Package com.github.ferstl.streams

Class ParallelLongStreamSupport

java.lang.Object

com.github.ferstl.streams.ParallelLongStreamSupport

All Implemented Interfaces:

AutoCloseable, BaseStream<Long,LongStream>, LongStream

public class ParallelLongStreamSupport
extends Object
implements LongStream

An implementation of LongStream which uses a custom ForkJoinPool for parallel aggregate operations. This is the long primitive specialization of ParallelStreamSupport.

The following example illustrates an aggregate operation using ParallelStreamSupport and ParallelLongStreamSupport with a custom ForkJoinPool, computing the sum of the weights of the red widgets:

 ForkJoinPool pool = new ForkJoinPool();
 long sum = ParallelStreamSupport.parallelStream(widgets, pool)
     .filter(w -> w.getColor() == RED)
     .mapToLong(w -> w.getWeight())
     .sum();
 

In case this stream is configured for parallel execution, i.e. BaseStream.isParallel() returns true, a terminal operation will be executed as ForkJoinTask in the custom ForkJoinPool. Otherwise it will be executed in the calling thread.

This implementation offers various factory methods which are based on:

• The static factory methods of LongStream, which are meaningful for parallel streams
• Arrays.stream(long[])
• StreamSupport.longStream(Spliterator.OfLong, boolean)
• StreamSupport.longStream(Supplier, int, boolean)

API Note:

Internally, this stream wraps a long stream which is initially created in one of the static factory methods. Whenever a non-terminal operation is called the underlying stream will be replaced with the result of calling the same method on that stream. The return value of these operations is always this stream or, in case of operations that return a different type of stream, one of ParallelStreamSupport, ParallelIntStreamSupport or ParallelDoubleStreamSupport.

Although each factory method returns a parallel stream, calling BaseStream.sequential() is still possible and leads to sequential execution of a terminal operation within the calling thread.

Implementation Note:

See the class documentation for Stream and the package documentation for java.util.stream for additional specification.

Nested Class Summary

Nested classes/interfaces inherited from interface java.util.stream.LongStream

LongStream.Builder

Method Summary

Modifier and Type	Method	Description
boolean	allMatch(LongPredicate predicate)
boolean	anyMatch(LongPredicate predicate)
DoubleStream	asDoubleStream()
OptionalDouble	average()
Stream<Long>	boxed()
void	close()
<R> R	collect(Supplier<R> supplier, ObjLongConsumer<R> accumulator, BiConsumer<R,R> combiner)
static LongStream	concat(LongStream a, LongStream b, ForkJoinPool workerPool)	Creates a lazily concatenated parallel long stream whose elements are all the elements of the first stream followed by all the elements of the second stream.
long	count()
LongStream	distinct()
LongStream	dropWhile(LongPredicate predicate)
protected void	execute(Runnable terminalOperation)
protected <R> R	execute(Callable<R> terminalOperation)
LongStream	filter(LongPredicate predicate)
OptionalLong	findAny()
OptionalLong	findFirst()
LongStream	flatMap(LongFunction<? extends LongStream> mapper)
void	forEach(LongConsumer action)
void	forEachOrdered(LongConsumer action)
static LongStream	generate(LongSupplier supplier, ForkJoinPool workerPool)	Creates a parallel infinite sequential unordered long stream where each element is generated by the provided LongSupplier.
boolean	isParallel()
static LongStream	iterate(long seed, LongUnaryOperator operator, ForkJoinPool workerPool)	Creates a parallel infinite ordered long stream produced by iterative application of a function f to an initial element seed.
PrimitiveIterator.OfLong	iterator()
LongStream	limit(long maxSize)
LongStream	map(LongUnaryOperator mapper)
DoubleStream	mapToDouble(LongToDoubleFunction mapper)
IntStream	mapToInt(LongToIntFunction mapper)
<U> Stream<U>	mapToObj(LongFunction<? extends U> mapper)
OptionalLong	max()
OptionalLong	min()
boolean	noneMatch(LongPredicate predicate)
S	onClose(Runnable closeHandler)
S	parallel()
static LongStream	parallelStream(long[] array, ForkJoinPool workerPool)	Creates a parallel long stream from the given Array.
static LongStream	parallelStream(Supplier<? extends Spliterator.OfLong> supplier, int characteristics, ForkJoinPool workerPool)	Creates a parallel long stream from the given Spliterator supplier.
static LongStream	parallelStream(Spliterator.OfLong spliterator, ForkJoinPool workerPool)	Creates a parallel long stream from the given Spliterator.
static LongStream	parallelStream(LongStream.Builder builder, ForkJoinPool workerPool)	Creates a parallel long stream from the given LongStream.Builder.
LongStream	peek(LongConsumer action)
static LongStream	range(long startInclusive, long endExclusive, ForkJoinPool workerPool)	Creates a parallel ordered long stream from startInclusive (inclusive) to endExclusive (exclusive) by an incremental step of 1.
static LongStream	rangeClosed(long startInclusive, long endInclusive, ForkJoinPool workerPool)	Creates a parallel ordered long stream from startInclusive (inclusive) to endInclusive (inclusive) by an incremental step of 1.
long	reduce(long identity, LongBinaryOperator op)
OptionalLong	reduce(LongBinaryOperator op)
S	sequential()
LongStream	skip(long n)
LongStream	sorted()
Spliterator.OfLong	spliterator()
long	sum()
LongSummaryStatistics	summaryStatistics()
LongStream	takeWhile(LongPredicate predicate)
long[]	toArray()
S	unordered()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.stream.BaseStream

