org.apache.flink.streaming.api.operators

Class AbstractStreamOperatorV2<OUT>

java.lang.Object

org.apache.flink.streaming.api.operators.AbstractStreamOperatorV2<OUT>

Type Parameters:

OUT - The output type of the operator

All Implemented Interfaces:

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

Direct Known Subclasses:

FusionStreamOperatorBase, MultipleInputStreamOperatorBase

@Experimental
public abstract class AbstractStreamOperatorV2<OUT>
extends Object
implements StreamOperator<OUT>, StreamOperatorStateHandler.CheckpointedStreamOperator

New base class for all stream operators, intended to eventually replace AbstractStreamOperator. Currently intended to work smoothly just with MultipleInputStreamOperator.

One note-able difference in comparison to AbstractStreamOperator is lack of AbstractStreamOperator.setup(StreamTask, StreamConfig, Output) in favor of initialisation in the constructor, and removed some tight coupling with classes like StreamTask.

Methods are guaranteed not to be called concurrently.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected StreamConfig	config
protected LatencyStats	latencyStats
protected static org.slf4j.Logger	LOG The logger used by the operator class and its subclasses.
protected InternalOperatorMetricGroup	metrics Metric group for the operator.
protected Output<StreamRecord<OUT>>	output
protected ProcessingTimeService	processingTimeService

Constructor Summary

Constructors

Constructor and Description
AbstractStreamOperatorV2(StreamOperatorParameters<OUT> parameters, int numberOfInputs)

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.
Object	getCurrentKey()
ExecutionConfig	getExecutionConfig() Gets the execution config defined on the execution environment of the job to which this operator belongs.
<K,N> InternalTimerService<N>	getInternalTimerService(String name, TypeSerializer<N> namespaceSerializer, Triggerable<K,N> triggerable) Returns a InternalTimerService that can be used to query current processing time and event time and to set timers.
<K> KeyedStateBackend<K>	getKeyedStateBackend()
Optional<KeyedStateStore>	getKeyedStateStore()
OperatorMetricGroup	getMetricGroup()
StreamConfig	getOperatorConfig()
OperatorID	getOperatorID()
protected String	getOperatorName() Return the operator name.
OperatorStateBackend	getOperatorStateBackend()
protected <N,S extends State,T> S	getOrCreateKeyedState(TypeSerializer<N> namespaceSerializer, StateDescriptor<S,T> stateDescriptor)
protected <S extends State,N> S	getPartitionedState(N namespace, TypeSerializer<N> namespaceSerializer, StateDescriptor<S,?> stateDescriptor) Creates a partitioned state handle, using the state backend configured for this task.
protected <S extends State> S	getPartitionedState(StateDescriptor<S,?> stateDescriptor) Creates a partitioned state handle, using the state backend configured for this task.
ProcessingTimeService	getProcessingTimeService() Returns the ProcessingTimeService responsible for getting the current processing time and registering timers.
StreamingRuntimeContext	getRuntimeContext() Returns a context that allows the operator to query information about the execution and also to interact with systems such as broadcast variables and managed state.
protected Optional<InternalTimeServiceManager<?>>	getTimeServiceManager()
ClassLoader	getUserCodeClassloader()
void	initializeState(StateInitializationContext context) Stream operators with state which can be restored need to override this hook method.
void	initializeState(StreamTaskStateInitializer streamTaskStateManager) Provides a context to initialize all state in the operator.
protected <T> void	internalSetKeyContextElement(StreamRecord<T> record, KeySelector<T,?> selector)
protected boolean	isUsingCustomRawKeyedState() Indicates whether or not implementations of this class is writing to the raw keyed state streams on snapshots, using snapshotState(StateSnapshotContext).
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. state initialization.
void	prepareSnapshotPreBarrier(long checkpointId) This method is called when the operator should do a snapshot, before it emits its own checkpoint barrier.
void	processWatermark(Watermark mark)
void	processWatermarkStatus(WatermarkStatus watermarkStatus, int inputId)
protected void	reportOrForwardLatencyMarker(LatencyMarker marker)
protected void	reportWatermark(Watermark mark, int inputId)
void	setCurrentKey(Object key)
void	setKeyContextElement1(StreamRecord<?> record)
void	setKeyContextElement2(StreamRecord<?> record)
OperatorSnapshotFutures	snapshotState(long checkpointId, long timestamp, CheckpointOptions checkpointOptions, CheckpointStreamFactory factory) Called to draw a state snapshot from 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 java.lang.Object

