org.apache.beam.runners.spark.aggregators

Class NamedAggregators

java.lang.Object

org.apache.beam.runners.spark.aggregators.NamedAggregators

All Implemented Interfaces:

Serializable

public class NamedAggregators
extends Object
implements Serializable

This class wraps a map of named aggregators. Spark expects that all accumulators be declared before a job is launched. Beam allows aggregators to be used and incremented on the fly. We create a map of named aggregators and instantiate in the the spark context before the job is launched. We can then add aggregators on the fly in Spark.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	NamedAggregators.CombineFunctionState<InputT,InterT,OutputT>
static interface	NamedAggregators.State<InputT,InterT,OutputT>

Constructor Summary

Constructors

Constructor and Description
NamedAggregators() Constructs a new NamedAggregators instance.
NamedAggregators(String name, NamedAggregators.State<?,?,?> state) Constructs a new named aggregators instance that contains a mapping from the specified `named` to the associated initial state.

Method Summary

Modifier and Type	Method and Description
<T> T	getValue(String name, Class<T> typeClass)
NamedAggregators	merge(NamedAggregators other) Merges another NamedAggregators instance with this instance.
Map<String,?>	renderAll()
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

NamedAggregators

public NamedAggregators()

Constructs a new NamedAggregators instance.

NamedAggregators

public NamedAggregators(String name,
                        NamedAggregators.State<?,?,?> state)

Constructs a new named aggregators instance that contains a mapping from the specified `named` to the associated initial state.

Parameters:

name - Name of aggregator.

state - Associated State.

Method Detail

getValue

public <T> T getValue(String name,
                      Class<T> typeClass)

Type Parameters:

T - Type to be returned.

Parameters:

name - Name of aggregator to retrieve.

typeClass - Type class to cast the value to.

Returns:

the value of the aggregator associated with the specified name, or null if the specified aggregator could not be found.

renderAll

public Map<String,?> renderAll()

Returns:

a map of all the aggregator names and their rendered values

merge

public NamedAggregators merge(NamedAggregators other)

Merges another NamedAggregators instance with this instance.

Parameters:

other - The other instance of named aggregators ot merge.

Returns:

This instance of Named aggregators with associated states updated to reflect the other instance's aggregators.

toString

public String toString()

Overrides:

toString in class Object