CalvinKirs commented on a change in pull request #3601: URL: https://github.com/apache/incubator-dolphinscheduler/pull/3601#discussion_r495015429
########## File path: dolphinscheduler-alert/src/main/java/org/apache/dolphinscheduler/alert/plugin/DolphinPluginClassLoader.java ########## @@ -0,0 +1,136 @@ +/* + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the 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. + */ + +package org.apache.dolphinscheduler.alert.plugin; + +import static java.util.Objects.requireNonNull; + +import java.io.IOException; +import java.lang.reflect.InvocationTargetException; +import java.lang.reflect.Method; +import java.net.URL; +import java.net.URLClassLoader; +import java.util.Enumeration; +import java.util.List; + +import com.google.common.collect.ImmutableList; +import com.google.common.collect.Iterables; + +class DolphinPluginClassLoader + extends URLClassLoader { + private static final ClassLoader PLATFORM_CLASS_LOADER = findPlatformClassLoader(); + + private final ClassLoader spiClassLoader; + private final List<String> spiPackages; + private final List<String> spiResources; + + public DolphinPluginClassLoader( + List<URL> urls, + ClassLoader spiClassLoader, + Iterable<String> spiPackages) { + this(urls, + spiClassLoader, + spiPackages, + Iterables.transform(spiPackages, DolphinPluginClassLoader::classNameToResource)); + } + + private DolphinPluginClassLoader( + List<URL> urls, + ClassLoader spiClassLoader, + Iterable<String> spiPackages, + Iterable<String> spiResources) { + // plugins should not have access to the system (application) class loader + super(urls.toArray(new URL[urls.size()]), PLATFORM_CLASS_LOADER); + this.spiClassLoader = requireNonNull(spiClassLoader, "spiClassLoader is null"); + this.spiPackages = ImmutableList.copyOf(spiPackages); + this.spiResources = ImmutableList.copyOf(spiResources); + } + + @Override + protected Class<?> loadClass(String name, boolean resolve) + throws ClassNotFoundException { + // grab the magic lock + synchronized (getClassLoadingLock(name)) { + // Check if class is in the loaded classes cache + Class<?> cachedClass = findLoadedClass(name); + if (cachedClass != null) { + return resolveClass(cachedClass, resolve); + } + + // If this is an SPI class, only check SPI class loader + if (isSpiClass(name)) { + return resolveClass(spiClassLoader.loadClass(name), resolve); + } + + // Look for class locally + return super.loadClass(name, resolve); + } + } + + private Class<?> resolveClass(Class<?> clazz, boolean resolve) { + if (resolve) { + resolveClass(clazz); + } + return clazz; + } + + @Override + public URL getResource(String name) { + // If this is an SPI resource, only check SPI class loader + if (isSpiResource(name)) { + return spiClassLoader.getResource(name); + } + + // Look for resource locally + return super.getResource(name); + } + + @Override + public Enumeration<URL> getResources(String name) + throws IOException { + // If this is an SPI resource, use SPI resources + if (isSpiClass(name)) { + return spiClassLoader.getResources(name); + } + + // Use local resources + return super.getResources(name); + } + + private boolean isSpiClass(String name) { + return spiPackages.stream().anyMatch(name::startsWith); + } + + private boolean isSpiResource(String name) { + return spiResources.stream().anyMatch(name::startsWith); + } + + private static String classNameToResource(String className) { + return className.replace('.', '/'); + } + + @SuppressWarnings("JavaReflectionMemberAccess") + private static ClassLoader findPlatformClassLoader() { + try { + // use platform class loader on Java 9 + Method method = ClassLoader.class.getMethod("getPlatformClassLoader"); + return (ClassLoader) method.invoke(null); + } catch (NoSuchMethodException ignored) { + // use null class loader on Java 8 + return null; + } catch (IllegalAccessException | InvocationTargetException e) { Review comment: Do we have a better way to determine the current Java version? OSUtils may have a similar method. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
