Github user ottobackwards commented on a diff in the pull request:
https://github.com/apache/metron/pull/530#discussion_r131968916
--- Diff:
bundles-lib/src/main/java/org/apache/metron/bundles/BundleClassLoaders.java ---
@@ -0,0 +1,353 @@
+/*
+ * 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.metron.bundles;
+
+import java.net.URISyntaxException;
+import java.util.*;
+
+import org.apache.commons.collections.CollectionUtils;
+import org.apache.commons.vfs2.FileObject;
+import org.apache.commons.vfs2.FileSystemException;
+import org.apache.commons.vfs2.FileSystemManager;
+import org.apache.metron.bundles.bundle.Bundle;
+import org.apache.metron.bundles.bundle.BundleCoordinate;
+import org.apache.metron.bundles.bundle.BundleDetails;
+import org.apache.metron.bundles.util.BundleProperties;
+import org.apache.metron.bundles.util.BundleSelector;
+import org.apache.metron.bundles.util.FileUtils;
+import org.apache.metron.bundles.util.BundleUtil;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * A singleton class used to initialize the extension and framework
classloaders.
+ */
+public final class BundleClassLoaders {
+
+ private static volatile BundleClassLoaders bundleClassLoaders;
+ private volatile InitContext initContext;
+ private static final Logger logger =
LoggerFactory.getLogger(BundleClassLoaders.class);
+
+ private final static class InitContext {
+
+ private final List<FileObject> extensionDirs;
+ private final Map<String, Bundle> bundles;
+
+ private InitContext(
+ final List<FileObject> extensionDirs,
+ final Map<String, Bundle> bundles) {
+ this.extensionDirs = extensionDirs;
+ this.bundles = bundles;
+ }
+ }
+
+ private BundleClassLoaders() {
+ }
+
+ /**
+ * @return The singleton instance of the BundleClassLoaders
+ */
+ public static BundleClassLoaders getInstance() {
+ BundleClassLoaders result = bundleClassLoaders;
+ if (result == null) {
+ synchronized (BundleClassLoaders.class) {
+ result = bundleClassLoaders;
+ if (result == null) {
+ bundleClassLoaders = result = new BundleClassLoaders();
+ }
+ }
+ }
+ return result;
+ }
+
+ public static void reset() {
+ getInstance().unInit();
+ }
+
+ private void unInit() {
+ synchronized (this) {
+ initContext = null;
+ }
+ }
+
+ /**
+ * Initializes and loads the BundleClassLoaders. This method must be
called before the rest of the
+ * methods to access the classloaders are called and it can be safely
called any number of times
+ * provided the same framework and extension working dirs are used.
+ *
+ * @param fileSystemManager the FileSystemManager
+ * @param extensionsDirs where to find extension artifacts
+ * @param props BundleProperties
+ * @throws FileSystemException if any issue occurs while exploding
bundle working directories.
+ * @throws java.lang.ClassNotFoundException if unable to load class
definition
+ * @throws IllegalStateException already initialized with a given pair
of directories cannot
+ * reinitialize or use a different pair of directories.
+ */
+ public void init(final FileSystemManager fileSystemManager, final
List<FileObject> extensionsDirs,
+ BundleProperties props)
+ throws FileSystemException, ClassNotFoundException,
URISyntaxException {
+ if (extensionsDirs == null || fileSystemManager == null) {
+ throw new NullPointerException("cannot have empty arguments");
+ }
+ InitContext ic = initContext;
+ if (ic == null) {
+ synchronized (this) {
+ ic = initContext;
+ if (ic == null) {
+ initContext = ic = load(fileSystemManager, extensionsDirs,
props);
+ }
+ }
+ } else {
+ boolean matching = CollectionUtils
+ .isEqualCollection(initContext.extensionDirs, extensionsDirs);
+ if (!matching) {
+ throw new IllegalStateException(
+ "Cannot reinitialize and extension/framework directories
cannot change");
+ }
+ }
+ }
+
+ /**
+ * Should be called at most once.
+ */
+ private InitContext load(final FileSystemManager fileSystemManager,
+ final List<FileObject> extensionsDirs, BundleProperties props)
+ throws FileSystemException, ClassNotFoundException,
URISyntaxException {
+ // get the system classloader
+ final ClassLoader systemClassLoader =
ClassLoader.getSystemClassLoader();
+
+ // find all bundle files and create class loaders for them.
