
producers | ||
state | ||
storage | ||
types | ||
version | ||
README.md | ||
roomserver_test.go | ||
roomserver.go |
RoomServer
RoomServer Internals
Numeric IDs
To save space matrix string identifiers are mapped to local numeric IDs. The numeric IDs are more efficient to manipulate and use less space to store. The numeric IDs are never exposed in the API the room server exposes. The numeric IDs are converted to string IDs before they leave the room server. The numeric ID for a string ID is never 0 to avoid being confused with go's default zero value. Zero is used to indicate that there was no corresponding string ID. Well-known event types and event state keys are preassigned numeric IDs.
State Snapshot Storage
The room server stores the state of the matrix room at each event. For efficiency the state is stored as blocks of 3-tuples of numeric IDs for the event type, event state key and event ID. For further efficiency the state snapshots are stored as the combination of up to 64 these blocks. This allows blocks of the room state to be reused in multiple snapshots.
The resulting database tables look something like this:
+-------------------------------------------------------------------+
| Events |
+---------+-------------------+------------------+------------------+
| EventNID| EventTypeNID | EventStateKeyNID | StateSnapshotNID |
+---------+-------------------+------------------+------------------+
| 1 | m.room.create 1 | "" 1 | <nil> 0 |
| 2 | m.room.member 2 | "@user:foo" 2 | <nil> 0 |
| 3 | m.room.member 2 | "@user:bar" 3 | {1,2} 1 |
| 4 | m.room.message 3 | <nil> 0 | {1,2,3} 2 |
| 5 | m.room.member 2 | "@user:foo" 2 | {1,2,3} 2 |
| 6 | m.room.message 3 | <nil> 0 | {1,3,6} 3 |
+---------+-------------------+------------------+------------------+
+----------------------------------------+
| State Snapshots |
+-----------------------+----------------+
| EventStateSnapshotNID | StateBlockNIDs |
+-----------------------+----------------|
| 1 | {1} |
| 2 | {1,2} |
| 3 | {1,2,3} |
+-----------------------+----------------+
+-----------------------------------------------------------------+
| State Blocks |
+---------------+-------------------+------------------+----------+
| StateBlockNID | EventTypeNID | EventStateKeyNID | EventNID |
+---------------+-------------------+------------------+----------+
| 1 | m.room.create 1 | "" 1 | 1 |
| 1 | m.room.member 2 | "@user:foo" 2 | 2 |
| 2 | m.room.member 2 | "@user:bar" 3 | 3 |
| 3 | m.room.member 2 | "@user:foo" 2 | 6 |
+---------------+-------------------+------------------+----------+