XidFactory.java |
/* * JBoss, the OpenSource J2EE webOS * * Distributable under LGPL license. * See terms of license at gnu.org. * */ package org.jboss.tm; import java.net.InetAddress; import javax.transaction.xa.Xid; import java.net.UnknownHostException; /** * XidFactory.java * * * Created: Sat Jun 15 19:01:18 2002 * * @author <a href="mailto:d_jencks@users.sourceforge.net">David Jencks</a> * @version * * @jmx.mbean */ public class XidFactory implements XidFactoryMBean { /** * The default value of baseGlobalId is the host name of this host, * followed by a slash. * * This is used for building globally unique transaction identifiers. * It would be safer to use the IP address, but a host name is better * for humans to read and will do for now. * This must be set individually if multiple jboss instances are * running on the same machine. */ private String baseGlobalId; /** * The next transaction id to use on this host. */ private long globalIdNumber = 0; /** * The variable <code>pad</code> says whether the byte[] should be their * maximum 64 byte length or the minimum. * The max length is required for Oracle.. */ private boolean pad = false; /** * The variable <code>noBranchQualifier</code> is the 1 or 64 byte zero * array used for initial xids. */ private byte[] noBranchQualifier = new byte[1]; // len > 0, per the XA spec /** * This field stores the byte reprsentation of baseGlobalId * to avoid the expensive getBytes() call on this String object * when we create a new Xid, which we do VERY often! */ private byte[] baseGlobalIdBytes; public XidFactory() { try { baseGlobalId = InetAddress.getLocalHost().getHostName(); // Ensure room for 14 digits of serial no. if (baseGlobalId.length() > Xid.MAXGTRIDSIZE - 15) baseGlobalId = baseGlobalId.substring(0, Xid.MAXGTRIDSIZE - 15); baseGlobalId = baseGlobalId + "/"; } catch (UnknownHostException e) { baseGlobalId = "localhost/"; } baseGlobalIdBytes = baseGlobalId.getBytes(); } /** * mbean get-set pair for field BaseGlobalId * Get the value of BaseGlobalId * @return value of BaseGlobalId * * @jmx:managed-attribute */ public String getBaseGlobalId() { return baseGlobalId; } /** * Set the value of BaseGlobalId * @param BaseGlobalId Value to assign to BaseGlobalId * * @jmx:managed-attribute */ public void setBaseGlobalId(final String baseGlobalId) { this.baseGlobalId = baseGlobalId; baseGlobalIdBytes = baseGlobalId.getBytes(); } /** * mbean get-set pair for field globalIdNumber * Get the value of globalIdNumber * @return value of globalIdNumber * * @jmx:managed-attribute */ public synchronized long getGlobalIdNumber() { return globalIdNumber; } /** * Set the value of globalIdNumber * @param globalIdNumber Value to assign to globalIdNumber * * @jmx:managed-attribute */ public synchronized void setGlobalIdNumber(final long globalIdNumber) { this.globalIdNumber = globalIdNumber; } /** * mbean get-set pair for field pad * Get the value of pad * @return value of pad * * @jmx:managed-attribute */ public boolean isPad() { return pad; } /** * Set the value of pad * @param pad Value to assign to pad * * @jmx:managed-attribute */ public void setPad(boolean pad) { this.pad = pad; if (pad) noBranchQualifier = new byte[Xid.MAXBQUALSIZE]; else noBranchQualifier = new byte[1]; // length > 0, per the XA spec } /** * mbean get-set pair for field instance * Get the value of instance * @return value of instance * * @jmx:managed-attribute */ public XidFactoryMBean getInstance() { return this; } /** * Describe <code>newXid</code> method here. * * @return a <code>XidImpl</code> value * @jmx.managed-operation */ public XidImpl newXid() { long localId = getNextId(); String id = Long.toString(localId); int len = pad?Xid.MAXGTRIDSIZE:id.length()+baseGlobalIdBytes.length; byte[] globalId = new byte[len]; System.arraycopy(baseGlobalIdBytes, 0, globalId, 0, baseGlobalIdBytes.length); // this method is deprecated, but does exactly what we need in a very fast way // the default conversion from String.getBytes() is way too expensive id.getBytes(0, id.length(), globalId, baseGlobalIdBytes.length); return new XidImpl(globalId, noBranchQualifier, (int)localId, localId); } /** * Describe <code>newBranch</code> method here. * * @param xid a <code>XidImpl</code> value * @param branchIdNum a <code>long</code> value * @return a <code>XidImpl</code> value * @jmx.managed-operation */ public XidImpl newBranch(XidImpl xid, long branchIdNum) { String id = Long.toString(branchIdNum); int len = pad?Xid.MAXBQUALSIZE:id.length(); byte[] branchId = new byte[len]; // this method is deprecated, but does exactly what we need in a very fast way // the default conversion from String.getBytes() is way too expensive id.getBytes(0, id.length(), branchId, 0); return new XidImpl(xid, branchId); } /** * Extracts the local id contained in a global id. * * @param globalId a global id * @return the local id extracted from the global id * @jmx:managed-operation */ public long extractLocalIdFrom(byte[] globalId) { int i, start, stop; int len = globalId.length; for (i = 0; globalId[i++] != (byte)'/'; ) ; start = i; while (i < len && globalId[i] != 0) i++; String globalIdNumber = new String(globalId, 0, start, i - start); return Long.parseLong(globalIdNumber); } /** * Describe <code>toString</code> method here. * * @param xid a <code>Xid</code> value * @return a <code>String</code> value * @jmx.managed-operation */ public String toString(Xid xid) { if (xid instanceof XidImpl) return XidImpl.toString(xid); else return xid.toString(); } private synchronized long getNextId() { return ++globalIdNumber; } }
XidFactory.java |