Package 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, KeyContextHandler, StreamOperator<OUT>, StreamOperatorStateHandler.CheckpointedStreamOperator, YieldingOperator<OUT>
Direct Known Subclasses:
AbstractAsyncStateStreamOperator, AbstractUdfStreamOperator, CacheTransformationTranslator.IdentityStreamOperator, CacheTransformationTranslator.NoOpStreamOperator, ContinuousFileReaderOperator, GlobalCommitterOperator, KeyedSortPartitionOperator, QueryableAppendingStateOperator, QueryableValueStateOperator, SortPartitionOperator, SourceOperator, StreamProject, TimestampsAndWatermarksOperator
@PublicEvolving public abstract class AbstractStreamOperator<OUT> extends Object implements StreamOperator<OUT>, YieldingOperator<OUT>, StreamOperatorStateHandler.CheckpointedStreamOperator, KeyContextHandler, 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:

  • Field Details

    • LOG

      protected static final org.slf4j.Logger LOG
      The logger used by the operator class and its subclasses.

    • config

      protected transient StreamConfig config

    • output

      protected transient Output<StreamRecord<OUT>> output

    • combinedWatermark

      protected transient org.apache.flink.api.common.eventtime.IndexedCombinedWatermarkStatus combinedWatermark

    • stateKeySelector1

      protected transient org.apache.flink.api.java.functions.KeySelector<?,?> stateKeySelector1
      KeySelector for extracting a key from an element being processed. This is used to scope keyed state to a key. This is null if the operator is not a keyed operator.

      This is for elements from the first input.

    • stateKeySelector2

      protected transient org.apache.flink.api.java.functions.KeySelector<?,?> stateKeySelector2
      KeySelector for extracting a key from an element being processed. This is used to scope keyed state to a key. This is null if the operator is not a keyed operator.

      This is for elements from the second input.

    • stateHandler

      protected transient StreamOperatorStateHandler stateHandler

    • timeServiceManager

      protected transient InternalTimeServiceManager<?> timeServiceManager

    • metrics

      protected transient InternalOperatorMetricGroup metrics
      Metric group for the operator.

    • latencyStats

      protected transient LatencyStats latencyStats

    • processingTimeService

      protected transient ProcessingTimeService processingTimeService

    • lastRecordAttributes1

      protected transient RecordAttributes lastRecordAttributes1

    • lastRecordAttributes2

      protected transient RecordAttributes lastRecordAttributes2

  • Constructor Details

    • AbstractStreamOperator

      public AbstractStreamOperator()

    • AbstractStreamOperator

      public AbstractStreamOperator(StreamOperatorParameters<OUT> parameters)

  • Method Details

    • setup

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

    • setProcessingTimeService

      protected void setProcessingTimeService(ProcessingTimeService processingTimeService)

    • getMetricGroup

      public org.apache.flink.metrics.groups.OperatorMetricGroup getMetricGroup()
      Specified by:
      getMetricGroup in interface StreamOperator<OUT>

    • beforeInitializeStateHandler

      protected void beforeInitializeStateHandler()
      Initialize necessary state components before initializing state components.

    • 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).

    • isAsyncStateProcessingEnabled

      @Internal public boolean isAsyncStateProcessingEnabled()
      Indicates whether this operator is enabling the async state. Can be overridden by subclasses.

    • setMailboxExecutor

      @Internal public void setMailboxExecutor(org.apache.flink.api.common.operators.MailboxExecutor mailboxExecutor)
      Specified by:
      setMailboxExecutor in interface YieldingOperator<OUT>

    • useSplittableTimers

      @Internal public boolean useSplittableTimers()
      Can be overridden to disable splittable timers for this particular operator even if config option is enabled. By default, splittable timers are disabled.
      Returns:
      true if splittable timers should be used (subject to StreamConfig.isUnalignedCheckpointsEnabled() and StreamConfig.isUnalignedCheckpointsSplittableTimersEnabled(). false if splittable timers should never be used.

    • 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 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
      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

      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 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

      public <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

    • hasKeyContext1

      @Internal public boolean hasKeyContext1()
      Description copied from interface: KeyContextHandler
      Whether the first input of StreamOperator has "KeyContext". If false, we can omit the call of StreamOperator.setKeyContextElement1(org.apache.flink.streaming.runtime.streamrecord.StreamRecord<?>) for each record arrived on the first input.
      Specified by:
      hasKeyContext1 in interface KeyContextHandler
      Returns:
      True if the first input has "KeyContext", false otherwise.

    • hasKeyContext2

      @Internal public boolean hasKeyContext2()
      Description copied from interface: KeyContextHandler
      Whether the second input of StreamOperator has "KeyContext". If false, we can omit the call of StreamOperator.setKeyContextElement1(org.apache.flink.streaming.runtime.streamrecord.StreamRecord<?>) for each record arrived on the second input.
      Specified by:
      hasKeyContext2 in interface KeyContextHandler
      Returns:
      True if the second input has "KeyContext", false otherwise.

    • 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()

    • getStateKeySelector1

      protected org.apache.flink.api.java.functions.KeySelector<?,?> getStateKeySelector1()

    • getStateKeySelector2

      protected org.apache.flink.api.java.functions.KeySelector<?,?> getStateKeySelector2()

    • 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

    • processWatermarkStatus

      public void processWatermarkStatus(WatermarkStatus watermarkStatus) throws Exception
      Throws:
      Exception

    • processWatermarkStatus

      protected void processWatermarkStatus(WatermarkStatus watermarkStatus, int index) throws Exception
      Throws:
      Exception

    • processWatermarkStatus1

      public final void processWatermarkStatus1(WatermarkStatus watermarkStatus) throws Exception
      Throws:
      Exception

    • processWatermarkStatus2

      public final void processWatermarkStatus2(WatermarkStatus watermarkStatus) throws Exception
      Throws:
      Exception

    • getOperatorID

      public OperatorID getOperatorID()
      Specified by:
      getOperatorID in interface StreamOperator<OUT>

    • getTimeServiceManager

      protected Optional<InternalTimeServiceManager<?>> getTimeServiceManager()

    • processRecordAttributes

      @Experimental public void processRecordAttributes(RecordAttributes recordAttributes) throws Exception
      Throws:
      Exception

    • processRecordAttributes1

      @Experimental public void processRecordAttributes1(RecordAttributes recordAttributes)

    • processRecordAttributes2

      @Experimental public void processRecordAttributes2(RecordAttributes recordAttributes)

    • processWatermark

      @Experimental public void processWatermark(WatermarkEvent watermark) throws Exception
      Throws:
      Exception

    • processWatermark1

      @Experimental public void processWatermark1(WatermarkEvent watermark) throws Exception
      Throws:
      Exception

    • processWatermark2

      @Experimental public void processWatermark2(WatermarkEvent watermark) throws Exception
      Throws:
      Exception