Google Cloud Dataflow SDK for Java, version 1.9.1
Class Combine.BinaryCombineFn<V>
- java.lang.Object
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- com.google.cloud.dataflow.sdk.transforms.Combine.CombineFn<V,Combine.Holder<V>,V>
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- com.google.cloud.dataflow.sdk.transforms.Combine.BinaryCombineFn<V>
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- All Implemented Interfaces:
- CombineFnBase.GlobalCombineFn<V,Combine.Holder<V>,V>, HasDisplayData, Serializable
- Enclosing class:
- Combine
public abstract static class Combine.BinaryCombineFn<V> extends Combine.CombineFn<V,Combine.Holder<V>,V>
An abstract subclass ofCombine.CombineFn
for implementing combiners that are more easily expressed as binary operations.- See Also:
- Serialized Form
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Constructor Summary
Constructors Constructor and Description BinaryCombineFn()
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method and Description Combine.Holder<V>
addInput(Combine.Holder<V> accumulator, V input)
Adds the given input value to the given accumulator, returning the new accumulator value.abstract V
apply(V left, V right)
Applies the binary operation to the two operands, returning the result.Combine.Holder<V>
createAccumulator()
Returns a new, mutable accumulator value, representing the accumulation of zero input values.V
extractOutput(Combine.Holder<V> accumulator)
Returns the output value that is the result of combining all the input values represented by the given accumulator.TypeVariable<?>
getAccumTVariable()
Returns theTypeVariable
ofAccumT
.Coder<Combine.Holder<V>>
getAccumulatorCoder(CoderRegistry registry, Coder<V> inputCoder)
Returns theCoder
to use for accumulatorAccumT
values, or null if it is not able to be inferred.Coder<V>
getDefaultOutputCoder(CoderRegistry registry, Coder<V> inputCoder)
Returns theCoder
to use by default for outputOutputT
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 theTypeVariable
ofInputT
.TypeVariable<?>
getOutputTVariable()
Returns theTypeVariable
ofOutputT
.V
identity()
Returns the value that should be used for the combine of the empty set.Combine.Holder<V>
mergeAccumulators(Iterable<Combine.Holder<V>> 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 com.google.cloud.dataflow.sdk.transforms.Combine.CombineFn
apply, asKeyedFn, compact, defaultValue, getOutputType
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Method Detail
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apply
public abstract V apply(V left, V right)
Applies the binary operation to the two operands, returning the result.
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identity
public V identity()
Returns the value that should be used for the combine of the empty set.
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createAccumulator
public Combine.Holder<V> createAccumulator()
Description copied from class:Combine.CombineFn
Returns a new, mutable accumulator value, representing the accumulation of zero input values.- Specified by:
createAccumulator
in classCombine.CombineFn<V,Combine.Holder<V>,V>
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addInput
public Combine.Holder<V> addInput(Combine.Holder<V> accumulator, V input)
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 classCombine.CombineFn<V,Combine.Holder<V>,V>
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mergeAccumulators
public Combine.Holder<V> mergeAccumulators(Iterable<Combine.Holder<V>> 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 classCombine.CombineFn<V,Combine.Holder<V>,V>
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extractOutput
public V extractOutput(Combine.Holder<V> 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 classCombine.CombineFn<V,Combine.Holder<V>,V>
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getAccumulatorCoder
public Coder<Combine.Holder<V>> getAccumulatorCoder(CoderRegistry registry, Coder<V> inputCoder)
Description copied from interface:CombineFnBase.GlobalCombineFn
Returns theCoder
to use for accumulatorAccumT
values, or null if it is not able to be inferred.By default, uses the knowledge of the
Coder
being used forInputT
values and the enclosingPipeline
'sCoderRegistry
to try to infer the Coder forAccumT
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 interfaceCombineFnBase.GlobalCombineFn<V,Combine.Holder<V>,V>
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getDefaultOutputCoder
public Coder<V> getDefaultOutputCoder(CoderRegistry registry, Coder<V> inputCoder)
Description copied from interface:CombineFnBase.GlobalCombineFn
Returns theCoder
to use by default for outputOutputT
values, or null if it is not able to be inferred.By default, uses the knowledge of the
Coder
being used for inputInputT
values and the enclosingPipeline
'sCoderRegistry
to try to infer the Coder forOutputT
values.- Specified by:
getDefaultOutputCoder
in interfaceCombineFnBase.GlobalCombineFn<V,Combine.Holder<V>,V>
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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 interfaceCombineFnBase.GlobalCombineFn<InputT,AccumT,OutputT>
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getInputTVariable
public TypeVariable<?> getInputTVariable()
Returns theTypeVariable
ofInputT
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getAccumTVariable
public TypeVariable<?> getAccumTVariable()
Returns theTypeVariable
ofAccumT
.
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getOutputTVariable
public TypeVariable<?> getOutputTVariable()
Returns theTypeVariable
ofOutputT
.
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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 viaDisplayData.from(HasDisplayData)
. Implementations may callsuper.populateDisplayData(builder)
in order to register display data in the current namespace, but should otherwise usesubcomponent.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 interfaceHasDisplayData
- Parameters:
builder
- The builder to populate with display data.- See Also:
HasDisplayData
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