//Prevayler(TM) - The Free-Software Prevalence Layer.
//Copyright (C) 2001-2003 Klaus Wuestefeld
//This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
package org.prevayler.implementation.journal;
import org.prevayler.implementation.TransactionGuide;
import org.prevayler.implementation.TransactionTimestamp;
import org.prevayler.implementation.publishing.TransactionSubscriber;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
public class TransientJournal implements Journal {
private final List journal = new ArrayList();
private long _initialTransaction;
private boolean _initialTransactionInitialized = false;
public void append(TransactionGuide guide) {
if (!_initialTransactionInitialized)
throw new IllegalStateException("Journal.update() has to be called at least once before Journal.journal().");
guide.startTurn();
try {
guide.checkSystemVersion(_initialTransaction + journal.size());
journal.add(guide.timestamp().cleanCopy());
} finally {
guide.endTurn();
}
}
public synchronized void update(TransactionSubscriber subscriber, long initialTransaction) throws IOException {
if (!_initialTransactionInitialized) {
_initialTransactionInitialized = true;
_initialTransaction = initialTransaction;
return;
}
if (initialTransaction < _initialTransaction)
throw new IOException("Unable to recover transaction " + initialTransaction + ". The oldest recoverable transaction is " + _initialTransaction + ".");
int i = (int) (initialTransaction - _initialTransaction);
if (i > journal.size())
throw new IOException("The transaction journal has not yet reached transaction " + initialTransaction + ". The last logged transaction was " + (_initialTransaction + journal.size() - 1) + ".");
while (i != journal.size()) {
TransactionTimestamp entry = (TransactionTimestamp) journal.get(i);
long recoveringTransaction = _initialTransaction + i;
if (entry.systemVersion() != recoveringTransaction) {
throw new IOException("Expected " + recoveringTransaction + " but was " + entry.systemVersion());
}
subscriber.receive(entry);
i++;
}
}
public void close() {
}
public synchronized long nextTransaction() {
if (!_initialTransactionInitialized) throw new IllegalStateException("update() must be called at least once");
return _initialTransaction + journal.size();
}
}