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| 1 | /* | ||
| 2 | * Copyright (c) 2005, 2006, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | package sun.misc; | ||
| 27 | |||
| 28 | import java.io.BufferedReader; | ||
| 29 | import java.io.FileReader; | ||
| 30 | import java.io.File; | ||
| 31 | import java.io.IOException; | ||
| 32 | import java.util.ArrayList; | ||
| 33 | import java.util.Collections; | ||
| 34 | import java.util.HashMap; | ||
| 35 | import java.util.List; | ||
| 36 | import java.util.Map; | ||
| 37 | |||
| 38 | /* | ||
| 39 | * MetaIndex is intended to decrease startup time (in particular cold | ||
| 40 | * start, when files are not yet in the disk cache) by providing a | ||
| 41 | * quick reject mechanism for probes into jar files. The on-disk | ||
| 42 | * representation of the meta-index is a flat text file with per-jar | ||
| 43 | * entries indicating (generally speaking) prefixes of package names | ||
| 44 | * contained in the jar. As an example, here is an edited excerpt of | ||
| 45 | * the meta-index generated for jre/lib in the current build: | ||
| 46 | * | ||
| 47 | <PRE> | ||
| 48 | % VERSION 1 | ||
| 49 | # charsets.jar | ||
| 50 | sun/ | ||
| 51 | # jce.jar | ||
| 52 | javax/ | ||
| 53 | ! jsse.jar | ||
| 54 | sun/ | ||
| 55 | com/sun/net/ | ||
| 56 | javax/ | ||
| 57 | com/sun/security/ | ||
| 58 | @ resources.jar | ||
| 59 | com/sun/xml/ | ||
| 60 | com/sun/rowset/ | ||
| 61 | com/sun/org/ | ||
| 62 | sun/ | ||
| 63 | com/sun/imageio/ | ||
| 64 | javax/ | ||
| 65 | com/sun/java/swing/ | ||
| 66 | META-INF/services/ | ||
| 67 | com/sun/java/util/jar/pack/ | ||
| 68 | com/sun/corba/ | ||
| 69 | com/sun/jndi/ | ||
| 70 | ! rt.jar | ||
| 71 | org/w3c/ | ||
| 72 | com/sun/imageio/ | ||
| 73 | javax/ | ||
| 74 | sunw/util/ | ||
| 75 | java/ | ||
| 76 | sun/ | ||
| 77 | ... | ||
| 78 | </PRE> | ||
| 79 | * <p> A few notes about the design of the meta-index: | ||
| 80 | * | ||
| 81 | * <UL> | ||
| 82 | * | ||
| 83 | * <LI> It contains entries for multiple jar files. This is | ||
| 84 | * intentional, to reduce the number of disk accesses that need to be | ||
| 85 | * performed during startup. | ||
| 86 | * | ||
| 87 | * <LI> It is only intended to act as a fast reject mechanism to | ||
| 88 | * prevent application and other classes from forcing all jar files on | ||
| 89 | * the boot and extension class paths to be opened. It is not intended | ||
| 90 | * as a precise index of the contents of the jar. | ||
| 91 | * | ||
| 92 | * <LI> It should be as small as possible to reduce the amount of time | ||
| 93 | * required to parse it during startup. For example, adding on the | ||
| 94 | * secondary package element to java/ and javax/ packages | ||
| 95 | * ("javax/swing/", for example) causes the meta-index to grow | ||
| 96 | * significantly. This is why substrings of the packages have been | ||
| 97 | * chosen as the principal contents. | ||
| 98 | * | ||
| 99 | * <LI> It is versioned, and optional, to prevent strong dependencies | ||
| 100 | * between the JVM and JDK. It is also potentially applicable to more | ||
| 101 | * than just the boot and extension class paths. | ||
| 102 | * | ||
| 103 | * <LI> Precisely speaking, it plays different role in JVM and J2SE | ||
| 104 | * side. On the JVM side, meta-index file is used to speed up locating the | ||
| 105 | * class files only while on the J2SE side, meta-index file is used to speed | ||
| 106 | * up the resources file & class file. | ||
| 107 | * To help the JVM and J2SE code to better utilize the information in meta-index | ||
