org.jgroups.blocks

Class Xid

public class Xid extends Object implements Externalizable

Distributed transaction ID modeled after the JTA spec. This is used to identify entities of work, with which resources are associated. A transaction will thus trigger the creation of an associated entry on each receiver, which keeps track of resources acquired and their locks, operations to be committed in case commitis called.

A transaction is identified by its creator and a transaction ID. The creator is currently a JGroups address, consisting of the IP address and port of the member.

Note that this class might be replaced in the future with the real JTA counterpart.

Version: $Revision: 1.5 $

Revisions:

Dec 28 2002 Bela Ban: first implementation

Author: Bela Ban.

Field Summary
protected Address	creator
static int	DIRTY_READS Writes are serialized, but reads can be dirty; e.g., a data might have been changed while we read it.
protected long	id
protected int	mode
protected static long	next_id
static int	READ_COMMITTED Reads are dirty until another transaction actually commits; at that points the modified data will be reflected here.
static int	REPEATABLE_READ Each read causes the data read to be copied to the private workspace, so subsequent reads always read the private data.
static int	SERIALIZABLE Reads and writes require locks.
static String	XID

Constructor Summary
	Xid()

Method Summary
int	compareTo(Object o)
static Xid	create(Address creator)
static Xid	create(Address creator, int mode)
boolean	equals(Object other)
Address	getCreator()
long	getId()
long	getMode()
int	hashCode()
static String	modeToString(int m)
void	readExternal(ObjectInput in)
String	toString()
void	writeExternal(ObjectOutput out)

Field Detail

creator

protected Address creator

DIRTY_READS

public static final int DIRTY_READS

Writes are serialized, but reads can be dirty; e.g., a data might have been changed while we read it. This is fast because we don't need to acquire locks for reads.