--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk.dynalink/share/classes/jdk/dynalink/ClassMap.java Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,183 @@
+/*
+ * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
+ * 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * This file is available under and governed by the GNU General Public
+ * License version 2 only, as published by the Free Software Foundation.
+ * However, the following notice accompanied the original version of this
+ * file, and Oracle licenses the original version of this file under the BSD
+ * license:
+ */
+/*
+ Copyright 2009-2013 Attila Szegedi
+
+ Licensed under both the Apache License, Version 2.0 (the "Apache License")
+ and the BSD License (the "BSD License"), with licensee being free to
+ choose either of the two at their discretion.
+
+ You may not use this file except in compliance with either the Apache
+ License or the BSD License.
+
+ If you choose to use this file in compliance with the Apache License, the
+ following notice applies to you:
+
+ You may obtain a copy of the Apache License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+ implied. See the License for the specific language governing
+ permissions and limitations under the License.
+
+ If you choose to use this file in compliance with the BSD License, the
+ following notice applies to you:
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions are
+ met:
+ * Redistributions of source code must retain the above copyright
+ notice, this list of conditions and the following disclaimer.
+ * Redistributions in binary form must reproduce the above copyright
+ notice, this list of conditions and the following disclaimer in the
+ documentation and/or other materials provided with the distribution.
+ * Neither the name of the copyright holder nor the names of
+ contributors may be used to endorse or promote products derived from
+ this software without specific prior written permission.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDER
+ BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+package jdk.dynalink;
+
+import java.lang.ref.Reference;
+import java.lang.ref.SoftReference;
+import java.security.AccessControlContext;
+import java.security.AccessController;
+import java.security.PrivilegedAction;
+import java.util.Map;
+import java.util.WeakHashMap;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import jdk.dynalink.internal.AccessControlContextFactory;
+import jdk.dynalink.internal.InternalTypeUtilities;
+
+/**
+ * A dual map that can either strongly or weakly reference a given class depending on whether the class is visible from
+ * a class loader or not.
+ *
+ * @param <T> the type of the values in the map
+ */
+abstract class ClassMap<T> {
+ private static final AccessControlContext GET_CLASS_LOADER_CONTEXT =
+ AccessControlContextFactory.createAccessControlContext("getClassLoader");
+
+ private final ConcurrentMap<Class<?>, T> map = new ConcurrentHashMap<>();
+ private final Map<Class<?>, Reference<T>> weakMap = new WeakHashMap<>();
+ private final ClassLoader classLoader;
+
+ /**
+ * Creates a new class map. It will use strong references for all keys and values where the key is a class visible
+ * from the class loader, and will use weak keys and soft values for all other classes.
+ *
+ * @param classLoader the classloader that determines strong referenceability.
+ */
+ ClassMap(final ClassLoader classLoader) {
+ this.classLoader = classLoader;
+ }
+
+ /**
+ * Compute the value associated with the given class. It is possible that the method will be invoked several times
+ * (or even concurrently) for the same class parameter.
+ *
+ * @param clazz the class to compute the value for
+ * @return the return value. Must not be null.
+ */
+ abstract T computeValue(Class<?> clazz);
+
+ /**
+ * Returns the value associated with the class
+ *
+ * @param clazz the class
+ * @return the value associated with the class
+ */
+ T get(final Class<?> clazz) {
+ // Check in fastest first - objects we're allowed to strongly reference
+ final T v = map.get(clazz);
+ if(v != null) {
+ return v;
+ }
+ // Check objects we're not allowed to strongly reference
+ Reference<T> ref;
+ synchronized(weakMap) {
+ ref = weakMap.get(clazz);
+ }
+ if(ref != null) {
+ final T refv = ref.get();
+ if(refv != null) {
+ return refv;
+ }
+ }
+ // Not found in either place; create a new value
+ final T newV = computeValue(clazz);
+ assert newV != null;
+
+ final Boolean canReferenceDirectly = AccessController.doPrivileged(new PrivilegedAction<Boolean>() {
+ @Override
+ public Boolean run() {
+ return InternalTypeUtilities.canReferenceDirectly(classLoader, clazz.getClassLoader());
+ }
+ }, GET_CLASS_LOADER_CONTEXT);
+
+ // If allowed to strongly reference, put it in the fast map
+ if(canReferenceDirectly) {
+ final T oldV = map.putIfAbsent(clazz, newV);
+ return oldV != null ? oldV : newV;
+ }
+ // Otherwise, put it into the weak map
+ synchronized(weakMap) {
+ ref = weakMap.get(clazz);
+ if(ref != null) {
+ final T oldV = ref.get();
+ if(oldV != null) {
+ return oldV;
+ }
+ }
+ weakMap.put(clazz, new SoftReference<>(newV));
+ return newV;
+ }
+ }
+}