Struct ClusterState 

pub struct ClusterState {
    pub nodes: HashMap<NodeId, ClusterNode>,
    pub local_id: NodeId,
    pub config_epoch: u64,
    pub slot_map: SlotMap,
    pub state: ClusterHealth,
}

The complete state of the cluster as seen by a node.

Fields

nodes: HashMap<NodeId, ClusterNode>

All known nodes in the cluster, indexed by ID.

local_id: NodeId

This node’s ID.

config_epoch: u64

Current configuration epoch (increases on topology changes).

slot_map: SlotMap

Slot-to-node mapping.

state: ClusterHealth

Cluster state: ok, fail, or unknown.

Implementations

impl ClusterState

pub fn single_node(local_node: ClusterNode) -> Self

Creates a new cluster state for a single-node cluster.

pub fn new(local_id: NodeId) -> Self

Creates a new empty cluster state (for joining an existing cluster).

pub fn local_node(&self) -> Option<&ClusterNode>

Returns the local node.

pub fn local_node_mut(&mut self) -> Option<&mut ClusterNode>

Returns a mutable reference to the local node.

pub fn add_node(&mut self, node: ClusterNode)

Adds a node to the cluster.

pub fn remove_node(&mut self, node_id: NodeId) -> Option<ClusterNode>

Removes a node from the cluster.

pub fn slot_owner(&self, slot: u16) -> Option<&ClusterNode>

Returns the node that owns the given slot.

pub fn owns_slot(&self, slot: u16) -> bool

Returns true if the local node owns the given slot.

pub fn primaries(&self) -> impl Iterator<Item = &ClusterNode>

Returns all primary nodes.

pub fn replicas(&self) -> impl Iterator<Item = &ClusterNode>

Returns all replica nodes.

pub fn replicas_of( &self, primary_id: NodeId, ) -> impl Iterator<Item = &ClusterNode>

Returns replicas of a specific primary.

pub fn update_health(&mut self)

Computes and updates the cluster health state.

pub fn promote_replica(&mut self, replica_id: NodeId) -> Result<(), String>

Promotes a replica to primary, transferring slots from its current primary.

Performs the full state transition for a failover:

• Transfers all slots from the old primary to the promoted replica.
• Demotes the old primary to a replica of the new primary.
• Updates replica lists on both nodes.
• Bumps the global config epoch.

Returns an error if the target is not a replica with a configured primary.

pub fn cluster_info(&self) -> String

Generates the response for CLUSTER INFO command.

pub fn cluster_nodes(&self) -> String

Generates the response for CLUSTER NODES command.

pub fn moved_redirect( &self, slot: u16, ) -> Result<(u16, SocketAddr), ClusterError>

Generates MOVED redirect information for a slot.

pub fn to_nodes_conf(&self, incarnation: u64) -> String

Serializes the cluster state to the nodes.conf format.

The output consists of a comment header, a vars line with the current epoch and gossip incarnation, followed by one line per node in the standard CLUSTER NODES format.

pub fn from_nodes_conf(data: &str) -> Result<(Self, u64), ConfigParseError>

Parses a nodes.conf file and reconstructs the cluster state.

Returns the reconstructed state and the saved gossip incarnation number. Instant fields on nodes are initialized to Instant::now() since wall-clock timestamps aren’t persisted.

Trait Implementations

impl Debug for ClusterState

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

Formats the value using the given formatter.