Package org.pipecraft.pipes.sync.inter.reduct

Class ListReductorPipe<S,T>

java.lang.Object

org.pipecraft.pipes.sync.inter.reduct.SequenceReductorPipe<S,T>

org.pipecraft.pipes.sync.inter.reduct.ListReductorPipe<S,T>

Type Parameters:

S - The data type of items in the input pipe

T - The data type of the output items

All Implemented Interfaces:

Closeable, AutoCloseable, BasePipe, Pipe<T>

public class ListReductorPipe<S,T>
extends SequenceReductorPipe<S,T>

Scans the input pipe and groups sequential items based on some discriminating property. The group is then being reduced into a single item using the caller's provided logic. Since each sequence is internally stored in a list, this class provides protection defined by groupSizeLimit and sizeLimitPolicy.

Author:

Eyal Schneider

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ListReductorPipe.GroupSizeLimitPolicy

Constructor Summary

Constructors

Constructor	Description
ListReductorPipe(Pipe<S> input, FailableFunction<S,?,PipeException> discriminator, Function<List<S>,T> postProcessor)	Constructor Creates a sequence reductor pipe with no protective threshold on group sizes.
ListReductorPipe(Pipe<S> input, FailableFunction<S,?,PipeException> discriminator, Function<List<S>,T> postProcessor, int groupSizeLimit, ListReductorPipe.GroupSizeLimitPolicy sizeLimitPolicy)	Constructor

Method Summary

Methods inherited from class org.pipecraft.pipes.sync.inter.reduct.SequenceReductorPipe

close, getProgress, next, peek, start

Methods inherited from class java.lang.Object

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

Constructor Detail

ListReductorPipe

public ListReductorPipe(Pipe<S> input,
                        FailableFunction<S,?,PipeException> discriminator,
                        Function<List<S>,T> postProcessor,
                        int groupSizeLimit,
                        ListReductorPipe.GroupSizeLimitPolicy sizeLimitPolicy)

Constructor

Parameters:

input - The input pipe

discriminator - The function that maps input pipe values to some discriminator value used for reduction

postProcessor - A function that accepts a list of values to group (i.e. having the same discriminator value), and aggregates them into an output item.

groupSizeLimit - The maximum size for a group. Used for avoiding excessive heap usage when collecting items for the reductor. Use 0 for no limit.

sizeLimitPolicy - Use TRUNCATE for ignoring group items beyond the threshold, and FAIL for throwing an exception when this happens.

ListReductorPipe

public ListReductorPipe(Pipe<S> input,
                        FailableFunction<S,?,PipeException> discriminator,
                        Function<List<S>,T> postProcessor)

Constructor Creates a sequence reductor pipe with no protective threshold on group sizes.

Parameters:

input - The input pipe

discriminator - The function that maps input pipe values to some discriminator value used for reduction

postProcessor - A function that accepts a list of values to group (i.e. having the same discriminator value), and aggregates them into an output item.