org.apache.beam.sdk.transforms

Class CombineWithContext.KeyedCombineFnWithContext<K,InputT,AccumT,OutputT>

java.lang.Object

org.apache.beam.sdk.transforms.CombineWithContext.KeyedCombineFnWithContext<K,InputT,AccumT,OutputT>

All Implemented Interfaces:

Serializable, CombineFnBase.PerKeyCombineFn<K,InputT,AccumT,OutputT>, CombineWithContext.RequiresContextInternal, HasDisplayData

Direct Known Subclasses:

CombineFns.ComposedKeyedCombineFnWithContext

Enclosing class:

CombineWithContext

public abstract static class CombineWithContext.KeyedCombineFnWithContext<K,InputT,AccumT,OutputT>
extends Object
implements CombineWithContext.RequiresContextInternal

A keyed combine function that has access to PipelineOptions and side inputs through CombineWithContext.Context. See the equivalent Combine.KeyedCombineFn for details about keyed combine functions.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
KeyedCombineFnWithContext()

Method Summary

Modifier and Type	Method and Description
abstract AccumT	addInput(K key, AccumT accumulator, InputT value, CombineWithContext.Context c) Adds the given input value to the given accumulator, returning the new accumulator value.
OutputT	apply(K key, Iterable<? extends InputT> inputs, CombineWithContext.Context c) Applies this KeyedCombineFnWithContext to a key and a collection of input values to produce a combined output value.
AccumT	compact(K key, AccumT accumulator, CombineWithContext.Context c) Returns an accumulator that represents the same logical value as the input accumulator, but may have a more compact representation.
abstract AccumT	createAccumulator(K key, CombineWithContext.Context c) Returns a new, mutable accumulator value representing the accumulation of zero input values.
abstract OutputT	extractOutput(K key, AccumT accumulator, CombineWithContext.Context c) Returns the output value that is the result of combining all the input values represented by the given accumulator.
CombineWithContext.CombineFnWithContext<InputT,AccumT,OutputT>	forKey(K key, Coder<K> keyCoder) Returns the a regular CombineFnBase.GlobalCombineFn that operates on a specific key.
TypeVariable<?>	getAccumTVariable() Returns the TypeVariable of AccumT.
Coder<AccumT>	getAccumulatorCoder(CoderRegistry registry, Coder<K> keyCoder, Coder<InputT> inputCoder) Returns the Coder to use for accumulator AccumT values, or null if it is not able to be inferred.
Coder<OutputT>	getDefaultOutputCoder(CoderRegistry registry, Coder<K> keyCoder, Coder<InputT> inputCoder) Returns the Coder to use by default for output OutputT values, or null if it is not able to be inferred.
TypeVariable<?>	getInputTVariable() Returns the TypeVariable of InputT.
TypeVariable<?>	getKTypeVariable() Returns the TypeVariable of K.
TypeVariable<?>	getOutputTVariable() Returns the TypeVariable of OutputT.
abstract AccumT	mergeAccumulators(K key, Iterable<AccumT> accumulators, CombineWithContext.Context c) Returns an accumulator representing the accumulation of all the input values accumulated in the merging accumulators.
void	populateDisplayData(DisplayData.Builder builder) Register display data for the given transform or component.

Methods inherited from class java.lang.Object

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

Constructor Detail

KeyedCombineFnWithContext

public KeyedCombineFnWithContext()

Method Detail

createAccumulator

public abstract AccumT createAccumulator(K key,
                                         CombineWithContext.Context c)

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

It is equivalent to Combine.KeyedCombineFn.createAccumulator(K), but it has additional access to CombineWithContext.Context.

addInput

public abstract AccumT addInput(K key,
                                AccumT accumulator,
                                InputT value,
                                CombineWithContext.Context c)

Adds the given input value to the given accumulator, returning the new accumulator value.

It is equivalent to Combine.KeyedCombineFn.addInput(K, AccumT, InputT), but it has additional access to CombineWithContext.Context.

mergeAccumulators

public abstract AccumT mergeAccumulators(K key,
                                         Iterable<AccumT> accumulators,
                                         CombineWithContext.Context c)

Returns an accumulator representing the accumulation of all the input values accumulated in the merging accumulators.

It is equivalent to Combine.KeyedCombineFn.mergeAccumulators(K, java.lang.Iterable<AccumT>), but it has additional access to CombineWithContext.Context..

extractOutput

public abstract OutputT extractOutput(K key,
                                      AccumT accumulator,
                                      CombineWithContext.Context c)

Returns the output value that is the result of combining all the input values represented by the given accumulator.

It is equivalent to Combine.KeyedCombineFn.extractOutput(K, AccumT), but it has additional access to CombineWithContext.Context.

compact

public AccumT compact(K key,
                      AccumT accumulator,
                      CombineWithContext.Context c)

Returns an accumulator that represents the same logical value as the input accumulator, but may have a more compact representation.

It is equivalent to Combine.KeyedCombineFn.compact(K, AccumT), but it has additional access to CombineWithContext.Context.

apply

public OutputT apply(K key,
                     Iterable<? extends InputT> inputs,
                     CombineWithContext.Context c)

Applies this KeyedCombineFnWithContext to a key and a collection of input values to produce a combined output value.

forKey

public CombineWithContext.CombineFnWithContext<InputT,AccumT,OutputT> forKey(K key,
                                                                             Coder<K> keyCoder)

Description copied from interface: CombineFnBase.PerKeyCombineFn

Returns the a regular CombineFnBase.GlobalCombineFn that operates on a specific key.

Specified by:

forKey in interface CombineFnBase.PerKeyCombineFn<K,InputT,AccumT,OutputT>

getAccumulatorCoder

public Coder<AccumT> getAccumulatorCoder(CoderRegistry registry,
                                         Coder<K> keyCoder,
                                         Coder<InputT> inputCoder)
                                  throws CannotProvideCoderException

Description copied from interface: CombineFnBase.PerKeyCombineFn

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 K keys and input 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.PerKeyCombineFn<K,InputT,AccumT,OutputT>

Throws:

CannotProvideCoderException

getDefaultOutputCoder

public Coder<OutputT> getDefaultOutputCoder(CoderRegistry registry,
                                            Coder<K> keyCoder,
                                            Coder<InputT> inputCoder)
                                     throws CannotProvideCoderException

Description copied from interface: CombineFnBase.PerKeyCombineFn

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 K keys and input InputT values and the enclosing Pipeline's CoderRegistry to try to infer the Coder for OutputT values.

Specified by:

getDefaultOutputCoder in interface CombineFnBase.PerKeyCombineFn<K,InputT,AccumT,OutputT>

Throws:

CannotProvideCoderException

getKTypeVariable

public TypeVariable<?> getKTypeVariable()

Returns the TypeVariable of K.

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.

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