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

Field Detail

LOG

protected static final org.slf4j.Logger LOG

The logger used by the operator class and its subclasses.

config

protected final StreamConfig config

output

protected final Output<StreamRecord<OUT>> output

metrics

protected final InternalOperatorMetricGroup metrics

Metric group for the operator.

latencyStats

protected final LatencyStats latencyStats

processingTimeService

protected final ProcessingTimeService processingTimeService

Constructor Detail

AbstractStreamOperatorV2

public AbstractStreamOperatorV2(StreamOperatorParameters<OUT> parameters,
                                int numberOfInputs)

Method Detail

getMetricGroup

public OperatorMetricGroup getMetricGroup()

Specified by:

getMetricGroup in interface StreamOperator<OUT>

initializeState

public final void initializeState(StreamTaskStateInitializer streamTaskStateManager)
                           throws Exception

Description copied from interface: StreamOperator

Provides a context to initialize all state in the operator.

Specified by:

initializeState in interface StreamOperator<OUT>

Throws:

Exception

isUsingCustomRawKeyedState

@Internal
protected boolean isUsingCustomRawKeyedState()

Indicates whether or not implementations of this class is writing to the raw keyed state streams on snapshots, using snapshotState(StateSnapshotContext). If yes, subclasses should override this method to return true.

Subclasses need to explicitly indicate the use of raw keyed state because, internally, the AbstractStreamOperator may attempt to read from it as well to restore heap-based timers and ultimately fail with read errors. By setting this flag to true, this allows the AbstractStreamOperator to know that the data written in the raw keyed states were not written by the timer services, and skips the timer restore attempt.

Please refer to FLINK-19741 for further details.

TODO: this method can be removed once all timers are moved to be managed by state backends.

Returns:

flag indicating whether or not this operator is writing to raw keyed state via snapshotState(StateSnapshotContext).

open

public void open()
          throws Exception

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>

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>

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>

Throws:

Exception

prepareSnapshotPreBarrier

public void prepareSnapshotPreBarrier(long checkpointId)
                               throws Exception

Description copied from interface: StreamOperator

This method is called when the operator should do a snapshot, before it emits its own checkpoint barrier.

This method is intended not for any actual state persistence, but only for emitting some data before emitting the checkpoint barrier. Operators that maintain some small transient state that is inefficient to checkpoint (especially when it would need to be checkpointed in a re-scalable way) but can simply be sent downstream before the checkpoint. An example are opportunistic pre-aggregation operators, which have small the pre-aggregation state that is frequently flushed downstream.

Important: This method should not be used for any actual state snapshot logic, because it will inherently be within the synchronous part of the operator's checkpoint. If heavy work is done within this method, it will affect latency and downstream checkpoint alignments.

Specified by:

prepareSnapshotPreBarrier in interface StreamOperator<OUT>

Parameters:

checkpointId - The ID of the checkpoint.

Throws:

Exception - Throwing an exception here causes the operator to fail and go into recovery.

snapshotState

public final OperatorSnapshotFutures snapshotState(long checkpointId,
                                                   long timestamp,
                                                   CheckpointOptions checkpointOptions,
                                                   CheckpointStreamFactory factory)
                                            throws Exception

Description copied from interface: StreamOperator

Called to draw a state snapshot from the operator.

Specified by:

snapshotState in interface StreamOperator<OUT>

Returns:

a runnable future to the state handle that points to the snapshotted state. For synchronous implementations, the runnable might already be finished.

Throws:

Exception - exception that happened during snapshotting.

snapshotState

public void snapshotState(StateSnapshotContext context)
                   throws Exception

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

Specified by:

snapshotState in interface StreamOperatorStateHandler.CheckpointedStreamOperator

Parameters:

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

Throws:

Exception

initializeState

public void initializeState(StateInitializationContext context)
                     throws Exception

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

Specified by:

initializeState in interface StreamOperatorStateHandler.CheckpointedStreamOperator

Parameters:

context - context that allows to register different states.

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

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

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.

getExecutionConfig

public ExecutionConfig getExecutionConfig()

Gets the execution config defined on the execution environment of the job to which this operator belongs.

Returns:

The job's execution config.

getOperatorConfig

public StreamConfig getOperatorConfig()

getUserCodeClassloader

public ClassLoader getUserCodeClassloader()

getOperatorName

protected String getOperatorName()

Return the operator name. If the runtime context has been set, then the task name with subtask index is returned. Otherwise, the simple class name is returned.

