com.google.cloud.dataflow.sdk.transforms

Class CombineFns.ComposedCombineFn<DataT>

java.lang.Object

com.google.cloud.dataflow.sdk.transforms.Combine.CombineFn<DataT,Object[],CombineFns.CoCombineResult>

com.google.cloud.dataflow.sdk.transforms.CombineFns.ComposedCombineFn<DataT>

All Implemented Interfaces:

CombineFnBase.GlobalCombineFn<DataT,Object[],CombineFns.CoCombineResult>, HasDisplayData, Serializable

Enclosing class:

CombineFns

public static class CombineFns.ComposedCombineFn<DataT>
extends Combine.CombineFn<DataT,Object[],CombineFns.CoCombineResult>

A composed Combine.CombineFn that applies multiple CombineFns.

For each Combine.CombineFn it extracts inputs from DataT with the extractInputFn and combines them, and then it outputs each combined value with a TupleTag to a CombineFns.CoCombineResult.

See Also:

Serialized Form

Method Summary

Modifier and Type	Method and Description
Object[]	addInput(Object[] accumulator, DataT value) Adds the given input value to the given accumulator, returning the new accumulator value.
Object[]	compact(Object[] accumulator) Returns an accumulator that represents the same logical value as the input accumulator, but may have a more compact representation.
Object[]	createAccumulator() Returns a new, mutable accumulator value, representing the accumulation of zero input values.
CombineFns.CoCombineResult	extractOutput(Object[] accumulator) Returns the output value that is the result of combining all the input values represented by the given accumulator.
TypeVariable<?>	getAccumTVariable() Returns the TypeVariable of AccumT.
Coder<Object[]>	getAccumulatorCoder(CoderRegistry registry, Coder<DataT> dataCoder) 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<InputT> 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.
TypeVariable<?>	getOutputTVariable() Returns the TypeVariable of OutputT.
Object[]	mergeAccumulators(Iterable<Object[]> accumulators) 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.
<InputT,OutputT> CombineFns.ComposedCombineFn<DataT>	with(SimpleFunction<DataT,InputT> extractInputFn, Combine.CombineFn<InputT,?,OutputT> combineFn, TupleTag<OutputT> outputTag) Returns a CombineFns.ComposedCombineFn with an additional Combine.CombineFn.
<InputT,OutputT> CombineFns.ComposedCombineFnWithContext<DataT>	with(SimpleFunction<DataT,InputT> extractInputFn, CombineWithContext.CombineFnWithContext<InputT,?,OutputT> combineFn, TupleTag<OutputT> outputTag) Returns a CombineFns.ComposedCombineFnWithContext with an additional CombineWithContext.CombineFnWithContext.

Methods inherited from class com.google.cloud.dataflow.sdk.transforms.Combine.CombineFn

apply, asKeyedFn, defaultValue, getOutputType

Methods inherited from class java.lang.Object

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

Method Detail

with

public <InputT,OutputT> CombineFns.ComposedCombineFn<DataT> with(SimpleFunction<DataT,InputT> extractInputFn,
                                                                 Combine.CombineFn<InputT,?,OutputT> combineFn,
                                                                 TupleTag<OutputT> outputTag)

Returns a CombineFns.ComposedCombineFn with an additional Combine.CombineFn.

with

public <InputT,OutputT> CombineFns.ComposedCombineFnWithContext<DataT> with(SimpleFunction<DataT,InputT> extractInputFn,
                                                                            CombineWithContext.CombineFnWithContext<InputT,?,OutputT> combineFn,
                                                                            TupleTag<OutputT> outputTag)

Returns a CombineFns.ComposedCombineFnWithContext with an additional CombineWithContext.CombineFnWithContext.

createAccumulator

public Object[] 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<DataT,Object[],CombineFns.CoCombineResult>

addInput

public Object[] addInput(Object[] accumulator,
                         DataT value)

Description copied from class: Combine.CombineFn

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

For efficiency, the input accumulator may be modified and returned.

Specified by:

addInput in class Combine.CombineFn<DataT,Object[],CombineFns.CoCombineResult>

mergeAccumulators

public Object[] mergeAccumulators(Iterable<Object[]> accumulators)

Description copied from class: Combine.CombineFn

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

May modify any of the argument accumulators. May return a fresh accumulator, or may return one of the (modified) argument accumulators.

Specified by:

mergeAccumulators in class Combine.CombineFn<DataT,Object[],CombineFns.CoCombineResult>

extractOutput

public CombineFns.CoCombineResult extractOutput(Object[] accumulator)

Description copied from class: Combine.CombineFn

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

Specified by:

extractOutput in class Combine.CombineFn<DataT,Object[],CombineFns.CoCombineResult>

compact

public Object[] compact(Object[] accumulator)

Description copied from class: Combine.CombineFn

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

For most CombineFns this would be a no-op, but should be overridden by CombineFns that (for example) buffer up elements and combine them in batches.

For efficiency, the input accumulator may be modified and returned.

By default returns the original accumulator.

Overrides:

compact in class Combine.CombineFn<DataT,Object[],CombineFns.CoCombineResult>

getAccumulatorCoder

public Coder<Object[]> getAccumulatorCoder(CoderRegistry registry,
                                           Coder<DataT> dataCoder)
                                    throws CannotProvideCoderException

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<DataT,Object[],CombineFns.CoCombineResult>

Throws:

CannotProvideCoderException

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

getDefaultOutputCoder

public Coder<OutputT> getDefaultOutputCoder(CoderRegistry registry,
                                            Coder<InputT> 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

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<InputT,AccumT,OutputT>

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.