Struct OnRefreshStrategy 

pub struct OnRefreshStrategy;

The ON REFRESH scheduling strategy.

Engaged for clusters with a non-MANUAL ClusterSchedule. It contributes one replica at the cluster’s realized shape while the cluster is inside a refresh window, and nothing otherwise. The window decision keys on the bound REFRESH materialized views’ write frontiers, their refresh schedules, the configured hydration-time estimate, and the current read timestamp (the same signals the legacy scheduler reads), all carried in RefreshWindowInputs.

The controller (not the user’s replication_factor) owns a scheduled cluster’s replica set, so Strategy::update_state normalizes the realized replication_factor to 0. This is self-healing (no migration needed to enable the controller) and makes mz_clusters.replication_factor read 0 for a scheduled cluster, with mz_cluster_replicas authoritative for what is actually running.

NB: the decision is re-derived purely from the live signals each tick; there is no “all policies have decided” latch like cluster_scheduling.rs needs. That scheduler collects policy decisions asynchronously and across ticks, so turning a cluster off is only safe once every policy has reported. We pull a complete decision from durable + storage state on every tick, so the first tick after a restart already decides from the same inputs as a steady tick.

Trait Implementations

impl Clone for OnRefreshStrategy

fn clone(&self) -> OnRefreshStrategy

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for OnRefreshStrategy

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

Formats the value using the given formatter.

impl Default for OnRefreshStrategy

fn default() -> OnRefreshStrategy

Returns the “default value” for a type.

impl Strategy for OnRefreshStrategy

fn signal_request( &self, state: &ClusterState, _config: &ConfigSignals, ) -> SignalRequest

The live signals this strategy needs to evaluate state this tick, declared as a pure function of the durable state and the tick’s config signals. The kernel unions the requests across strategies, fetches them through the ctx, and passes the result to Strategy::update_state and Strategy::desired_replicas. The default requests nothing, which suits a strategy that works off durable state alone (like the baseline).

fn update_state( &self, state: &ClusterState, _signals: &LiveSignals, _config: &ConfigSignals, _now: Timestamp, ) -> StateWrite

The durable writes this strategy wants for state at time now. The default is no write, which suits a strategy that only ever contributes replicas (like the baseline). An empty StateWrite means “write nothing”: the kernel drops it without emitting a decision.

fn desired_replicas( &self, state: &ClusterState, signals: &LiveSignals, _config: &ConfigSignals, _now: Timestamp, ) -> Vec<DesiredReplica>

The replica slots this strategy contributes to state’s desired set at time now.

impl Copy for OnRefreshStrategy