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1   /*
2    * Copyright (C) 2016, Google Inc.
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;
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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.internal.storage.reftree;
45  
46  import org.eclipse.jgit.lib.RefDatabase;
47  
48  /**
49   * Magic reference name logic for RefTrees.
50   */
51  public class RefTreeNames {
52  	/**
53  	 * Suffix used on a {@link RefTreeDatabase#getTxnNamespace()} for user data.
54  	 * <p>
55  	 * A {@link RefTreeDatabase}'s namespace may include a subspace (e.g.
56  	 * {@code "refs/txn/stage/"}) containing commit objects from the usual user
57  	 * portion of the repository (e.g. {@code "refs/heads/"}). These should be
58  	 * packed by the garbage collector alongside other user content rather than
59  	 * with the RefTree.
60  	 */
61  	private static final String STAGE = "stage/"; //$NON-NLS-1$
62  
63  	/**
64  	 * Determine if the reference is likely to be a RefTree.
65  	 *
66  	 * @param refdb
67  	 *            database instance.
68  	 * @param ref
69  	 *            reference name.
70  	 * @return {@code true} if the reference is a RefTree.
71  	 */
72  	public static boolean isRefTree(RefDatabase refdb, String ref) {
73  		if (refdb instanceof RefTreeDatabase) {
74  			RefTreeDatabase b = (RefTreeDatabase) refdb;
75  			if (ref.equals(b.getTxnCommitted())) {
76  				return true;
77  			}
78  
79  			String namespace = b.getTxnNamespace();
80  			if (namespace != null
81  					&& ref.startsWith(namespace)
82  					&& !ref.startsWith(namespace + STAGE)) {
83  				return true;
84  			}
85  		}
86  		return false;
87  	}
88  
89  	private RefTreeNames() {
90  	}
91  }