org.apache.flink.streaming.api.checkpoint.ExternallyInducedSource Maven / Gradle / Ivy
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*
* http://www.apache.org/licenses/LICENSE-2.0
*
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package org.apache.flink.streaming.api.checkpoint;
import org.apache.flink.annotation.Internal;
import org.apache.flink.streaming.api.functions.source.legacy.SourceFunction;
import org.apache.flink.util.FlinkException;
/**
* Sources that implement this interface delay checkpoints when receiving a trigger message from the
* checkpoint coordinator to the point when their input data/events indicate that a checkpoint
* should be triggered.
*
* Since sources cannot simply create a new checkpoint on their own, this mechanism always goes
* together with a {@link WithMasterCheckpointHook hook on the master side}. In a typical setup, the
* hook on the master tells the source system (for example the message queue) to prepare a
* checkpoint. The exact point when the checkpoint is taken is then controlled by the event stream
* received from the source, and triggered by the source function (implementing this interface) in
* Flink when seeing the relevant events.
*
* @param Type of the elements produced by the source function
* @param The type of the data stored in the checkpoint by the master that triggers
* @deprecated This interface is based on the {@link SourceFunction} API, which is due to be
* removed. Use the new {@link org.apache.flink.api.connector.source.Source} API instead.
*/
@Internal
public interface ExternallyInducedSource
extends SourceFunction, WithMasterCheckpointHook {
/**
* Sets the checkpoint trigger through which the source can trigger the checkpoint.
*
* @param checkpointTrigger The checkpoint trigger to set
*/
void setCheckpointTrigger(CheckpointTrigger checkpointTrigger);
// ------------------------------------------------------------------------
/**
* Through the {@code CheckpointTrigger}, the source function notifies the Flink source operator
* when to trigger the checkpoint.
*/
interface CheckpointTrigger {
/**
* Triggers a checkpoint. This method should be called by the source when it sees the event
* that indicates that a checkpoint should be triggered.
*
* When this method is called, the parallel operator instance in which the calling source
* function runs will perform its checkpoint and insert the checkpoint barrier into the data
* stream.
*
* @param checkpointId The ID that identifies the checkpoint.
* @throws FlinkException Thrown when the checkpoint could not be triggered, for example
* because of an invalid state or errors when storing the checkpoint state.
*/
void triggerCheckpoint(long checkpointId) throws FlinkException;
}
}