Crate dstate 

dstate

Framework-agnostic distributed state replication for Rust actor systems.

dstate provides traits and replication logic for managing state that is replicated across nodes in a cluster. State changes are projected into public views, synchronized via configurable strategies, and persisted through a pluggable storage interface.

Core Traits

• DistributedState — Simple state where the entire value is the public view
• DeltaDistributedState — State with separate view/delta projections
• ActorRuntime — Actor spawning, timers, and processing groups
• StatePersistence — Async save/load for crash recovery
• Clock — Time abstraction for deterministic testing

Adapter Crates

Use dstate with a concrete actor framework via an adapter:

• dstate-ractor — ractor adapter
• dstate-kameo — kameo adapter

Re-exports

pub use engine::DistributedStateEngine;

pub use engine::EngineAction;

pub use engine::EngineHealth;

pub use engine::EngineQueryResult;

pub use engine::HealthStatus;

pub use engine::MutateResult;

pub use engine::DeltaMutateResult;

pub use engine::SyncMetrics;

pub use engine::WireMessage;

Modules

engine

Public API for driving the dstate replication protocol.

test_support

Structs

ActorSendError

Error returned by ActorRef::send().

BatchedChangeFeed

A batched collection of change notifications broadcast by the aggregator. No target node is specified because this message is broadcast to all nodes in the cluster.

ChangeFeedConfig

Configuration for the change feed aggregator.

ChangeNotification

A notification that a state has changed on a node (used by the change feed).

ClusterError

Error returned by ClusterEvents operations.

Generation

Logical version of a state, used for ordering and staleness detection.

GroupError

Error returned by processing group operations.

NodeId

Unique identifier for a node in the cluster.

StateConfig

Per-state-type configuration.

StateObject

The local node’s authoritative copy of a distributed state.

StateRegistry

Registry of all distributed state types on this node.

StateViewObject

A peer node’s replicated view of a distributed state.

SubscriptionId

Opaque handle returned by ClusterEvents::subscribe, used to cancel a subscription via ClusterEvents::unsubscribe.

SyncStrategy

Synchronization strategy composed from independent options.

SystemClock

Production clock delegating to std::time.

Enums

ClusterEvent

Events emitted by the cluster membership system.

DeserializeError

Errors from deserializing state/view/delta data.

MutationError

Errors from mutation operations.

PersistError

Errors from persistence operations.

PushMode

Push mode for synchronization.

QueryError

Errors from query operations.

RegistryError

Errors from state registration.

SyncMessage

Wire-level synchronization messages exchanged between nodes.

SyncUrgency

Urgency hint returned by DeltaDistributedState::sync_urgency().

VersionMismatchPolicy

Policy for handling wire version mismatches on inbound sync messages.

Traits

ActorRef

A handle to a running actor that can receive messages of type M.

ActorRuntime

The top-level actor runtime abstraction. One instance per node.

AnyStateShard

Type-erased interface for a registered state shard.

Clock

Abstraction over time sources, enabling deterministic testing.

ClusterEvents

Subscription to cluster membership events.

DeltaDistributedState

A distributed state type with separate State/View/Delta projections.

DistributedState

A distributed state type whose full state is the public view (no projection).

StatePersistence

Async trait for persisting state to durable storage.

TimerHandle

A handle to a scheduled timer that can be cancelled.