com.google.cloud.dataflow.sdk.transforms

Class Combine.SimpleCombineFn<V>

java.lang.Object

com.google.cloud.dataflow.sdk.transforms.Combine.CombineFn<V,java.util.List<V>,V>

com.google.cloud.dataflow.sdk.transforms.Combine.SimpleCombineFn<V>

All Implemented Interfaces:

java.io.Serializable

Enclosing class:

Combine

public static class Combine.SimpleCombineFn<V>
extends Combine.CombineFn<V,java.util.List<V>,V>

Converts a SerializableFunction from Iterable<V>s to Vs into a simple Combine.CombineFn over Vs.

Used in the implementation of convenience methods like Combine.globally(SerializableFunction), Combine.perKey(SerializableFunction), and Combine.groupedValues(SerializableFunction).

See Also:

Serialized Form

Method Summary

Methods

Modifier and Type	Method and Description
java.util.List<V>	addInput(java.util.List<V> accumulator, V input) Adds the given input value to the given accumulator, returning the new accumulator value.
java.util.List<V>	createAccumulator() Returns a new, mutable accumulator value, representing the accumulation of zero input values.
V	extractOutput(java.util.List<V> accumulator) Returns the output value that is the result of combining all the input values represented by the given accumulator.
java.util.List<V>	mergeAccumulators(java.lang.Iterable<java.util.List<V>> accumulators) Returns an accumulator representing the accumulation of all the input values accumulated in the merging accumulators.
static <V> Combine.SimpleCombineFn<V>	of(SerializableFunction<java.lang.Iterable<V>,V> combiner) Returns a CombineFn that uses the given SerializableFunction to combine values.

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

apply, asKeyedFn, getAccumulatorCoder, getDefaultOutputCoder

Methods inherited from class java.lang.Object

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

Method Detail

of

public static <V> Combine.SimpleCombineFn<V> of(SerializableFunction<java.lang.Iterable<V>,V> combiner)

Returns a CombineFn that uses the given SerializableFunction to combine values.

createAccumulator

public java.util.List<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 class Combine.CombineFn<V,java.util.List<V>,V>

addInput

public java.util.List<V> addInput(java.util.List<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 class Combine.CombineFn<V,java.util.List<V>,V>

mergeAccumulators

public java.util.List<V> mergeAccumulators(java.lang.Iterable<java.util.List<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 class Combine.CombineFn<V,java.util.List<V>,V>

extractOutput

public V extractOutput(java.util.List<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 class Combine.CombineFn<V,java.util.List<V>,V>