org.apache.flink.streaming.api.operators

Class AbstractStreamOperator<OUT>

java.lang.Object

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

Type Parameters:

OUT - The output type of the operator.

All Implemented Interfaces:

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

Direct Known Subclasses:

AbstractUdfStreamOperator, ContinuousFileReaderOperator, GenericWriteAheadSink, QueryableAppendingStateOperator, QueryableValueStateOperator, SourceOperator, StreamingGlobalCommitterOperator, StreamProject, TimestampsAndWatermarksOperator

@PublicEvolving
public abstract class AbstractStreamOperator<OUT>
extends Object
implements StreamOperator<OUT>, SetupableStreamOperator<OUT>, StreamOperatorStateHandler.CheckpointedStreamOperator, Serializable

Base class for all stream operators. Operators that contain a user function should extend the class AbstractUdfStreamOperator instead (which is a specialized subclass of this class).

For concrete implementations, one of the following two interfaces must also be implemented, to mark the operator as unary or binary: OneInputStreamOperator or TwoInputStreamOperator.

Methods of StreamOperator are guaranteed not to be called concurrently. Also, if using the timer service, timer callbacks are also guaranteed not to be called concurrently with methods on StreamOperator.

Note, this class is going to be removed and replaced in the future by AbstractStreamOperatorV2. However as AbstractStreamOperatorV2 is currently experimental, AbstractStreamOperator has not been deprecated just yet.

See Also:

Serialized Form

Field Summary

Fields

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

Constructor Summary

Constructors

Constructor and Description
AbstractStreamOperator()

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	dispose() 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.
ChainingStrategy	getChainingStrategy()
StreamTask<?,?>	getContainingTask()
Object	getCurrentKey()
org.apache.flink.api.common.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, org.apache.flink.api.common.typeutils.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> org.apache.flink.runtime.state.KeyedStateBackend<K>	getKeyedStateBackend()
org.apache.flink.api.common.state.KeyedStateStore	getKeyedStateStore()
org.apache.flink.metrics.MetricGroup	getMetricGroup()
StreamConfig	getOperatorConfig()
org.apache.flink.runtime.jobgraph.OperatorID	getOperatorID()
protected String	getOperatorName() Return the operator name.
org.apache.flink.runtime.state.OperatorStateBackend	getOperatorStateBackend()
protected <N,S extends org.apache.flink.api.common.state.State,T> S	getOrCreateKeyedState(org.apache.flink.api.common.typeutils.TypeSerializer<N> namespaceSerializer, org.apache.flink.api.common.state.StateDescriptor<S,T> stateDescriptor)
protected <S extends org.apache.flink.api.common.state.State,N> S	getPartitionedState(N namespace, org.apache.flink.api.common.typeutils.TypeSerializer<N> namespaceSerializer, org.apache.flink.api.common.state.StateDescriptor<S,?> stateDescriptor) Creates a partitioned state handle, using the state backend configured for this task.
protected <S extends org.apache.flink.api.common.state.State> S	getPartitionedState(org.apache.flink.api.common.state.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(org.apache.flink.runtime.state.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 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)
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	prepareSnapshotPreBarrier(long checkpointId) This method is called when the operator should do a snapshot, before it emits its own checkpoint barrier.
void	processLatencyMarker(LatencyMarker latencyMarker)
void	processLatencyMarker1(LatencyMarker latencyMarker)
void	processLatencyMarker2(LatencyMarker latencyMarker)
void	processWatermark(Watermark mark)
void	processWatermark1(Watermark mark)
void	processWatermark2(Watermark mark)
protected void	reportOrForwardLatencyMarker(LatencyMarker marker)
void	setChainingStrategy(ChainingStrategy strategy)
void	setCurrentKey(Object key)
void	setKeyContextElement1(StreamRecord record)
void	setKeyContextElement2(StreamRecord record)
void	setProcessingTimeService(ProcessingTimeService processingTimeService) Deprecated. The ProcessingTimeService instance should be passed by the operator constructor and this method will be removed along with SetupableStreamOperator.
void	setup(StreamTask<?,?> containingTask, StreamConfig config, Output<StreamRecord<OUT>> output) Initializes the operator.
OperatorSnapshotFutures	snapshotState(long checkpointId, long timestamp, org.apache.flink.runtime.checkpoint.CheckpointOptions checkpointOptions, org.apache.flink.runtime.state.CheckpointStreamFactory factory) Called to draw a state snapshot from the operator.
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 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.

