Package org.apache.beam.sdk.fn.stream
Class PrefetchableIterators
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- org.apache.beam.sdk.fn.stream.PrefetchableIterators
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public class PrefetchableIterators extends java.lang.Object
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Constructor Summary
Constructors Constructor Description PrefetchableIterators()
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Method Summary
All Methods Static Methods Concrete Methods Modifier and Type Method Description static <T> PrefetchableIterator<T>concat(java.util.Iterator<T>... iterators)Concatentates theIterators.static <T> PrefetchableIterator<T>concatIterators(java.util.Iterator<java.util.Iterator<T>> iterators)static <T> PrefetchableIterator<T>emptyIterator()Returns an emptyPrefetchableIterator.static <T> PrefetchableIterator<T>fromArray(T... values)Returns aPrefetchableIteratorover the specified values.
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Method Detail
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emptyIterator
public static <T> PrefetchableIterator<T> emptyIterator()
Returns an emptyPrefetchableIterator.
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fromArray
public static <T> PrefetchableIterator<T> fromArray(T... values)
Returns aPrefetchableIteratorover the specified values.PrefetchableIterator.prefetch()is a no-op andPrefetchableIterator.isReady()always returns true.
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concatIterators
public static <T> PrefetchableIterator<T> concatIterators(java.util.Iterator<java.util.Iterator<T>> iterators)
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concat
public static <T> PrefetchableIterator<T> concat(java.util.Iterator<T>... iterators)
Concatentates theIterators.Iterables are first converted into aPrefetchableIterableviamaybePrefetchable(java.util.Iterator<T>).The returned
PrefetchableIterableensures that iterators which are returned guarantee thatPrefetchableIterator.isReady()always advances till it finds anIterablethat is notPrefetchableIterator.isReady().PrefetchableIterator.prefetch()is also guaranteed to advance past empty iterators till it finds one that is not ready.
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