CacheFSInfo.java revision 3827:44bdefe64114 
1/*
2 * Copyright (c) 2005, 2014, 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
26package com.sun.tools.javac.file;
27
28import java.io.IOException;
29import java.nio.file.Path;
30import java.util.List;
31import java.util.Map;
32import java.util.concurrent.ConcurrentHashMap;
33
34import com.sun.tools.javac.util.Context;
35import com.sun.tools.javac.util.Context.Factory;
36
37/**
38 * Caching implementation of FSInfo.
39 *
40 * <p><b>This is NOT part of any supported API.
41 * If you write code that depends on this, you do so at your own risk.
42 * This code and its internal interfaces are subject to change or
43 * deletion without notice.</b>
44 */
45public class CacheFSInfo extends FSInfo {
46
47    /**
48     * Register a Context.Factory to create a CacheFSInfo.
49     */
50    public static void preRegister(Context context) {
51        context.put(FSInfo.class, (Factory<FSInfo>)c -> {
52                FSInfo instance = new CacheFSInfo();
53                c.put(FSInfo.class, instance);
54                return instance;
55            });
56    }
57
58    public void clearCache() {
59        cache.clear();
60    }
61
62    @Override
63    public Path getCanonicalFile(Path file) {
64        Entry e = getEntry(file);
65        return e.canonicalFile;
66    }
67
68    @Override
69    public boolean exists(Path file) {
70        Entry e = getEntry(file);
71        return e.exists;
72    }
73
74    @Override
75    public boolean isDirectory(Path file) {
76        Entry e = getEntry(file);
77        return e.isDirectory;
78    }
79
80    @Override
81    public boolean isFile(Path file) {
82        Entry e = getEntry(file);
83        return e.isFile;
84    }
85
86    @Override
87    public List<Path> getJarClassPath(Path file) throws IOException {
88        // don't bother to lock the cache, because it is thread-safe, and
89        // because the worst that can happen would be to create two identical
90        // jar class paths together and have one overwrite the other.
91        Entry e = getEntry(file);
92        if (e.jarClassPath == null)
93            e.jarClassPath = super.getJarClassPath(file);
94        return e.jarClassPath;
95    }
96
97    private Entry getEntry(Path file) {
98        // don't bother to lock the cache, because it is thread-safe, and
99        // because the worst that can happen would be to create two identical
100        // entries together and have one overwrite the other.
101        Entry e = cache.get(file);
102        if (e == null) {
103            e = new Entry();
104            e.canonicalFile = super.getCanonicalFile(file);
105            e.exists = super.exists(file);
106            e.isDirectory = super.isDirectory(file);
107            e.isFile = super.isFile(file);
108            cache.put(file, e);
109        }
110        return e;
111    }
112
113    // could also be a Map<File,SoftReference<Entry>> ?
114    private final Map<Path,Entry> cache = new ConcurrentHashMap<>();
115
116    private static class Entry {
117        Path canonicalFile;
118        boolean exists;
119        boolean isFile;
120        boolean isDirectory;
121        List<Path> jarClassPath;
122    }
123}
124