org.apache.flink.streaming.connectors.gcp.pubsub.common

Class AcknowledgeOnCheckpoint<ACKID extends Serializable>

java.lang.Object

org.apache.flink.streaming.connectors.gcp.pubsub.common.AcknowledgeOnCheckpoint<ACKID>

Type Parameters:

ACKID - Type of Ids to acknowledge

All Implemented Interfaces:

org.apache.flink.api.common.state.CheckpointListener, org.apache.flink.streaming.api.checkpoint.ListCheckpointed<AcknowledgeIdsForCheckpoint<ACKID>>

public class AcknowledgeOnCheckpoint<ACKID extends Serializable>
extends Object
implements org.apache.flink.api.common.state.CheckpointListener, org.apache.flink.streaming.api.checkpoint.ListCheckpointed<AcknowledgeIdsForCheckpoint<ACKID>>

Helper class for SourceFunctions to acknowledge messages to external systems after a successful checkpoint.

The mechanism for this source assumes that messages are identified by a unique ID. When messages are taken from the message queue, the message must not be dropped immediately from the external system, but must be retained until acknowledged. Messages that are not acknowledged within a certain time interval will be served again (to a different connection, established by the recovered source).

Note that this source can give no guarantees about message order in the case of failures, because messages that were retrieved but not yet acknowledged will be returned later again, after a set of messages that was not retrieved before the failure.

Internally, this class gathers the IDs of elements it emits. Per checkpoint, the IDs are stored and acknowledged when the checkpoint is complete. That way, no message is acknowledged unless it is certain that it has been successfully processed throughout the topology and the updates to any state caused by that message are persistent.

Constructor Summary

Constructors

Constructor and Description
AcknowledgeOnCheckpoint(Acknowledger<ACKID> acknowledger)

Method Summary

Modifier and Type	Method and Description
void	addAcknowledgeId(ACKID id)
void	notifyCheckpointAborted(long checkpointId)
void	notifyCheckpointComplete(long checkpointId)
int	numberOfOutstandingAcknowledgements()
void	restoreState(List<AcknowledgeIdsForCheckpoint<ACKID>> state)
List<AcknowledgeIdsForCheckpoint<ACKID>>	snapshotState(long checkpointId, long timestamp)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AcknowledgeOnCheckpoint

public AcknowledgeOnCheckpoint(Acknowledger<ACKID> acknowledger)

Method Detail

addAcknowledgeId

public void addAcknowledgeId(ACKID id)

notifyCheckpointComplete

public void notifyCheckpointComplete(long checkpointId)

Specified by:

notifyCheckpointComplete in interface org.apache.flink.api.common.state.CheckpointListener

notifyCheckpointAborted

public void notifyCheckpointAborted(long checkpointId)

Specified by:

notifyCheckpointAborted in interface org.apache.flink.api.common.state.CheckpointListener

snapshotState

public List<AcknowledgeIdsForCheckpoint<ACKID>> snapshotState(long checkpointId,
                                                              long timestamp)

Specified by:

snapshotState in interface org.apache.flink.streaming.api.checkpoint.ListCheckpointed<AcknowledgeIdsForCheckpoint<ACKID extends Serializable>>

restoreState

public void restoreState(List<AcknowledgeIdsForCheckpoint<ACKID>> state)

Specified by:

restoreState in interface org.apache.flink.streaming.api.checkpoint.ListCheckpointed<AcknowledgeIdsForCheckpoint<ACKID extends Serializable>>

numberOfOutstandingAcknowledgements

public int numberOfOutstandingAcknowledgements()