close, isParallel, onClose, unordered

Methods inherited from interface java.util.stream.LongStream

parallel, sequential

Method Detail

parallelStream

public static LongStream parallelStream(long[] array,
                                        ForkJoinPool workerPool)

Creates a parallel long stream from the given Array. This operation is similar to calling Arrays.stream(array).parallel() with the difference that a parallel terminal operation will be executed in the given ForkJoinPool.

Parameters:

array - Array to create the parallel stream from. Must not be null.

workerPool - Thread pool for parallel execution of a terminal operation. Must not be null.

Returns:

A parallel long stream that executes a terminal operation in the given ForkJoinPool.

See Also:

Arrays.stream(long[])

parallelStream

public static LongStream parallelStream(Spliterator.OfLong spliterator,
                                        ForkJoinPool workerPool)

Creates a parallel long stream from the given Spliterator. This operation is similar to calling StreamSupport.longStream(spliterator, true) with the difference that a parallel terminal operation will be executed in the given ForkJoinPool.

Parameters:

spliterator - A Spliterator.OfLong describing the stream elements. Must not be null.

workerPool - Thread pool for parallel execution of a terminal operation. Must not be null.

Returns:

A parallel long stream that executes a terminal operation in the given ForkJoinPool.

See Also:

StreamSupport.longStream(Spliterator.OfLong, boolean)

parallelStream

public static LongStream parallelStream(Supplier<? extends Spliterator.OfLong> supplier,
                                        int characteristics,
                                        ForkJoinPool workerPool)

Creates a parallel long stream from the given Spliterator supplier. This operation is similar to calling StreamSupport.longStream(supplier, characteristics, true) with the difference that a parallel terminal operation will be executed in the given ForkJoinPool.

Parameters:

supplier - A Supplier of a Spliterator.OfLong. Must not be null.

characteristics - Spliterator characteristics of the supplied Spliterator. The characteristics must be equal to supplier.get().characteristics(), otherwise undefined behavior may occur when terminal operation commences.

workerPool - Thread pool for parallel execution of a terminal operation. Must not be null.

Returns:

A parallel long stream that executes a terminal operation in the given ForkJoinPool.

See Also:

StreamSupport.longStream(Supplier, int, boolean)

parallelStream

public static LongStream parallelStream(LongStream.Builder builder,
                                        ForkJoinPool workerPool)

Creates a parallel long stream from the given LongStream.Builder. This operation is similar to calling builder.build().parallel() with the difference that a parallel terminal operation will be executed in the given ForkJoinPool.

