com.persistit

Class TimelyResource<V extends com.persistit.Version>

java.lang.Object

com.persistit.TimelyResource<V>

Type Parameters:

V - specific type of Version this TimelyResource manages

public class TimelyResource<V extends com.persistit.Version>
extends Object

Transactionally manage multiple versions of a resource. For example, a resource which caches state created and either committed or rolled back by a transaction may be use a TimelyResource to hold its versions. Each version must implement the Version interface and may optionally implement Version.PrunableVersion in which case its Version.PrunableVersion.prune() method is called when TimelyResource detects that the version is obsolete.

The method addVersion(Version, Transaction) attempts to add a new version on behalf of the supplied transaction.

The method getVersion() returns the snapshot version associated with the transaction, in other words, an instance of a P which was either committed last before this transaction started, or which was created by this transaction. If there is no such version the method returns null .

The method getVersion(com.persistit.Version.VersionCreator) does the same thing, except that if there is no snapshot version the Version.VersionCreator.createVersion(TimelyResource) method is called to construct a new version.

Constructor Summary

Constructors

Constructor and Description
TimelyResource(Persistit persistit)

Method Summary

Modifier and Type	Method and Description
void	addVersion(V resource, Transaction txn)
void	delete()
V	getVersion()
V	getVersion(Version.VersionCreator<V> creator)
boolean	isEmpty()
boolean	isTransactionPrivate(boolean byStep)
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

TimelyResource

public TimelyResource(Persistit persistit)

Method Detail

delete

public void delete()
            throws RollbackException,
                   PersistitException

Throws:

RollbackException

PersistitException

addVersion

public void addVersion(V resource,
                       Transaction txn)
                throws PersistitInterruptedException,
                       RollbackException

Throws:

PersistitInterruptedException

RollbackException

getVersion

public V getVersion()
             throws TimeoutException,
                    PersistitInterruptedException

Throws:

TimeoutException

PersistitInterruptedException

getVersion

public V getVersion(Version.VersionCreator<V> creator)
             throws PersistitException,
                    RollbackException

Throws:

PersistitException

RollbackException

isEmpty

public boolean isEmpty()
                throws TimeoutException,
                       PersistitInterruptedException

Returns:

true if and only if this TimelyResource has no Version instances.

Throws:

TimeoutException

PersistitInterruptedException

isTransactionPrivate

public boolean isTransactionPrivate(boolean byStep)
                             throws TimeoutException,
                                    PersistitInterruptedException

Returns:

Whether this resource exists only within the context of the current transaction.

Throws:

TimeoutException

PersistitInterruptedException

toString

public String toString()

Overrides:

toString in class Object