Expose arena pressure without logging packet contents
Operators can see allocation failures only in verbose decoder logs that include synthetic payload bytes and unbounded record labels.
- Focused work estimate
- 4h + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Observability · Privacy · Cardinality control
Estimated field mix
- Systems programming70%
- Site reliability30%
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
A fictional telemetry collector copies decoded packet fields into a small native arena. The prototype misaligns wide values and reuses memory while readers still hold views. Create a local Rust crate or C library with generated byte fixtures; no device traffic or production allocator replacement is supplied.
Setup prerequisites
- Pointers and slices
- Integer overflow
- Memory alignment
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
- SMEM-102 · Return exhaustion without handing out a partial slice
- SMEM-101 · Specify aligned arena offsets without relying on host luck
- SMEM-104 · Free large spill blocks without double-releasing arena pages
- SMEM-105 · Coalesce adjacent free spans without corrupting the index
- SMEM-106 · Bound fragmentation before adding a more complex allocator
Acceptance criteria
- Publish bounded counters for allocations, spills, resets, and exhaustion
- Record capacity and high-water mark without payload content
- Reject unbounded caller-provided metric dimensions
Implementation constraints
- Metrics are diagnostic observations for this component, not proof of production capacity.
Verification to include
- Drive allocations and reconcile counters with the deterministic workload.
- Supply a unique record label per request and confirm it cannot become a dimension.
Deliverables
- Bounded arena telemetry and reconciliation test
Rollout and recovery
Enable metrics before changing allocation policy; remove verbose payload logging.
Value of the work
For the engineer: Practice representation invariants, lifetimes, unsafe-boundary review and memory diagnostics.
For the team: Review a component whose allocation failures and corruption cases are explicit before reuse in latency-sensitive code.
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.