org.apache.flink.streaming.api.checkpoint

Interface ExternallyInducedSource<T,CD>

Type Parameters:

T - Type of the elements produced by the source function

CD - The type of the data stored in the checkpoint by the master that triggers

All Superinterfaces:

org.apache.flink.api.common.functions.Function, Serializable, SourceFunction<T>, WithMasterCheckpointHook<CD>

@PublicEvolving
public interface ExternallyInducedSource<T,CD>
extends SourceFunction<T>, WithMasterCheckpointHook<CD>

Sources that implement this interface do not trigger checkpoints when receiving a trigger message from the checkpoint coordinator, but 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 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.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	ExternallyInducedSource.CheckpointTrigger Through the CheckpointTrigger, the source function notifies the Flink source operator when to trigger the checkpoint.

Nested classes/interfaces inherited from interface org.apache.flink.streaming.api.functions.source.SourceFunction

SourceFunction.SourceContext<T>

Method Summary

Modifier and Type	Method and Description
void	setCheckpointTrigger(ExternallyInducedSource.CheckpointTrigger checkpointTrigger) Sets the checkpoint trigger through which the source can trigger the checkpoint.

Methods inherited from interface org.apache.flink.streaming.api.functions.source.SourceFunction

cancel, run

Methods inherited from interface org.apache.flink.streaming.api.checkpoint.WithMasterCheckpointHook

createMasterTriggerRestoreHook

Method Detail

setCheckpointTrigger

void setCheckpointTrigger(ExternallyInducedSource.CheckpointTrigger checkpointTrigger)

Sets the checkpoint trigger through which the source can trigger the checkpoint.

Parameters:

checkpointTrigger - The checkpoint trigger to set