Returns:

If runtime context is set, then return task name with subtask index. Otherwise return simple class name.

getRuntimeContext

public StreamingRuntimeContext getRuntimeContext()

Returns a context that allows the operator to query information about the execution and also to interact with systems such as broadcast variables and managed state. This also allows to register timers.

getKeyedStateBackend

public <K> KeyedStateBackend<K> getKeyedStateBackend()

getOperatorStateBackend

@VisibleForTesting
public OperatorStateBackend getOperatorStateBackend()

getProcessingTimeService

@VisibleForTesting
public ProcessingTimeService getProcessingTimeService()

Returns the ProcessingTimeService responsible for getting the current processing time and registering timers.

getPartitionedState

protected <S extends State> S getPartitionedState(StateDescriptor<S,?> stateDescriptor)
                                           throws Exception

Creates a partitioned state handle, using the state backend configured for this task.

Throws:

IllegalStateException - Thrown, if the key/value state was already initialized.

Exception - Thrown, if the state backend cannot create the key/value state.

getOrCreateKeyedState

protected <N,S extends State,T> S getOrCreateKeyedState(TypeSerializer<N> namespaceSerializer,
                                                        StateDescriptor<S,T> stateDescriptor)
                                                 throws Exception

Throws:

Exception

getPartitionedState

protected <S extends State,N> S getPartitionedState(N namespace,
                                                    TypeSerializer<N> namespaceSerializer,
                                                    StateDescriptor<S,?> stateDescriptor)
                                             throws Exception

Creates a partitioned state handle, using the state backend configured for this task.

Throws:

IllegalStateException - Thrown, if the key/value state was already initialized.

Exception - Thrown, if the state backend cannot create the key/value state.

internalSetKeyContextElement

protected <T> void internalSetKeyContextElement(StreamRecord<T> record,
                                                KeySelector<T,?> selector)
                                         throws Exception

Throws:

Exception

setCurrentKey

public void setCurrentKey(Object key)

Specified by:

setCurrentKey in interface KeyContext

getCurrentKey

public Object getCurrentKey()

Specified by:

getCurrentKey in interface KeyContext

getKeyedStateStore

public Optional<KeyedStateStore> getKeyedStateStore()

reportOrForwardLatencyMarker

protected void reportOrForwardLatencyMarker(LatencyMarker marker)

getInternalTimerService

@VisibleForTesting
public <K,N> InternalTimerService<N> getInternalTimerService(String name,
                                                                                TypeSerializer<N> namespaceSerializer,
                                                                                Triggerable<K,N> triggerable)

Returns a InternalTimerService that can be used to query current processing time and event time and to set timers. An operator can have several timer services, where each has its own namespace serializer. Timer services are differentiated by the string key that is given when requesting them, if you call this method with the same key multiple times you will get the same timer service instance in subsequent requests.

Timers are always scoped to a key, the currently active key of a keyed stream operation. When a timer fires, this key will also be set as the currently active key.

Each timer has attached metadata, the namespace. Different timer services can have a different namespace type. If you don't need namespace differentiation you can use VoidNamespaceSerializer as the namespace serializer.

Type Parameters:

N - The type of the timer namespace.

Parameters:

name - The name of the requested timer service. If no service exists under the given name a new one will be created and returned.

namespaceSerializer - TypeSerializer for the timer namespace.

triggerable - The Triggerable that should be invoked when timers fire

processWatermark

public void processWatermark(Watermark mark)
                      throws Exception

Throws:

Exception

reportWatermark

protected void reportWatermark(Watermark mark,
                               int inputId)
                        throws Exception

Throws:

Exception

processWatermarkStatus

public final void processWatermarkStatus(WatermarkStatus watermarkStatus,
                                         int inputId)
                                  throws Exception

Throws:

Exception

getOperatorID

public OperatorID getOperatorID()

Specified by:

getOperatorID in interface StreamOperator<OUT>

setKeyContextElement1

public void setKeyContextElement1(StreamRecord<?> record)
                           throws Exception

Specified by:

setKeyContextElement1 in interface StreamOperator<OUT>

Throws:

Exception

setKeyContextElement2

public void setKeyContextElement2(StreamRecord<?> record)
                           throws Exception

Specified by:

setKeyContextElement2 in interface StreamOperator<OUT>

Throws:

Exception

getTimeServiceManager

protected Optional<InternalTimeServiceManager<?>> getTimeServiceManager()