/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package com.sun.tools.javac.file;

import java.io.File;

import java.io.IOException;

import java.util.List;

import com.sun.tools.javac.util.Context;

/**

 * Caching implementation of FSInfo.

 *

 * <p><b>This is NOT part of any supported API.

 * If you write code that depends on this, you do so at your own risk.

 * This code and its internal interfaces are subject to change or

 * deletion without notice.</b>

 */

public class CacheFSInfo extends FSInfo {

    /**

     * Register a Context.Factory to create a singleton CacheFSInfo.

     */

    public static void preRegister(final Context context) {

        context.put(FSInfo.class, new Context.Factory<FSInfo>() {

            public FSInfo make() {

                if (singleton == null)

                    singleton = new CacheFSInfo();

                context.put(FSInfo.class, singleton);

                return singleton;

            }

        });

    }

    static CacheFSInfo singleton;

    public void clearCache() {

        cache.clear();

    }

    @Override

    public File getCanonicalFile(File file) {

        Entry e = getEntry(file);

        return e.canonicalFile;

    }

    @Override

    public boolean exists(File file) {

        Entry e = getEntry(file);

        return e.exists;

    }

    @Override

    public boolean isDirectory(File file) {

        Entry e = getEntry(file);

        return e.isDirectory;

    }

    @Override

    public boolean isFile(File file) {

        Entry e = getEntry(file);

        return e.isFile;

    }

    @Override

    public List<File> getJarClassPath(File file) throws IOException {

        // don't bother to lock the cache, because it is thread-safe, and

        // because the worst that can happen would be to create two identical

        // jar class paths together and have one overwrite the other.

        Entry e = getEntry(file);

        if (e.jarClassPath == null)

            e.jarClassPath = super.getJarClassPath(file);

        return e.jarClassPath;

    }

    private Entry getEntry(File file) {

        // don't bother to lock the cache, because it is thread-safe, and

        // because the worst that can happen would be to create two identical

        // entries together and have one overwrite the other.

        Entry e = cache.get(file);

        if (e == null) {

            e = new Entry();

            e.canonicalFile = super.getCanonicalFile(file);

            e.exists = super.exists(file);

            e.isDirectory = super.isDirectory(file);

            e.isFile = super.isFile(file);

            cache.put(file, e);

        }

        return e;

    }

    // could also be a Map<File,SoftReference<Entry>> ?

    private Map<File,Entry> cache = new ConcurrentHashMap<File,Entry>();

    private static class Entry {

        File canonicalFile;

        boolean exists;

        boolean isFile;

        boolean isDirectory;

        List<File> jarClassPath;

    }

}