Struct MembershipSnapshot 

pub struct MembershipSnapshot {
    pub members: BTreeSet<u32>,
    pub learners: BTreeSet<u32>,
    pub committed_index: u64,
}

A point-in-time snapshot of committed cluster membership.

Delivered via crate::EmbeddedEngine::watch_membership whenever a ConfChange entry commits. The snapshot reflects the membership state after the change has been applied, so borrow() always returns a consistent view.

Idempotency

committed_index is the Raft log index of the ConfChange entry that triggered this snapshot. It is strictly monotonically increasing across snapshots and can be used as an idempotency key:

if snapshot.committed_index <= self.last_applied {
    return; // already handled
}
self.last_applied = snapshot.committed_index;
scheduler.rebalance(&snapshot);

Diff computation

No diff fields are included. Because watch::channel is lossy (only the latest value is retained), a diff embedded in the snapshot could be stale if the receiver is slow and skips an intermediate change. Callers that need a diff should compute it against their own previous snapshot:

let prev = std::mem::replace(&mut self.prev_snapshot, snapshot.clone());
let joined: BTreeSet<_> = snapshot.members.difference(&prev.members).copied().collect();
let left:   BTreeSet<_> = prev.members.difference(&snapshot.members).copied().collect();

Fields

members: BTreeSet<u32>

Current voting members (Follower / Leader role, Active status).

learners: BTreeSet<u32>

Current non-voting learners (Learner role, Promotable or ReadOnly status).

committed_index: u64

Raft log index of the ConfChange entry that produced this snapshot. Monotonically increasing; use as an idempotency key.

Trait Implementations

impl Clone for MembershipSnapshot

fn clone(&self) -> MembershipSnapshot

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for MembershipSnapshot

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

Formats the value using the given formatter.

impl Default for MembershipSnapshot

fn default() -> MembershipSnapshot

Returns the “default value” for a type.

impl Eq for MembershipSnapshot

impl PartialEq for MembershipSnapshot

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for MembershipSnapshot