Package org.apache.hadoop.util.functional

Class RemoteIterators.WrappingRemoteIterator<S,T>

java.lang.Object

org.apache.hadoop.util.functional.RemoteIterators.WrappingRemoteIterator<S,T>

Type Parameters:

S - source type

T - type of returned value

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, RemoteIterator<T>, IOStatisticsSource

Enclosing class:

RemoteIterators

public abstract static class RemoteIterators.WrappingRemoteIterator<S,T>
extends java.lang.Object
implements RemoteIterator<T>, IOStatisticsSource, java.io.Closeable

Wrapper of another remote iterator; IOStatistics and Closeable methods are passed down if implemented. This class may be subclassed within the hadoop codebase if custom iterators are needed.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	WrappingRemoteIterator(RemoteIterator<S> source)

Method Summary

Modifier and Type	Method	Description
void	close()
IOStatistics	getIOStatistics()	Return a statistics instance.
protected RemoteIterator<S>	getSource()
protected boolean	sourceHasNext()	Check for the source having a next element.
protected S	sourceNext()	Get the next source value.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.hadoop.fs.RemoteIterator

hasNext, next

Constructor Detail

WrappingRemoteIterator

protected WrappingRemoteIterator(RemoteIterator<S> source)

Method Detail

getSource

protected RemoteIterator<S> getSource()

getIOStatistics

public IOStatistics getIOStatistics()

Description copied from interface: IOStatisticsSource

Return a statistics instance.

It is not a requirement that the same instance is returned every time. IOStatisticsSource.

If the object implementing this is Closeable, this method may return null if invoked on a closed object, even if it returns a valid instance when called earlier.

Specified by:

getIOStatistics in interface IOStatisticsSource

Returns:

an IOStatistics instance or null

close

public void close()
           throws java.io.IOException

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface java.io.Closeable

Throws:

java.io.IOException

sourceHasNext

protected boolean sourceHasNext()
                         throws java.io.IOException

Check for the source having a next element. If it does not, this object's close() method is called and false returned

Returns:

true if there is a new value

Throws:

java.io.IOException - failure to retrieve next value

sourceNext

protected S sourceNext()
                throws java.io.IOException

Get the next source value. This calls sourceHasNext() first to verify that there is data.

Returns:

the next value

Throws:

java.io.IOException - failure

java.util.NoSuchElementException - no more data

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object