kevinrr888 commented on code in PR #28: URL: https://github.com/apache/accumulo-classloaders/pull/28#discussion_r2408586463
########## modules/vfs-class-loader/src/main/java/org/apache/accumulo/classloader/vfs/SimpleHDFSClassLoaderFactory.java: ########## @@ -0,0 +1,139 @@ +/* + * 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 + * + * https://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.accumulo.classloader.vfs; + +import java.io.IOException; +import java.net.URL; +import java.net.URLClassLoader; +import java.nio.file.Files; +import java.nio.file.Path; +import java.util.List; +import java.util.Set; +import java.util.stream.Collectors; + +import org.apache.accumulo.core.conf.AccumuloConfiguration; +import org.apache.accumulo.core.spi.common.ContextClassLoaderFactory; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import com.google.common.annotations.VisibleForTesting; +import com.google.common.cache.Cache; +import com.google.common.cache.CacheBuilder; +import com.google.gson.Gson; + +public class SimpleHDFSClassLoaderFactory implements ContextClassLoaderFactory { + private static final Logger LOG = LoggerFactory.getLogger(SimpleHDFSClassLoaderFactory.class); + // TODO KEVIN RATHBUN see URLContextClassLoaderFactory from main + // Cache the class loaders for re-use + // WeakReferences are used so that the class loaders can be cleaned up when no longer needed + // Classes that are loaded contain a reference to the class loader used to load them + // so the class loader will be garbage collected when no more classes are loaded that reference it + private final Cache<Path,URLClassLoader> classLoaders = + CacheBuilder.newBuilder().weakValues().build(); + // TODO KEVIN RATHBUN need to get from a new configurable prop + private final Path userDefDir = Path.of(System.getProperty("user.dir"), "target", "contexts"); + private static final String MANIFEST_FILE_NAME = "manifest.json"; + + @VisibleForTesting + public static class Context { + private final String contextName; + private final List<JarInfo> jars; + + public Context(String contextName, List<JarInfo> jars) { + this.contextName = contextName; + this.jars = List.copyOf(jars); + } + + public String getContextName() { + return contextName; + } + + public List<JarInfo> getJars() { + return jars; + } + } + + @VisibleForTesting + public static class JarInfo { + private final String jarName; + private final String checksum; + + public JarInfo(String jarName, String checksum) { + this.jarName = jarName; + this.checksum = checksum; + } + + public String getJarName() { + return jarName; + } + + public String getChecksum() { + return checksum; + } + } + + public SimpleHDFSClassLoaderFactory(AccumuloConfiguration conf) { + try { + initializeContexts(conf); + } catch (IOException e) { + throw new IllegalStateException(this.getClass().getSimpleName() + " could not be created.", + e); + } + } + + private void initializeContexts(AccumuloConfiguration conf) throws IOException { + if (classLoaders.size() != 0) { + LOG.debug("Contexts already initialized, skipping..."); + return; + } + final Set<Path> allContextPaths; + try (var childPathsStream = Files.list(userDefDir)) { + allContextPaths = childPathsStream.filter(Files::isDirectory).collect(Collectors.toSet()); + } + for (var contextPath : allContextPaths) { + Path manifestFile = contextPath.resolve(MANIFEST_FILE_NAME); + createClassLoader(manifestFile); + } + } + + private void createClassLoader(Path manifestFile) throws IOException { + Context jsonData = new Gson().fromJson(Files.newBufferedReader(manifestFile), Context.class); + URL[] urls = new URL[jsonData.getJars().size()]; + int i = 0; + for (var jar : jsonData.getJars()) { + var manifestFileParent = manifestFile.getParent(); + if (manifestFileParent != null) { + urls[i++] = manifestFileParent.resolve(jar.getJarName()).toUri().toURL(); + } else { + throw new IllegalStateException("Parent path of " + manifestFile + " does not exist."); + } + } + classLoaders.put(manifestFile, new URLClassLoader(urls, ClassLoader.getSystemClassLoader())); + } + + @Override + public ClassLoader getClassLoader(String contextName) throws ContextClassLoaderException { + var expectedPath = userDefDir.resolve(contextName).resolve(MANIFEST_FILE_NAME); + var classLoader = classLoaders.getIfPresent(expectedPath); + if (classLoader == null) { + throw new ContextClassLoaderException(contextName); + } + return classLoader; + } Review Comment: Thanks for the detailed explanation. I believe this is fully addressed in 7dce18cf535d7d92c4fc0c29b8407967cb9a7e94 -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
