Crate tsoracle_yieldpoint 

tsoracle-yieldpoint

Async yield points for tsoracle — the structural analogue of fail-rs failpoints, but driven by a tokio::sync::Notify so the production code yields its tokio worker while parked instead of blocking the thread.

Why it exists

A fail-crate pause action uses std::thread::park / a condvar, which blocks the OS thread the failpoint fires on. Inside a tokio task that starves the runtime’s timer driver — tokio::time::sleep stops returning for every task on that worker, and any race the test is trying to observe gets masked. Yield points exist for exactly the case where the call site is in an async path that must keep yielding to the runtime while parked.

What’s in the box

• yieldpoint!(name) — the macro consumers sprinkle into their async code paths. Inert with yieldpoints feature off; under the feature, suspends on a tokio::sync::Notify keyed by name until a test fires it.
• registry — runtime registry the macro hits (arm, disarm, fire). Used by chaos / integration tests to drive injection sites deterministically.

Quick reference

Opt in by declaring a feature on the consumer crate that flips tsoracle-yieldpoint/yieldpoints:

# consumer Cargo.toml
[features]
yieldpoints = ["tsoracle-yieldpoint/yieldpoints"]

[dependencies]
tsoracle-yieldpoint = { workspace = true }

Then in code:

use tsoracle_yieldpoint::yieldpoint;

async fn some_path() {
    yieldpoint!("after-leader-promotion");
    // ...
}

With yieldpoints off (production), the macro expands to nothing. With it on (CI tests via cargo test --features yieldpoints), the macro suspends on a Notify until the test calls registry::fire("after-leader-promotion").

Feature flags

• yieldpoints (off by default) — enables the registry + macro body. Production builds carry zero overhead; CI tests opt in via the consumer crate’s feature.

Related

• fail — synchronous failpoints. Use these for sites that can block their thread.
• tsoracle-server / tsoracle-driver-paxos / others — consumers that expose yieldpoints features wiring tsoracle-yieldpoint/yieldpoints for their async paths.

Macros

yieldpoint