Struct LeaderElection

pub struct LeaderElection { /* private fields */ }

A handle for one independently scoped leader lease.

lease_duration is this caller’s non-zero desired duration. It is persisted on every successful acquisition, takeover, and renewal. Existing foreign records remain governed by their own persisted duration. The handle holds no caller-local state and performs no scheduling or retries.

Implementations

impl LeaderElection

pub fn new(subspace: Subspace, lease_duration: Duration) -> Result<Self>

Creates an election handle with the non-zero duration it will persist on successful ownership changes.

Constructing a handle does not read or initialize durable state.

pub fn lease_duration(&self) -> Duration

Returns this handle’s desired duration for its future owner records.

pub async fn poll<T>( &self, txn: &T, participant: &ParticipantId, local_state: &LocalState, attempt_started_at: Duration, ) -> Result<PollResult>

where T: Deref<Target = Transaction>,

Polls the durable lease state in the caller’s transaction.

A released state is acquired immediately. An exact, locally unexpired Leadership token renews ownership with a fresh revision. A first or changed Observation never steals; only an exact unchanged observation may take over, or same-owner reacquire, after the observed record’s persisted duration. An expired or mismatched leadership token becomes observation/reacquisition state and cannot renew directly.

attempt_started_at must be read from the caller’s monotonic clock immediately before this call in each retry attempt. It is deliberately before the durable read, making renewal and takeover decisions conservative relative to read and commit delay. After the enclosing Database::run succeeds, pass a fresh caller-clock reading to PollResult::into_next_state to adopt the returned state.

Renew well before the local deadline represented by Leadership, leaving headroom for scheduling delay, retries, and commit latency. This affects availability only; it is not a durable expiry or safety condition.

pub async fn state<T>(&self, txn: &T) -> Result<ElectionState>

where T: Deref<Target = Transaction>,

Reads durable state without making any liveness or leadership-validity claim.

This is a snapshot only. It does not create a local observation, permit renewal or takeover, or authorize protected work.

pub async fn resign<T>( &self, txn: &T, leadership: &Leadership, ) -> Result<ResignOutcome>

where T: Deref<Target = Transaction>,

Releases ownership only when leadership still exactly matches durable state.

The revision and persisted duration remain, so a later acquisition has a strictly newer fencing rank. A stale delayed resignation is rejected. This conditional operation does not make a liveness claim and may be used to relinquish an otherwise exact durable token after its local renewal window has elapsed.

Trait Implementations

impl Clone for LeaderElection

fn clone(&self) -> LeaderElection

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for LeaderElection

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.