com.google.cloud.dataflow.sdk.util.common.worker

Class AbstractBoundedReaderIterator<T>

java.lang.Object

com.google.cloud.dataflow.sdk.util.common.worker.Reader.AbstractReaderIterator<T>

com.google.cloud.dataflow.sdk.util.common.worker.AbstractBoundedReaderIterator<T>

Type Parameters:

T - Type of records returned by the reader.

All Implemented Interfaces:

Reader.ReaderIterator<T>, AutoCloseable

Direct Known Subclasses:

FileBasedReader.FileBasedIterator

public abstract class AbstractBoundedReaderIterator<T>
extends Reader.AbstractReaderIterator<T>

An abstract base class for implementations of ReaderIterator classes for bounded sources, where hasNext() returns the same value if called multiple times.

Provides basic treatment of hasNext()/next() to simplify implementations (e.g. ensuring hasNext() is called only once and verifying hasNext() in next()) and default no-op implementations of other operations.

This class is intended for internal usage. Users of Dataflow must not subclass it.

Constructor Summary

Constructors

Constructor and Description
AbstractBoundedReaderIterator()

Method Summary

Modifier and Type	Method and Description
boolean	hasNext() Returns whether the source has any more elements.
protected abstract boolean	hasNextImpl()
T	next() Returns the next element.
protected abstract T	nextImpl()

Methods inherited from class com.google.cloud.dataflow.sdk.util.common.worker.Reader.AbstractReaderIterator

close, copy, getProgress, requestDynamicSplit

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractBoundedReaderIterator

public AbstractBoundedReaderIterator()

Method Detail

hasNext

public final boolean hasNext()
                      throws IOException

Description copied from interface: Reader.ReaderIterator

Returns whether the source has any more elements. Some sources, such as GroupingShuffleReader, invalidate the return value of the previous next() call during the call to hasNext().

Throws:

IOException

hasNextImpl

protected abstract boolean hasNextImpl()
                                throws IOException

Throws:

IOException

next

public final T next()
             throws IOException,
                    NoSuchElementException

Description copied from interface: Reader.ReaderIterator

Returns the next element.

Throws:

IOException - if attempting to access an element involves IO that fails

NoSuchElementException - if there are no more elements

nextImpl

protected abstract T nextImpl()
                       throws IOException

Throws:

IOException