+ final Map<String, Bundle> directoryBundleLookup = new
LinkedHashMap<>();
+ final Map<String, ClassLoader> coordinateClassLoaderLookup = new
HashMap<>();
+ final Map<String, Set<BundleCoordinate>> idBundleLookup = new
HashMap<>();
+
+ for (FileObject extensionsDir : extensionsDirs) {
+ // make sure the bundle directory is there and accessible
+ FileUtils.ensureDirectoryExistAndCanRead(extensionsDir);
+
+ final List<FileObject> bundleDirContents = new ArrayList<>();
+ FileObject[] dirFiles = extensionsDir.findFiles(new
BundleSelector(props.getArchiveExtension()));
+ if (dirFiles != null) {
+ List<FileObject> fileList = Arrays.asList(dirFiles);
+ bundleDirContents.addAll(fileList);
+ }
+
+ if (!bundleDirContents.isEmpty()) {
+ final List<BundleDetails> bundleDetails = new ArrayList<>();
+ final Map<String, String> bundleCoordinatesToBundleFile = new
HashMap<>();
+
+ // load the bundle details which includes bundle dependencies
+ for (final FileObject bundleFile : bundleDirContents) {
+ if(!bundleFile.exists() || !bundleFile.isFile()) {
+ continue;
+ }
+ BundleDetails bundleDetail = null;
+ try {
+ bundleDetail = getBundleDetails(bundleFile, props);
+ } catch (IllegalStateException e) {
+ logger.warn("Unable to load BUNDLE {} due to {}, skipping...",
+ new Object[]{bundleFile.getURL(), e.getMessage()});
+ }
+
+ // prevent the application from starting when there are two
BUNDLEs with same group, id, and version
+ final String bundleCoordinate =
bundleDetail.getCoordinate().getCoordinate();
+ if (bundleCoordinatesToBundleFile.containsKey(bundleCoordinate))
{
+ final String existingBundleWorkingDir =
bundleCoordinatesToBundleFile
+ .get(bundleCoordinate);
+ throw new IllegalStateException(
+ "Unable to load BUNDLE with coordinates " +
bundleCoordinate
+ + " and working directory " +
bundleDetail.getBundleFile()
+ + " because another BUNDLE with the same coordinates
already exists at "
+ + existingBundleWorkingDir);
+ }
+
+ bundleDetails.add(bundleDetail);
+ bundleCoordinatesToBundleFile.put(bundleCoordinate,
+ bundleDetail.getBundleFile().getURL().toURI().toString());
+ }
+
+ // attempt to locate the jetty bundle
+ ClassLoader jettyClassLoader = null;
+ for (final Iterator<BundleDetails> bundleDetailsIter =
bundleDetails.iterator();
+ bundleDetailsIter.hasNext(); ) {
+ final BundleDetails bundleDetail = bundleDetailsIter.next();
+ // populate bundle lookup
+
idBundleLookup.computeIfAbsent(bundleDetail.getCoordinate().getId(),
+ id -> new HashSet<>()).add(bundleDetail.getCoordinate());
+ }
+
+ int bundleCount;
+ do {
+ // record the number of bundles to be loaded
+ bundleCount = bundleDetails.size();
+
+ // attempt to create each bundle class loader
+ for (final Iterator<BundleDetails> bundleDetailsIter =
bundleDetails.iterator();
+ bundleDetailsIter.hasNext(); ) {
+ final BundleDetails bundleDetail = bundleDetailsIter.next();
+ final BundleCoordinate bundleDependencyCoordinate =
bundleDetail
+ .getDependencyCoordinate();
+
+ // see if this class loader is eligible for loading
+ ClassLoader potentialBundleClassLoader = null;
+ if (bundleDependencyCoordinate == null) {
+ potentialBundleClassLoader =
createBundleClassLoader(fileSystemManager,
+ bundleDetail.getBundleFile(),
ClassLoader.getSystemClassLoader());
+ } else {
+ final String dependencyCoordinateStr =
bundleDependencyCoordinate
+ .getCoordinate();
+
+ // if the declared dependency has already been loaded
+ if
(coordinateClassLoaderLookup.containsKey(dependencyCoordinateStr)) {
