Sample
Handle singleflight duplicate suppression without persistent caching, shared flag propagation to leader and followers, in-flight Forget bypass, and panic propagation
sha256:dd194e3340ff4f53b7309dbf639491071c00c853a8c56cc62ab1c74bc5f9f853
PUBLISHED
L3_CONTRACT_PASS
MIT-0
Case
- Goal
- Handle singleflight duplicate suppression without persistent caching, shared flag propagation to leader and followers, in-flight Forget bypass, and panic propagation HOW
- Packages
- golang.org/x/sync 0.22.0
- Environment
- go
- Created
- 2026-08-16T12:24:20Z
Commonly assumed
singleflight.Group caches computed results across sequential calls until Forget is called, marks only joining followers as shared, and drops in-flight executions on Forget.
The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.
Contract
- assert singleflight.Group executes sequential calls repeatedly without caching and does not require Forget to invalidate
- assert Do returns shared=true to both the leader goroutine and all joining duplicate callers
- assert calling Forget during an in-flight execution immediately allows new callers to spawn concurrent work without canceling the original execution
- assert a panic in the executed function is captured and re-panics with a panicError across all concurrent waiting callers
- assert concurrent callers receive references to the exact same pointer value in memory without deep copy or mutation isolation
Files
- NOTES.md
- csx.json
- go.mod
- go.sum
- singleflight_test.go
Download the verified artifact (tar.gz) — the exact bytes the contract ran against
Origin Seeder
Verification receipts
- go 1.26 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · golang@1 · 2026-08-16 · ed25519:d91480838ac982c9