/* * Copyright (c) 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017 David Berkman * * This file is part of the SmallMind Code Project. * * The SmallMind Code Project is free software, you can redistribute * it and/or modify it under either, at your discretion... * * 1) The terms of GNU Affero General Public License as published by the * Free Software Foundation, either version 3 of the License, or (at * your option) any later version. * * ...or... * * 2) The terms of the Apache License, Version 2.0. * * The SmallMind Code Project 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 or Apache License for more details. * * You should have received a copy of the GNU Affero General Public License * and the Apache License along with the SmallMind Code Project. If not, see * <http://www.gnu.org/licenses/> or <http://www.apache.org/licenses/LICENSE-2.0>. * * Additional permission under the GNU Affero GPL version 3 section 7 * ------------------------------------------------------------------ * If you modify this Program, or any covered work, by linking or * combining it with other code, such other code is not for that reason * alone subject to any of the requirements of the GNU Affero GPL * version 3. */ package org.smallmind.nutsnbolts.lang; import java.io.IOException; import java.io.InputStream; import java.net.URL; import java.util.Enumeration; import java.util.HashMap; import java.util.HashSet; import java.util.LinkedList; import org.smallmind.nutsnbolts.util.IteratorEnumeration; public class GatingClassLoader extends ClassLoader { private final HashMap<String, ClassGateTicket> ticketMap; private final HashSet<String> packageSet = new HashSet<>(); private final ClassGate[] classGates; private final int gracePeriodSeconds; static { ClassLoader.registerAsParallelCapable(); } public GatingClassLoader (int gracePeriodSeconds, ClassGate... classGates) { this(null, gracePeriodSeconds, classGates); } public GatingClassLoader (ClassLoader parent, int gracePeriodSeconds, ClassGate... classGates) { super(parent); this.classGates = classGates; this.gracePeriodSeconds = gracePeriodSeconds; ticketMap = new HashMap<>(); } public ClassGate[] getClassGates () { return classGates; } @Override public synchronized Class loadClass (String name, boolean resolve) throws ClassNotFoundException { Class gatedClass; ClassGateTicket classGateTicket; if ((gatedClass = findLoadedClass(name)) != null) { if (gracePeriodSeconds >= 0) { synchronized (ticketMap) { classGateTicket = ticketMap.get(name); } if (classGateTicket.getTimeStamp() != ClassGate.STATIC_CLASS) { if (System.currentTimeMillis() >= (classGateTicket.getTimeStamp() + (gracePeriodSeconds * 1000))) { if (classGateTicket.getClassGate().getLastModDate(name) > classGateTicket.getTimeStamp()) { throw new StaleClassLoaderException(name); } } } } } else { if (getParent() != null) { try { gatedClass = getParent().loadClass(name); } catch (ClassNotFoundException c) { gatedClass = findClass(name); } } else { try { gatedClass = findSystemClass(name); } catch (ClassNotFoundException c) { gatedClass = findClass(name); } } } if (resolve) { resolveClass(gatedClass); } return gatedClass; } @Override public synchronized Class findClass (String name) throws ClassNotFoundException { Class definedClass; ClassStreamTicket classStreamTicket; InputStream classInputStream; byte[] classData; for (ClassGate classGate : classGates) { try { if ((classStreamTicket = classGate.getClassAsTicket(name)) != null) { classInputStream = classStreamTicket.getInputStream(); classData = getClassData(classInputStream); classInputStream.close(); definePackage(name); definedClass = defineClass(name, classData, 0, classData.length); if (gracePeriodSeconds >= 0) { synchronized (ticketMap) { ticketMap.put(name, new ClassGateTicket(classGate, classStreamTicket.getTimeStamp())); } } return definedClass; } } catch (Exception exception) { throw new ClassNotFoundException("Exception encountered while attempting to define class (" + name + ")", exception); } } throw new ClassNotFoundException(name); } private void definePackage (String name) { String packageName; int lastDotPos = name.lastIndexOf('.'); packageName = name.substring(0, lastDotPos); if (packageSet.add(packageName)) { definePackage(packageName, System.getProperty("java.vm.specification.name"), System.getProperty("java.vm.specification.version"), System.getProperty("java.vm.specification.vendor"), System.getProperty("java.specification.name"), System.getProperty("java.specification.version"), System.getProperty("java.specification.vendor"), null); } } private byte[] getClassData (InputStream classInputStream) throws IOException { byte[] classData; int dataLength; int totalBytesRead = 0; int bytesRead; dataLength = classInputStream.available(); classData = new byte[dataLength]; while (totalBytesRead < dataLength) { bytesRead = classInputStream.read(classData, totalBytesRead, dataLength - totalBytesRead); totalBytesRead += bytesRead; } return classData; } @Override public InputStream getResourceAsStream (String name) { InputStream resourceStream; if ((resourceStream = super.getResourceAsStream(name)) != null) { return resourceStream; } for (ClassGate classGate : classGates) { try { if ((resourceStream = classGate.getResourceAsStream(name)) != null) { return resourceStream; } } catch (Exception exception) { } } return null; } @Override public URL findResource (String name) { URL resourceURL; for (ClassGate classGate : classGates) { try { if ((resourceURL = classGate.getResource(name)) != null) { return resourceURL; } } catch (Exception exception) { } } return null; } @Override protected Enumeration<URL> findResources (String name) { LinkedList<URL> urlList = new LinkedList<>(); for (ClassGate classGate : classGates) { URL resourceURL; try { if ((resourceURL = classGate.getResource(name)) != null) { urlList.add(resourceURL); } } catch (Exception exception) { } } return new IteratorEnumeration<>(urlList.iterator()); } }