Struct AssignmentSnapshot 

pub struct AssignmentSnapshot {
    pub version: u64,
    pub partitioning_abi_version: u16,
    pub vnodes: BTreeMap<u32, NodeId>,
    pub participants: Vec<CheckpointParticipant>,
    pub updated_at_ms: i64,
    pub draining: bool,
    pub drain_transition: Option<AssignmentDrainTransition>,
}

Durable vnode-to-instance assignment snapshot.

Fields

version: u64

Monotonic version. Writers bump on each update.

partitioning_abi_version: u16

Key encoding, hashing, and key-group mapping contract used by this owner map.

vnodes: BTreeMap<u32, NodeId>

Vnode id → owning instance. BTreeMap (not Vec) so snapshots with different vnode_count are still deserializable — sparse indices surface as missing keys the caller can diagnose.

participants: Vec<CheckpointParticipant>

Exact process roster certified for this assignment generation. A stable node restart changes this roster and therefore requires a new version even when vnode owners do not.

updated_at_ms: i64

Wall-clock timestamp of the last update, millis since epoch.

draining: bool

Pre-rotation drain phase: when set, this snapshot carries the intended next assignment but ownership has NOT changed yet. Nodes mark the vnodes they are about to lose as draining (pausing those source partitions) so the pre-rotation checkpoint is a clean cut; the leader then publishes the same assignment with draining = false to commit the rotation.

drain_transition: Option<AssignmentDrainTransition>

Exact predecessor, successor, and durable leader term for a draining generation. Present if and only if draining is true.

Implementations

impl AssignmentSnapshot

pub fn empty() -> Self

Empty snapshot at version 0.

pub fn next(&self, vnodes: BTreeMap<u32, NodeId>) -> Result<Self, SnapshotError>

Next snapshot with bumped version and current wall-clock time.

Errors

Returns an error if the version overflows or the successor is noncanonical.

pub fn next_for_participants( &self, vnodes: BTreeMap<u32, NodeId>, participants: Vec<CheckpointParticipant>, ) -> Result<Self, SnapshotError>

Next snapshot bound to the supplied canonical process roster.

Errors

Returns an error if the version overflows or the successor is noncanonical.

pub fn validate(&self) -> Result<(), SnapshotError>

Validate the durable owner map, process roster, and optional drain transition.

Errors

Returns an error when the snapshot or drain transition is noncanonical.

pub fn assignment_fence( &self, ) -> Result<CheckpointAssignmentFence, SnapshotError>

Exact checkpoint certificate represented by this snapshot.

Errors

Returns an error when the assignment map or process roster is noncanonical.

pub fn next_draining( &self, vnodes: BTreeMap<u32, NodeId>, participants: Vec<CheckpointParticipant>, leader: LeaderProof, ) -> Result<Self, SnapshotError>

Create the exact successor as a leader-fenced draining generation.

Errors

Rejects a non-committed predecessor, invalid successor, or leader proof outside both certified rosters.

pub fn committed_target(&self) -> Result<Self, SnapshotError>

Convert a draining generation into its committed target without changing identity.

Errors

Returns an error unless this is a valid draining snapshot.

pub fn aborted_target(&self, predecessor: &Self) -> Result<Self, SnapshotError>

Convert a draining generation into a committed rollback of its predecessor map.

Errors

Returns an error when either snapshot is invalid or the predecessor does not match.

pub fn has_canonical_participants(&self) -> bool

Whether the durable process roster is canonical and covers every vnode owner.

pub fn vnodes_from_vec(assignment: &[NodeId]) -> BTreeMap<u32, NodeId>

Convert a Vec<NodeId> (one entry per vnode id, dense) into the BTreeMap shape this snapshot uses. Mirrors the layout returned by rendezvous_assignment.

pub fn to_vnode_vec( &self, vnode_count: u32, ) -> Result<Vec<NodeId>, SnapshotError>

Convert the canonical owner map to a dense vector of exactly vnode_count entries.

Errors

Returns an error when the snapshot is invalid or its vnode map is not exactly dense.

Trait Implementations

impl Clone for AssignmentSnapshot

fn clone(&self) -> AssignmentSnapshot

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for AssignmentSnapshot

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for AssignmentSnapshot

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Eq for AssignmentSnapshot

impl PartialEq for AssignmentSnapshot

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for AssignmentSnapshot

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for AssignmentSnapshot