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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.lang.ref.SoftReference;
20  import java.util.HashMap;
21  import java.util.Map;
22  
23  import org.apache.bcel.classfile.JavaClass;
24  
25  /**
26   * This repository is used in situations where a Class is created outside the realm of a ClassLoader. Classes are loaded
27   * from the file systems using the paths specified in the given class path. By default, this is the value returned by
28   * ClassPath.getClassPath(). This repository holds onto classes with SoftReferences, and will reload as needed, in cases
29   * where memory sizes are important.
30   *
31   * @see org.apache.bcel.Repository
32   */
33  public class MemorySensitiveClassPathRepository extends AbstractClassPathRepository {
34  
35      private final Map<String, SoftReference<JavaClass>> loadedClasses = new HashMap<>(); // CLASSNAME X JAVACLASS
36  
37      public MemorySensitiveClassPathRepository(final ClassPath path) {
38          super(path);
39      }
40  
41      /**
42       * Clear all entries from cache.
43       */
44      @Override
45      public void clear() {
46          loadedClasses.clear();
47      }
48  
49      /**
50       * Find an already defined (cached) JavaClass object by name.
51       */
52      @Override
53      public JavaClass findClass(final String className) {
54          final SoftReference<JavaClass> ref = loadedClasses.get(className);
55          return ref == null ? null : ref.get();
56      }
57  
58      /**
59       * Remove class from repository
60       */
61      @Override
62      public void removeClass(final JavaClass clazz) {
63          loadedClasses.remove(clazz.getClassName());
64      }
65  
66      /**
67       * Store a new JavaClass instance into this Repository.
68       */
69      @Override
70      public void storeClass(final JavaClass clazz) {
71          // Not calling super.storeClass because this subclass maintains the mapping.
72          loadedClasses.put(clazz.getClassName(), new SoftReference<>(clazz));
73          clazz.setRepository(this);
74      }
75  }