Package org.apache.hadoop.yarn.server.utils

Class LeveldbIterator

java.lang.Object

org.apache.hadoop.yarn.server.utils.LeveldbIterator

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, java.util.Iterator<java.util.Map.Entry<byte[],byte[]>>

@Public
@Evolving
public class LeveldbIterator
extends java.lang.Object
implements java.util.Iterator<java.util.Map.Entry<byte[],byte[]>>, java.io.Closeable

A wrapper for a DBIterator to translate the raw RuntimeExceptions that can be thrown into DBExceptions.

Constructor Summary

Constructors

Constructor	Description
LeveldbIterator(org.iq80.leveldb.DB db)	Create an iterator for the specified database.
LeveldbIterator(org.iq80.leveldb.DBIterator iter)	Create an iterator using the specified underlying DBIterator.
LeveldbIterator(org.iq80.leveldb.DB db, org.iq80.leveldb.ReadOptions options)	Create an iterator for the specified database.

Method Summary

Modifier and Type	Method	Description
void	close()	Closes the iterator.
boolean	hasNext()	Returns true if the iteration has more elements.
boolean	hasPrev()
java.util.Map.Entry<byte[],byte[]>	next()	Returns the next element in the iteration.
java.util.Map.Entry<byte[],byte[]>	peekNext()	Returns the next element in the iteration, without advancing the iteration.
java.util.Map.Entry<byte[],byte[]>	peekPrev()
java.util.Map.Entry<byte[],byte[]>	prev()
void	remove()	Removes from the database the last element returned by the iterator.
void	seek(byte[] key)	Repositions the iterator so the key of the next BlockElement returned greater than or equal to the specified targetKey.
void	seekToFirst()	Repositions the iterator so is is at the beginning of the Database.
void	seekToLast()	Repositions the iterator so it is at the end of of the Database.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Iterator

forEachRemaining

Constructor Detail

LeveldbIterator

public LeveldbIterator(org.iq80.leveldb.DB db)

Create an iterator for the specified database.

Parameters:

db - database.

LeveldbIterator

public LeveldbIterator(org.iq80.leveldb.DB db,
                       org.iq80.leveldb.ReadOptions options)

Create an iterator for the specified database.

Parameters:

db - db.

options - ReadOptions.

LeveldbIterator

public LeveldbIterator(org.iq80.leveldb.DBIterator iter)

Create an iterator using the specified underlying DBIterator.

Parameters:

iter - DB Iterator.

Method Detail

seek

public void seek(byte[] key)
          throws org.iq80.leveldb.DBException

Repositions the iterator so the key of the next BlockElement returned greater than or equal to the specified targetKey.

Parameters:

key - key of the next BlockElement.

Throws:

org.iq80.leveldb.DBException - db Exception.

seekToFirst

public void seekToFirst()
                 throws org.iq80.leveldb.DBException

Repositions the iterator so is is at the beginning of the Database.

Throws:

org.iq80.leveldb.DBException

seekToLast

public void seekToLast()
                throws org.iq80.leveldb.DBException

Repositions the iterator so it is at the end of of the Database.

Throws:

org.iq80.leveldb.DBException

hasNext

public boolean hasNext()
                throws org.iq80.leveldb.DBException

Returns true if the iteration has more elements.

Specified by:

hasNext in interface java.util.Iterator<java.util.Map.Entry<byte[],byte[]>>

Throws:

org.iq80.leveldb.DBException

next

public java.util.Map.Entry<byte[],byte[]> next()
                                              throws org.iq80.leveldb.DBException

Returns the next element in the iteration.

Specified by:

next in interface java.util.Iterator<java.util.Map.Entry<byte[],byte[]>>

Returns:

the next element in the iteration.

Throws:

org.iq80.leveldb.DBException - DB Exception.

peekNext

public java.util.Map.Entry<byte[],byte[]> peekNext()
                                                  throws org.iq80.leveldb.DBException

Returns the next element in the iteration, without advancing the iteration.

Returns:

the next element in the iteration.

Throws:

org.iq80.leveldb.DBException - db Exception.

hasPrev

public boolean hasPrev()
                throws org.iq80.leveldb.DBException

Returns:

true if there is a previous entry in the iteration.

Throws:

org.iq80.leveldb.DBException

prev

public java.util.Map.Entry<byte[],byte[]> prev()
                                              throws org.iq80.leveldb.DBException

Returns:

the previous element in the iteration and rewinds the iteration.

Throws:

org.iq80.leveldb.DBException

peekPrev

public java.util.Map.Entry<byte[],byte[]> peekPrev()
                                                  throws org.iq80.leveldb.DBException

Returns:

the previous element in the iteration, without rewinding the iteration.

Throws:

org.iq80.leveldb.DBException

remove

public void remove()
            throws org.iq80.leveldb.DBException

Removes from the database the last element returned by the iterator.

Specified by:

remove in interface java.util.Iterator<java.util.Map.Entry<byte[],byte[]>>

Throws:

org.iq80.leveldb.DBException

close

public void close()
           throws java.io.IOException

Closes the iterator.

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface java.io.Closeable

Throws:

java.io.IOException