Enum ReplicaClass 

pub enum ReplicaClass {
    Voting,
    AsyncReadReplica,
}

How a node chooses its WAL upstream.

This is orthogonal to the election MemberKind/VotingState model: a node’s streaming class answers “may this node accept a cascade source?”, where the membership model answers “does this node vote / can it become primary?”. A witness has no data stream at all, so it is irrelevant here; the meaningful split is between members on the durability path (which must stream directly) and pure read scale-out replicas (which may cascade).

Variants

Voting

Participates in the durability/election quorum. Streams directly from the primary and refuses any cascade source (ADR 0030). This is the safe default: a node only cascades when explicitly declared a read-replica.

AsyncReadReplica

Async read-scale-out replica. Not in the durability path, so it may stream from an intermediate replica to bound the primary’s fan-out.

Implementations

impl ReplicaClass

pub fn from_member(member: &Member) -> Self

Derive the streaming class from an election membership view.

Any member that currently counts toward quorum (Member::is_voter) is on the durability path and must stream directly; a data member that is non-voting (e.g. a read-replica that never joins the voter set) may cascade. This lets a caller that already holds a Member derive the cascade policy without re-declaring intent.

pub fn may_cascade(self) -> bool

Whether a node of this class is permitted to stream from an intermediate replica rather than the primary.

Trait Implementations

impl Clone for ReplicaClass

fn clone(&self) -> ReplicaClass

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for ReplicaClass

impl Debug for ReplicaClass

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

Formats the value using the given formatter.

impl Default for ReplicaClass

fn default() -> ReplicaClass

Returns the “default value” for a type.

impl Eq for ReplicaClass

impl PartialEq for ReplicaClass

fn eq(&self, other: &ReplicaClass) -> 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 ReplicaClass