Package org.apache.ignite.lang

Interface IgniteReducer<E,R>

Type Parameters:

E - Type of collected values.

R - Type of reduced value.

All Superinterfaces:

Serializable

All Known Subinterfaces:

R1<E1,R>

All Known Implementing Classes:

AlwaysTrueReducer, IgniteReducerX, IntSumReducer, LongSumReducer, RX1, StringConcatReducer

public interface IgniteReducer<E,R>
extends Serializable

Defines generic reducer that collects multiple values and reduces them into one. Reducers are useful in computations when results from multiple remote jobs need to be reduced into one, e.g. IgniteCompute.call(Collection, IgniteReducer) method.

Method Summary

Modifier and Type	Method	Description
boolean	collect(E e)	Collects given value.
R	reduce()	Reduces collected values into one.

Method Detail

collect

boolean collect(@Nullable
                E e)

Collects given value. If this method returns false then reduce() will be called right away. Otherwise caller will continue collecting until all values are processed.

Parameters:

e - Value to collect.

Returns:

true to continue collecting, false to instruct caller to stop collecting and call reduce() method.

reduce

R reduce()

Reduces collected values into one.

Returns:

Reduced value.