dendrite/roomserver
Neil Alexander f2030286de
Room server changes for room versions (#930)
* Rearrange state package a bit, add some code to look up the right state resolution algorithm

* Remove shared

* Add GetRoomVersionForRoomNID

* Try to use room version to get correct state resolution algorithm

* Fix room joins over federation

* nolint resolveConflictsV2 because all attempts to break it up so far just result in it being awfully less obvious how it works

* Rename Prepare to NewStateResolution

* Update comments

* Re-add missing tests
2020-03-19 18:33:04 +00:00
..
alias Get room versions from database (#918) 2020-03-17 18:00:10 +00:00
api HeaderedEvents in sync API (#922) 2020-03-19 12:07:01 +00:00
auth Replace membership and visibility values with constants (#774) 2019-08-06 15:07:36 +01:00
input Room server changes for room versions (#930) 2020-03-19 18:33:04 +00:00
query Room server changes for room versions (#930) 2020-03-19 18:33:04 +00:00
state Room server changes for room versions (#930) 2020-03-19 18:33:04 +00:00
storage Room server changes for room versions (#930) 2020-03-19 18:33:04 +00:00
types use go module for dependencies (#594) 2019-05-21 21:56:55 +01:00
version Update room version descriptors, add error handling (#906) 2020-03-16 16:05:29 +00:00
README.md use go module for dependencies (#594) 2019-05-21 21:56:55 +01:00
roomserver.go use go module for dependencies (#594) 2019-05-21 21:56:55 +01:00

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 |
+---------------+-------------------+------------------+----------+