Bound heap-like values without adding a garbage collector
A proposed LIST instruction allocates on every loop iteration and the prototype retains all intermediate values.
- Focused work estimate
- 4h + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Runtime memory · Tradeoff analysis · Leak testing
Estimated field mix
- Systems programming60%
- Performance engineering40%
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 rules engine executes a tiny arithmetic bytecode over synthetic integers. Its interpreter trusts jump offsets and can run forever. Build a local Rust runtime; it has no filesystem, network, dynamic loading, host calls, or candidate-source execution.
Setup prerequisites
- Stacks
- Instruction decoding
- Control flow
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
- SRUNTIME-101 · Decode instructions without reading past the bytecode buffer
- SRUNTIME-102 · Validate stack depth across both sides of a branch
- SRUNTIME-103 · Reject jumps that land inside instruction operands
- SRUNTIME-104 · Report integer overflow instead of changing arithmetic by build mode
- SRUNTIME-105 · Stop infinite programs with a deterministic instruction budget
Acceptance criteria
- Compare arena reset, reference counting, and no-list alternatives for the bounded language
- Chosen design defines maximum live bytes and value count
- Budget failure releases all runtime-owned allocations
Implementation constraints
- Do not introduce tracing collection without a workload and cycle requirement that needs it.
Verification to include
- Evaluate a bounded list program and reconcile peak live bytes.
- Allocate until the value budget and confirm clean failure without leaks.
Deliverables
- Memory strategy decision and bounded-value prototype
Rollout and recovery
Keep LIST disabled until the memory contract is accepted.
Value of the work
For the engineer: Practice runtime invariants, validation, resource accounting and compatibility.
For the team: Review a constrained execution component whose malformed programs fail deterministically without gaining host capabilities.
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.