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

Class IntervalJoinOperator<K,T1,T2,OUT>

java.lang.Object

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

org.apache.flink.streaming.api.operators.AbstractUdfStreamOperator<OUT,ProcessJoinFunction<T1,T2,OUT>>

org.apache.flink.streaming.api.operators.co.IntervalJoinOperator<K,T1,T2,OUT>

Type Parameters:

K - The type of the key based on which we join elements.

T1 - The type of the elements in the left stream.

T2 - The type of the elements in the right stream.

OUT - The output type created by the user-defined function.

All Implemented Interfaces:

Serializable, CheckpointListener, KeyContext, KeyContextHandler, OutputTypeConfigurable<OUT>, StreamOperator<OUT>, StreamOperatorStateHandler.CheckpointedStreamOperator, Triggerable<K,String>, TwoInputStreamOperator<T1,T2,OUT>, UserFunctionProvider<ProcessJoinFunction<T1,T2,OUT>>, YieldingOperator<OUT>

@Internal
public class IntervalJoinOperator<K,T1,T2,OUT>
extends AbstractUdfStreamOperator<OUT,ProcessJoinFunction<T1,T2,OUT>>
implements TwoInputStreamOperator<T1,T2,OUT>, Triggerable<K,String>

An operator to execute time-bounded stream inner joins.

By using a configurable lower and upper bound this operator will emit exactly those pairs (T1, T2) where t2.ts ∈ [T1.ts + lowerBound, T1.ts + upperBound]. Both the lower and the upper bound can be configured to be either inclusive or exclusive.

As soon as elements are joined they are passed to a user-defined ProcessJoinFunction.

The basic idea of this implementation is as follows: Whenever we receive an element at processElement1(StreamRecord) (a.k.a. the left side), we add it to the left buffer. We then check the right buffer to see whether there are any elements that can be joined. If there are, they are joined and passed to the aforementioned function. The same happens the other way around when receiving an element on the right side.

Whenever a pair of elements is emitted it will be assigned the max timestamp of either of the elements.

In order to avoid the element buffers to grow indefinitely a cleanup timer is registered per element. This timer indicates when an element is not considered for joining anymore and can be removed from the state.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	IntervalJoinOperator.BufferEntry<T>	A container for elements put in the left/write buffer.
static class	IntervalJoinOperator.BufferEntrySerializer<T>	A serializer for the IntervalJoinOperator.BufferEntry.
static class	IntervalJoinOperator.BufferEntrySerializerSnapshot<T>	A TypeSerializerSnapshot for IntervalJoinOperator.BufferEntrySerializer.

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

config, lastRecordAttributes1, lastRecordAttributes2, latencyStats, LOG, metrics, output, processingTimeService, stateHandler, stateKeySelector1, stateKeySelector2, timeServiceManager

Constructor Summary

Constructors

Constructor	Description
IntervalJoinOperator(long lowerBound, long upperBound, boolean lowerBoundInclusive, boolean upperBoundInclusive, OutputTag<T1> leftLateDataOutputTag, OutputTag<T2> rightLateDataOutputTag, TypeSerializer<T1> leftTypeSerializer, TypeSerializer<T2> rightTypeSerializer, ProcessJoinFunction<T1,T2,OUT> udf)	Creates a new IntervalJoinOperator.

Method Summary

Modifier and Type	Method	Description
void	initializeState(StateInitializationContext context)	Stream operators with state which can be restored need to override this hook method.
void	onEventTime(InternalTimer<K,String> timer)	Invoked when an event-time timer fires.
void	onProcessingTime(InternalTimer<K,String> timer)	Invoked when a processing-time timer fires.
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	processElement1(StreamRecord<T1> record)	Process a StreamRecord from the left stream.
void	processElement2(StreamRecord<T2> record)	Process a StreamRecord from the right stream.
protected <T> void	sideOutput(T value, long timestamp, boolean isLeft)	Write skipped late arriving element to SideOutput.

