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| author | Erik Johnston <erik@matrix.org> | 2020-10-12 15:51:41 +0100 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2020-10-12 15:51:41 +0100 |
| commit | 8de3703d214c814ad637793a0cc2220e20579ffa (patch) | |
| tree | 3daec0f9a8d7baf92f8746b12c8b54d92b8d7d6d /docs | |
| parent | Docker: support passing additional commandline args to synapse (#8390) (diff) | |
| download | synapse-8de3703d214c814ad637793a0cc2220e20579ffa.tar.xz | |
Make event persisters periodically announce position over replication. (#8499)
Currently background proccesses stream the events stream use the "minimum persisted position" (i.e. `get_current_token()`) rather than the vector clock style tokens. This is broadly fine as it doesn't matter if the background processes lag a small amount. However, in extreme cases (i.e. SyTests) where we only write to one event persister the background processes will never make progress. This PR changes it so that the `MultiWriterIDGenerator` keeps the current position of a given instance as up to date as possible (i.e using the latest token it sees if its not in the process of persisting anything), and then periodically announces that over replication. This then allows the "minimum persisted position" to advance, albeit with a small lag.
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/tcp_replication.md | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/docs/tcp_replication.md b/docs/tcp_replication.md index db318baa9d..ad145439b4 100644 --- a/docs/tcp_replication.md +++ b/docs/tcp_replication.md @@ -15,7 +15,7 @@ example flow would be (where '>' indicates master to worker and > SERVER example.com < REPLICATE - > POSITION events master 53 + > POSITION events master 53 53 > RDATA events master 54 ["$foo1:bar.com", ...] > RDATA events master 55 ["$foo4:bar.com", ...] @@ -138,9 +138,9 @@ the wire: < NAME synapse.app.appservice < PING 1490197665618 < REPLICATE - > POSITION events master 1 - > POSITION backfill master 1 - > POSITION caches master 1 + > POSITION events master 1 1 + > POSITION backfill master 1 1 + > POSITION caches master 1 1 > RDATA caches master 2 ["get_user_by_id",["@01register-user:localhost:8823"],1490197670513] > RDATA events master 14 ["$149019767112vOHxz:localhost:8823", "!AFDCvgApUmpdfVjIXm:localhost:8823","m.room.guest_access","",null] @@ -185,6 +185,11 @@ client (C): updates via HTTP API, rather than via the DB, then processes should make the request to the appropriate process. + Two positions are included, the "new" position and the last position sent respectively. + This allows servers to tell instances that the positions have advanced but no + data has been written, without clients needlessly checking to see if they + have missed any updates. + #### ERROR (S, C) There was an error |