Struct LeaseConfig 

pub struct LeaseConfig { /* private fields */ }

The lease timings of one role.

The three extents are independent of the record layout, so one process can hold several roles with different timings. Build a value with LeaseConfig::new, which rejects a set of extents that cannot work, or take the defaults with LeaseConfig::default.

Implementations

impl LeaseConfig

pub fn new( duration: Time, renew_interval: Time, challenge_stagger: Time, ) -> Result<Self, CoordinationError>

Builds a lease policy from three extents.

A caller should set renew_interval to at most a third of duration. The holder then keeps two more attempts before the deadline. The constructor accepts a larger value and does not reject it. Ask LeaseConfig::renews_with_margin which side of that bound a value is on.

Errors

Returns CoordinationError::InvalidConfig when duration, renew_interval, or challenge_stagger is zero, negative, infinite, or NaN. Returns the same error when renew_interval is equal to or larger than duration, because the holder then never renews in time.

pub const fn duration(&self) -> Time

The extent of a lease that a member takes now.

pub const fn renew_interval(&self) -> Time

The gap between two renewals by the holder.

pub const fn challenge_stagger(&self) -> Time

The extra delay that one rank of succession adds.

pub fn renews_with_margin(&self) -> bool

Reports whether the renew interval leaves the holder two spare attempts.

The renew interval that this crate recommends is at most a third of the lease duration. A configuration outside that bound still works, and the holder then loses the role after fewer missed renewals.

pub fn challenge_delay_millis(&self, rank: usize) -> i64

The extra delay in milliseconds that a challenger of rank rank takes.

The value saturates at i64::MAX, so a very large rank does not wrap the instant that a caller adds it to.

pub fn grant( &self, member: MemberId, token: FencingToken, now_millis: i64, ) -> Lease

The lease record that a member writes after it mints token.

A renewal writes the same record with the same token and a later now_millis, so this one function covers a first grant and a renewal.

pub const fn timing<'lease>(&self, lease: &'lease Lease) -> LeaseTiming<'lease>

The clock questions that this policy answers about lease.

Trait Implementations

impl Clone for LeaseConfig

fn clone(&self) -> LeaseConfig

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for LeaseConfig

impl Debug for LeaseConfig

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

Formats the value using the given formatter.

impl Default for LeaseConfig

fn default() -> Self

Returns the “default value” for a type.

impl PartialEq for LeaseConfig

fn eq(&self, other: &LeaseConfig) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for LeaseConfig