Mon, 12 Aug 2013 12:46:01 +0200
8022789: Revisit doPrivileged blocks in Dynalink
Reviewed-by: lagergren, sundar
attila@90 | 1 | /* |
attila@90 | 2 | * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved. |
attila@90 | 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
attila@90 | 4 | * |
attila@90 | 5 | * This code is free software; you can redistribute it and/or modify it |
attila@90 | 6 | * under the terms of the GNU General Public License version 2 only, as |
attila@90 | 7 | * published by the Free Software Foundation. Oracle designates this |
attila@90 | 8 | * particular file as subject to the "Classpath" exception as provided |
attila@90 | 9 | * by Oracle in the LICENSE file that accompanied this code. |
attila@90 | 10 | * |
attila@90 | 11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
attila@90 | 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
attila@90 | 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
attila@90 | 14 | * version 2 for more details (a copy is included in the LICENSE file that |
attila@90 | 15 | * accompanied this code). |
attila@90 | 16 | * |
attila@90 | 17 | * You should have received a copy of the GNU General Public License version |
attila@90 | 18 | * 2 along with this work; if not, write to the Free Software Foundation, |
attila@90 | 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
attila@90 | 20 | * |
attila@90 | 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
attila@90 | 22 | * or visit www.oracle.com if you need additional information or have any |
attila@90 | 23 | * questions. |
attila@90 | 24 | */ |
attila@90 | 25 | |
attila@90 | 26 | /* |
attila@90 | 27 | * This file is available under and governed by the GNU General Public |
attila@90 | 28 | * License version 2 only, as published by the Free Software Foundation. |
attila@90 | 29 | * However, the following notice accompanied the original version of this |
attila@90 | 30 | * file, and Oracle licenses the original version of this file under the BSD |
attila@90 | 31 | * license: |
attila@90 | 32 | */ |
attila@90 | 33 | /* |
attila@90 | 34 | Copyright 2009-2013 Attila Szegedi |
attila@90 | 35 | |
attila@90 | 36 | Licensed under both the Apache License, Version 2.0 (the "Apache License") |
attila@90 | 37 | and the BSD License (the "BSD License"), with licensee being free to |
attila@90 | 38 | choose either of the two at their discretion. |
attila@90 | 39 | |
attila@90 | 40 | You may not use this file except in compliance with either the Apache |
attila@90 | 41 | License or the BSD License. |
attila@90 | 42 | |
attila@90 | 43 | If you choose to use this file in compliance with the Apache License, the |
attila@90 | 44 | following notice applies to you: |
attila@90 | 45 | |
attila@90 | 46 | You may obtain a copy of the Apache License at |
attila@90 | 47 | |
attila@90 | 48 | http://www.apache.org/licenses/LICENSE-2.0 |
attila@90 | 49 | |
attila@90 | 50 | Unless required by applicable law or agreed to in writing, software |
attila@90 | 51 | distributed under the License is distributed on an "AS IS" BASIS, |
attila@90 | 52 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or |
attila@90 | 53 | implied. See the License for the specific language governing |
attila@90 | 54 | permissions and limitations under the License. |
attila@90 | 55 | |
attila@90 | 56 | If you choose to use this file in compliance with the BSD License, the |
attila@90 | 57 | following notice applies to you: |
attila@90 | 58 | |
attila@90 | 59 | Redistribution and use in source and binary forms, with or without |
attila@90 | 60 | modification, are permitted provided that the following conditions are |
attila@90 | 61 | met: |
attila@90 | 62 | * Redistributions of source code must retain the above copyright |
attila@90 | 63 | notice, this list of conditions and the following disclaimer. |
attila@90 | 64 | * Redistributions in binary form must reproduce the above copyright |
attila@90 | 65 | notice, this list of conditions and the following disclaimer in the |
attila@90 | 66 | documentation and/or other materials provided with the distribution. |
attila@90 | 67 | * Neither the name of the copyright holder nor the names of |
attila@90 | 68 | contributors may be used to endorse or promote products derived from |
attila@90 | 69 | this software without specific prior written permission. |
attila@90 | 70 | |
attila@90 | 71 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS |
attila@90 | 72 | IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
attila@90 | 73 | TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A |
attila@90 | 74 | PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDER |
attila@90 | 75 | BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
attila@90 | 76 | CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
attila@90 | 77 | SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR |
attila@90 | 78 | BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