Parameters:

builder - The builder to create the stream from. Must not be null.

workerPool - Thread pool for parallel execution of a terminal operation. Must not be null.

Returns:

A parallel long stream that executes a terminal operation in the given ForkJoinPool. builder()

iterate

public static LongStream iterate(long seed,
                                 LongUnaryOperator operator,
                                 ForkJoinPool workerPool)

Creates a parallel infinite ordered long stream produced by iterative application of a function f to an initial element seed. This operation is similar to calling LongStream.iterate(seed, operator).parallel() with the difference that a parallel terminal operation will be executed in the given ForkJoinPool.

Parameters:

seed - The initial element.

operator - A function to be applied to to the previous element to produce a new element. Must not be null.

workerPool - Thread pool for parallel execution of a terminal operation. Must not be null.

Returns:

A parallel long stream that executes a terminal operation in the given ForkJoinPool.

See Also:

LongStream.iterate(long, LongUnaryOperator)

generate

public static LongStream generate(LongSupplier supplier,
                                  ForkJoinPool workerPool)

Creates a parallel infinite sequential unordered long stream where each element is generated by the provided LongSupplier. This operation is similar to calling LongStream.generate(supplier).parallel() with the difference that a parallel terminal operation will be executed in the given ForkJoinPool.

Parameters:

supplier - The LongSupplier of generated elements. Must not be null.

workerPool - Thread pool for parallel execution of a terminal operation. Must not be null.

Returns:

A parallel long stream that executes a terminal operation in the given ForkJoinPool.

See Also:

LongStream.generate(LongSupplier)

range

public static LongStream range(long startInclusive,
                               long endExclusive,
                               ForkJoinPool workerPool)

Creates a parallel ordered long stream from startInclusive (inclusive) to endExclusive (exclusive) by an incremental step of 1. This operation is similar to calling LongStream.range(startInclusive, endExclusive).parallel() with the difference that a parallel terminal operation will be executed in the given ForkJoinPool.

Parameters:

startInclusive - the (inclusive) initial value

endExclusive - the exclusive upper bound

workerPool - Thread pool for parallel execution of a terminal operation. Must not be null.

Returns:

A parallel long stream that executes a terminal operation in the given ForkJoinPool for the range of long elements.

See Also:

LongStream.range(long, long)

rangeClosed

public static LongStream rangeClosed(long startInclusive,
                                     long endInclusive,
                                     ForkJoinPool workerPool)

Creates a parallel ordered long stream from startInclusive (inclusive) to endInclusive (inclusive) by an incremental step of 1. This operation is similar to calling LongStream.rangeClosed(startInclusive, endInclusive).parallel() with the difference that a parallel terminal operation will be executed in the given ForkJoinPool.

Parameters:

startInclusive - the (inclusive) initial value

endInclusive - the inclusive upper bound

workerPool - Thread pool for parallel execution of a terminal operation. Must not be null.

Returns:

A parallel long stream that executes a terminal operation in the given ForkJoinPool for the range of long elements.

See Also:

LongStream.rangeClosed(long, long)

concat

public static LongStream concat(LongStream a,
                                LongStream b,
                                ForkJoinPool workerPool)

Creates a lazily concatenated parallel long stream whose elements are all the elements of the first stream followed by all the elements of the second stream. This operation is similar to calling LongStream.concat(a, b).parallel() with the difference that a parallel terminal operation will be executed in the given ForkJoinPool.

Parameters:

a - The first stream. Must not be null.

b - The second stream. Must not be null.

workerPool - Thread pool for parallel execution of a terminal operation. Must not be null.

Returns:

A parallel stream that executes a terminal operation in the given ForkJoinPool.