chainingStrategy

protected ChainingStrategy chainingStrategy

config

protected transient StreamConfig config

output

protected transient Output<StreamRecord<OUT>> output

metrics

protected transient org.apache.flink.runtime.metrics.groups.OperatorMetricGroup metrics

Metric group for the operator.

latencyStats

protected transient LatencyStats latencyStats

processingTimeService

protected transient ProcessingTimeService processingTimeService

Constructor Detail

AbstractStreamOperator

public AbstractStreamOperator()

Method Detail

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>

setProcessingTimeService

@Deprecated
public void setProcessingTimeService(ProcessingTimeService processingTimeService)

Deprecated. The ProcessingTimeService instance should be passed by the operator constructor and this method will be removed along with SetupableStreamOperator.

getMetricGroup

public org.apache.flink.metrics.MetricGroup 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.

close

public void close()
           throws Exception

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<OUT>

Throws:

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

dispose

public void dispose()
             throws Exception

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.

Specified by:

dispose in interface StreamOperator<OUT>

Specified by:

dispose in interface org.apache.flink.util.Disposable

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,
                                                   org.apache.flink.runtime.checkpoint.CheckpointOptions checkpointOptions,
                                                   org.apache.flink.runtime.state.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(org.apache.flink.runtime.state.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(org.apache.flink.runtime.state.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

Specified by:

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

Throws:

Exception

notifyCheckpointAborted

public void notifyCheckpointAborted(long checkpointId)
                             throws Exception

Specified by:

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

Throws:

Exception

getExecutionConfig

public org.apache.flink.api.common.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()

getContainingTask

public StreamTask<?,?> getContainingTask()

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

@VisibleForTesting
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

@VisibleForTesting
public <K> org.apache.flink.runtime.state.KeyedStateBackend<K> getKeyedStateBackend()

getOperatorStateBackend

@VisibleForTesting
public org.apache.flink.runtime.state.OperatorStateBackend getOperatorStateBackend()

getProcessingTimeService

@VisibleForTesting
public ProcessingTimeService getProcessingTimeService()

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

getPartitionedState

protected <S extends org.apache.flink.api.common.state.State> S getPartitionedState(org.apache.flink.api.common.state.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 org.apache.flink.api.common.state.State,T> S getOrCreateKeyedState(org.apache.flink.api.common.typeutils.TypeSerializer<N> namespaceSerializer,
                                                                                          org.apache.flink.api.common.state.StateDescriptor<S,T> stateDescriptor)
                                                                                   throws Exception

Throws:

Exception

getPartitionedState

protected <S extends org.apache.flink.api.common.state.State,N> S getPartitionedState(N namespace,
                                                                                      org.apache.flink.api.common.typeutils.TypeSerializer<N> namespaceSerializer,
                                                                                      org.apache.flink.api.common.state.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.

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

setCurrentKey

public void setCurrentKey(Object key)

Specified by:

setCurrentKey in interface KeyContext

getCurrentKey

public Object getCurrentKey()

Specified by:

getCurrentKey in interface KeyContext

getKeyedStateStore

public org.apache.flink.api.common.state.KeyedStateStore getKeyedStateStore()

setChainingStrategy

public final void setChainingStrategy(ChainingStrategy strategy)

Specified by:

setChainingStrategy in interface SetupableStreamOperator<OUT>

getChainingStrategy

public final ChainingStrategy getChainingStrategy()

Specified by:

getChainingStrategy in interface SetupableStreamOperator<OUT>

processLatencyMarker

public void processLatencyMarker(LatencyMarker latencyMarker)
                          throws Exception

Throws:

Exception

processLatencyMarker1

public void processLatencyMarker1(LatencyMarker latencyMarker)
                           throws Exception

Throws:

Exception

processLatencyMarker2

public void processLatencyMarker2(LatencyMarker latencyMarker)
                           throws Exception

Throws:

Exception

reportOrForwardLatencyMarker

protected void reportOrForwardLatencyMarker(LatencyMarker marker)

getInternalTimerService

public <K,N> InternalTimerService<N> getInternalTimerService(String name,
                                                             org.apache.flink.api.common.typeutils.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

processWatermark1

public void processWatermark1(Watermark mark)
                       throws Exception

Throws:

Exception

processWatermark2

public void processWatermark2(Watermark mark)
                       throws Exception

Throws:

Exception

getOperatorID

public org.apache.flink.runtime.jobgraph.OperatorID getOperatorID()

Specified by:

getOperatorID in interface StreamOperator<OUT>

getTimeServiceManager

protected Optional<InternalTimeServiceManager<?>> getTimeServiceManager()