attila@90 | 79 | WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR |
attila@90 | 80 | OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
attila@90 | 81 | ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
attila@90 | 82 | */ |
attila@90 | 83 | |
attila@90 | 84 | package jdk.internal.dynalink.support; |
attila@90 | 85 | |
attila@90 | 86 | import java.lang.ref.Reference; |
attila@90 | 87 | import java.lang.ref.SoftReference; |
attila@488 | 88 | import java.security.AccessController; |
attila@488 | 89 | import java.security.PrivilegedAction; |
attila@90 | 90 | import java.util.Map; |
attila@90 | 91 | import java.util.WeakHashMap; |
attila@90 | 92 | import java.util.concurrent.ConcurrentHashMap; |
attila@90 | 93 | import java.util.concurrent.ConcurrentMap; |
attila@90 | 94 | |
attila@90 | 95 | /** |
attila@90 | 96 | * A dual map that can either strongly or weakly reference a given class depending on whether the class is visible from |
attila@90 | 97 | * a class loader or not. |
attila@90 | 98 | * |
attila@90 | 99 | * @author Attila Szegedi |
attila@90 | 100 | * @param <T> the type of the values in the map |
attila@90 | 101 | */ |
attila@90 | 102 | public abstract class ClassMap<T> { |
attila@90 | 103 | private final ConcurrentMap<Class<?>, T> map = new ConcurrentHashMap<>(); |
attila@90 | 104 | private final Map<Class<?>, Reference<T>> weakMap = new WeakHashMap<>(); |
attila@90 | 105 | private final ClassLoader classLoader; |
attila@90 | 106 | |
attila@90 | 107 | /** |
attila@90 | 108 | * Creates a new class map. It will use strong references for all keys and values where the key is a class visible |
attila@90 | 109 | * from the class loader, and will use weak keys and soft values for all other classes. |
attila@90 | 110 | * |
attila@90 | 111 | * @param classLoader the classloader that determines strong referenceability. |
attila@90 | 112 | */ |
attila@90 | 113 | protected ClassMap(ClassLoader classLoader) { |
attila@90 | 114 | this.classLoader = classLoader; |
attila@90 | 115 | } |
attila@90 | 116 | |
attila@90 | 117 | /** |
attila@90 | 118 | * Compute the value associated with the given class. It is possible that the method will be invoked several times |
attila@90 | 119 | * (or even concurrently) for the same class parameter. |
attila@90 | 120 | * |
attila@90 | 121 | * @param clazz the class to compute the value for |
attila@90 | 122 | * @return the return value. Must not be null. |
attila@90 | 123 | */ |
attila@90 | 124 | protected abstract T computeValue(Class<?> clazz); |
attila@90 | 125 | |
attila@90 | 126 | /** |
attila@90 | 127 | * Returns the value associated with the class |
attila@90 | 128 | * |
attila@90 | 129 | * @param clazz the class |
attila@90 | 130 | * @return the value associated with the class |
attila@90 | 131 | */ |
attila@488 | 132 | public T get(final Class<?> clazz) { |
attila@90 | 133 | // Check in fastest first - objects we're allowed to strongly reference |
attila@90 | 134 | final T v = map.get(clazz); |
attila@90 | 135 | if(v != null) { |
attila@90 | 136 | return v; |
attila@90 | 137 | } |
attila@90 | 138 | // Check objects we're not allowed to strongly reference |
attila@90 | 139 | Reference<T> ref; |
attila@90 | 140 | synchronized(weakMap) { |
attila@90 | 141 | ref = weakMap.get(clazz); |
attila@90 | 142 | } |
attila@90 | 143 | if(ref != null) { |
attila@90 | 144 | final T refv = ref.get(); |
attila@90 | 145 | if(refv != null) { |
attila@90 | 146 | return refv; |
attila@90 | 147 | } |
attila@90 | 148 | } |
attila@90 | 149 | // Not found in either place; create a new value |
attila@90 | 150 | final T newV = computeValue(clazz); |
attila@90 | 151 | assert newV != null; |
attila@488 | 152 | |
attila@488 | 153 | final ClassLoader clazzLoader = AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() { |
attila@488 | 154 | @Override |
attila@488 | 155 | public ClassLoader run() { |
attila@488 | 156 | return clazz.getClassLoader(); |
attila@488 | 157 | } |
attila@494 | 158 | }, ClassLoaderGetterContextProvider.GET_CLASS_LOADER_CONTEXT); |
attila@488 | 159 | |
attila@90 | 160 | // If allowed to strongly reference, put it in the fast map |
attila@488 | 161 | if(Guards.canReferenceDirectly(classLoader, clazzLoader)) { |
attila@90 | 162 | final T oldV = map.putIfAbsent(clazz, newV); |
attila@90 | 163 | return oldV != null ? oldV : newV; |
attila@90 | 164 | } |
attila@90 | 165 | // Otherwise, put it into the weak map |
attila@90 | 166 | synchronized(weakMap) { |
attila@90 | 167 | ref = weakMap.get(clazz); |
attila@90 | 168 | if(ref != null) { |
attila@90 | 169 | final T oldV = ref.get(); |
attila@90 | 170 | if(oldV != null) { |
attila@90 | 171 | return oldV; |
attila@90 | 172 | } |
attila@90 | 173 | } |
attila@90 | 174 | weakMap.put(clazz, new SoftReference<>(newV)); |
attila@90 | 175 | return newV; |
attila@90 | 176 | } |
attila@90 | 177 | } |
attila@90 | 178 | } |