snehashisp commented on code in PR #16984: URL: https://github.com/apache/kafka/pull/16984#discussion_r1873349188
########## connect/runtime/src/main/java/org/apache/kafka/connect/runtime/isolation/DelegatingClassLoader.java: ########## @@ -1,132 +1,253 @@ -/* - * Licensed to the Apache Software Foundation (ASF) under one or more - * contributor license agreements. See the NOTICE file distributed with - * this work for additional information regarding copyright ownership. - * The ASF licenses this file to You 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.kafka.connect.runtime.isolation; - -import org.slf4j.Logger; -import org.slf4j.LoggerFactory; - -import java.net.URL; -import java.net.URLClassLoader; -import java.util.HashMap; -import java.util.Map; -import java.util.SortedMap; -import java.util.TreeMap; -import java.util.concurrent.ConcurrentHashMap; -import java.util.concurrent.ConcurrentMap; - -/** - * A custom classloader dedicated to loading Connect plugin classes in classloading isolation. - * - * <p> - * Under the current scheme for classloading isolation in Connect, the delegating classloader loads - * plugin classes that it finds in its child plugin classloaders. For classes that are not plugins, - * this delegating classloader delegates its loading to its parent. This makes this classloader a - * child-first classloader. - * <p> - * This class is thread-safe and parallel capable. - */ -public class DelegatingClassLoader extends URLClassLoader { - private static final Logger log = LoggerFactory.getLogger(DelegatingClassLoader.class); - - private final ConcurrentMap<String, SortedMap<PluginDesc<?>, ClassLoader>> pluginLoaders; - private final ConcurrentMap<String, String> aliases; - - // Although this classloader does not load classes directly but rather delegates loading to a - // PluginClassLoader or its parent through its base class, because of the use of inheritance - // in the latter case, this classloader needs to also be declared as parallel capable to use - // fine-grain locking when loading classes. - static { - ClassLoader.registerAsParallelCapable(); - } - - public DelegatingClassLoader(ClassLoader parent) { - super(new URL[0], parent); - this.pluginLoaders = new ConcurrentHashMap<>(); - this.aliases = new ConcurrentHashMap<>(); - } - - public DelegatingClassLoader() { - // Use as parent the classloader that loaded this class. In most cases this will be the - // System classloader. But this choice here provides additional flexibility in managed - // environments that control classloading differently (OSGi, Spring and others) and don't - // depend on the System classloader to load Connect's classes. - this(DelegatingClassLoader.class.getClassLoader()); - } - - /** - * Retrieve the PluginClassLoader associated with a plugin class - * @param name The fully qualified class name of the plugin - * @return the PluginClassLoader that should be used to load this, or null if the plugin is not isolated. - */ - // VisibleForTesting - PluginClassLoader pluginClassLoader(String name) { - if (!PluginUtils.shouldLoadInIsolation(name)) { - return null; - } - SortedMap<PluginDesc<?>, ClassLoader> inner = pluginLoaders.get(name); - if (inner == null) { - return null; - } - ClassLoader pluginLoader = inner.get(inner.lastKey()); - return pluginLoader instanceof PluginClassLoader - ? (PluginClassLoader) pluginLoader - : null; - } - - ClassLoader connectorLoader(String connectorClassOrAlias) { - String fullName = aliases.getOrDefault(connectorClassOrAlias, connectorClassOrAlias); - ClassLoader classLoader = pluginClassLoader(fullName); - if (classLoader == null) classLoader = this; - log.debug( - "Getting plugin class loader: '{}' for connector: {}", - classLoader, - connectorClassOrAlias - ); - return classLoader; - } - - public void installDiscoveredPlugins(PluginScanResult scanResult) { - pluginLoaders.putAll(computePluginLoaders(scanResult)); - for (String pluginClassName : pluginLoaders.keySet()) { - log.info("Added plugin '{}'", pluginClassName); - } - aliases.putAll(PluginUtils.computeAliases(scanResult)); - for (Map.Entry<String, String> alias : aliases.entrySet()) { - log.info("Added alias '{}' to plugin '{}'", alias.getKey(), alias.getValue()); - } - } - - @Override - protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException { - String fullName = aliases.getOrDefault(name, name); - PluginClassLoader pluginLoader = pluginClassLoader(fullName); - if (pluginLoader != null) { - log.trace("Retrieving loaded class '{}' from '{}'", fullName, pluginLoader); - return pluginLoader.loadClass(fullName, resolve); - } - - return super.loadClass(fullName, resolve); - } - - private static Map<String, SortedMap<PluginDesc<?>, ClassLoader>> computePluginLoaders(PluginScanResult plugins) { - Map<String, SortedMap<PluginDesc<?>, ClassLoader>> pluginLoaders = new HashMap<>(); - plugins.forEach(pluginDesc -> - pluginLoaders.computeIfAbsent(pluginDesc.className(), k -> new TreeMap<>()) - .put(pluginDesc, pluginDesc.loader())); - return pluginLoaders; - } -} +/* Review Comment: I'm not sure why this is the case tbh. Maybe just the magnitude of changes in the class is making the diff look so big 🤔 -- 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. To unsubscribe, e-mail: jira-unsubscr...@kafka.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
