Keep wall-clock changes out of elapsed-time deadlines
An NTP correction moves wall time backwards and extends a file-processing deadline by several minutes.
- Focused work estimate
- 2h 30m + prerequisites
- Priority in the scenario
- Medium
- Engineering practice
- Clocks · Time modeling
Estimated field mix
- Systems programming70%
- Real-time systems30%
Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence.
Review it, then add it to your workspace.
The board opens an editable draft; nothing is saved until you confirm it. Sign-in and workspace permissions apply, and Demo boards remain ephemeral.
Project context
A fictional local agent watches generated inbox files and schedules bounded processing. Direct system calls are scattered across the code, mishandle interrupted operations, and make tests platform-dependent. Build a Rust OS adapter with temporary fixture directories; no kernel module, elevated privilege, or production host modification is required.
Setup prerequisites
- System calls
- File descriptors
- Monotonic clocks
Preceding work
No earlier ticket is required. Complete the project setup above.
Acceptance criteria
- Elapsed deadlines use an injected monotonic clock
- User-facing timestamps remain UTC wall time
- Conversion between the two clock domains is prohibited
Implementation constraints
- Tests advance fake clocks; they do not alter the host clock.
Verification to include
- Expire a deadline through monotonic advancement.
- Move wall time forward and backward and prove elapsed behavior is unchanged.
Deliverables
- Clock boundary and time-jump tests
Rollout and recovery
Migrate deadline call sites before changing displayed timestamps.
Value of the work
For the engineer: Practice OS error semantics, partial I/O, portability and deterministic abstraction boundaries.
For the team: Review host-facing code whose retries, resource limits, and platform differences are explicit before packaging it as a local agent.
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.