org.apache.flink.streaming.runtime.operators

Class GenericWriteAheadSink<IN>

java.lang.Object

org.apache.flink.streaming.api.operators.AbstractStreamOperator<IN>

org.apache.flink.streaming.runtime.operators.GenericWriteAheadSink<IN>

Type Parameters:

IN - Type of the elements emitted by this sink

All Implemented Interfaces:

Serializable, org.apache.flink.api.common.state.CheckpointListener, Input<IN>, KeyContext, OneInputStreamOperator<IN,IN>, SetupableStreamOperator<IN>, StreamOperator<IN>, StreamOperatorStateHandler.CheckpointedStreamOperator, org.apache.flink.util.Disposable

public abstract class GenericWriteAheadSink<IN>
extends AbstractStreamOperator<IN>
implements OneInputStreamOperator<IN,IN>

Generic Sink that emits its input elements into an arbitrary backend. This sink is integrated with Flink's checkpointing mechanism and can provide exactly-once guarantees; depending on the storage backend and sink/committer implementation.

Incoming records are stored within a AbstractStateBackend, and only committed if a checkpoint is completed.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected static org.slf4j.Logger	LOG
protected org.apache.flink.api.common.typeutils.TypeSerializer<IN>	serializer

Fields inherited from class org.apache.flink.streaming.api.operators.AbstractStreamOperator

chainingStrategy, config, latencyStats, metrics, output, processingTimeService

Constructor Summary

Constructors

Constructor and Description
GenericWriteAheadSink(CheckpointCommitter committer, org.apache.flink.api.common.typeutils.TypeSerializer<IN> serializer, String jobID)

Method Summary

Modifier and Type	Method and Description
void	close() This method is called after all records have been added to the operators via the methods Input.processElement(StreamRecord), or TwoInputStreamOperator.processElement1(StreamRecord) and TwoInputStreamOperator.processElement2(StreamRecord).
void	initializeState(org.apache.flink.runtime.state.StateInitializationContext context) Stream operators with state which can be restored need to override this hook method.
void	notifyCheckpointComplete(long checkpointId)
void	open() This method is called immediately before any elements are processed, it should contain the operator's initialization logic, e.g.
void	processElement(StreamRecord<IN> element) Processes one element that arrived on this input of the MultipleInputStreamOperator.
protected abstract boolean	sendValues(Iterable<IN> values, long checkpointId, long timestamp) Write the given element into the backend.
void	snapshotState(org.apache.flink.runtime.state.StateSnapshotContext context) Stream operators with state, which want to participate in a snapshot need to override this hook method.

Methods inherited from class org.apache.flink.streaming.api.operators.AbstractStreamOperator

dispose, getChainingStrategy, getContainingTask, getCurrentKey, getExecutionConfig, getInternalTimerService, getKeyedStateBackend, getKeyedStateStore, getMetricGroup, getOperatorConfig, getOperatorID, getOperatorName, getOperatorStateBackend, getOrCreateKeyedState, getPartitionedState, getPartitionedState, getProcessingTimeService, getRuntimeContext, getTimeServiceManager, getUserCodeClassloader, initializeState, isUsingCustomRawKeyedState, notifyCheckpointAborted, prepareSnapshotPreBarrier, processLatencyMarker, processLatencyMarker1, processLatencyMarker2, processWatermark, processWatermark1, processWatermark2, reportOrForwardLatencyMarker, setChainingStrategy, setCurrentKey, setKeyContextElement1, setKeyContextElement2, setProcessingTimeService, setup, snapshotState

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.flink.streaming.api.operators.OneInputStreamOperator

setKeyContextElement

Methods inherited from interface org.apache.flink.streaming.api.operators.StreamOperator

dispose, getMetricGroup, getOperatorID, initializeState, prepareSnapshotPreBarrier, setKeyContextElement1, setKeyContextElement2, snapshotState

Methods inherited from interface org.apache.flink.api.common.state.CheckpointListener

notifyCheckpointAborted

Methods inherited from interface org.apache.flink.streaming.api.operators.KeyContext

getCurrentKey, setCurrentKey

Methods inherited from interface org.apache.flink.streaming.api.operators.Input

processLatencyMarker, processWatermark

Field Detail

LOG

protected static final org.slf4j.Logger LOG

serializer

protected final org.apache.flink.api.common.typeutils.TypeSerializer<IN> serializer

Constructor Detail

GenericWriteAheadSink

public GenericWriteAheadSink(CheckpointCommitter committer,
                             org.apache.flink.api.common.typeutils.TypeSerializer<IN> serializer,
                             String jobID)
                      throws Exception

Throws:

Exception

Method Detail

initializeState

public void initializeState(org.apache.flink.runtime.state.StateInitializationContext context)
                     throws Exception

Description copied from class: AbstractStreamOperator

Stream operators with state which can be restored need to override this hook method.

Specified by:

initializeState in interface StreamOperatorStateHandler.CheckpointedStreamOperator

Overrides:

initializeState in class AbstractStreamOperator<IN>

Parameters:

context - context that allows to register different states.

Throws:

Exception

open

public void open()
          throws Exception

Description copied from class: AbstractStreamOperator

This method is called immediately before any elements are processed, it should contain the operator's initialization logic, e.g. state initialization.

The default implementation does nothing.

Specified by:

open in interface StreamOperator<IN>

Overrides:

open in class AbstractStreamOperator<IN>

Throws:

Exception - An exception in this method causes the operator to fail.

close

public void close()
           throws Exception

Description copied from class: AbstractStreamOperator

This method is called after all records have been added to the operators via the methods Input.processElement(StreamRecord), or TwoInputStreamOperator.processElement1(StreamRecord) and TwoInputStreamOperator.processElement2(StreamRecord).

The method is expected to flush all remaining buffered data. Exceptions during this flushing of buffered should be propagated, in order to cause the operation to be recognized asa failed, because the last data items are not processed properly.

Specified by:

close in interface StreamOperator<IN>

Overrides:

close in class AbstractStreamOperator<IN>

Throws:

Exception - An exception in this method causes the operator to fail.

snapshotState

public void snapshotState(org.apache.flink.runtime.state.StateSnapshotContext context)
                   throws Exception

Description copied from class: AbstractStreamOperator

Stream operators with state, which want to participate in a snapshot need to override this hook method.

Specified by:

snapshotState in interface StreamOperatorStateHandler.CheckpointedStreamOperator

Overrides:

snapshotState in class AbstractStreamOperator<IN>

Parameters:

context - context that provides information and means required for taking a snapshot

Throws:

Exception

notifyCheckpointComplete

public void notifyCheckpointComplete(long checkpointId)
                              throws Exception

Specified by:

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

Overrides:

notifyCheckpointComplete in class AbstractStreamOperator<IN>

Throws:

Exception

sendValues

protected abstract boolean sendValues(Iterable<IN> values,
                                      long checkpointId,
                                      long timestamp)
                               throws Exception

Write the given element into the backend.

Parameters:

values - The values to be written

checkpointId - The checkpoint ID of the checkpoint to be written

timestamp - The wall-clock timestamp of the checkpoint

Returns:

true, if the sending was successful, false otherwise

Throws:

Exception

processElement

public void processElement(StreamRecord<IN> element)
                    throws Exception

Description copied from interface: Input

Processes one element that arrived on this input of the MultipleInputStreamOperator. This method is guaranteed to not be called concurrently with other methods of the operator.

Specified by:

processElement in interface Input<IN>

Throws:

Exception