org.apache.flink.streaming.api.operators

Class AbstractUdfStreamOperator<OUT,F extends Function>

java.lang.Object

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

org.apache.flink.streaming.api.operators.AbstractUdfStreamOperator<OUT,F>

Type Parameters:

OUT - The output type of the operator

F - The type of the user function

All Implemented Interfaces:

Serializable, CheckpointListener, KeyContext, OutputTypeConfigurable<OUT>, SetupableStreamOperator<OUT>, StreamOperator<OUT>, StreamOperatorStateHandler.CheckpointedStreamOperator

Direct Known Subclasses:

AsyncWaitOperator, BatchGroupedReduceOperator, BroadcastStateBootstrapOperator, CepOperator, CoBroadcastWithKeyedOperator, CoBroadcastWithNonKeyedOperator, CoProcessOperator, CoStreamFlatMap, CoStreamMap, GroupReduceOperator, IntervalJoinOperator, KeyedCoProcessOperator, KeyedProcessOperator, KeyedStateBootstrapOperator, LegacyKeyedCoProcessOperator, LegacyKeyedProcessOperator, ProcessOperator, SinkOperator, StateBootstrapOperator, StreamFilter, StreamFlatMap, StreamGroupedReduceOperator, StreamMap, StreamSink, StreamSource, WindowOperator

@PublicEvolving
public abstract class AbstractUdfStreamOperator<OUT,F extends Function>
extends AbstractStreamOperator<OUT>
implements OutputTypeConfigurable<OUT>

This is used as the base class for operators that have a user-defined function. This class handles the opening and closing of the user-defined functions, as part of the operator life cycle.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected F	userFunction The user function.

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

chainingStrategy, config, latencyStats, LOG, metrics, output, processingTimeService

Constructor Summary

Constructors

Constructor and Description
AbstractUdfStreamOperator(F userFunction)

Method Summary

Modifier and Type	Method and Description
void	close() This method is called at the very end of the operator's life, both in the case of a successful completion of the operation, and in the case of a failure and canceling.
void	finish() This method is called at the end of data processing.
F	getUserFunction() Gets the user function executed in this operator.
Configuration	getUserFunctionParameters() Since the streaming API does not implement any parametrization of functions via a configuration, the config returned here is actually empty.
void	initializeState(StateInitializationContext context) Stream operators with state which can be restored need to override this hook method.
void	notifyCheckpointAborted(long checkpointId) This method is called as a notification once a distributed checkpoint has been aborted.
void	notifyCheckpointComplete(long checkpointId) Notifies the listener that the checkpoint with the given checkpointId completed and was committed.
void	open() This method is called immediately before any elements are processed, it should contain the operator's initialization logic, e.g.
void	setOutputType(TypeInformation<OUT> outTypeInfo, ExecutionConfig executionConfig) Is called by the org.apache.flink.streaming.api.graph.StreamGraph#addOperator(Integer, String, StreamOperator, TypeInformation, TypeInformation, String) method when the StreamGraph is generated.
void	setup(StreamTask<?,?> containingTask, StreamConfig config, Output<StreamRecord<OUT>> output) Initializes the operator.
void	snapshotState(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

getChainingStrategy, getContainingTask, getCurrentKey, getExecutionConfig, getInternalTimerService, getKeyedStateBackend, getKeyedStateStore, getMetricGroup, getOperatorConfig, getOperatorID, getOperatorName, getOperatorStateBackend, getOrCreateKeyedState, getPartitionedState, getPartitionedState, getProcessingTimeService, getRuntimeContext, getTimeServiceManager, getUserCodeClassloader, initializeState, isUsingCustomRawKeyedState, prepareSnapshotPreBarrier, processLatencyMarker, processLatencyMarker1, processLatencyMarker2, processWatermark, processWatermark1, processWatermark2, processWatermarkStatus, processWatermarkStatus1, processWatermarkStatus2, registerCounterOnOutput, reportOrForwardLatencyMarker, setChainingStrategy, setCurrentKey, setKeyContextElement1, setKeyContextElement2, setProcessingTimeService, snapshotState

Methods inherited from class java.lang.Object

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

Field Detail

userFunction

protected final F extends Function userFunction

The user function.

Constructor Detail

AbstractUdfStreamOperator

public AbstractUdfStreamOperator(F userFunction)

Method Detail

getUserFunction

public F getUserFunction()

Gets the user function executed in this operator.

Returns:

The user function of this operator.

setup

public void setup(StreamTask<?,?> containingTask,
                  StreamConfig config,
                  Output<StreamRecord<OUT>> output)

Description copied from interface: SetupableStreamOperator

Initializes the operator. Sets access to the context and the output.

