CombinerAggregator (Storm 2.2.1 API)

All Superinterfaces:

Operation, Serializable

All Known Implementing Classes:

Count, LongSum
```
public interface CombinerAggregator<T,A,R>
extends Operation
```
Interface for aggregating values.

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method and Description
`A`	`apply(A accumulator, T value)` Updates the accumulator by applying the current accumulator with the value.
`A`	`init()` The initial value of the accumulator to start with.
`A`	`merge(A accum1, A accum2)` Merges two accumulators and returns the merged accumulator.
`static <T,R> CombinerAggregator<T,R,R>`	`of(R initialValue, BiFunction<? super R,? super T,? extends R> accumulator, BiFunction<? super R,? super R,? extends R> combiner)` A static factory to create a `CombinerAggregator` based on initial value, accumulator and combiner.
`R`	`result(A accum)` Produces a result value out of the accumulator.

- Method Detail
  - of
```
static <T,R> CombinerAggregator<T,R,R> of(R initialValue,
                                          BiFunction<? super R,? super T,? extends R> accumulator,
                                          BiFunction<? super R,? super R,? extends R> combiner)
```
    A static factory to create a CombinerAggregator based on initial value, accumulator and combiner.
    
    Parameters:
    
    initialValue - the initial value of the result to start with
    
    accumulator - a function that accumulates values into a partial result
    
    combiner - a function that combines partially accumulated results
    
    T - the value type
    
    R - the result type
    
    Returns:
    
    the CombinerAggregator
  - init
```
A init()
```
    The initial value of the accumulator to start with.
    
    Returns:
    
    the initial value of the accumulator
  - apply
```
A apply(A accumulator,
        T value)
```
    Updates the accumulator by applying the current accumulator with the value.
    
    Parameters:
    
    accumulator - the current accumulator
    
    value - the value
    
    Returns:
    
    the updated accumulator
  - merge
```
A merge(A accum1,
        A accum2)
```
    Merges two accumulators and returns the merged accumulator.
    
    Parameters:
    
    accum1 - the first accumulator
    
    accum2 - the second accumulator
    
    Returns:
    
    the merged accumulator
  - result
```
R result(A accum)
```
    Produces a result value out of the accumulator.
    
    Parameters:
    
    accum - the accumulator
    
    Returns:
    
    the result

Interface CombinerAggregator<T,A,R>

Method Summary

Method Detail

of

init

apply

merge

result