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My first initial commit with all of mine experimental changes.

Dmitry Kabak (userdima committed 13 years ago

Commit d37b88d1 parent 3f5b46618352 files · +2598093 −-8690Browse files

Showing the changes to java/pkg/sun/misc/MetaIndex.java (1 of 18352 files). Show all

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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+}