Package org.apache.beam.sdk.extensions.sql

Class TypedCombineFnDelegate<InputT,AccumT,OutputT>

java.lang.Object

org.apache.beam.sdk.transforms.Combine.CombineFn<InputT,AccumT,OutputT>

org.apache.beam.sdk.extensions.sql.TypedCombineFnDelegate<InputT,AccumT,OutputT>

Type Parameters:

InputT - the type of input

AccumT - the type of accumulator

OutputT - the type of output

All Implemented Interfaces:

Serializable, CombineFnBase.GlobalCombineFn<InputT,AccumT,OutputT>, HasDisplayData

public class TypedCombineFnDelegate<InputT,AccumT,OutputT>
extends Combine.CombineFn<InputT,AccumT,OutputT>

A Combine.CombineFn delegating all relevant calls to given delegate. This is used to create a type anonymous class for cases where the CombineFn is a generic class. The anonymous class can then be used in a UDAF as

   .registerUdaf("UDAF", new TypedCombineFnDelegateinvalid input: '<'>(genericCombineFn) {})
 

See Also:

• Serialized Form

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	TypedCombineFnDelegate(Combine.CombineFn<InputT,AccumT,OutputT> delegate)

Method Summary

Modifier and Type	Method	Description
AccumT	addInput(AccumT mutableAccumulator, InputT input)	Adds the given input value to the given accumulator, returning the new accumulator value.
OutputT	apply(Iterable<? extends InputT> inputs)	Applies this CombineFn to a collection of input values to produce a combined output value.
AccumT	compact(AccumT accumulator)	Returns an accumulator that represents the same logical value as the input accumulator, but may have a more compact representation.
AccumT	createAccumulator()	Returns a new, mutable accumulator value, representing the accumulation of zero input values.
OutputT	defaultValue()	Returns the default value when there are no values added to the accumulator.
OutputT	extractOutput(AccumT 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<AccumT>	getAccumulatorCoder(CoderRegistry registry, 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<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.
TypeDescriptor<InputT>	getInputType()	Returns a TypeDescriptor capturing what is known statically about the input type of this CombineFn instance's most-derived class.
TypeVariable<?>	getOutputTVariable()	Returns the TypeVariable of OutputT.
TypeDescriptor<OutputT>	getOutputType()	Returns a TypeDescriptor capturing what is known statically about the output type of this CombineFn instance's most-derived class.
AccumT	mergeAccumulators(Iterable<AccumT> 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.

Methods inherited from class java.lang.Object

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

Constructor Details

TypedCombineFnDelegate

protected TypedCombineFnDelegate(Combine.CombineFn<InputT,AccumT,OutputT> delegate)

Method Details

getOutputType

public TypeDescriptor<OutputT> getOutputType()

Description copied from class: Combine.CombineFn

Returns a TypeDescriptor capturing what is known statically about the output type of this CombineFn instance's most-derived class.

In the normal case of a concrete CombineFn subclass with no generic type parameters of its own, this will be a complete non-generic type.

Overrides:

getOutputType in class Combine.CombineFn<InputT,AccumT,OutputT>

getInputType

public TypeDescriptor<InputT> getInputType()

Description copied from class: Combine.CombineFn

Returns a TypeDescriptor capturing what is known statically about the input type of this CombineFn instance's most-derived class.

In the normal case of a concrete CombineFn subclass with no generic type parameters of its own, this will be a complete non-generic type.

Overrides:

getInputType in class Combine.CombineFn<InputT,AccumT,OutputT>

createAccumulator

public AccumT 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<InputT,AccumT,OutputT>

addInput

public AccumT addInput(AccumT mutableAccumulator,
 InputT input)

Description copied from class: Combine.CombineFn

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

Specified by:

addInput in class Combine.CombineFn<InputT,AccumT,OutputT>

Parameters:

mutableAccumulator - may be modified and returned for efficiency

input - should not be mutated

mergeAccumulators

public AccumT mergeAccumulators(Iterable<AccumT> accumulators)

Description copied from class: Combine.CombineFn

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

Specified by:

mergeAccumulators in class Combine.CombineFn<InputT,AccumT,OutputT>

Parameters:

accumulators - only the first accumulator may be modified and returned for efficiency; the other accumulators should not be mutated, because they may be shared with other code and mutating them could lead to incorrect results or data corruption.

extractOutput

public OutputT extractOutput(AccumT 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<InputT,AccumT,OutputT>

Parameters:

accumulator - can be modified for efficiency

compact

public AccumT compact(AccumT 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<InputT,AccumT,OutputT>

apply

public OutputT apply(Iterable<? extends InputT> inputs)

Description copied from class: Combine.CombineFn

Applies this CombineFn to a collection of input values to produce a combined output value.

Useful when using a CombineFn separately from a Combine transform. Does not invoke the Combine.CombineFn.mergeAccumulators(java.lang.Iterable<AccumT>) operation.

Overrides:

apply in class Combine.CombineFn<InputT,AccumT,OutputT>

defaultValue

public OutputT defaultValue()

Description copied from class: Combine.CombineFn

Returns the default value when there are no values added to the accumulator.

By default returns the extract output of an empty accumulator.

Specified by:

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

Overrides:

defaultValue in class Combine.CombineFn<InputT,AccumT,OutputT>

getAccumulatorCoder

public Coder<AccumT> getAccumulatorCoder(CoderRegistry registry,
 Coder<InputT> inputCoder)
                                  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<InputT,AccumT,OutputT>

Throws:

CannotProvideCoderException

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.

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