uk.ac.starlink.util

Interface Splittable<S extends Splittable<S>>

All Known Subinterfaces:

CoordSequence, RowSplittable, TupleSequence

All Known Implementing Classes:

AbortTupleSequence, CachedTupleSequence, DataPosSequence, EmptyRowSequence, MappingRowSplittable, ProgressRowSplittable, RandomRowSplittable, SequentialRowSplittable

public interface Splittable<S extends Splittable<S>>

Defines an object which can be split into two for subdivided processing.

This does a similar job to Spliterator, but it imposes no assumptions about the form of the split objects, for instance that they form a sequence that can be iterated over internally, which idiom forms the basis of the Java 8 streams framework. Collections or sequences based on Splittable can use external iteration, which allows better control in some cases.

Since:

12 Sep 2019

Author:

Mark Taylor

Method Summary

Modifier and Type	Method and Description
S	split() Attempts to partition this object into two halves, ideally of similar size.
long	splittableSize() Provides an estimate of the number of processable items in this object.

Method Detail

split

S split()

Attempts to partition this object into two halves, ideally of similar size. If a non-null value is returned, then the content previously contained by this object is now split between this object and the returned object. If for any reason a split is not carried out, null is returned.

Following a successful call, the two parts may be processed in different threads.

Returns:

other half of this splittable, or null

See Also:

Spliterator.trySplit()

splittableSize

long splittableSize()

Provides an estimate of the number of processable items in this object. A processable item is not a well-defined quantity, but it should generally be something that can be processed fast. For instance, if this object represents a collection of collections, the value that should be returned is the total number of elements rather than the number of collections.

If no estimate for the size is available, a negative value should be returned.

Returns:

approximate size, or negative value if not known