Struct DistributedStateManager 

pub struct DistributedStateManager { /* private fields */ }

The main distributed state manager that coordinates state across stream processors.

Provides:

• Periodic state checkpointing via operator snapshots
• Exactly-once semantics via sequence-number deduplication
• State migration when processors join or leave the cluster

Implementations

impl DistributedStateManager

pub fn new( node_id: impl Into<String>, checkpoint_config: CheckpointConfig, dedup_config: DeduplicationConfig, ) -> Self

Creates a new distributed state manager.

pub fn node_id(&self) -> &str

Returns the node ID of this manager.

pub fn register_processor(&self, node_id: impl Into<String>)

Registers a processor node as active.

pub fn remove_processor(&self, node_id: &str)

Removes a processor node.

pub fn assign_partition(&self, assignment: PartitionAssignment)

Assigns a partition to a processor.

pub fn check_exactly_once(&self, source_id: &str, sequence_number: u64) -> bool

Checks and records a message for exactly-once processing.

Returns true if the message is new and should be processed.

pub fn high_watermark(&self, source_id: &str) -> u64

Returns the high watermark for a source.

pub fn take_checkpoint( &self, operator_states: HashMap<String, Vec<u8>>, ) -> StateResult<StateCheckpoint>

Takes a checkpoint of the given operator states.

Returns the checkpoint if successful.

pub fn restore_from_latest(&self) -> Option<HashMap<String, Vec<u8>>>

Restores state from the latest checkpoint.

Returns the operator states map if a checkpoint exists.

pub fn checkpoints(&self) -> Vec<StateCheckpoint>

Returns all stored checkpoints (most recent first).

pub fn is_checkpoint_due(&self) -> bool

Returns whether a checkpoint is due based on the configured interval.

pub fn plan_migration(&self, reason: MigrationReason) -> Option<MigrationPlan>

Plans a migration based on the current partition assignments and processor set.

Returns None if no migration is needed.

pub fn execute_migration(&self, plan: &MigrationPlan) -> usize

Executes a migration plan by updating partition assignments.

Returns the number of partitions migrated.

pub fn handle_node_joined(&self, node_id: &str) -> Option<MigrationPlan>

Handles a node joining the cluster: registers it and optionally migrates.

pub fn handle_node_left(&self, node_id: &str) -> Option<MigrationPlan>

Handles a node leaving the cluster: reassigns its partitions.

pub fn partition_assignments(&self) -> Vec<PartitionAssignment>

Returns current partition assignments.

pub fn active_processors(&self) -> Vec<String>

Returns active processor node IDs.

pub fn migration_history(&self) -> Vec<MigrationPlan>

Returns migration history.

pub fn stats(&self) -> DistributedStateManagerStats

Returns comprehensive statistics.