uk.ac.starlink.table.join

Class CollectionRunner<E>

java.lang.Object

uk.ac.starlink.table.join.CollectionRunner<E>

public class CollectionRunner<E>
extends Object

Harnesses a SplitProcessor to perform parallel processing on elements of a Java Collection.

This more or less duplicates part of the behaviour of the Java 8 streams framework, but it provides the additional control available from SplitProcessor, and also works with a ProgressIndicator to provide interruption control and progress logging.

Since:

21 Sep 2022

Author:

Mark Taylor

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	CollectionRunner.ElementCollector<E,A> Interface to define a collection operation for use with this class.

Field Summary

Fields

Modifier and Type	Field and Description
static CollectionRunner<?>	DFLT Untyped instance using default policy.
static CollectionRunner<?>	SEQUENTIAL Untyped instance for sequential operation.

Constructor Summary

Constructors

Constructor and Description
CollectionRunner() Default constructor, using default policy.
CollectionRunner(SplitProcessor<?> processor) Constructs an instance with a given SplitProcessor.

Method Summary

Modifier and Type	Method and Description
<A> A	collect(CollectionRunner.ElementCollector<E,A> collector, Collection<E> collection) Performs a collect operation without logging.
<A> A	collect(CollectionRunner.ElementCollector<E,A> collector, Collection<E> collection, ProgressIndicator progger) Performs a collect operation with optional progress logging.
static <E,A> A	collectStream(CollectionRunner.ElementCollector<E,A> collector, java.util.stream.Stream<E> stream) Performs a collection operation using the Java 8 streams framework.
SplitProcessor<?>	getSplitProcessor() Returns this runner's SplitProcessor.

Methods inherited from class java.lang.Object

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

Field Detail

SEQUENTIAL

public static final CollectionRunner<?> SEQUENTIAL

Untyped instance for sequential operation.

DFLT

public static final CollectionRunner<?> DFLT

Untyped instance using default policy.

Constructor Detail

CollectionRunner

public CollectionRunner()

Default constructor, using default policy.

CollectionRunner

public CollectionRunner(SplitProcessor<?> processor)

Constructs an instance with a given SplitProcessor.

Parameters:

processor - controls behaviour

Method Detail

getSplitProcessor

public SplitProcessor<?> getSplitProcessor()

Returns this runner's SplitProcessor.

Returns:

split processor

collect

public <A> A collect(CollectionRunner.ElementCollector<E,A> collector,
                     Collection<E> collection)

Performs a collect operation without logging.

Parameters:

collector - defines behaviour

collection - data on which to operate

Returns:

result of collection

collect

public <A> A collect(CollectionRunner.ElementCollector<E,A> collector,
                     Collection<E> collection,
                     ProgressIndicator progger)

Performs a collect operation with optional progress logging.

Parameters:

collector - defines behaviour

collection - data on which to operate

progger - progress logger

Returns:

result of collection

collectStream

public static <E,A> A collectStream(CollectionRunner.ElementCollector<E,A> collector,
                                    java.util.stream.Stream<E> stream)

Performs a collection operation using the Java 8 streams framework. This does not use any of the implementation code associated with SplitProcessor, it just creates a Collector based on the supplied ElementCollector and feeds the stream to it.

This method is only intended for testing and comparison purposes; if you actually want to use Java 8 streams, you might as well use the Collector interface directly.

Parameters:

collector - collector

stream - input stream

Returns:

result of collection operation