Checkpointable

The Checkpointable trait enables an actor to define how its internal state can be saved and restored. This allows actors to participate in checkpointing and recovery mechanisms when supported by the surrounding system.

Trait definition

#[async_trait]
pub trait Checkpointable: Send + Sync + Sized {
    type State: RemoteMessage;

    async fn save(&self) -> Result<Self::State, CheckpointError>;
    async fn load(state: Self::State) -> Result<Self, CheckpointError>;
}

Associated Type

• type State: A serializable type representing the object’s saved state. This must implement RemoteMessage so it can serialized and transmitted.

save

Persists the current state of the component. Returns the Returns a Self::State value. If the operation fails, returns CheckpointError::Save.

load

Reconstructs a new instance from a previously saved Self::State. If deserialization or reconstruction fails, returns CheckpointError::Load.

CheckpointError

Errors returned by save and load operations:

pub enum CheckpointError {
    Save(anyhow::Error),
    Load(SeqId, anyhow::Error),
}

Blanket Implementation

Any type T that implements RemoteMessage and Clone automatically satisfies Checkpointable:

#[async_trait]
impl<T> Checkpointable for T
where
    T: RemoteMessage + Clone,
{
    type State = T;

    async fn save(&self) -> Result<Self::State, CheckpointError> {
        Ok(self.clone())
    }

    async fn load(state: Self::State) -> Result<Self, CheckpointError> {
        Ok(state)
    }
}

This implementation uses clone() to produce a checkpoint and simply returns the cloned state in load.