Package io.permazen.kv.util

Class PrefixKVDatabase

java.lang.Object

io.permazen.kv.util.PrefixKVDatabase

All Implemented Interfaces:

KVDatabase

public class PrefixKVDatabase
extends Object
implements KVDatabase

Prefix KVDatabase implementation.

Instances use a fixed byte[] key prefix for all key access, thereby providing a nested KVDatabase view of the corresponding sub-range of keys within the containing KVDatabase. This allows, for example, multiple KVDatabases to exist within a single containing KVDatabase under different key prefixes.

Instances ignore invocations to start() and stop(); instead, invoke these methods on the underlying KVDatabase.

Constructor Summary

Constructors

Constructor	Description
PrefixKVDatabase(KVDatabase db, ByteData keyPrefix)	Constructor.

Method Summary

Modifier and Type	Method	Description
PrefixKVTransaction	createTransaction()	Create a new transaction.
PrefixKVTransaction	createTransaction(Map<String,?> options)	Create a new transaction with the specified options.
KVDatabase	getContainingKVDatabase()	Get the containing KVDatabase associated with this instance.
final ByteData	getKeyPrefix()	Get the key prefix associated with this instance.
void	start()	Start this instance.
void	stop()	Stop this instance.

Methods inherited from class java.lang.Object

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

Constructor Details

PrefixKVDatabase

public PrefixKVDatabase(KVDatabase db,
 ByteData keyPrefix)

Constructor.

Parameters:

db - the containing KVDatabase

keyPrefix - prefix for all keys

Throws:

IllegalArgumentException - if db or keyPrefix is null

Method Details

getContainingKVDatabase

public KVDatabase getContainingKVDatabase()

Get the containing KVDatabase associated with this instance.

Returns:

the containing KVDatabase

getKeyPrefix

public final ByteData getKeyPrefix()

Get the key prefix associated with this instance.

Returns:

this instance's key prefix

start

public void start()

Description copied from interface: KVDatabase

Start this instance. This method must be called prior to creating any transactions.

This method is idempotent: if this instance is already started, nothing happens.

Whether an instance that has been started and stopped can be restarted is implementation-dependent.

Specified by:

start in interface KVDatabase

stop

public void stop()

Description copied from interface: KVDatabase

Stop this instance.

This method is idempotent: if this instance has not been started, or is already stopped, nothing happens.

Specified by:

stop in interface KVDatabase

createTransaction

public PrefixKVTransaction createTransaction(Map<String,?> options)

Description copied from interface: KVDatabase

Create a new transaction with the specified options.

Specified by:

createTransaction in interface KVDatabase

Parameters:

options - optional transaction options; may be null

Returns:

newly created transaction

createTransaction

public PrefixKVTransaction createTransaction()

Description copied from interface: KVDatabase

Create a new transaction.

Specified by:

createTransaction in interface KVDatabase

Returns:

newly created transaction