| 108 | * file, we mark the jar file differently. Here is the current rule we use. | ||
| 109 | * For jar file containing only class file, we put '!' before the jar file name; | ||
| 110 | * for jar file containing only resources file, we put '@' before the jar file name; | ||
| 111 | * for jar file containing both resources and class file, we put '#' before the | ||
| 112 | * jar name. | ||
| 113 | * Notice the fact that every jar file contains at least the manifest file, so when | ||
| 114 | * we say "jar file containing only class file", we don't include that file. | ||
| 115 | * | ||
| 116 | * </UL> | ||
| 117 | * | ||
| 118 | * <p> To avoid changing the behavior of the current application | ||
| 119 | * loader and other loaders, the current MetaIndex implementation in | ||
| 120 | * the JDK requires that the directory containing the meta-index be | ||
| 121 | * registered with the MetaIndex class before construction of the | ||
| 122 | * associated URLClassPath. This prevents the need for automatic | ||
| 123 | * searching for the meta-index in the URLClassPath code and potential | ||
| 124 | * changes in behavior for non-core ClassLoaders. | ||
| 125 | * | ||
| 126 | * This class depends on make/tools/MetaIndex/BuildMetaIndex.java and | ||
| 127 | * is used principally by sun.misc.URLClassPath. | ||
| 128 | */ | ||
| 129 | |||
| 130 | public class MetaIndex { | ||
| 131 | // Maps jar file names in registered directories to meta-indices | ||
| 132 | private static volatile Map<File, MetaIndex> jarMap; | ||
| 133 | |||
| 134 | // List of contents of this meta-index | ||
| 135 | private String[] contents; | ||
| 136 | |||
| 137 | // Indicate whether the coresponding jar file is a pure class jar file or not | ||
| 138 | private boolean isClassOnlyJar; | ||
| 139 | |||
| 140 | //---------------------------------------------------------------------- | ||
| 141 | // Registration of directories (which can cause parsing of the | ||
| 142 | // meta-index file if it is present), and fetching of parsed | ||
| 143 | // meta-indices | ||
| 144 | // jarMap is not strictly thread-safe when the meta index mechanism | ||
| 145 | // is extended for user-provided jar files in future. | ||
| 146 | |||
| 147 | public static MetaIndex forJar(File jar) { | ||
| 148 | return getJarMap().get(jar); | ||
| 149 | } | ||
| 150 | |||
| 151 | // 'synchronized' is added to protect the jarMap from being modified | ||
| 152 | // by multiple threads. | ||
| 153 | public static synchronized void registerDirectory(File dir) { | ||
| 154 | // Note that this does not currently check to see whether the | ||
| 155 | // directory has previously been registered, since the meta-index | ||
| 156 | // in a particular directory creates multiple entries in the | ||
| 157 | // jarMap. If this mechanism is extended beyond the boot and | ||
| 158 | // extension class paths (for example, automatically searching for | ||
| 159 | // meta-index files in directories containing jars which have been | ||
| 160 | // explicitly opened) then this code should be generalized. | ||
| 161 | // | ||
| 162 | // This method must be called from a privileged context. | ||
| 163 | File indexFile = new File(dir, "meta-index"); | ||
| 164 | if (indexFile.exists()) { | ||
| 165 | try { | ||
| 166 | BufferedReader reader = new BufferedReader(new FileReader(indexFile)); | ||
| 167 | String line = null; | ||
| 168 | String curJarName = null; | ||
| 169 | boolean isCurJarContainClassOnly = false; | ||
| 170 | List<String> contents = new ArrayList<String>(); | ||
| 171 | Map<File, MetaIndex> map = getJarMap(); | ||
| 172 | |||
| 173 | /* Convert dir into canonical form. */ | ||
