io.ray.api

Interface Checkpointable

public interface Checkpointable

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	Checkpointable.Checkpoint
static class	Checkpointable.CheckpointContext

Method Summary

Modifier and Type	Method and Description
void	checkpointExpired(ActorId actorId, UniqueId checkpointId) Delete an expired checkpoint; This method will be called when an checkpoint is expired.
UniqueId	loadCheckpoint(ActorId actorId, List<Checkpointable.Checkpoint> availableCheckpoints) Load actor's previous checkpoint, and restore actor's state.
void	saveCheckpoint(ActorId actorId, UniqueId checkpointId) Save a checkpoint to persistent storage.
boolean	shouldCheckpoint(Checkpointable.CheckpointContext checkpointContext) Whether this actor needs to be checkpointed.

Method Detail

shouldCheckpoint

boolean shouldCheckpoint(Checkpointable.CheckpointContext checkpointContext)

Whether this actor needs to be checkpointed. This method will be called after every task. You should implement this callback to decide whether this actor needs to be checkpointed at this time, based on the checkpoint context, or any other factors.

Parameters:

checkpointContext - An object that contains info about last checkpoint.

Returns:

A boolean value that indicates whether this actor needs to be checkpointed.

saveCheckpoint

void saveCheckpoint(ActorId actorId,
                    UniqueId checkpointId)

Save a checkpoint to persistent storage. If `shouldCheckpoint` returns true, this method will be called. You should implement this callback to save actor's checkpoint and the given checkpoint id to persistent storage.

Parameters:

actorId - Actor's ID.

checkpointId - An ID that represents this actor's current state in GCS. You should save this checkpoint ID together with actor's checkpoint data.

loadCheckpoint

UniqueId loadCheckpoint(ActorId actorId,
                        List<Checkpointable.Checkpoint> availableCheckpoints)

Load actor's previous checkpoint, and restore actor's state. This method will be called when an actor is restarted, after the actor's constructor. If the actor needs to restore from previous checkpoint, this function should restore actor's state and return the checkpoint ID. Otherwise, it should do nothing and return null.

Parameters:

actorId - Actor's ID.

availableCheckpoints - A list of available checkpoint IDs and their timestamps, sorted by timestamp in descending order. Note, this method must return the ID of one checkpoint in this list, or null. Otherwise, an exception will be thrown.

Returns:

The ID of the checkpoint from which the actor was resumed, or null if the actor should restart from the beginning.

checkpointExpired

void checkpointExpired(ActorId actorId,
                       UniqueId checkpointId)

Delete an expired checkpoint; This method will be called when an checkpoint is expired. You should implement this method to delete your application checkpoint data. Note, the maximum number of checkpoints kept in the backend can be configured at `RayConfig.num_actor_checkpoints_to_keep`.

Parameters:

actorId - ID of the actor.

checkpointId - ID of the checkpoint that has expired.