Specified by:

setup in interface SetupableStreamOperator<OUT>

Overrides:

setup in class AbstractStreamOperator<OUT>

snapshotState

public void snapshotState(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<OUT>

Parameters:

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

Throws:

Exception

initializeState

public void initializeState(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<OUT>

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<OUT>

Overrides:

open in class AbstractStreamOperator<OUT>

Throws:

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

finish

public void finish()
            throws Exception

Description copied from interface: StreamOperator

This method is called at the end of data processing.

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

After this method is called, no more records can be produced for the downstream operators.

WARNING: It is not safe to use this method to commit any transactions or other side effects! You can use this method to flush any buffered data that can later on be committed e.g. in a CheckpointListener.notifyCheckpointComplete(long).

NOTE:This method does not need to close any resources. You should release external resources in the StreamOperator.close() method.

Specified by:

finish in interface StreamOperator<OUT>

Overrides:

finish in class AbstractStreamOperator<OUT>

Throws:

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

close

public void close()
           throws Exception

Description copied from interface: StreamOperator

This method is called at the very end of the operator's life, both in the case of a successful completion of the operation, and in the case of a failure and canceling.

This method is expected to make a thorough effort to release all resources that the operator has acquired.

NOTE:It can not emit any records! If you need to emit records at the end of processing, do so in the StreamOperator.finish() method.

Specified by:

close in interface StreamOperator<OUT>

Overrides:

close in class AbstractStreamOperator<OUT>

Throws:

Exception

notifyCheckpointComplete

public void notifyCheckpointComplete(long checkpointId)
                              throws Exception

Description copied from interface: CheckpointListener

Notifies the listener that the checkpoint with the given checkpointId completed and was committed.

These notifications are "best effort", meaning they can sometimes be skipped. To behave properly, implementers need to follow the "Checkpoint Subsuming Contract". Please see the class-level JavaDocs for details.

Please note that checkpoints may generally overlap, so you cannot assume that the notifyCheckpointComplete() call is always for the latest prior checkpoint (or snapshot) that was taken on the function/operator implementing this interface. It might be for a checkpoint that was triggered earlier. Implementing the "Checkpoint Subsuming Contract" (see above) properly handles this situation correctly as well.

Please note that throwing exceptions from this method will not cause the completed checkpoint to be revoked. Throwing exceptions will typically cause task/job failure and trigger recovery.

Specified by:

notifyCheckpointComplete in interface CheckpointListener

Overrides:

notifyCheckpointComplete in class AbstractStreamOperator<OUT>

Parameters:

checkpointId - The ID of the checkpoint that has been completed.

Throws:

Exception - This method can propagate exceptions, which leads to a failure/recovery for the task. Note that this will NOT lead to the checkpoint being revoked.

notifyCheckpointAborted

public void notifyCheckpointAborted(long checkpointId)
                             throws Exception

Description copied from interface: CheckpointListener

This method is called as a notification once a distributed checkpoint has been aborted.

Important: The fact that a checkpoint has been aborted does NOT mean that the data and artifacts produced between the previous checkpoint and the aborted checkpoint are to be discarded. The expected behavior is as if this checkpoint was never triggered in the first place, and the next successful checkpoint simply covers a longer time span. See the "Checkpoint Subsuming Contract" in the class-level JavaDocs for details.

These notifications are "best effort", meaning they can sometimes be skipped.

This method is very rarely necessary to implement. The "best effort" guarantee, together with the fact that this method should not result in discarding any data (per the "Checkpoint Subsuming Contract") means it is mainly useful for earlier cleanups of auxiliary resources. One example is to pro-actively clear a local per-checkpoint state cache upon checkpoint failure.

Specified by:

notifyCheckpointAborted in interface CheckpointListener

Overrides:

notifyCheckpointAborted in class AbstractStreamOperator<OUT>

Parameters:

checkpointId - The ID of the checkpoint that has been aborted.

Throws:

Exception - This method can propagate exceptions, which leads to a failure/recovery for the task or job.

setOutputType

public void setOutputType(TypeInformation<OUT> outTypeInfo,
                          ExecutionConfig executionConfig)

Description copied from interface: OutputTypeConfigurable

Is called by the org.apache.flink.streaming.api.graph.StreamGraph#addOperator(Integer, String, StreamOperator, TypeInformation, TypeInformation, String) method when the StreamGraph is generated. The method is called with the output TypeInformation which is also used for the StreamTask output serializer.

Specified by:

setOutputType in interface OutputTypeConfigurable<OUT>

Parameters:

outTypeInfo - Output type information of the StreamTask

executionConfig - Execution configuration

getUserFunctionParameters

public Configuration getUserFunctionParameters()

Since the streaming API does not implement any parametrization of functions via a configuration, the config returned here is actually empty.

Returns:

The user function parameters (currently empty)