See Also:

LongStream.concat(LongStream, LongStream)

filter

public LongStream filter(LongPredicate predicate)

Specified by:

filter in interface LongStream

map

public LongStream map(LongUnaryOperator mapper)

Specified by:

map in interface LongStream

mapToObj

public <U> Stream<U> mapToObj(LongFunction<? extends U> mapper)

Specified by:

mapToObj in interface LongStream

mapToInt

public IntStream mapToInt(LongToIntFunction mapper)

Specified by:

mapToInt in interface LongStream

mapToDouble

public DoubleStream mapToDouble(LongToDoubleFunction mapper)

Specified by:

mapToDouble in interface LongStream

flatMap

public LongStream flatMap(LongFunction<? extends LongStream> mapper)

Specified by:

flatMap in interface LongStream

distinct

public LongStream distinct()

Specified by:

distinct in interface LongStream

sorted

public LongStream sorted()

Specified by:

sorted in interface LongStream

peek

public LongStream peek(LongConsumer action)

Specified by:

peek in interface LongStream

limit

public LongStream limit(long maxSize)

Specified by:

limit in interface LongStream

skip

public LongStream skip(long n)

Specified by:

skip in interface LongStream

takeWhile

public LongStream takeWhile(LongPredicate predicate)

Specified by:

takeWhile in interface LongStream

dropWhile

public LongStream dropWhile(LongPredicate predicate)

Specified by:

dropWhile in interface LongStream

forEach

public void forEach(LongConsumer action)

Specified by:

forEach in interface LongStream

forEachOrdered

public void forEachOrdered(LongConsumer action)

Specified by:

forEachOrdered in interface LongStream

toArray

public long[] toArray()

Specified by:

toArray in interface LongStream

reduce

public long reduce(long identity,
                   LongBinaryOperator op)

Specified by:

reduce in interface LongStream

reduce

public OptionalLong reduce(LongBinaryOperator op)

Specified by:

reduce in interface LongStream

collect

public <R> R collect(Supplier<R> supplier,
                     ObjLongConsumer<R> accumulator,
                     BiConsumer<R,R> combiner)

Specified by:

collect in interface LongStream

sum

public long sum()

Specified by:

sum in interface LongStream

min

public OptionalLong min()

Specified by:

min in interface LongStream

max

public OptionalLong max()

Specified by:

max in interface LongStream

count

public long count()

Specified by:

count in interface LongStream

average

public OptionalDouble average()

Specified by:

average in interface LongStream

summaryStatistics

public LongSummaryStatistics summaryStatistics()

Specified by:

summaryStatistics in interface LongStream

anyMatch

public boolean anyMatch(LongPredicate predicate)

Specified by:

anyMatch in interface LongStream

allMatch

public boolean allMatch(LongPredicate predicate)

Specified by:

allMatch in interface LongStream

noneMatch

public boolean noneMatch(LongPredicate predicate)

Specified by:

noneMatch in interface LongStream

findFirst

public OptionalLong findFirst()

Specified by:

findFirst in interface LongStream

findAny

public OptionalLong findAny()

Specified by:

findAny in interface LongStream

asDoubleStream

public DoubleStream asDoubleStream()

Specified by:

asDoubleStream in interface LongStream

boxed

public Stream<Long> boxed()

Specified by:

boxed in interface LongStream

iterator

public PrimitiveIterator.OfLong iterator()

Specified by:

iterator in interface BaseStream<Long,LongStream>

Specified by:

iterator in interface LongStream

spliterator

public Spliterator.OfLong spliterator()

Specified by:

spliterator in interface BaseStream<Long,LongStream>

Specified by:

spliterator in interface LongStream

isParallel

public boolean isParallel()

Specified by:

isParallel in interface BaseStream<T,S extends BaseStream<T,S>>

sequential

public S sequential()

Specified by:

sequential in interface BaseStream<T,S extends BaseStream<T,S>>

parallel

public S parallel()

Specified by:

parallel in interface BaseStream<T,S extends BaseStream<T,S>>

unordered

public S unordered()

Specified by:

unordered in interface BaseStream<T,S extends BaseStream<T,S>>

onClose

public S onClose(Runnable closeHandler)

Specified by:

onClose in interface BaseStream<T,S extends BaseStream<T,S>>

close

public void close()

Specified by:

close in interface AutoCloseable

Specified by:

close in interface BaseStream<T,S extends BaseStream<T,S>>

execute

protected void execute(Runnable terminalOperation)

execute

protected <R> R execute(Callable<R> terminalOperation)