| /* |
| * Copyright (c) 1999, 2004, 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. |
| */ |
| /* |
| * Licensed Materials - Property of IBM |
| * RMI-IIOP v1.0 |
| * Copyright IBM Corp. 1998 1999 All Rights Reserved |
| * |
| */ |
| |
| package com.sun.corba.se.impl.util; |
| |
| import sun.corba.Bridge ; |
| |
| import java.util.Map ; |
| import java.util.WeakHashMap ; |
| import java.util.Collections ; |
| |
| import java.security.AccessController ; |
| import java.security.PrivilegedAction ; |
| |
| /** |
| * Utility method for crawling call stack to load class |
| */ |
| class JDKClassLoader { |
| |
| private static final JDKClassLoaderCache classCache |
| = new JDKClassLoaderCache(); |
| |
| private static final Bridge bridge = |
| (Bridge)AccessController.doPrivileged( |
| new PrivilegedAction() { |
| public Object run() { |
| return Bridge.get() ; |
| } |
| } |
| ) ; |
| |
| static Class loadClass(Class aClass, String className) |
| throws ClassNotFoundException { |
| |
| // Maintain the same error semantics as Class.forName() |
| if (className == null) { |
| throw new NullPointerException(); |
| } |
| if (className.length() == 0) { |
| throw new ClassNotFoundException(); |
| } |
| |
| // It would be nice to bypass JDKClassLoader's attempts completely |
| // if it's known that the latest user defined ClassLoader will |
| // fail. |
| // |
| // Otherwise, we end up calling Class.forName here as well as in |
| // the next step in JDKBridge. That can take a long time depending |
| // on the length of the classpath. |
| |
| // Note: Looking at the only place in JDKBridge where this code |
| // is invoked, it is clear that aClass will always be null. |
| ClassLoader loader; |
| if (aClass != null) { |
| loader = aClass.getClassLoader(); |
| } else { |
| loader = bridge.getLatestUserDefinedLoader(); |
| } |
| // See createKey for a description of what's involved |
| Object key = classCache.createKey(className, loader); |
| |
| if (classCache.knownToFail(key)) { |
| throw new ClassNotFoundException(className); |
| } else { |
| try { |
| // Loading this class with the call stack |
| // loader isn't known to fail, so try |
| // to load it. |
| return Class.forName(className, false, loader); |
| } catch(ClassNotFoundException cnfe) { |
| // Record that we failed to find the class |
| // with this particular loader. This way, we won't |
| // waste time looking with this loader, again. |
| classCache.recordFailure(key); |
| throw cnfe; |
| } |
| } |
| } |
| |
| /** |
| * Private cache implementation specific to JDKClassLoader. |
| */ |
| private static class JDKClassLoaderCache |
| { |
| // JDKClassLoader couldn't find the class with the located |
| // ClassLoader. Note this in our cache so JDKClassLoader |
| // can abort early next time. |
| public final void recordFailure(Object key) { |
| cache.put(key, JDKClassLoaderCache.KNOWN_TO_FAIL); |
| } |
| |
| // Factory for a key (CacheKey is an implementation detail |
| // of JDKClassLoaderCache). |
| // |
| // A key currently consists of the class name as well as |
| // the latest user defined class loader, so it's fairly |
| // expensive to create. |
| public final Object createKey(String className, ClassLoader latestLoader) { |
| return new CacheKey(className, latestLoader); |
| } |
| |
| // Determine whether or not this combination of class name |
| // and ClassLoader is known to fail. |
| public final boolean knownToFail(Object key) { |
| return cache.get(key) == JDKClassLoaderCache.KNOWN_TO_FAIL; |
| } |
| |
| // Synchronized WeakHashMap |
| private final Map cache |
| = Collections.synchronizedMap(new WeakHashMap()); |
| |
| // Cache result used to mark the caches when there is |
| // no way JDKClassLoader could succeed with the given |
| // key |
| private static final Object KNOWN_TO_FAIL = new Object(); |
| |
| // Key consisting of the class name and the latest |
| // user defined class loader |
| private static class CacheKey |
| { |
| String className; |
| ClassLoader loader; |
| |
| public CacheKey(String className, ClassLoader loader) { |
| this.className = className; |
| this.loader = loader; |
| } |
| |
| // Try to incorporate both class name and loader |
| // into the hashcode |
| public int hashCode() { |
| if (loader == null) |
| return className.hashCode(); |
| else |
| return className.hashCode() ^ loader.hashCode(); |
| } |
| |
| public boolean equals(Object obj) { |
| try { |
| |
| // WeakHashMap may compare null keys |
| if (obj == null) |
| return false; |
| |
| CacheKey other = (CacheKey)obj; |
| |
| // I've made a decision to actually compare the |
| // loader references. I don't want a case when |
| // two loader instances override their equals |
| // methods and only compare code base. |
| // |
| // This way, at worst, our performance will |
| // be slower, but we know we'll do the correct |
| // loading. |
| return (className.equals(other.className) && |
| loader == other.loader); |
| |
| } catch (ClassCastException cce) { |
| return false; |
| } |
| } |
| } |
| } |
| } |