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

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

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

getContainingTask, getCurrentKey, getExecutionConfig, getInternalTimerService, getKeyedStateBackend, getKeyedStateStore, getMetricGroup, getOperatorConfig, getOperatorID, getOperatorName, getOperatorStateBackend, getOrCreateKeyedState, getPartitionedState, getPartitionedState, getProcessingTimeService, getRuntimeContext, getStateKeySelector1, getStateKeySelector2, getTimeServiceManager, getUserCodeClassloader, hasKeyContext1, hasKeyContext2, initializeState, isUsingCustomRawKeyedState, prepareSnapshotPreBarrier, processLatencyMarker, processLatencyMarker1, processLatencyMarker2, processRecordAttributes, processRecordAttributes1, processRecordAttributes2, processWatermark, processWatermark1, processWatermark2, processWatermarkStatus, processWatermarkStatus1, processWatermarkStatus2, reportOrForwardLatencyMarker, setCurrentKey, setKeyContextElement1, setKeyContextElement2, setMailboxExecutor, setProcessingTimeService, snapshotState, useSplittableTimers

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.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.StreamOperator

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

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

processLatencyMarker1, processLatencyMarker2, processRecordAttributes1, processRecordAttributes2, processWatermark1, processWatermark2, processWatermarkStatus1, processWatermarkStatus2

Constructor Detail

IntervalJoinOperator

public IntervalJoinOperator(long lowerBound,
                            long upperBound,
                            boolean lowerBoundInclusive,
                            boolean upperBoundInclusive,
                            OutputTag<T1> leftLateDataOutputTag,
                            OutputTag<T2> rightLateDataOutputTag,
                            TypeSerializer<T1> leftTypeSerializer,
                            TypeSerializer<T2> rightTypeSerializer,
                            ProcessJoinFunction<T1,T2,OUT> udf)

Creates a new IntervalJoinOperator.

Parameters:

lowerBound - The lower bound for evaluating if elements should be joined

upperBound - The upper bound for evaluating if elements should be joined

lowerBoundInclusive - Whether or not to include elements where the timestamp matches the lower bound

upperBoundInclusive - Whether or not to include elements where the timestamp matches the upper bound

udf - A user-defined ProcessJoinFunction that gets called whenever two elements of T1 and T2 are joined

Method Detail

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<K>

Overrides:

open in class AbstractUdfStreamOperator<OUT,ProcessJoinFunction<T1,T2,OUT>>

Throws:

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

initializeState

public void initializeState(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,ProcessJoinFunction<T1,T2,OUT>>

Parameters:

context - context that allows to register different states.

Throws:

Exception

processElement1

public void processElement1(StreamRecord<T1> record)
                     throws Exception

Process a StreamRecord from the left stream. Whenever an StreamRecord arrives at the left stream, it will get added to the left buffer. Possible join candidates for that element will be looked up from the right buffer and if the pair lies within the user defined boundaries, it gets passed to the ProcessJoinFunction.

Specified by:

processElement1 in interface TwoInputStreamOperator<K,T1,T2>

Parameters:

record - An incoming record to be joined

Throws:

Exception - Can throw an Exception during state access

processElement2

public void processElement2(StreamRecord<T2> record)
                     throws Exception

Process a StreamRecord from the right stream. Whenever a StreamRecord arrives at the right stream, it will get added to the right buffer. Possible join candidates for that element will be looked up from the left buffer and if the pair lies within the user defined boundaries, it gets passed to the ProcessJoinFunction.

Specified by:

processElement2 in interface TwoInputStreamOperator<K,T1,T2>

Parameters:

record - An incoming record to be joined

Throws:

Exception - Can throw an exception during state access

sideOutput

protected <T> void sideOutput(T value,
                              long timestamp,
                              boolean isLeft)

Write skipped late arriving element to SideOutput.

onEventTime

public void onEventTime(InternalTimer<K,String> timer)
                 throws Exception

Description copied from interface: Triggerable

Invoked when an event-time timer fires.

Specified by:

onEventTime in interface Triggerable<K,T1>

Throws:

Exception

onProcessingTime

public void onProcessingTime(InternalTimer<K,String> timer)
                      throws Exception

Description copied from interface: Triggerable

Invoked when a processing-time timer fires.

Specified by:

onProcessingTime in interface Triggerable<K,T1>

Throws:

Exception