| 174 | dir = dir.getCanonicalFile(); | ||
| 175 | /* Note: The first line should contain the version of | ||
| 176 | * the meta-index file. We have to match the right version | ||
| 177 | * before trying to parse this file. */ | ||
| 178 | line = reader.readLine(); | ||
| 179 | if (line == null || | ||
| 180 | !line.equals("% VERSION 2")) { | ||
| 181 | reader.close(); | ||
| 182 | return; | ||
| 183 | } | ||
| 184 | while ((line = reader.readLine()) != null) { | ||
| 185 | switch (line.charAt(0)) { | ||
| 186 | case '!': | ||
| 187 | case '#': | ||
| 188 | case '@': { | ||
| 189 | // Store away current contents, if any | ||
| 190 | if ((curJarName != null) && (contents.size() > 0)) { | ||
| 191 | map.put(new File(dir, curJarName), | ||
| 192 | new MetaIndex(contents, | ||
| 193 | isCurJarContainClassOnly)); | ||
| 194 | |||
| 195 | contents.clear(); | ||
| 196 | } | ||
| 197 | // Fetch new current jar file name | ||
| 198 | curJarName = line.substring(2); | ||
| 199 | if (line.charAt(0) == '!') { | ||
| 200 | isCurJarContainClassOnly = true; | ||
| 201 | } else if (isCurJarContainClassOnly) { | ||
| 202 | isCurJarContainClassOnly = false; | ||
| 203 | } | ||
| 204 | |||
| 205 | break; | ||
| 206 | } | ||
| 207 | case '%': | ||
| 208 | break; | ||
| 209 | default: { | ||
| 210 | contents.add(line); | ||
| 211 | } | ||
| 212 | } | ||
| 213 | } | ||
| 214 | // Store away current contents, if any | ||
| 215 | if ((curJarName != null) && (contents.size() > 0)) { | ||
| 216 | map.put(new File(dir, curJarName), | ||
| 217 | new MetaIndex(contents, isCurJarContainClassOnly)); | ||
| 218 | } | ||
| 219 | |||
| 220 | reader.close(); | ||
| 221 | |||
| 222 | } catch (IOException e) { | ||
| 223 | // Silently fail for now (similar behavior to elsewhere in | ||
| 224 | // extension and core loaders) | ||
| 225 | } | ||
| 226 | } | ||
| 227 | } | ||
| 228 | |||
| 229 | //---------------------------------------------------------------------- | ||
| 230 | // Public APIs | ||
| 231 | // | ||
| 232 | |||
| 233 | public boolean mayContain(String entry) { | ||
| 234 | // Ask non-class file from class only jar returns false | ||
| 235 | // This check is important to avoid some class only jar | ||
| 236 | // files such as rt.jar are opened for resource request. | ||
| 237 | if (isClassOnlyJar && !entry.endsWith(".class")){ | ||
| 238 | return false; | ||
| 239 | } | ||
| 240 | |||
| 241 | String[] conts = contents; | ||
| 242 | for (int i = 0; i < conts.length; i++) { | ||
| 243 | if (entry.startsWith(conts[i])) { | ||
| 244 | return true; | ||
| 245 | } | ||
| 246 | } | ||
| 247 | return false; | ||
| 248 | } | ||
| 249 | |||
| 250 | |||
| 251 | //---------------------------------------------------------------------- | ||
| 252 | // Implementation only below this point | ||
| 253 | // @IllegalArgumentException if entries is null. | ||
| 254 | private MetaIndex(List<String> entries, boolean isClassOnlyJar) | ||
| 255 | throws IllegalArgumentException { | ||
| 256 | if (entries == null) { | ||
| 257 | throw new IllegalArgumentException(); | ||
| 258 | } | ||
| 259 | |||
| 260 | contents = entries.toArray(new String[0]); | ||
| 261 | this.isClassOnlyJar = isClassOnlyJar; | ||
| 262 | } | ||
| 263 | |||
| 264 | private static Map<File, MetaIndex> getJarMap() { | ||
| 265 | if (jarMap == null) { | ||
| 266 | synchronized (MetaIndex.class) { | ||
| 267 | if (jarMap == null) { | ||
| 268 | jarMap = new HashMap<File, MetaIndex>(); | ||
| 269 | } | ||
| 270 | } | ||
| 271 | } | ||
| 272 | assert jarMap != null; | ||
| 273 | return jarMap; | ||
| 274 | } | ||
| 275 | } | ||