Trait RoutingStrategy 

pub trait RoutingStrategy<Route: DeliveryRoute + Clone + PartialEq>: Clone {
    type Observation;
    type Error;

    // Required methods
    fn select(
        &mut self,
        members: &[Route],
        message: &<Route::Protocol as Protocol>::Msg,
    ) -> Option<usize>;
    fn observe(
        &mut self,
        _members: &[Route],
        observation: Self::Observation,
    ) -> Result<(), RoutingObservationRejection<Self::Observation, Self::Error>>;

    // Provided methods
    fn added(&mut self, _recipient: Route) { ... }
    fn removed(&mut self, _index: usize, _recipient: Route, _remaining: usize) { ... }
}

Static recipient-selection policy used by Router.

Implementations receive the current membership snapshot and return at most one index into it. Returning an out-of-range index is a typed RouterError::InvalidSelection; the command is returned and the cloned policy candidate is discarded without committing policy state. Policies perform no effects and obtain no ambient entropy.

Required Associated Types

type Observation

Closed observation type accepted by this policy.

type Error

Concrete observation rejection reason.

Required Methods

fn select( &mut self, members: &[Route], message: &<Route::Protocol as Protocol>::Msg, ) -> Option<usize>

Select at most one index from this exact typed membership snapshot.

Returning None means no member is currently eligible. The selected route receives ownership of the message, so unicast routing does not require the destination protocol’s message to implement Clone.

fn observe( &mut self, _members: &[Route], observation: Self::Observation, ) -> Result<(), RoutingObservationRejection<Self::Observation, Self::Error>>

Fold one typed observation against the same membership snapshot.

Errors

Returns the exact owned observation and concrete reason when evidence is unknown, stale, or contradictory. Router discards the policy candidate on rejection, so no partial policy mutation is committed.

Provided Methods

fn added(&mut self, _recipient: Route)

Update policy-local state after one new membership is committed.

fn removed(&mut self, _index: usize, _recipient: Route, _remaining: usize)

Repair policy-local position after a membership removal.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl<Route, K> RoutingStrategy<Route> for ConsistentHash<K>

where Route: DeliveryRoute + Clone + PartialEq, <Route::Protocol as Protocol>::Msg: RouteKey<K>,

type Observation = MemberTokenObservation<Route>

type Error = MemberEvidenceError

impl<Route, K> RoutingStrategy<Route> for RendezvousHash<K>

where Route: DeliveryRoute + Clone + PartialEq, <Route::Protocol as Protocol>::Msg: RouteKey<K>,

type Observation = MemberTokenObservation<Route>

type Error = MemberEvidenceError

impl<Route: DeliveryRoute + Clone + PartialEq> RoutingStrategy<Route> for LeastLoaded

type Observation = LoadObservation<Route>

type Error = MemberEvidenceError

impl<Route: DeliveryRoute + Clone + PartialEq> RoutingStrategy<Route> for RoundRobin

type Observation = Never

type Error = Never