Enum MetaCommand 

pub enum MetaCommand {
    RegisterNode {
        descriptor: NodeDescriptor,
    },
    UpdateNodeState {
        node_id: NodeId,
        state: NodeState,
        expected_version: Option<MetadataVersion>,
    },
    RemoveNode {
        node_id: NodeId,
    },
    CreateDatabase {
        descriptor: DatabaseDescriptor,
    },
    DropDatabase {
        database_id: DatabaseId,
    },
    SetTableSchema {
        record: TableSchemaRecord,
    },
    SetTabletDescriptor {
        descriptor: TabletDescriptor,
    },
    RemoveTabletDescriptor {
        tablet_id: TabletId,
        generation: u64,
    },
    SetReplicaPlacement {
        placement: ReplicaPlacement,
    },
    SetPlacementPolicy {
        name: String,
        policy: PlacementPolicy,
    },
    SubmitSchemaJob {
        job: SchemaJobRecord,
    },
    UpdateSchemaJob {
        job_id: u64,
        state: SchemaJobState,
        updated_at: HlcTimestamp,
        error: Option<String>,
        expected_version: Option<MetadataVersion>,
    },
    SetClusterSetting {
        key: String,
        value: Value,
    },
    ActivateFeature {
        activation: FeatureActivation,
    },
    SetTxnStatusPartition {
        partition: TxnStatusPartition,
    },
    PublishSplit {
        command: SplitPublishCommand,
    },
    PublishMerge {
        command: MergePublishCommand,
    },
    AllocateRaftNodeIds {
        count: u32,
    },
}

One replicated meta control-plane command (spec section 12.1).

Every variant is deterministic and idempotent at apply: records are versioned (MetadataVersion, schema_version, or generation per record) and last-writer-wins guards reject stale or conflicting writes with a typed MetaRejectionReason instead of faulting the state machine.

Variants

RegisterNode

Registers (or re-registers) a cluster node’s descriptor. Identical re-registration is a no-op.

Fields

descriptor: NodeDescriptor

The node’s advertised descriptor.

UpdateNodeState

Updates a node’s lifecycle state; Decommissioned is terminal.

Fields

node_id: NodeId

The node to update.

state: NodeState

Requested lifecycle state.

expected_version: Option<MetadataVersion>

Optimistic-concurrency guard: when Some, the write applies only if the record’s current MetadataVersion equals it.

RemoveNode

Removes a node from membership. Refused while any tablet or placement still references the node; absent nodes are a no-op.

Fields

node_id: NodeId

The node to remove.

CreateDatabase

Creates a logical database. Name and id must both be free.

Fields

descriptor: DatabaseDescriptor

The new database’s descriptor.

DropDatabase

Drops a database. Refused while tables reference it; absent databases are a no-op.

Fields

database_id: DatabaseId

The database to drop.

SetTableSchema

Publishes a table schema (last-writer-wins by schema_version).

Fields

record: TableSchemaRecord

The schema record to publish.

SetTabletDescriptor

Publishes a tablet descriptor (last-writer-wins by generation).

Review m7: LWW is the intended concurrency model for SetTabletDescriptor / SetTableSchema. Only UpdateNodeState and UpdateSchemaJob carry expected_version CAS tokens. Two admins doing read-modify-write on one tablet descriptor can lose updates silently when the later write carries a higher generation — tooling must re-read before rewrite, or use a CAS-guarded command when added.

Fields

descriptor: TabletDescriptor

The tablet descriptor to publish.

RemoveTabletDescriptor

Removes a tablet descriptor at or above its stored generation.

Fields

tablet_id: TabletId

The tablet to remove.

generation: u64

Removal generation; below the stored generation the command is stale.

SetReplicaPlacement

Publishes the replica placement of one raft group.

Fields

placement: ReplicaPlacement

The placement to publish.

SetPlacementPolicy

Publishes (or replaces) a named placement policy (spec section 12.7).

Fields

name: String

Policy name.

policy: PlacementPolicy

The policy.

SubmitSchemaJob

Submits a schema/index job (starts SchemaJobState::Pending).

Fields

job: SchemaJobRecord

The job record.

UpdateSchemaJob

Transitions a schema job along the legal state graph.

Fields

job_id: u64

The job to transition.

state: SchemaJobState

Requested state.

updated_at: HlcTimestamp

Timestamp of the update.

error: Option<String>

Failure detail to record (cleared with None).

expected_version: Option<MetadataVersion>

Optimistic-concurrency guard; see MetaCommand::UpdateNodeState::expected_version.

SetClusterSetting

Sets one dynamic cluster setting (spec section 16.2; see KNOWN_SETTING_KEYS and SECRET_SETTING_KEY_DENYLIST).

Fields

key: String

Setting key.

value: Value

Setting value (typed per key).

ActivateFeature

Activates a cluster feature (spec section 11.8 step 5): refused at apply unless every non-decommissioned registered node supports the feature and the level satisfies the registry.

Fields

activation: FeatureActivation

The activation record.

SetTxnStatusPartition

Publishes one transaction status partition’s home group.

Fields

partition: TxnStatusPartition

The partition record.

PublishSplit

Publishes the atomic routing change of one tablet split (spec section 12.5 step 8): the children become Active and the source Retiring in ONE command. Refused unless the stored source is the command’s Splitting precursor and the stored children its Creating precursors at exactly one generation below the publication generation, the child bounds partition the source at the split key, and no other routable tablet of the table overlaps a child. An exact re-application (the stored descriptors already carry the command’s content) is a no-op, so a split resumed after a crash in the publication barrier may re-publish.

Fields

command: SplitPublishCommand

The publication (see crate::split::SplitPublishCommand).

PublishMerge

Publishes the atomic routing change of one tablet merge (spec section 12.6): the hidden replacement becomes Active and both sources Retiring in ONE command. Refused unless the stored sources are the command’s Merging precursors and the stored replacement its Creating precursor, with the command-wide generation one above the highest stored generation (a lagging source jumps to it), the replacement bounds covering exactly the source union, and no other routable tablet of the table overlapping the replacement. Exact re-application is a no-op (see Self::PublishSplit).

Fields

command: MergePublishCommand

The publication (see crate::merge::MergePublishCommand).

AllocateRaftNodeIds

Allocates count fresh per-group raft node ids from the meta-owned allocator (spec section 12.1: the meta control plane owns the node-id ↔ raft-id mapping; tablet replica raft ids come from this allocator, never the ad-hoc node-id projection the meta group itself uses). Ids are drawn from a monotonic counter that skips ids already in use (registered-node projections, tablet and placement replicas). The allocation is recorded under the command id, so a replayed command never double-allocates; the proposer reads the base back through MetaGroup::allocate_raft_node_ids.

Fields

count: u32

Number of ids to allocate (1..=MAX_RAFT_NODE_ID_ALLOCATION).

Trait Implementations

impl Clone for MetaCommand

fn clone(&self) -> MetaCommand

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for MetaCommand

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for MetaCommand

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for MetaCommand

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for MetaCommand

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 MetaCommand