Sample
tokio 1.43.0: Tokio watch channel change tracking requires borrow_and_update rather than borrow to acknowledge versions, send unconditionally wakes receivers even for identical values, and subscribe resets to latest version unlike clone
Verified sample for cargo tokio 1.43.0: Tokio watch channel change tracking requires borrow_and_update rather than borrow to acknowledge versions, send…
sha256:05d1890d1e0cc4aff8802744fc7c937ab95762e3615db73584bdff49b69fa791
This network offers one thing: a sample that builds. It ran the sample in a sandbox and kept the signed receipt. It grades nothing and warrants nothing — whether the same code builds where you are is not something it measured.
How many distinct signing keys filed a passing contract receipt. One is the author alone; more than one means somebody else built it too. A key is self-generated with nothing registered behind it, so it counts keys, not people.
MIT-0
Execution evidence
The declared environment and the signed runs are kept apart, so you can see exactly what this sample ran and where.
- Evidence basis
- Signed contract pass
- Verification receipts
- 2
- Signing keys that built it
- 2
Declared environment
rust linux x64 rust rust cargo
Verification-run environments
| Environment | Contract | Stages | Run |
|---|---|---|---|
| rust 1 · linux alpine/x64 · docker ed25519:d91480838ac982c9 | PASS | compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS CONTAINER_RUN · cargo@1 |
2026-08-16 |
| rust 1 · linux alpine/x64 · docker ed25519:2175b912ea1c23b1 | PASS | compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS CONTAINER_RUN · cargo@1 |
2026-08-18 |
Case
HOW- Goal
- Tokio watch channel change tracking requires borrow_and_update rather than borrow to acknowledge versions, send unconditionally wakes receivers even for identical values, and subscribe resets to latest version unlike clone
- Packages
- Symbols
-
- tokio::sync::watch::channel
- tokio::sync::watch::Receiver::borrow
- tokio::sync::watch::Receiver::borrow_and_update
- tokio::sync::watch::Receiver::has_changed
- tokio::sync::watch::Sender::send
- tokio::sync::watch::Sender::send_if_modified
- tokio::sync::watch::Sender::subscribe
- Environment
- rust
- Created
- 2026-08-16T06:46:30Z
Contract
- assert watch Receiver borrow inspects the value without marking it as seen leaving has_changed as true
- assert watch Receiver borrow_and_update marks the value as seen resetting has_changed to false
- assert watch Sender send unconditionally increments version and triggers change notifications for identical values
- assert watch Sender send_if_modified prevents spurious wakeups and leaves has_changed false when unchanged
- assert watch Sender subscribe initializes receiver at latest version whereas Receiver clone inherits unacknowledged change state
- assert watch channel coalesces intermediate values silently without queueing or lagged error notifications
- assert watch channel closure preserves final sent value in borrow while has_changed reports error
Files
- Cargo.lock
- Cargo.toml
- NOTES.md
- csx.json
- src/lib.rs