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Erik JohnstonandClaude Fable 5
b45bbd9cdc
Clients may resend the same sliding sync position many times, e.g. if they repeatedly fail to process our responses. Each such request records a new connection position, but the clean-up of old positions only ran the first time a position was used: it lives in `get_and_clear_connection_positions`, whose result is cached, so replayed positions never triggered it. A wedged client replaying one position could thus accumulate unboundedly many rows in `sliding_sync_connection_positions` (and, via the per-position state, in `sliding_sync_connection_streams`/`_room_configs`). Seen in the wild: ~1k positions on one connection over a few hours. Fix by deleting all other positions for the connection whenever we persist a new one: only the position the request was based on (which the client may retry from, not yet having seen our response) and the newly created position remain valid. Also update the connection's `last_used_ts` when persisting, since for replayed positions the cached read no longer does so; otherwise a connection in constant use from the same position would be expired as idle. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>