Cancel emulated edge jobs without accepting late callbacks
A cancelled timer callback runs after a replacement job is registered. Bind callbacks to registration generation.
- Focused work estimate
- 2h 45m + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Cancellation · Concurrency
Estimated field mix
- Embedded and edge100%
Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence.
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Project context
Fictional kiosk software schedules cache refresh and display housekeeping. Build a software clock and job adapter; do not control real machinery or purchase hardware.
Setup prerequisites
- Implement injected wall and monotonic clocks.
- Create synthetic jobs with controllable completion and failure.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
Acceptance criteria
- Cancel invalidates current generation
- Late callback performs no work
- Replacement generation can run
Implementation constraints
- Clearing the runtime timer alone is insufficient.
Verification to include
- Cancel before deadline
- Deliver old callback after replacement
Deliverables
- Generation guard and race cases
Rollout and recovery
Recreate scheduler instance if generations become inconsistent.
Value of the work
For the engineer: Practice timer semantics, cancellation and bounded scheduling.
For the team: Inspect predictable edge resource use and honest execution status.
Evidence boundaries
Outcome Evidence: Tests, patches, and runbooks are requested deliverables. They become Outcome Evidence only through a qualified Mission and immutable Evidence IDs.
Ownership Evidence: Independent adaptation must be observed under a declared verification policy and cite immutable Evidence IDs. Completing a planning ticket establishes no Ownership Evidence.