1 /*
2 * Copyright (C) 2017, 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.reftable;
45
46 import static org.eclipse.jgit.lib.RefDatabase.MAX_SYMBOLIC_REF_DEPTH;
47
48 import java.io.ByteArrayOutputStream;
49 import java.io.IOException;
50 import java.util.Collection;
51
52 import org.eclipse.jgit.annotations.Nullable;
53 import org.eclipse.jgit.internal.storage.io.BlockSource;
54 import org.eclipse.jgit.lib.AnyObjectId;
55 import org.eclipse.jgit.lib.Ref;
56 import org.eclipse.jgit.lib.SymbolicRef;
57
58 /** Abstract table of references. */
59 public abstract class Reftable implements AutoCloseable {
60 /**
61 * @param refs
62 * references to convert into a reftable; may be empty.
63 * @return a reader for the supplied references.
64 */
65 public static Reftable from(Collection<Ref> refs) {
66 try {
67 ReftableConfig cfg = new ReftableConfig();
68 cfg.setIndexObjects(false);
69 cfg.setAlignBlocks(false);
70 ByteArrayOutputStream buf = new ByteArrayOutputStream();
71 new ReftableWriter()
72 .setConfig(cfg)
73 .begin(buf)
74 .sortAndWriteRefs(refs)
75 .finish();
76 return new ReftableReader(BlockSource.from(buf.toByteArray()));
77 } catch (IOException e) {
78 throw new RuntimeException(e);
79 }
80 }
81
82 /** {@code true} if deletions should be included in results. */
83 protected boolean includeDeletes;
84
85 /**
86 * @param deletes
87 * if {@code true} deleted references will be returned. If
88 * {@code false} (default behavior), deleted references will be
89 * skipped, and not returned.
90 */
91 public void setIncludeDeletes(boolean deletes) {
92 includeDeletes = deletes;
93 }
94
95 /**
96 * Seek to the first reference, to iterate in order.
97 *
98 * @return cursor to iterate.
99 * @throws IOException
100 * if references cannot be read.
101 */
102 public abstract RefCursor allRefs() throws IOException;
103
104 /**
105 * Seek either to a reference, or a reference subtree.
106 * <p>
107 * If {@code refName} ends with {@code "/"} the method will seek to the
108 * subtree of all references starting with {@code refName} as a prefix. If
109 * no references start with this prefix, an empty cursor is returned.
110 * <p>
111 * Otherwise exactly {@code refName} will be looked for. If present, the
112 * returned cursor will iterate exactly one entry. If not found, an empty
113 * cursor is returned.
114 *
115 * @param refName
116 * reference name or subtree to find.
117 * @return cursor to iterate; empty cursor if no references match.
118 * @throws IOException
119 * if references cannot be read.
120 */
121 public abstract RefCursor seekRef(String refName) throws IOException;
122
123 /**
124 * Match references pointing to a specific object.
125 *
126 * @param id
127 * object to find.
128 * @return cursor to iterate; empty cursor if no references match.
129 * @throws IOException
130 * if references cannot be read.
131 */
132 public abstract RefCursor byObjectId(AnyObjectId id) throws IOException;
133
134 /**
135 * Seek reader to read log records.
136 *
137 * @return cursor to iterate; empty cursor if no logs are present.
138 * @throws IOException
139 * if logs cannot be read.
140 */
141 public abstract LogCursor allLogs() throws IOException;
142
143 /**
144 * Read a single reference's log.
145 *
146 * @param refName
147 * exact name of the reference whose log to read.
148 * @return cursor to iterate; empty cursor if no logs match.
149 * @throws IOException
150 * if logs cannot be read.
151 */
152 public LogCursor seekLog(String refName) throws IOException {
153 return seekLog(refName, Long.MAX_VALUE);
154 }
155
156 /**
157 * Seek to an update index in a reference's log.
158 *
159 * @param refName
160 * exact name of the reference whose log to read.
161 * @param updateIndex
162 * most recent index to return first in the log cursor. Log
163 * records at or before {@code updateIndex} will be returned.
164 * @return cursor to iterate; empty cursor if no logs match.
165 * @throws IOException
166 * if logs cannot be read.
167 */
168 public abstract LogCursor seekLog(String refName, long updateIndex)
169 throws IOException;
170
171 /**
172 * Lookup a reference, or null if not found.
173 *
174 * @param refName
175 * reference name to find.
176 * @return the reference, or {@code null} if not found.
177 * @throws IOException
178 * if references cannot be read.
179 */
180 @Nullable
181 public Ref exactRef(String refName) throws IOException {
182 try (RefCursor rc = seekRef(refName)) {
183 return rc.next() ? rc.getRef() : null;
184 }
185 }
186
187 /**
188 * Test if a reference or reference subtree exists.
189 * <p>
190 * If {@code refName} ends with {@code "/"}, the method tests if any
191 * reference starts with {@code refName} as a prefix.
192 * <p>
193 * Otherwise, the method checks if {@code refName} exists.
194 *
195 * @param refName
196 * reference name or subtree to find.
197 * @return {@code true} if the reference exists, or at least one reference
198 * exists in the subtree.
199 * @throws IOException
200 * if references cannot be read.
201 */
202 public boolean hasRef(String refName) throws IOException {
203 try (RefCursor rc = seekRef(refName)) {
204 return rc.next();
205 }
206 }
207
208 /**
209 * Test if any reference directly refers to the object.
210 *
211 * @param id
212 * ObjectId to find.
213 * @return {@code true} if any reference exists directly referencing
214 * {@code id}, or a annotated tag that peels to {@code id}.
215 * @throws IOException
216 * if references cannot be read.
217 */
218 public boolean hasId(AnyObjectId id) throws IOException {
219 try (RefCursor rc = byObjectId(id)) {
220 return rc.next();
221 }
222 }
223
224 /**
225 * Resolve a symbolic reference to populate its value.
226 *
227 * @param symref
228 * reference to resolve.
229 * @return resolved {@code symref}, or {@code null}.
230 * @throws IOException
231 * if references cannot be read.
232 */
233 @Nullable
234 public Ref resolve(Ref symref) throws IOException {
235 return resolve(symref, 0);
236 }
237
238 private Ref resolve(Ref ref, int depth) throws IOException {
239 if (!ref.isSymbolic()) {
240 return ref;
241 }
242
243 Ref dst = ref.getTarget();
244 if (MAX_SYMBOLIC_REF_DEPTH <= depth) {
245 return null; // claim it doesn't exist
246 }
247
248 dst = exactRef(dst.getName());
249 if (dst == null) {
250 return ref;
251 }
252
253 dst = resolve(dst, depth + 1);
254 if (dst == null) {
255 return null; // claim it doesn't exist
256 }
257 return new SymbolicRef(ref.getName(), dst);
258 }
259
260 @Override
261 public abstract void close() throws IOException;
262 }