1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.bcel.util;
18
19 import java.util.LinkedHashMap;
20 import java.util.Map;
21
22 import org.apache.bcel.classfile.JavaClass;
23
24 /**
25 * Maintains a least-recently-used (LRU) cache of {@link JavaClass} with maximum size {@code cacheSize}.
26 *
27 * <p>
28 * This repository supports a class path consisting of too many JAR files to handle in {@link ClassPathRepository} or
29 * {@link MemorySensitiveClassPathRepository} without causing {@code OutOfMemoryError}.
30 * </p>
31 *
32 * @since 6.4.0
33 */
34 public class LruCacheClassPathRepository extends AbstractClassPathRepository {
35
36 private final LinkedHashMap<String, JavaClass> loadedClasses;
37
38 public LruCacheClassPathRepository(final ClassPath path, final int cacheSize) {
39 super(path);
40
41 if (cacheSize < 1) {
42 throw new IllegalArgumentException("cacheSize must be a positive number.");
43 }
44 final int initialCapacity = (int) (0.75 * cacheSize);
45 final boolean accessOrder = true; // Evicts least-recently-accessed
46 loadedClasses = new LinkedHashMap<String, JavaClass>(initialCapacity, cacheSize, accessOrder) {
47
48 private static final long serialVersionUID = 1L;
49
50 @Override
51 protected boolean removeEldestEntry(final Map.Entry<String, JavaClass> eldest) {
52 return size() > cacheSize;
53 }
54 };
55 }
56
57 @Override
58 public void clear() {
59 loadedClasses.clear();
60 }
61
62 @Override
63 public JavaClass findClass(final String className) {
64 return loadedClasses.get(className);
65 }
66
67 @Override
68 public void removeClass(final JavaClass javaClass) {
69 loadedClasses.remove(javaClass.getClassName());
70 }
71
72 @Override
73 public void storeClass(final JavaClass javaClass) {
74 // Not storing parent's _loadedClass
75 loadedClasses.put(javaClass.getClassName(), javaClass);
76 javaClass.setRepository(this);
77 }
78 }