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A room's version can restart at 1 after an hour of steady presence #891
Description
The _version row expires one hour after its last bump, but a write that only refreshes a timestamp doesn't bump it, so a room whose people stay for more than an hour loses its _version row to cleanup, and the next change starts the counter again at 1, which a reader that last saw 1 takes as no change.
Checked on main (ce76757), without an external object cache:
| Step | wp_get_presence_room_versions() |
|---|---|
Client a joins |
'1' |
a keeps refreshing; _version passes its expiry, which the refreshes don't push back |
'1' |
wp_delete_expired_presence_data() runs |
null |
Client b joins |
'1' |
The comment in wp_presence_bump_room_version() says the row "outlives every row in the room", which holds for a room that changes but not for one that stays still. With an external object cache, evicting version:{room} restarts the counter the same way.
Tasks
- Keep a room's version from repeating a value it has already handed out, whether by extending
_versionon refresh or by giving the counter a part that changes when it's recreated - Test: a version read before the
_versionrow is cleaned up differs from the one read after the next arrival
Activity
huzaifaalmesbah commentedon Oct 23, 2026
Not a bug in practice: once cleanup removes
_versionthe version readsnulluntil the next arrival, and the only reader, gutenberg-sync-engines' SSE stream, polls every 0.5s, so it sees1 → nullas a change and rereads the room; missing an arrival would need the cleanup and that arrival inside the same half second.