Package org.apache.flink.streaming.api.operators.async

Class AsyncWaitOperator<IN,OUT>

java.lang.Object

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

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

org.apache.flink.streaming.api.operators.async.AsyncWaitOperator<IN,OUT>

Type Parameters:

IN - Input type for the operator.

OUT - Output type for the operator.

All Implemented Interfaces:

Serializable, org.apache.flink.api.common.state.CheckpointListener, BoundedOneInput, Input<IN>, KeyContext, KeyContextHandler, OneInputStreamOperator<IN,OUT>, org.apache.flink.streaming.api.operators.OutputTypeConfigurable<OUT>, SetupableStreamOperator<OUT>, StreamOperator<OUT>, StreamOperatorStateHandler.CheckpointedStreamOperator, UserFunctionProvider<AsyncFunction<IN,OUT>>

@Internal
public class AsyncWaitOperator<IN,OUT>
extends AbstractUdfStreamOperator<OUT,AsyncFunction<IN,OUT>>
implements OneInputStreamOperator<IN,OUT>, BoundedOneInput

The AsyncWaitOperator allows to asynchronously process incoming stream records. For that the operator creates an ResultFuture which is passed to an AsyncFunction. Within the async function, the user can complete the async collector arbitrarily. Once the async collector has been completed, the result is emitted by the operator's emitter to downstream operators.

The operator offers different output modes depending on the chosen AsyncDataStream.OutputMode. In order to give exactly once processing guarantees, the operator stores all currently in-flight StreamElement in it's operator state. Upon recovery the recorded set of stream elements is replayed.

The operator also support retry on predefined condition and strategy AsyncRetryStrategy. If given strategy is NO_RETRY_STRATEGY or a custom implemented AsyncRetryPredicate which defines empty retry predicate, then no retry will happen, everything keeps the same as the AsyncWaitOperator without retry support.

In case of chaining of this operator, it has to be made sure that the operators in the chain are opened tail to head. The reason for this is that an opened AsyncWaitOperator starts already emitting recovered StreamElement to downstream operators.

See Also:

Serialized Form

Field Summary

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

userFunction

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

chainingStrategy, config, lastRecordAttributes1, lastRecordAttributes2, latencyStats, LOG, metrics, output, processingTimeService

Constructor Summary

Constructors

Constructor	Description
AsyncWaitOperator(AsyncFunction<IN,OUT> asyncFunction, long timeout, int capacity, AsyncDataStream.OutputMode outputMode, AsyncRetryStrategy<OUT> asyncRetryStrategy, ProcessingTimeService processingTimeService, org.apache.flink.api.common.operators.MailboxExecutor mailboxExecutor)

Method Summary

Modifier and Type	Method	Description
void	endInput()	It is notified that no more data will arrive from the input.
void	initializeState(org.apache.flink.runtime.state.StateInitializationContext context)	Stream operators with state which can be restored need to override this hook method.
void	open()	This method is called immediately before any elements are processed, it should contain the operator's initialization logic, e.g.
void	processElement(StreamRecord<IN> record)	Processes one element that arrived on this input of the MultipleInputStreamOperator.
void	processWatermark(Watermark mark)	Processes a Watermark that arrived on the first input of this two-input operator.
void	setup(StreamTask<?,?> containingTask, StreamConfig config, Output<StreamRecord<OUT>> output)	Initializes 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 org.apache.flink.streaming.api.operators.AbstractUdfStreamOperator

close, finish, getUserFunction, getUserFunctionParameters, notifyCheckpointAborted, notifyCheckpointComplete, setOutputType

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, hasKeyContext1, hasKeyContext2, initializeState, isUsingCustomRawKeyedState, prepareSnapshotPreBarrier, processLatencyMarker, processLatencyMarker1, processLatencyMarker2, processRecordAttributes, processRecordAttributes1, processRecordAttributes2, processWatermark1, processWatermark2, processWatermarkStatus, processWatermarkStatus1, processWatermarkStatus2, 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

Methods inherited from interface org.apache.flink.api.common.state.CheckpointListener

notifyCheckpointAborted, notifyCheckpointComplete

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

processLatencyMarker, processRecordAttributes, processWatermarkStatus

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

getCurrentKey, setCurrentKey

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

hasKeyContext

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

setKeyContextElement

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

close, finish, getMetricGroup, getOperatorID, initializeState, prepareSnapshotPreBarrier, setKeyContextElement1, setKeyContextElement2, snapshotState

Constructor Detail

AsyncWaitOperator

public AsyncWaitOperator(@Nonnull
                         AsyncFunction<IN,OUT> asyncFunction,
                         long timeout,
                         int capacity,
                         @Nonnull
                         AsyncDataStream.OutputMode outputMode,
                         @Nonnull
                         AsyncRetryStrategy<OUT> asyncRetryStrategy,
                         @Nonnull
                         ProcessingTimeService processingTimeService,
                         @Nonnull
                         org.apache.flink.api.common.operators.MailboxExecutor mailboxExecutor)

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<IN>

Overrides:

setup in class AbstractUdfStreamOperator<OUT,AsyncFunction<IN,OUT>>

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<IN>

Overrides:

open in class AbstractUdfStreamOperator<OUT,AsyncFunction<IN,OUT>>

Throws:

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

processElement

public void processElement(StreamRecord<IN> record)
                    throws Exception

Description copied from interface: Input

Processes one element that arrived on this input of the MultipleInputStreamOperator. This method is guaranteed to not be called concurrently with other methods of the operator.

Specified by:

processElement in interface Input<IN>

Throws:

Exception

processWatermark

public void processWatermark(Watermark mark)
                      throws Exception

Description copied from interface: Input

Processes a Watermark that arrived on the first input of this two-input operator. This method is guaranteed to not be called concurrently with other methods of the operator.

Specified by:

processWatermark in interface Input<IN>

Overrides:

processWatermark in class AbstractStreamOperator<OUT>

Throws:

Exception

See Also:

Watermark

snapshotState

public void snapshotState(org.apache.flink.runtime.state.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 AbstractUdfStreamOperator<OUT,AsyncFunction<IN,OUT>>

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

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 AbstractUdfStreamOperator<OUT,AsyncFunction<IN,OUT>>

Parameters:

context - context that allows to register different states.

Throws:

Exception

endInput

public void endInput()
              throws Exception

Description copied from interface: BoundedOneInput

It is notified that no more data will arrive from the input.

Stateful operators need to be aware that a restart with rescaling may occur after receiving this notification. A changed source split assignment may imply that the same subtask of this operator that received endInput, has its state after endInput snapshotted, and will receive new data after restart. Hence, the state should not contain any finalization that would make it impossible to process new data.

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: Given it is semantically very similar to the StreamOperator.finish() method. It might be dropped in favour of the other method at some point in time.

Specified by:

endInput in interface BoundedOneInput

Throws:

Exception