org.apache.flink.runtime.jobgraph.tasks.StatefulTask Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
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package org.apache.flink.runtime.jobgraph.tasks;
import org.apache.flink.runtime.state.StateHandle;
/**
* This interface must be implemented by any invokable that has recoverable state and participates
* in checkpointing.
*/
public interface StatefulTask> {
/**
* Sets the initial state of the operator, upon recovery. The initial state is typically
* a snapshot of the state from a previous execution.
*
* @param stateHandle The handle to the state.
*/
void setInitialState(T stateHandle) 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.
*
* @param checkpointId The ID of the checkpoint, incrementing.
* @param timestamp The timestamp when the checkpoint was triggered at the JobManager.
*
* @return {@code false} if the checkpoint can not be carried out, {@code true} otherwise
*/
boolean triggerCheckpoint(long checkpointId, long timestamp) throws Exception;
/**
* Invoked when a checkpoint has been completed, i.e., when the checkpoint coordinator has received
* the notification from all participating tasks.
*
* @param checkpointId The ID of the checkpoint that is complete..
* @throws Exception The notification method may forward its exceptions.
*/
void notifyCheckpointComplete(long checkpointId) throws Exception;
}