Auto-reconnect (server side only) - #5877
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Adds the two server-side changes needed for SDK auto-reconnect (proposal 0037). Connection replacement: a client which reconnects can now send a stable, client-generated `session_id` query parameter. Each connection still gets its own ConnectionId and its own lifecycle events. The session id only identifies which earlier connection a new one supersedes. When a connection claims a session held by a live connection of the same identity, that connection's actor is stopped and its module-side disconnect lifecycle is awaited before the new connection's client_connected, so a module never observes two live connections for one session, nor the old connection's client_disconnected after the new client_connected. Batch subscribe: SubscribeBatch and SubscribeBatchApplied register multiple query sets under one subscription-manager lock and evaluate them at a single transaction snapshot. No transaction update can interleave with the responses, so a reconnecting client can replay its subscriptions and reconcile its cache against a consistent snapshot. Per-set errors are reported in the response and the remaining sets still apply
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Description of Changes
Auto-Reconnect: Connection replacement and batch subscribe
Adds the two server-side changes needed for SDK auto-reconnect (proposal 0037).
Connection replacement: a client which reconnects can now send a stable, client-generated
session_idquery parameter. When a client re-connects while an existing connection is still open (likely waiting on server-side idle timeout to fire) the provided session id will match an existing session. The new connection is refused, and the previous one associated with the session id is torn down. Once the old connection is fully closed the session id is freed up allowing the next reconnect attempt to claim the session. This ensures that lifecycle reducers run fully for the previous connection before a new one is established.Batch subscribe: SubscribeBatch and SubscribeBatchApplied register multiple query sets under one subscription-manager lock and evaluate them at a single transaction snapshot. No transaction update can interleave with the responses, so a reconnecting client can replay its subscriptions and reconcile its cache against a consistent snapshot. Per-set errors are reported in the response and the remaining sets still apply.
API and ABI breaking changes
No API breaking change. New V3 websocket protocol message. New clients will not be able to send this to old servers.
Rollback safety impact
n/a.
Expected complexity level and risk
3 - Primarily because of the changes to connection takeover
Testing