可能與大家關(guān)注點有不同,有考慮不周處,請大家指出...
Ehcache獲取分布式事務(wù)支持可從net.sf.ehcache.transaction.manager. DefaultTransactionManagerLookup 類中知曉:
private final JndiSelector defaultJndiSelector = new JndiSelector("genericJNDI", "java:/TransactionManager");
private final Selector[] transactionManagerSelectors = new Selector[] {defaultJndiSelector,
new JndiSelector("Weblogic", "javax.transaction.TransactionManager"),
new FactorySelector("Bitronix", "bitronix.tm.TransactionManagerServices"),
new ClassSelector("Atomikos", "com.atomikos.icatch.jta.UserTransactionManager")};
默認(rèn)獲取JNDI名“java:/TransactionManager”。JBoss JTA事務(wù)。
現(xiàn)跟蹤Ehcache PUT操作時是如何加入事務(wù)的。
當(dāng)Ehcache配置成xa或者xa-strict時,內(nèi)部使用net.sf.ehcache.transaction.xa.XATransactionStore存儲邏輯,put操作如下:
public boolean put(Element element) throws CacheException {
LOG.debug("cache {} put {}", cache.getName(), element);
// this forces enlistment so the XA transaction timeout can be propagated to the XA resource
getOrCreateTransactionContext();
Element oldElement = getQuietFromUnderlyingStore(element.getObjectKey());
return internalPut( new StorePutCommand(oldElement, copyElementForWrite(element)));
}
紅色部分是事務(wù)關(guān)鍵操作:初始化事務(wù)上下文
private XATransactionContext getOrCreateTransactionContext() {
try {
EhcacheXAResourceImpl xaResource = getOrCreateXAResource();
XATransactionContext transactionContext = xaResource.getCurrentTransactionContext();
if (transactionContext == null ) {
transactionManagerLookup.register(xaResource);
LOG.debug("creating new XA context");
transactionContext = xaResource.createTransactionContext();
xaResource.addTwoPcExecutionListener( new UnregisterXAResource());
} else {
transactionContext = xaResource.getCurrentTransactionContext();
}
LOG.debug("using XA context {}", transactionContext);
return transactionContext;
} catch (SystemException e) {
throw new TransactionException("cannot get the current transaction", e);
} catch (RollbackException e) {
throw new TransactionException("transaction rolled back", e);
}
}
private final Ehcache cache;
private final Store underlyingStore;
private final TransactionIDFactory transactionIDFactory;
private final TransactionManager txnManager;
private final SoftLockFactory softLockFactory;
private final ConcurrentMap<Xid, XATransactionContext> xidToContextMap = new ConcurrentHashMap<Xid, XATransactionContext>();
private final XARequestProcessor processor;
private volatile Xid currentXid;
private volatile int transactionTimeout;
private final List<XAExecutionListener> listeners = new ArrayList<XAExecutionListener>();
private final ElementValueComparator comparator;
......
public void commit(Xid xid, boolean onePhase)
public void rollback(Xid xid) throws XAException
/**
* Add a listener which will be called back according to the 2PC lifecycle
* @param listener the XAExecutionListener
*/
void addTwoPcExecutionListener(XAExecutionListener listener);
/**
* Obtain the already associated { @link XATransactionContext} with the current Transaction,
* or create a new one should none be there yet.
* @return The associated Transaction associated { @link XATransactionContext}
*/
XATransactionContext createTransactionContext() throws SystemException, RollbackException;
?int rc = prepareInternal(xid);
?if (rc == XA_RDONLY) {
? ?return;
? ?}
public int prepareInternal(Xid xid) throws XAException {
fireBeforePrepare();
XATransactionContext twopcTransactionContext = xidToContextMap.get(xid);
if (twopcTransactionContext == null ) {
throw new EhcacheXAException("transaction never started: " + xid, XAException.XAER_NOTA);
}
XidTransactionID xidTransactionID = transactionIDFactory.createXidTransactionID(xid);
List<Command> commands = twopcTransactionContext.getCommands();
List<Command> preparedCommands = new LinkedList<Command>();
boolean prepareUpdated = false ;
LOG.debug("preparing {} command(s) for [{}]", commands.size(), xid);
for (Command command : commands) {
try {
prepareUpdated |= command.prepare(underlyingStore, softLockFactory, xidTransactionID, comparator);
preparedCommands.add(0, command);
} catch (OptimisticLockFailureException ie) {
for (Command preparedCommand : preparedCommands) {
preparedCommand.rollback(underlyingStore);
}
preparedCommands.clear();
throw new EhcacheXAException(command + " failed because value changed between execution and 2PC",
XAException.XA_RBINTEGRITY, ie);
}
}
xidToContextMap.remove(xid);
if (!prepareUpdated) {
rollbackInternal(xid);
}
LOG.debug("prepared xid [{}] read only? {}", xid, !prepareUpdated);
return prepareUpdated ? XA_OK : XA_RDONLY;
}
歡迎大家批評指正!
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