Module vnode 

VnodeRegistry — runtime-configurable virtual node topology.

Replaces the compile-time VNODE_COUNT constant that previously lived in laminar-storage. A registry owns:

• the runtime-selected vnode count,
• the node-per-vnode assignment (for distributed modes),
• a monotonically increasing assignment_version used by ObjectStoreBackend to fence out stale writers.

Vnode assignment is derived from the row’s primary key via key_hash (xxh3) and modulo vnode_count. Connectors that need a vnode ID for an event call VnodeRegistry::vnode_for_key.

Structs

ArchivedNodeId

An archived NodeId

InvalidKeyGroupCount

A key-group count outside the supported 1..=65535 range.

KeyGroupCount

Validated number of stable key groups in a pipeline.

Locality

A node’s failure-domain locality: ordered tier values, coarsest first (e.g. ["us-east-1", "us-east-1a", "r17"]). Parsed from the node’s failure_domain gossip string.

NodeId

Unique identifier for a node. Also the owner id for vnodes; cluster membership and vnode ownership identify the same thing.

NodeIdResolver

The resolver for an archived NodeId

VnodeAssignmentReadGuard

Read guard that pins one assignment publication while a source captures a data batch or checkpoint cursor.

VnodeAssignmentSnapshot

One immutable publication of vnode ownership and the source cursors that belong to the same assignment version.

VnodeRegistry

Runtime registry of vnode topology and assignment.

Enums

VnodeLifecycleState

Per-vnode lifecycle state. Distinct from ownership: a vnode this node owns can still be Restoring while its committed state is being rehydrated from durable storage after a rebalance.

Constants

DEFAULT_CLUSTER_KEY_GROUP_COUNT

Default key-group count for cluster runtimes.

LOCAL_KEY_GROUP_COUNT

Fixed key-group count for embedded and single-node runtimes.

MAX_KEY_GROUP_COUNT

Largest key-group count representable by the persisted checkpoint ABI.

PARTITIONING_ABI_VERSION

Durable encoding and hashing contract used to map keys to key groups.

Functions

key_hash

Hash a key to a 64-bit value. Used to derive vnode IDs and for any other keyed-partitioning decisions.

owned_vnodes

Vnodes currently assigned to owner.

owners_per_domain

Owner counts per failure domain at isolation_tier. The largest value over vnode_count is the blast radius — the share of state that goes Restoring if that one domain fails at once.

peer_owners

Distinct assigned nodes other than self_id, sorted by id — the peer set a node fans checkpoint barriers and shuffle data out to.

rendezvous_assignment

Build a vnode-to-owner assignment using Rendezvous Hashing (Highest Random Weight).