001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 *  Unless required by applicable law or agreed to in writing, software
012 *  distributed under the License is distributed on an "AS IS" BASIS,
013 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 *  See the License for the specific language governing permissions and
015 *  limitations under the License.
016 *
017 */
018package org.apache.bcel.util;
019
020import java.lang.ref.SoftReference;
021import java.util.HashMap;
022import java.util.Map;
023
024import org.apache.bcel.classfile.JavaClass;
025
026/**
027 * This repository is used in situations where a Class is created outside the realm of a ClassLoader. Classes are loaded from the file systems using the paths
028 * specified in the given class path. By default, this is the value returned by ClassPath.getClassPath(). This repository holds onto classes with
029 * SoftReferences, and will reload as needed, in cases where memory sizes are important.
030 *
031 * @see org.apache.bcel.Repository
032 */
033public class MemorySensitiveClassPathRepository extends AbstractClassPathRepository {
034
035    private final Map<String, SoftReference<JavaClass>> _loadedClasses = new HashMap<>(); // CLASSNAME X JAVACLASS
036
037    public MemorySensitiveClassPathRepository(final ClassPath path) {
038        super(path);
039    }
040
041    /**
042     * Store a new JavaClass instance into this Repository.
043     */
044    @Override
045    public void storeClass(final JavaClass clazz) {
046        // Not calling super.storeClass because this subclass maintains the mapping.
047        _loadedClasses.put(clazz.getClassName(), new SoftReference<>(clazz));
048        clazz.setRepository(this);
049    }
050
051    /**
052     * Remove class from repository
053     */
054    @Override
055    public void removeClass(final JavaClass clazz) {
056        _loadedClasses.remove(clazz.getClassName());
057    }
058
059    /**
060     * Find an already defined (cached) JavaClass object by name.
061     */
062    @Override
063    public JavaClass findClass(final String className) {
064        final SoftReference<JavaClass> ref = _loadedClasses.get(className);
065        if (ref == null) {
066            return null;
067        }
068        return ref.get();
069    }
070
071    /**
072     * Clear all entries from cache.
073     */
074    @Override
075    public void clear() {
076        _loadedClasses.clear();
077    }
078}