Java tutorial
/* * Quasar: lightweight threads and actors for the JVM. * Copyright (c) 2013-2014, Parallel Universe Software Co. All rights reserved. * * This program and the accompanying materials are dual-licensed under * either the terms of the Eclipse Public License v1.0 as published by * the Eclipse Foundation * * or (per the licensee's choosing) * * under the terms of the GNU Lesser General Public License version 3.0 * as published by the Free Software Foundation. */ package co.paralleluniverse.actors; import co.paralleluniverse.common.reflection.ASMUtil; import co.paralleluniverse.common.reflection.AnnotationUtil; import co.paralleluniverse.common.reflection.ClassLoaderUtil; import static co.paralleluniverse.common.reflection.ClassLoaderUtil.classToResource; import static co.paralleluniverse.common.reflection.ClassLoaderUtil.isClassFile; import com.google.common.collect.ImmutableSet; import com.google.common.io.Resources; import java.io.File; import java.io.IOException; import java.io.InputStream; import java.net.URISyntaxException; import java.net.URL; import java.net.URLClassLoader; import java.util.Set; import java.util.jar.Attributes; import java.util.jar.JarFile; import java.util.jar.Manifest; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * A module of actor code-upgrades contained in a jar file. * * @author pron */ class ActorModule extends URLClassLoader { private static final Class<?>[] AUTOMATIC_UPGRADE_CLASSES = new Class[] { Actor.class, co.paralleluniverse.actors.behaviors.Initializer.class, co.paralleluniverse.actors.behaviors.ServerHandler.class, co.paralleluniverse.actors.behaviors.EventHandler.class, }; static { ClassLoader.registerAsParallelCapable(); } private static final Logger LOG = LoggerFactory.getLogger(ActorModule.class); private static final String UPGRADE_CLASSES_ATTR = "Upgrade-Classes"; private final URL url; private final ClassLoader parent; private final Set<String> upgradeClasses; public ActorModule(URL jarUrl, ActorLoader parent) { super(new URL[] { jarUrl }, null); this.url = jarUrl; this.parent = parent; // determine upgrade classes try { JarFile jar = new JarFile(new File(jarUrl.toURI())); final ImmutableSet.Builder<String> builder = ImmutableSet.builder(); Manifest manifest = jar.getManifest(); Attributes attributes = manifest.getMainAttributes(); String ucstr = attributes.getValue(UPGRADE_CLASSES_ATTR); if (ucstr != null && !ucstr.trim().isEmpty()) { if (ucstr.trim().equals("*")) { ClassLoaderUtil.accept(this, new ClassLoaderUtil.Visitor() { @Override public void visit(String resource, URL url, ClassLoader cl) { if (!isClassFile(resource)) return; final String className = ClassLoaderUtil.resourceToClass(resource); // System.out.println("className: " + className + " " // + ASMUtil.isAssignableFrom(Actor.class, className, ActorModule.this) + " " // + " " + url + " " + ActorModule.this.parent.getResource(resource) + " " // + equalContent(ActorModule.this.parent.getResource(resource), url)); if (isAutomaticUpgrade(className) && !equalContent(ActorModule.this.parent.getResource(resource), url)) builder.add(className); } }); } else { for (String className : ucstr.split("\\s")) { LOG.debug("Upgrade of class {} (JAR manifest)", className); builder.add(className); } } } ClassLoaderUtil.accept(this, new ClassLoaderUtil.Visitor() { @Override public void visit(String resource, URL url, ClassLoader cl) { if (!isClassFile(resource)) return; final String className = ClassLoaderUtil.resourceToClass(resource); try (InputStream is = cl.getResourceAsStream(resource)) { if (AnnotationUtil.hasClassAnnotation(Upgrade.class, is)) { LOG.debug("Upgrade of class {} (annotated)", className); builder.add(className); } } catch (IOException e) { throw new RuntimeException( "Exception while scanning class " + className + " for Upgrade annotation", e); } } }); this.upgradeClasses = builder.build(); } catch (IOException | URISyntaxException e) { throw new RuntimeException(e); } } private boolean isAutomaticUpgrade(String className) { for (Class<?> c : AUTOMATIC_UPGRADE_CLASSES) { if (ASMUtil.isAssignableFrom(c, className, ActorModule.this)) { LOG.debug("Automatic upgrade of class {} (implements/extends {})", className, c); return true; } } return false; } public URL getURL() { return url; } public Set<String> getUpgradeClasses() { return upgradeClasses; } public Class<?> loadClassInModule(String name) throws ClassNotFoundException { Class<?> loaded = super.findLoadedClass(name); if (loaded != null) return loaded; return super.loadClass(name); // first try to use the URLClassLoader findClass } public Class<?> findLoadedClassInModule(String name) { return super.findLoadedClass(name); } @Override public Class<?> findClass(String name) throws ClassNotFoundException { Class<?> loaded = super.findLoadedClass(name); if (loaded != null) return loaded; LOG.debug("findClass {} in module {}", name, this); boolean isUpgraded = upgradeClasses.contains(name); if (!isUpgraded && parent != null && !name.contains("$")) { // if class is possibly an inner class, don't use parent's, which will be in a different runtime package try { String resourceName = classToResource(name); URL parentUrl = parent.getResource(resourceName); LOG.debug("findClass {} in module {} - parent URL: {}", name, this, parentUrl); if (parentUrl != null) { URL myUrl = super.getResource(resourceName); if (myUrl == null || equalContent(parentUrl, myUrl)) { // NOTE: classes may differ only in their Java source line information; considered a difference if (myUrl != null) LOG.debug("Class {} in module {} is identical to that in main module", name, this); else LOG.debug("findClass {} in module {} - not found in module", name, this); return parent.loadClass(name); } } } catch (ClassNotFoundException e) { } } try { Class<?> clazz = super.findClass(name); // first try to use the URLClassLoader findClass LOG.info("{} loaded {} class {}", this, isUpgraded ? "upgraded" : "internal", name); return clazz; } catch (ClassNotFoundException e) { if (parent != null) return parent.loadClass(name); throw e; } } @Override public URL getResource(String name) { URL url = super.getResource(name); if (url != null) LOG.debug("{} - getResource {}: {}", this, name, url); if (url == null && parent != null) url = parent.getResource(name); return url; } @Override public String toString() { return "ActorModule{" + "url=" + url + '}'; } private static boolean equalContent(URL url1, URL url2) { try { return Resources.asByteSource(url1).contentEquals(Resources.asByteSource(url2)); } catch (IOException e) { throw new RuntimeException(e); } } }