Module strategy 

The pure strategy interface and the strategy implementations.

A strategy is two pure functions over (observed cluster state, live signals, now):

• Strategy::update_state returns the durable writes the strategy wants (cut-overs, record writes/clears). The controller transacts these in the tick’s first phase.
• Strategy::desired_replicas returns the replica slots the strategy contributes to the cluster’s desired set. The controller unions every strategy’s contribution in the tick’s second phase.

Both are pure: same inputs, same output, no I/O. The controller is the sole mutator. Strategies never touch the ClusterControllerCtx directly. They declare the live signals they need via Strategy::signal_request and the controller fetches those before evaluating them.

Structs

BaselineStrategy

The implicit baseline strategy, always present.

DesiredReplica

A replica slot a strategy desires this tick. The reconcile kernel unions slots across strategies and matches them by ReplicaShape against the actual replica set.

GracefulReconfigurationStrategy

The graceful (zero-downtime) reconfiguration strategy.

LiveSignals

The fulfilled live signals for one cluster, fetched by the kernel per the unioned SignalRequest and passed alongside ClusterState.

SignalRequest

The live signals a strategy asks the kernel to fetch before evaluating a cluster, declared through Strategy::signal_request.

Constants

BASELINE_STRATEGY_NAME

The audit-attribution name of the baseline strategy.

GRACEFUL_RECONFIGURATION_STRATEGY_NAME

The audit-attribution name of the graceful reconfiguration strategy.

Traits

Strategy

One cluster-autoscaling strategy: a pair of pure functions the controller runs each tick. See the module docs.