org.apache.hadoop.mapreduce.lib.join

Class ResetableIterator.EMPTY<U extends org.apache.hadoop.io.Writable>

java.lang.Object

org.apache.hadoop.mapreduce.lib.join.ResetableIterator.EMPTY<U>

All Implemented Interfaces:

ResetableIterator<U>

Direct Known Subclasses:

ResetableIterator.EMPTY

Enclosing interface:

ResetableIterator<T extends org.apache.hadoop.io.Writable>

public static class ResetableIterator.EMPTY<U extends org.apache.hadoop.io.Writable>
extends Object
implements ResetableIterator<U>

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.hadoop.mapreduce.lib.join.ResetableIterator

ResetableIterator.EMPTY<U extends org.apache.hadoop.io.Writable>

Constructor Summary

Constructors

Constructor and Description
EMPTY()

Method Summary

Modifier and Type	Method and Description
void	add(U item) Add an element to the collection of elements to iterate over.
void	clear() Close datasources, but do not release internal resources.
void	close() Close datasources and release resources.
boolean	hasNext() True if a call to next may return a value.
boolean	next(U val) Assign next value to actual.
boolean	replay(U val) Assign last value returned to actual.
void	reset() Set iterator to return to the start of its range.

Methods inherited from class java.lang.Object

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

Constructor Detail

EMPTY

public EMPTY()

Method Detail

hasNext

public boolean hasNext()

Description copied from interface: ResetableIterator

True if a call to next may return a value. This is permitted false positives, but not false negatives.

Specified by:

hasNext in interface ResetableIterator<U extends org.apache.hadoop.io.Writable>

reset

public void reset()

Description copied from interface: ResetableIterator

Set iterator to return to the start of its range. Must be called after calling ResetableIterator.add(T) to avoid a ConcurrentModificationException.

Specified by:

reset in interface ResetableIterator<U extends org.apache.hadoop.io.Writable>

close

public void close()
           throws IOException

Description copied from interface: ResetableIterator

Close datasources and release resources. Calling methods on the iterator after calling close has undefined behavior.

Specified by:

close in interface ResetableIterator<U extends org.apache.hadoop.io.Writable>

Throws:

IOException

clear

public void clear()

Description copied from interface: ResetableIterator

Close datasources, but do not release internal resources. Calling this method should permit the object to be reused with a different datasource.

Specified by:

clear in interface ResetableIterator<U extends org.apache.hadoop.io.Writable>

next

public boolean next(U val)
             throws IOException

Description copied from interface: ResetableIterator

Assign next value to actual. It is required that elements added to a ResetableIterator be returned in the same order after a call to ResetableIterator.reset() (FIFO). Note that a call to this may fail for nested joins (i.e. more elements available, but none satisfying the constraints of the join)

Specified by:

next in interface ResetableIterator<U extends org.apache.hadoop.io.Writable>

Throws:

IOException

replay

public boolean replay(U val)
               throws IOException

Description copied from interface: ResetableIterator

Assign last value returned to actual.

Specified by:

replay in interface ResetableIterator<U extends org.apache.hadoop.io.Writable>

Throws:

IOException

add

public void add(U item)
         throws IOException

Description copied from interface: ResetableIterator

Add an element to the collection of elements to iterate over.

Specified by:

add in interface ResetableIterator<U extends org.apache.hadoop.io.Writable>

Throws:

IOException