org.apache.flink.streaming.api.operators

Interface StreamOperator<OUT>

Type Parameters:

OUT - The output type of the operator

All Superinterfaces:

CheckpointListener, Disposable, KeyContext, Serializable

All Known Subinterfaces:

OneInputStreamOperator<IN,OUT>, TwoInputStreamOperator<IN1,IN2,OUT>

All Known Implementing Classes:

AbstractKeyedCEPPatternOperator, AbstractStreamOperator, AbstractUdfStreamOperator, AsyncWaitOperator, BoltWrapper, CassandraRowWriteAheadSink, CassandraTupleWriteAheadSink, CoBroadcastWithKeyedOperator, CoBroadcastWithNonKeyedOperator, ContinuousFileReaderOperator, CoProcessOperator, CoStreamFlatMap, CoStreamMap, EvictingWindowOperator, ExtractTimestampsOperator, FlatSelectCepOperator, FlatSelectTimeoutCepOperator, GenericWriteAheadSink, KeyedCoProcessOperator, KeyedProcessOperator, LegacyKeyedProcessOperator, MergedInputsBoltWrapper, ProcessOperator, QueryableAppendingStateOperator, QueryableValueStateOperator, SelectCepOperator, SelectTimeoutCepOperator, StoppableStreamSource, StreamFilter, StreamFlatMap, StreamGroupedFold, StreamGroupedReduce, StreamMap, StreamProject, StreamSink, StreamSource, TimestampsAndPeriodicWatermarksOperator, TimestampsAndPunctuatedWatermarksOperator, WindowOperator

@PublicEvolving
public interface StreamOperator<OUT>
extends CheckpointListener, KeyContext, Disposable, Serializable

Basic interface for stream operators. Implementers would implement one of OneInputStreamOperator or TwoInputStreamOperator to create operators that process elements.

The class AbstractStreamOperator offers default implementation for the lifecycle and properties methods.

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.

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 OneInputStreamOperator.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()
MetricGroup	getMetricGroup()
OperatorID	getOperatorID()
void	initializeState() Provides a context to initialize all state in the operator.
void	open() This method is called immediately before any elements are processed, it should contain the operator's initialization logic.
void	setChainingStrategy(ChainingStrategy strategy)
void	setKeyContextElement1(StreamRecord<?> record)
void	setKeyContextElement2(StreamRecord<?> record)
void	setup(StreamTask<?,?> containingTask, StreamConfig config, Output<StreamRecord<OUT>> output) Initializes the operator.
OperatorSnapshotFutures	snapshotState(long checkpointId, long timestamp, CheckpointOptions checkpointOptions, CheckpointStreamFactory storageLocation) Called to draw a state snapshot from the operator.

Methods inherited from interface org.apache.flink.runtime.state.CheckpointListener

notifyCheckpointComplete

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

getCurrentKey, setCurrentKey

Method Detail

setup

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

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

open

void open()
   throws Exception

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

Throws:

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

close

void close()
    throws Exception

This method is called after all records have been added to the operators via the methods OneInputStreamOperator.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 as failed, because the last data items are not processed properly.

Throws:

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

dispose

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 Disposable

Throws:

Exception - if something goes wrong during disposal.

snapshotState

OperatorSnapshotFutures snapshotState(long checkpointId,
                                      long timestamp,
                                      CheckpointOptions checkpointOptions,
                                      CheckpointStreamFactory storageLocation)
                               throws Exception

Called to draw a state snapshot from the operator.

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.

initializeState

void initializeState()
              throws Exception

Provides a context to initialize all state in the operator.

Throws:

Exception

setKeyContextElement1

void setKeyContextElement1(StreamRecord<?> record)
                    throws Exception

Throws:

Exception

setKeyContextElement2

void setKeyContextElement2(StreamRecord<?> record)
                    throws Exception

Throws:

Exception

getChainingStrategy

ChainingStrategy getChainingStrategy()

setChainingStrategy

void setChainingStrategy(ChainingStrategy strategy)

getMetricGroup

MetricGroup getMetricGroup()

getOperatorID

OperatorID getOperatorID()