TimersSubscription

The built-in timers subscription of one bounded context: writes the timers the context's aggregates schedule into its store, from the system events wow.ScheduleSet and wow.ScheduleCancelled their streams commit. The store is a view of the log: this subscription rebuilds it from the beginning of the log under a new name, and a replay writes nothing twice.

Register subscription in the runtime of the log group whose timers store keeps: it runs on each partition's owner, checkpoints and parks like any subscription, and takes the streams that only change schedules.

• Set: the timer ref#key@version, of its owner's partition among the log's partitions, its first slot due as its rule says (ScheduleSlots.timerOf: a cron rule's first time after the commit); it replaces what the aggregate scheduled under the key before. A job instance's own tick (<context>.schedule) is sent as system:schedule in its tenant, without the setting command's headers and scope.

• Local: a timer this node writes is handed to written (the context's runner), which takes it into its firing wheel at once when it owns the timer's partition and the timer is due soon, without waiting for its next read of the store.

• Cancelled: cancels the aggregate's PENDING (or parked) timer of the key.

• Delete: a stream that deletes the aggregate cancels every PENDING timer the aggregate keeps, before its own changes apply; a restore does not bring them back.

• Idempotent: every write carries the stream's version, and the store ignores what it already holds at that version or a later one, so a replay or an old partition owner running beside the new one never moves a timer back nor revives one.