org.rocksdb

Class AbstractRocksIterator<P extends RocksObject>

java.lang.Object

org.rocksdb.AbstractNativeReference

org.rocksdb.AbstractImmutableNativeReference

org.rocksdb.RocksObject

org.rocksdb.AbstractRocksIterator<P>

Type Parameters:

P - The type of the Parent Object from which the Rocks Iterator was created. This is used by disposeInternal to avoid double-free issues with the underlying C++ object.

All Implemented Interfaces:

java.lang.AutoCloseable, RocksIteratorInterface

Direct Known Subclasses:

RocksIterator, WBWIRocksIterator

public abstract class AbstractRocksIterator<P extends RocksObject>
extends RocksObject
implements RocksIteratorInterface

Base class implementation for Rocks Iterators in the Java API

Multiple threads can invoke const methods on an RocksIterator without external synchronization, but if any of the threads may call a non-const method, all threads accessing the same RocksIterator must use external synchronization.

See Also:

RocksObject

Field Summary

Fields inherited from class org.rocksdb.RocksObject

nativeHandle_

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractRocksIterator(P parent, long nativeHandle)

Method Summary

Modifier and Type	Method and Description
protected void	disposeInternal() Deletes underlying C++ iterator pointer.
boolean	isValid() An iterator is either positioned at an entry, or not valid.
void	next() Moves to the next entry in the source.
void	prev() Moves to the previous entry in the source.
void	seek(byte[] target) Position at the first entry in the source whose key is that or past target.
void	seekForPrev(byte[] target) Position at the first entry in the source whose key is that or before target.
void	seekToFirst() Position at the first entry in the source.
void	seekToLast() Position at the last entry in the source.
void	status() If an error has occurred, return it.

Methods inherited from class org.rocksdb.RocksObject

disposeInternal

Methods inherited from class org.rocksdb.AbstractImmutableNativeReference

close, disOwnNativeHandle, isOwningHandle

Methods inherited from class org.rocksdb.AbstractNativeReference

dispose, finalize

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractRocksIterator

protected AbstractRocksIterator(P parent,
                                long nativeHandle)

Method Detail

isValid

public boolean isValid()

Description copied from interface: RocksIteratorInterface

An iterator is either positioned at an entry, or not valid. This method returns true if the iterator is valid.

Specified by:

isValid in interface RocksIteratorInterface

Returns:

true if iterator is valid.

seekToFirst

public void seekToFirst()

Description copied from interface: RocksIteratorInterface

Position at the first entry in the source. The iterator is Valid() after this call if the source is not empty.

Specified by:

seekToFirst in interface RocksIteratorInterface

seekToLast

public void seekToLast()

Description copied from interface: RocksIteratorInterface

Position at the last entry in the source. The iterator is valid after this call if the source is not empty.

Specified by:

seekToLast in interface RocksIteratorInterface

seek

public void seek(byte[] target)

Description copied from interface: RocksIteratorInterface

Position at the first entry in the source whose key is that or past target.

The iterator is valid after this call if the source contains a key that comes at or past target.

Specified by:

seek in interface RocksIteratorInterface

Parameters:

target - byte array describing a key or a key prefix to seek for.

seekForPrev

public void seekForPrev(byte[] target)

Description copied from interface: RocksIteratorInterface

Position at the first entry in the source whose key is that or before target.

The iterator is valid after this call if the source contains a key that comes at or before target.

Specified by:

seekForPrev in interface RocksIteratorInterface

Parameters:

target - byte array describing a key or a key prefix to seek for.

next

public void next()

Description copied from interface: RocksIteratorInterface

Moves to the next entry in the source. After this call, Valid() is true if the iterator was not positioned at the last entry in the source.

REQUIRES: RocksIteratorInterface.isValid()

Specified by:

next in interface RocksIteratorInterface

prev

public void prev()

Description copied from interface: RocksIteratorInterface

Moves to the previous entry in the source. After this call, Valid() is true if the iterator was not positioned at the first entry in source.

REQUIRES: RocksIteratorInterface.isValid()

Specified by:

prev in interface RocksIteratorInterface

status

public void status()
            throws RocksDBException

Description copied from interface: RocksIteratorInterface

If an error has occurred, return it. Else return an ok status. If non-blocking IO is requested and this operation cannot be satisfied without doing some IO, then this returns Status::Incomplete().

Specified by:

status in interface RocksIteratorInterface

Throws:

RocksDBException - thrown if error happens in underlying native library.

disposeInternal

protected void disposeInternal()

Deletes underlying C++ iterator pointer.

Note: the underlying handle can only be safely deleted if the parent instance related to a certain RocksIterator is still valid and initialized. Therefore disposeInternal() checks if the parent is initialized before freeing the native handle.

Overrides:

disposeInternal in class RocksObject