mirror of
https://github.com/matrix-org/dendrite
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59 lines
3 KiB
Markdown
59 lines
3 KiB
Markdown
# RoomServer
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## RoomServer Internals
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### Numeric IDs
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To save space matrix string identifiers are mapped to local numeric IDs.
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The numeric IDs are more efficient to manipulate and use less space to store.
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The numeric IDs are never exposed in the API the room server exposes.
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The numeric IDs are converted to string IDs before they leave the room server.
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The numeric ID for a string ID is never 0 to avoid being confused with go's
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default zero value.
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Zero is used to indicate that there was no corresponding string ID.
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Well-known event types and event state keys are preassigned numeric IDs.
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### State Snapshot Storage
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The room server stores the state of the matrix room at each event.
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For efficiency the state is stored as blocks of 3-tuples of numeric IDs for the
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event type, event state key and event ID. For further efficiency the state
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snapshots are stored as the combination of up to 64 these blocks. This allows
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blocks of the room state to be reused in multiple snapshots.
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The resulting database tables look something like this:
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+-------------------------------------------------------------------+
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| Events |
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+---------+-------------------+------------------+------------------+
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| EventNID| EventTypeNID | EventStateKeyNID | StateSnapshotNID |
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+---------+-------------------+------------------+------------------+
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| 1 | m.room.create 1 | "" 1 | <nil> 0 |
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| 2 | m.room.member 2 | "@user:foo" 2 | <nil> 0 |
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| 3 | m.room.member 2 | "@user:bar" 3 | {1,2} 1 |
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| 4 | m.room.message 3 | <nil> 0 | {1,2,3} 2 |
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| 5 | m.room.member 2 | "@user:foo" 2 | {1,2,3} 2 |
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| 6 | m.room.message 3 | <nil> 0 | {1,3,6} 3 |
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+---------+-------------------+------------------+------------------+
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+----------------------------------------+
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| State Snapshots |
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+-----------------------+----------------+
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| EventStateSnapshotNID | StateBlockNIDs |
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+-----------------------+----------------|
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| 1 | {1} |
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| 2 | {1,2} |
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| 3 | {1,2,3} |
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+-----------------------+----------------+
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+-----------------------------------------------------------------+
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| State Blocks |
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+---------------+-------------------+------------------+----------+
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| StateBlockNID | EventTypeNID | EventStateKeyNID | EventNID |
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+---------------+-------------------+------------------+----------+
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| 1 | m.room.create 1 | "" 1 | 1 |
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| 1 | m.room.member 2 | "@user:foo" 2 | 2 |
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| 2 | m.room.member 2 | "@user:bar" 3 | 3 |
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| 3 | m.room.member 2 | "@user:foo" 2 | 6 |
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+---------------+-------------------+------------------+----------+
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