org.apache.beam.sdk.fn.stream

Class PrefetchableIterators

java.lang.Object

org.apache.beam.sdk.fn.stream.PrefetchableIterators

public class PrefetchableIterators
extends java.lang.Object

Constructor Summary

Constructors

Constructor and Description
PrefetchableIterators()

Method Summary

Modifier and Type	Method and Description
static <T> PrefetchableIterator<T>	concat(java.util.Iterator<T>... iterators) Concatentates the Iterators.
static <T> PrefetchableIterator<T>	concatIterators(java.util.Iterator<java.util.Iterator<T>> iterators)
static <T> PrefetchableIterator<T>	emptyIterator() Returns an empty PrefetchableIterator.
static <T> PrefetchableIterator<T>	fromArray(T... values) Returns a PrefetchableIterator over the specified values.

Methods inherited from class java.lang.Object

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

Constructor Detail

PrefetchableIterators

public PrefetchableIterators()

Method Detail

emptyIterator

public static <T> PrefetchableIterator<T> emptyIterator()

Returns an empty PrefetchableIterator.

fromArray

public static <T> PrefetchableIterator<T> fromArray(T... values)

Returns a PrefetchableIterator over the specified values.

PrefetchableIterator.prefetch() is a no-op and PrefetchableIterator.isReady() always returns true.

concatIterators

public static <T> PrefetchableIterator<T> concatIterators(java.util.Iterator<java.util.Iterator<T>> iterators)

concat

public static <T> PrefetchableIterator<T> concat(java.util.Iterator<T>... iterators)

Concatentates the Iterators.

Iterables are first converted into a PrefetchableIterable via maybePrefetchable(java.util.Iterator<T>).

The returned PrefetchableIterable ensures that iterators which are returned guarantee that PrefetchableIterator.isReady() always advances till it finds an Iterable that is not PrefetchableIterator.isReady(). PrefetchableIterator.prefetch() is also guaranteed to advance past empty iterators till it finds one that is not ready.