Struct WatchGuard 

pub struct WatchGuard { /* private fields */ }

RAII handle to the leader-watch task spawned by Server::into_router.

The watch task holds an Arc<Server> (and thus the consensus driver) and maintains serving state across leadership transitions. This guard ties the task’s lifetime to the guard’s: dropping it cooperatively cancels the task, and the task publishes ServingState::NotServing before it stops, so any Routes an embedder still has mounted fails subsequent RPCs fast.

Cancellation is cooperative — the task stops at its next await boundary and never mid-fence, so it is never torn down while holding internal locks, in contrast to a raw tokio::task::JoinHandle::abort.

Implementations

impl WatchGuard

pub async fn shutdown(self) -> Result<(), ServerError>

Signal the leader-watch task to stop, wait for it to drain, and report its outcome.

A cooperatively cancelled task returns Ok(()) — the stop was requested, so it is not an error. If the task had already terminated on its own (driver error, stream EOF, or panic) the original outcome is surfaced verbatim: Err(e) or ServerError::WatchPanic. Either way serving state is NotServing once this returns.

The cooperative wait is bounded by the configured ServerBuilder::shutdown_grace: if the task is parked in a consensus-driver call that never returns it is aborted once the grace elapses (still reported as Ok(())), so an embedder’s shutdown can never wedge behind a hung driver.

pub fn abort(self)

Hard-abort the leader-watch task without waiting for a cooperative stop.

Prefer Self::shutdown or simply dropping the guard; both let the task stop at a safe point. This is an escape hatch for callers that cannot await and accept that the task may be torn down mid-fence.

pub fn is_finished(&self) -> bool

Whether the leader-watch task has finished — terminated for any reason (cooperative cancel, driver error, stream EOF, or panic).

A read-only liveness probe that neither consumes the guard nor disturbs its cancel-on-drop behavior, so an embedder can poll task health while keeping the guard alive.

Trait Implementations

impl Drop for WatchGuard

fn drop(&mut self)

Executes the destructor for this type.

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.