Mercurial > jhg
view src/org/tmatesoft/hg/internal/Transaction.java @ 658:d10399f80f4e
javac complained about casts, while eclipse compiler is fine
author | Artem Tikhomirov <tikhomirov.artem@gmail.com> |
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date | Thu, 04 Jul 2013 21:09:33 +0200 (2013-07-04) |
parents | 99ad1e3a4e4d |
children |
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/* * Copyright (c) 2013 TMate Software Ltd * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; version 2 of the License. * * This program 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. See the * GNU General Public License for more details. * * For information on how to redistribute this software under * the terms of a license other than GNU General Public License * contact TMate Software at support@hg4j.com */ package org.tmatesoft.hg.internal; import java.io.File; import java.io.IOException; import org.tmatesoft.hg.core.HgIOException; import org.tmatesoft.hg.core.SessionContext; import org.tmatesoft.hg.repo.HgInvalidStateException; /** * Implementation strategies possible:<ul> * <li> Get a copy, write changes to origin, keep copy as backup till #commit * <p>(-) doesn't break hard links * <li> Get a copy, write changes to a copy, on commit rename copy to origin. * <p>(-) What if we read newly written data (won't find it); * <p>(-) complex #commit * <p>(+) simple rollback * <li> Get a copy, rename origin to backup (breaks hard links), rename copy to origin, write changes * <p>(+) Modified file is in place right away; * <p>(+) easy #commit * <li> Do not copy, just record file size, truncate to that size on rollback * <li> ...? * </ul> * @author Artem Tikhomirov * @author TMate Software Ltd. */ public abstract class Transaction { /** * Record the file is going to be modified during this transaction, obtain actual * destination to write to. * The file to be modified not necessarily exists, might be just a name of an added file */ public abstract File prepare(File f) throws HgIOException; /** * overwrites backup if exists, backup is kept after successful {@link #commit()} */ public abstract File prepare(File origin, File backup) throws HgIOException; /** * Tell that file was successfully processed */ public abstract void done(File f) throws HgIOException; /** * optional? */ public abstract void failure(File f, IOException ex); /** * Complete the transaction */ public abstract void commit() throws HgIOException; /** * Undo all the changes */ public abstract void rollback() throws HgIOException; public interface Factory { public Transaction create(SessionContext.Source ctxSource); } public static class NoRollback extends Transaction { @Override public File prepare(File f) throws HgIOException { return f; } @Override public File prepare(File origin, File backup) throws HgIOException { return origin; } @Override public void done(File f) throws HgIOException { // no-op } @Override public void failure(File f, IOException ex) { // no-op } @Override public void commit() throws HgIOException { // no-op } @Override public void rollback() throws HgIOException { throw new HgInvalidStateException("This transaction doesn't support rollback"); } } }