org.hypergraphdb.transaction

Class HGTransaction

java.lang.Object

org.hypergraphdb.transaction.HGTransaction

All Implemented Interfaces:

HGStorageTransaction

public final class HGTransaction
extends Object
implements HGStorageTransaction

Implements a transaction in HyperGraphDB.

Each transaction can carry an arbitrary set of attributes along with it. This is useful for attaching contextual information to transactions without intruding to otherwise simple APIs. When a transaction is committed or aborted, all attributes are removed.

Author:

Borislav Iordanov

Method Summary

Methods

Modifier and Type	Method and Description
void	abort()
void	addAbortAction(Runnable r)
void	commit()
protected Cons<VBoxBody<?>>	doCommit() Commit all "written boxes" and return a linked list of the newly attached bodies to them.
<T> T	getAttribute(Object key)
Iterator<Object>	getAttributeKeys()
HGTransaction	getParent() Return the parent transaction of this transaction or null is this is not a nested transaction.
HGStorageTransaction	getStorageTransaction()
HGTransaction	getTopLevel() Return the top-level transaction of which this is a nested transaction, or this in case this is already a top-level transaction.
boolean	isReadOnly()
protected Cons<VBoxBody<?>>	performValidCommit()
void	removeAttribute(Object key)
void	setAttribute(Object key, Object value)
protected boolean	validateCommit() A commit can proceed only if none of the values we've read during the transaction has changed (i.e.

Methods inherited from class java.lang.Object

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

Method Detail

validateCommit

protected boolean validateCommit()

A commit can proceed only if none of the values we've read during the transaction has changed (i.e. has been committed) since we read them. In order words, the latest/current body of each VBox is the same as the one tagged with this transaction's number.

performValidCommit

protected Cons<VBoxBody<?>> performValidCommit()

doCommit

protected Cons<VBoxBody<?>> doCommit()

Commit all "written boxes" and return a linked list of the newly attached bodies to them. Those bodies will be garbage collected eventually when it is determined that no current transaction (or future) could be using them (see ActiveTransactionRecord.clean()).

getStorageTransaction

public HGStorageTransaction getStorageTransaction()

commit

public void commit()
            throws HGTransactionException

Specified by:

commit in interface HGStorageTransaction

Throws:

HGTransactionException

abort

public void abort()
           throws HGTransactionException

Specified by:

abort in interface HGStorageTransaction

Throws:

HGTransactionException

getAttribute

public <T> T getAttribute(Object key)

getAttributeKeys

public Iterator<Object> getAttributeKeys()

removeAttribute

public void removeAttribute(Object key)

setAttribute

public void setAttribute(Object key,
                Object value)

isReadOnly

public boolean isReadOnly()

addAbortAction

public void addAbortAction(Runnable r)

getParent

public HGTransaction getParent()

Return the parent transaction of this transaction or null is this is not a nested transaction.

getTopLevel

public HGTransaction getTopLevel()

Return the top-level transaction of which this is a nested transaction, or this in case this is already a top-level transaction.