1 /*
2 * Copyright (C) 2011, 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;
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.internal.storage.pack;
45
46 import java.io.IOException;
47
48 /**
49 * Describes a pack file
50 * {@link org.eclipse.jgit.internal.storage.pack.ObjectReuseAsIs} can append
51 * onto a stream.
52 */
53 public abstract class CachedPack {
54 /**
55 * Get the number of objects in this pack.
56 *
57 * @return the total object count for the pack.
58 * @throws java.io.IOException
59 * if the object count cannot be read.
60 */
61 public abstract long getObjectCount() throws IOException;
62
63 /**
64 * Get the number of delta objects stored in this pack.
65 * <p>
66 * This is an optional method, not every cached pack storage system knows
67 * the precise number of deltas stored within the pack. This number must be
68 * smaller than {@link #getObjectCount()} as deltas are not supposed to span
69 * across pack files.
70 * <p>
71 * This method must be fast, if the only way to determine delta counts is to
72 * scan the pack file's contents one object at a time, implementors should
73 * return 0 and avoid the high cost of the scan.
74 *
75 * @return the number of deltas; 0 if the number is not known or there are
76 * no deltas.
77 * @throws java.io.IOException
78 * if the delta count cannot be read.
79 */
80 public long getDeltaCount() throws IOException {
81 return 0;
82 }
83
84 /**
85 * Determine if this pack contains the object representation given.
86 * <p>
87 * PackWriter uses this method during the finding sources phase to prune
88 * away any objects from the leading thin-pack that already appear within
89 * this pack and should not be sent twice.
90 * <p>
91 * Implementors are strongly encouraged to rely on looking at {@code rep}
92 * only and using its internal state to decide if this object is within this
93 * pack. Implementors should ensure a representation from this cached pack
94 * is tested as part of
95 * {@link org.eclipse.jgit.internal.storage.pack.ObjectReuseAsIs#selectObjectRepresentation(PackWriter, org.eclipse.jgit.lib.ProgressMonitor, Iterable)}
96 * , ensuring this method would eventually return true if the object would
97 * be included by this cached pack.
98 *
99 * @param obj
100 * the object being packed. Can be used as an ObjectId.
101 * @param rep
102 * representation from the
103 * {@link org.eclipse.jgit.internal.storage.pack.ObjectReuseAsIs}
104 * instance that originally supplied this CachedPack.
105 * @return true if this pack contains this object.
106 */
107 public abstract boolean hasObject(ObjectToPack obj,
108 StoredObjectRepresentation rep);
109 }