Package org.apache.beam.sdk.transforms

Class Top.TopCombineFn<T,ComparatorT extends Comparator<T> & Serializable>

java.lang.Object

org.apache.beam.sdk.transforms.Combine.CombineFn<T,org.apache.beam.sdk.transforms.Top.BoundedHeap<T,ComparatorT>,List<T>>

org.apache.beam.sdk.transforms.Combine.AccumulatingCombineFn<T,org.apache.beam.sdk.transforms.Top.BoundedHeap<T,ComparatorT>,List<T>>

org.apache.beam.sdk.transforms.Top.TopCombineFn<T,ComparatorT>

Type Parameters:

T - type of element being compared

All Implemented Interfaces:

Serializable, CombineFnBase.GlobalCombineFn<T,org.apache.beam.sdk.transforms.Top.BoundedHeap<T,ComparatorT>,List<T>>, HasDisplayData, org.apache.beam.sdk.util.NameUtils.NameOverride

Enclosing class:

Top

public static class Top.TopCombineFn<T,ComparatorT extends Comparator<T> & Serializable>
extends Combine.AccumulatingCombineFn<T,org.apache.beam.sdk.transforms.Top.BoundedHeap<T,ComparatorT>,List<T>>
implements org.apache.beam.sdk.util.NameUtils.NameOverride

CombineFn for Top transforms that combines a bunch of Ts into a single count-long List<T>, using compareFn to choose the largest Ts.

See Also:

• Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.beam.sdk.transforms.Combine.AccumulatingCombineFn

Combine.AccumulatingCombineFn.Accumulator<InputT,AccumT,OutputT>

Constructor Summary

Constructors

Constructor	Description
TopCombineFn(int count, ComparatorT compareFn)

Method Summary

Modifier and Type	Method	Description
org.apache.beam.sdk.transforms.Top.BoundedHeap<T,ComparatorT>	createAccumulator()	Returns a new, mutable accumulator value, representing the accumulation of zero input values.
TypeVariable<?>	getAccumTVariable()	Returns the TypeVariable of AccumT.
Coder<org.apache.beam.sdk.transforms.Top.BoundedHeap<T,ComparatorT>>	getAccumulatorCoder(CoderRegistry registry, Coder<T> inputCoder)	Returns the Coder to use for accumulator AccumT values, or null if it is not able to be inferred.
Coder<List<T>>	getDefaultOutputCoder(CoderRegistry registry, Coder<T> inputCoder)	Returns the Coder to use by default for output OutputT values, or null if it is not able to be inferred.
String	getIncompatibleGlobalWindowErrorMessage()	Returns the error message for not supported default values in Combine.globally().
TypeVariable<?>	getInputTVariable()	Returns the TypeVariable of InputT.
String	getNameOverride()
TypeVariable<?>	getOutputTVariable()	Returns the TypeVariable of OutputT.
void	populateDisplayData(DisplayData.Builder builder)	Register display data for the given transform or component.

Methods inherited from class org.apache.beam.sdk.transforms.Combine.AccumulatingCombineFn

addInput, extractOutput, mergeAccumulators

Methods inherited from class org.apache.beam.sdk.transforms.Combine.CombineFn

apply, compact, defaultValue, getInputType, getOutputType

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

TopCombineFn

public TopCombineFn(int count,
 ComparatorT compareFn)

Method Details

getNameOverride

public String getNameOverride()

Specified by:

getNameOverride in interface org.apache.beam.sdk.util.NameUtils.NameOverride

createAccumulator

public org.apache.beam.sdk.transforms.Top.BoundedHeap<T,ComparatorT> createAccumulator()

Description copied from class: Combine.CombineFn

Returns a new, mutable accumulator value, representing the accumulation of zero input values.

Specified by:

createAccumulator in class Combine.CombineFn<T,org.apache.beam.sdk.transforms.Top.BoundedHeap<T,ComparatorT extends Comparator<T> & Serializable>,List<T>>

getAccumulatorCoder

public Coder<org.apache.beam.sdk.transforms.Top.BoundedHeap<T,ComparatorT>> getAccumulatorCoder(CoderRegistry registry,
 Coder<T> inputCoder)

Description copied from interface: CombineFnBase.GlobalCombineFn

Returns the Coder to use for accumulator AccumT values, or null if it is not able to be inferred.

By default, uses the knowledge of the Coder being used for InputT values and the enclosing Pipeline's CoderRegistry to try to infer the Coder for AccumT values.

This is the Coder used to send data through a communication-intensive shuffle step, so a compact and efficient representation may have significant performance benefits.

Specified by:

getAccumulatorCoder in interface CombineFnBase.GlobalCombineFn<T,org.apache.beam.sdk.transforms.Top.BoundedHeap<T,ComparatorT extends Comparator<T> & Serializable>,List<T>>

populateDisplayData

public void populateDisplayData(DisplayData.Builder builder)

Register display data for the given transform or component.

populateDisplayData(DisplayData.Builder) is invoked by Pipeline runners to collect display data via DisplayData.from(HasDisplayData). Implementations may call super.populateDisplayData(builder) in order to register display data in the current namespace, but should otherwise use subcomponent.populateDisplayData(builder) to use the namespace of the subcomponent.

By default, does not register any display data. Implementors may override this method to provide their own display data.

Specified by:

populateDisplayData in interface HasDisplayData

Parameters:

builder - The builder to populate with display data.

See Also:

• HasDisplayData

getIncompatibleGlobalWindowErrorMessage

public String getIncompatibleGlobalWindowErrorMessage()

Description copied from interface: CombineFnBase.GlobalCombineFn

Returns the error message for not supported default values in Combine.globally().

Specified by:

getIncompatibleGlobalWindowErrorMessage in interface CombineFnBase.GlobalCombineFn<T,org.apache.beam.sdk.transforms.Top.BoundedHeap<T,ComparatorT extends Comparator<T> & Serializable>,List<T>>

getDefaultOutputCoder

public Coder<List<T>> getDefaultOutputCoder(CoderRegistry registry,
 Coder<T> inputCoder)
                                     throws CannotProvideCoderException

Description copied from interface: CombineFnBase.GlobalCombineFn

Returns the Coder to use by default for output OutputT values, or null if it is not able to be inferred.

By default, uses the knowledge of the Coder being used for input InputT values and the enclosing Pipeline's CoderRegistry to try to infer the Coder for OutputT values.

Specified by:

getDefaultOutputCoder in interface CombineFnBase.GlobalCombineFn<InputT,AccumT,OutputT>

Throws:

CannotProvideCoderException

getInputTVariable

public TypeVariable<?> getInputTVariable()

Returns the TypeVariable of InputT.

getAccumTVariable

public TypeVariable<?> getAccumTVariable()

Returns the TypeVariable of AccumT.

getOutputTVariable

public TypeVariable<?> getOutputTVariable()

Returns the TypeVariable of OutputT.