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view agent/src/share/classes/sun/jvm/hotspot/jdi/SAJDIClassLoader.java @ 7353:b5280041f59e
Experiment with soft alignment for branch targets.
author | Thomas Wuerthinger <thomas.wuerthinger@oracle.com> |
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date | Sun, 13 Jan 2013 19:32:16 +0100 |
parents | c18cbe5936b8 |
children |
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/* * Copyright (c) 2003, 2008, 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. * * 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. * */ package sun.jvm.hotspot.jdi; import java.io.*; import java.net.*; /* * This class loader is used for two different reasons: * * 1) To support multiple simultaneous debuggees. * * SA's architecture does not allow us to use multiple simultaneous * debuggees. This is because of lots of static fields caching * vmStruct fields and singleton assumption in classes such as * 'sun.jvm.hotspot.runtime.VM'. Hence, we use instances of this * class loader to create a separate namespace for each debuggee VM. * * 2) To support cross VM version debugging. * * SA has very close dependency on VM data structures. Due to this, a * version of SA can only support debuggees running a same dot-dot release and * update releases only. For eg. this version of SA supports only 1.4.2 and * 1.4.2_xx releases only. But, users may want to debug debuggees running * a different version of VM. To support this, we use an instance of this * class loader to load classes from corresponding sa-jdi.jar. * * Note that JDI classes would still be loaded from the debugger's tools.jar * and not from debuggee's tools.jar. This means that if JDI interface evolved * b/w debuggee and debugger VM versions, user may still get problems. This is * the case when debugger runs on 1.5.0 and debuggee runs on 1.4.2. Because JDI * evolved b/w these versions (generics, enum, varargs etc.), 1.4.2 sa-jdi.jar * won't implement 1.5.0 JDI properly and user would get verifier errors. This * class loader solution is suited for different dot-dot release where JDI will * not evolve but VM data structures might change and SA implementation might * have to change. For example, a debuggee running 1.5.1 VM can be debugged * with debugger running on 1.5.0 VM. Here, JDI is same but VM data structures * could still change. */ class SAJDIClassLoader extends URLClassLoader { private static final boolean DEBUG; static { DEBUG = System.getProperty("sun.jvm.hotspot.jdi.SAJDIClassLoader.DEBUG") != null; } private ClassLoader parent; private boolean classPathSet; SAJDIClassLoader(ClassLoader parent) { super(new URL[0], parent); this.parent = parent; } SAJDIClassLoader(ClassLoader parent, String classPath) { this(parent); this.classPathSet = true; try { addURL(new File(classPath).toURI().toURL()); } catch(MalformedURLException mue) { throw new RuntimeException(mue); } } public synchronized Class loadClass(String name) throws ClassNotFoundException { // First, check if the class has already been loaded Class c = findLoadedClass(name); if (c == null) { /* If we are loading any class in 'sun.jvm.hotspot.' or any of the * sub-packages (except for 'debugger' sub-pkg. please refer below), * we load it by 'this' loader. Or else, we forward the request to * 'parent' loader, system loader etc. (rest of the code follows * the patten in java.lang.ClassLoader.loadClass). * * 'sun.jvm.hotspot.debugger.' and sub-package classes are * also loaded by parent loader. This is done for two reasons: * * 1. to avoid code bloat by too many classes. * 2. to avoid loading same native library multiple times * from multiple class loaders (which results in getting a * UnsatisifiedLinkageError from System.loadLibrary). */ if (name.startsWith("sun.jvm.hotspot.") && !name.startsWith("sun.jvm.hotspot.debugger.")) { return findClass(name); } if (parent != null) { c = parent.loadClass(name); } else { c = findSystemClass(name); } } return c; } protected Class findClass(String name) throws ClassNotFoundException { if (DEBUG) { System.out.println("SA/JDI loader: about to load " + name); } if (classPathSet) { return super.findClass(name); } else { byte[] b = null; try { InputStream in = getResourceAsStream(name.replace('.', '/') + ".class"); // Read until end of stream is reached b = new byte[1024]; int total = 0; int len = 0; while ((len = in.read(b, total, b.length - total)) != -1) { total += len; if (total >= b.length) { byte[] tmp = new byte[total * 2]; System.arraycopy(b, 0, tmp, 0, total); b = tmp; } } // Trim array to correct size, if necessary if (total != b.length) { byte[] tmp = new byte[total]; System.arraycopy(b, 0, tmp, 0, total); b = tmp; } } catch (Exception exp) { throw (ClassNotFoundException) new ClassNotFoundException().initCause(exp); } return defineClass(name, b, 0, b.length); } } }