1 /*
2 * Copyright (C) 2017 Two Sigma Open Source
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.file;
45
46 import static java.nio.charset.StandardCharsets.UTF_8;
47
48 import java.io.File;
49 import java.io.IOException;
50 import java.nio.file.Files;
51 import java.nio.file.NoSuchFileException;
52 import java.nio.file.attribute.FileTime;
53 import java.text.ParseException;
54 import java.time.Instant;
55
56 import org.eclipse.jgit.api.errors.JGitInternalException;
57 import org.eclipse.jgit.lib.ConfigConstants;
58 import org.eclipse.jgit.util.FileUtils;
59 import org.eclipse.jgit.util.GitDateParser;
60 import org.eclipse.jgit.util.SystemReader;
61
62 /**
63 * This class manages the gc.log file for a {@link FileRepository}.
64 */
65 class GcLog {
66 private final FileRepository repo;
67
68 private final File logFile;
69
70 private final LockFile lock;
71
72 private Instant gcLogExpire;
73
74 private static final String LOG_EXPIRY_DEFAULT = "1.day.ago"; //$NON-NLS-1$
75
76 private boolean nonEmpty = false;
77
78 /**
79 * Construct a GcLog object for a {@link FileRepository}
80 *
81 * @param repo
82 * the repository
83 */
84 GcLog(FileRepository repo) {
85 this.repo = repo;
86 logFile = new File(repo.getDirectory(), "gc.log"); //$NON-NLS-1$
87 lock = new LockFile(logFile);
88 }
89
90 private Instant getLogExpiry() throws ParseException {
91 if (gcLogExpire == null) {
92 String logExpiryStr = repo.getConfig().getString(
93 ConfigConstants.CONFIG_GC_SECTION, null,
94 ConfigConstants.CONFIG_KEY_LOGEXPIRY);
95 if (logExpiryStr == null) {
96 logExpiryStr = LOG_EXPIRY_DEFAULT;
97 }
98 gcLogExpire = GitDateParser.parse(logExpiryStr, null,
99 SystemReader.getInstance().getLocale()).toInstant();
100 }
101 return gcLogExpire;
102 }
103
104 private boolean autoGcBlockedByOldLockFile() {
105 try {
106 FileTime lastModified = Files.getLastModifiedTime(FileUtils.toPath(logFile));
107 if (lastModified.toInstant().compareTo(getLogExpiry()) > 0) {
108 // There is an existing log file, which is too recent to ignore
109 return true;
110 }
111 } catch (NoSuchFileException e) {
112 // No existing log file, OK.
113 } catch (IOException | ParseException e) {
114 throw new JGitInternalException(e.getMessage(), e);
115 }
116 return false;
117 }
118
119 /**
120 * Lock the GC log file for updates
121 *
122 * @return {@code true} if we hold the lock
123 */
124 boolean lock() {
125 try {
126 if (!lock.lock()) {
127 return false;
128 }
129 } catch (IOException e) {
130 throw new JGitInternalException(e.getMessage(), e);
131 }
132 if (autoGcBlockedByOldLockFile()) {
133 lock.unlock();
134 return false;
135 }
136 return true;
137 }
138
139 /**
140 * Unlock (roll back) the GC log lock
141 */
142 void unlock() {
143 lock.unlock();
144 }
145
146 /**
147 * Commit changes to the gc log, if there have been any writes. Otherwise,
148 * just unlock and delete the existing file (if any)
149 *
150 * @return true if committing (or unlocking/deleting) succeeds.
151 */
152 boolean commit() {
153 if (nonEmpty) {
154 return lock.commit();
155 } else {
156 logFile.delete();
157 lock.unlock();
158 return true;
159 }
160 }
161
162 /**
163 * Write to the pending gc log. Content will be committed upon a call to
164 * commit()
165 *
166 * @param content
167 * The content to write
168 * @throws IOException
169 */
170 void write(String content) throws IOException {
171 if (content.length() > 0) {
172 nonEmpty = true;
173 }
174 lock.write(content.getBytes(UTF_8));
175 }
176 }