Module timer 

Live timer scheduling and callback dispatch.

Scheduling

Runtime deadlines use the remaining duration to the nominal schedule and are computed before the timer task is spawned. A deadline already in the past starts immediately. Event timestamps retain the nominal schedule, and stop times are inclusive. An event whose following schedule is not representable in [UnixNanos] is the timer’s final event.

Task lifecycle

Each LiveTimer::start creates fresh public schedule and task-state atomics. Because aborting a runtime task does not join it, task retirement linearizes restart, cancellation, and drop against event reservation. Retirement either prevents the old task from dispatching, or observes what that task reserved with its event: the following schedule, or terminal exhaustion when no successor is representable. Fresh atomics keep that task from overwriting its replacement’s schedule.

Callback dispatch

Thread-safe callbacks cross the worker boundary as TimeEventMessage values. RustLocal callbacks remain in an owner-thread registry and cross the boundary only through tokens and leases. Senderless Python callbacks run inline and publish their following schedule, when one exists, after the callback returns.

Structs

LiveTimer

A live timer for use with a LiveClock.