org.apache.flink.runtime.jobgraph.tasks

Interface StatefulTask<T extends StateHandle<?>>

All Known Implementing Classes:

OneInputStreamTask, SourceStreamTask, StoppableSourceStreamTask, StreamIterationHead, StreamIterationTail, StreamTask, TwoInputStreamTask

public interface StatefulTask<T extends StateHandle<?>>

This interface must be implemented by any invokable that has recoverable state and participates in checkpointing.

Method Summary

Modifier and Type	Method and Description
void	abortCheckpointOnBarrier(long checkpointId, Throwable cause) Aborts a checkpoint as the result of receiving possibly some checkpoint barriers, but at least one CancelCheckpointMarker.
void	notifyCheckpointComplete(long checkpointId) Invoked when a checkpoint has been completed, i.e., when the checkpoint coordinator has received the notification from all participating tasks.
void	setInitialState(T stateHandle) Sets the initial state of the operator, upon recovery.
boolean	triggerCheckpoint(long checkpointId, long timestamp) This method is either called directly and asynchronously by the checkpoint coordinator (in the case of functions that are directly notified - usually the data sources), or called synchronously when all incoming channels have reported a checkpoint barrier.
void	triggerCheckpointOnBarrier(long checkpointId, long timestamp) This method is called when a checkpoint is triggered as a result of receiving checkpoint barriers on all input streams.

Method Detail

setInitialState

void setInitialState(T stateHandle)
              throws Exception

Sets the initial state of the operator, upon recovery. The initial state is typically a snapshot of the state from a previous execution.

Parameters:

stateHandle - The handle to the state.

Throws:

Exception

triggerCheckpoint

boolean triggerCheckpoint(long checkpointId,
                          long timestamp)
                   throws Exception

This method is either called directly and asynchronously by the checkpoint coordinator (in the case of functions that are directly notified - usually the data sources), or called synchronously when all incoming channels have reported a checkpoint barrier.

Parameters:

checkpointId - The ID of the checkpoint, incrementing.

timestamp - The timestamp when the checkpoint was triggered at the JobManager.

Returns:

false if the checkpoint can not be carried out, true otherwise

Throws:

Exception

triggerCheckpointOnBarrier

void triggerCheckpointOnBarrier(long checkpointId,
                                long timestamp)
                         throws Exception

This method is called when a checkpoint is triggered as a result of receiving checkpoint barriers on all input streams.

Parameters:

checkpointId - The ID of the checkpoint, incrementing.

timestamp - The timestamp when the checkpoint was triggered at the JobManager.

Throws:

Exception - Exceptions thrown as the result of triggering a checkpoint are forwarded.

abortCheckpointOnBarrier

void abortCheckpointOnBarrier(long checkpointId,
                              Throwable cause)
                       throws Exception

Aborts a checkpoint as the result of receiving possibly some checkpoint barriers, but at least one CancelCheckpointMarker.

This requires implementing tasks to forward a CancelCheckpointMarker to their outputs.

Parameters:

checkpointId - The ID of the checkpoint to be aborted.

cause - The reason why the checkpoint was aborted during alignment

Throws:

Exception

notifyCheckpointComplete

void notifyCheckpointComplete(long checkpointId)
                       throws Exception

Invoked when a checkpoint has been completed, i.e., when the checkpoint coordinator has received the notification from all participating tasks.

Parameters:

checkpointId - The ID of the checkpoint that is complete..

Throws:

Exception - The notification method may forward its exceptions.