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