1 /*
2 * Copyright (C) 2010, Sasa Zivkov <sasa.zivkov@sap.com>
3 * and other copyright owners as documented in the project's IP log.
4 *
5 * This program and the accompanying materials are made available
6 * under the terms of the Eclipse Distribution License v1.0 which
7 * accompanies this distribution, is reproduced below, and is
8 * available at http://www.eclipse.org/org/documents/edl-v10.php
9 *
10 * All rights reserved.
11 *
12 * Redistribution and use in source and binary forms, with or
13 * without modification, are permitted provided that the following
14 * conditions are met:
15 *
16 * - Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 *
19 * - Redistributions in binary form must reproduce the above
20 * copyright notice, this list of conditions and the following
21 * disclaimer in the documentation and/or other materials provided
22 * with the distribution.
23 *
24 * - Neither the name of the Eclipse Foundation, Inc. nor the
25 * names of its contributors may be used to endorse or promote
26 * products derived from this software without specific prior
27 * written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
30 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
31 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
32 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
33 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
34 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
35 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
36 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
37 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
38 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
40 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
41 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
42 */
43
44 package org.eclipse.jgit.notes;
45
46 import java.io.IOException;
47
48 import org.eclipse.jgit.lib.Constants;
49 import org.eclipse.jgit.lib.ObjectId;
50 import org.eclipse.jgit.lib.ObjectInserter;
51 import org.eclipse.jgit.lib.ObjectLoader;
52 import org.eclipse.jgit.lib.ObjectReader;
53 import org.eclipse.jgit.util.io.UnionInputStream;
54
55 /**
56 * Default implementation of the {@link NoteMerger}.
57 * <p>
58 * If ours and theirs are both non-null, which means they are either both edits
59 * or both adds, then this merger will simply join the content of ours and
60 * theirs (in that order) and return that as the merge result.
61 * <p>
62 * If one or ours/theirs is non-null and the other one is null then the non-null
63 * value is returned as the merge result. This means that an edit/delete
64 * conflict is resolved by keeping the edit version.
65 * <p>
66 * If both ours and theirs are null then the result of the merge is also null.
67 */
68 public class DefaultNoteMerger implements NoteMerger {
69
70 public Note merge(Note base, Note ours, Note theirs, ObjectReader reader,
71 ObjectInserter inserter) throws IOException {
72 if (ours == null)
73 return theirs;
74
75 if (theirs == null)
76 return ours;
77
78 if (ours.getData().equals(theirs.getData()))
79 return ours;
80
81 ObjectLoader lo = reader.open(ours.getData());
82 ObjectLoader lt = reader.open(theirs.getData());
83 UnionInputStream union = new UnionInputStream(lo.openStream(),
84 lt.openStream());
85 try {
86 ObjectId noteData = inserter.insert(Constants.OBJ_BLOB,
87 lo.getSize() + lt.getSize(), union);
88 return new Note(ours, noteData);
89 } finally {
90 union.close();
91 }
92 }
93 }