+ final ClassLoader bundleDependencyClassLoader =
coordinateClassLoaderLookup
+ .get(dependencyCoordinateStr);
+ potentialBundleClassLoader = createBundleClassLoader(
+ fileSystemManager, bundleDetail.getBundleFile(),
+ bundleDependencyClassLoader);
+ } else {
+ // get all bundles that match the declared dependency id
+ final Set<BundleCoordinate> coordinates = idBundleLookup
+ .get(bundleDependencyCoordinate.getId());
+
+ // ensure there are known bundles that match the declared
dependency id
+ if (coordinates != null && !coordinates
+ .contains(bundleDependencyCoordinate)) {
+ // ensure the declared dependency only has one possible
bundle
+ if (coordinates.size() == 1) {
+ // get the bundle with the matching id
+ final BundleCoordinate coordinate =
coordinates.stream()
+ .findFirst().get();
+
+ // if that bundle is loaded, use it
+ if (coordinateClassLoaderLookup
+ .containsKey(coordinate.getCoordinate())) {
+ logger.warn(String.format(
+ "While loading '%s' unable to locate exact
BUNDLE dependency '%s'. Only found one possible match '%s'. Continuing...",
+ bundleDetail.getCoordinate().getCoordinate(),
+ dependencyCoordinateStr,
+ coordinate.getCoordinate()));
+
+ final ClassLoader bundleDependencyClassLoader =
coordinateClassLoaderLookup
+ .get(coordinate.getCoordinate());
+ potentialBundleClassLoader = createBundleClassLoader(
+ fileSystemManager, bundleDetail.getBundleFile(),
+ bundleDependencyClassLoader);
+ }
+ }
+ }
+ }
+ }
+
+ // if we were able to create the bundle class loader, store it
and remove the details
+ final ClassLoader bundleClassLoader =
potentialBundleClassLoader;
+ if (bundleClassLoader != null) {
+ directoryBundleLookup
+
.put(bundleDetail.getBundleFile().getURL().toURI().toString(),
+ new Bundle(bundleDetail, bundleClassLoader));
+ coordinateClassLoaderLookup
+ .put(bundleDetail.getCoordinate().getCoordinate(),
+ bundleClassLoader);
+ bundleDetailsIter.remove();
+ }
+ }
+
+ // attempt to load more if some were successfully loaded this
iteration
+ } while (bundleCount != bundleDetails.size());
+
+ // see if any bundle couldn't be loaded
+ for (final BundleDetails bundleDetail : bundleDetails) {
+ logger.warn(String
+ .format("Unable to resolve required dependency '%s'.
Skipping BUNDLE '%s'",
+ bundleDetail.getDependencyCoordinate().getId(),
+
bundleDetail.getBundleFile().getURL().toURI().toString()));
+ }
+ }
+ }
+ return new InitContext(extensionsDirs, new
LinkedHashMap<>(directoryBundleLookup));
+ }
+
+ /**
+ * Creates a new BundleClassLoader. The parentClassLoader may be null.
+ *
+ * @param bundleFile the Bundle File
+ * @param parentClassLoader parent classloader of bundle
+ * @return the bundle classloader
+ * @throws FileSystemException ioe
+ * @throws ClassNotFoundException cfne
+ */
+ private static ClassLoader createBundleClassLoader(final
FileSystemManager fileSystemManager,
+ final FileObject bundleFile, final ClassLoader parentClassLoader)
+ throws FileSystemException, ClassNotFoundException {
+ logger.debug("Loading Bundle file: " + bundleFile.getURL());
+ VFSBundleClassLoader.Builder builder = new
VFSBundleClassLoader.Builder()
+ .withFileSystemManager(fileSystemManager)
+ .withBundleFile(bundleFile)
+ .withParentClassloader(parentClassLoader);
+ final ClassLoader bundleClassLoader = builder.build();
+ logger.info(
+ "Loaded Bundle file: " + bundleFile.getURL() + " as class loader "
+ bundleClassLoader);
+ return bundleClassLoader;
+ }
+
+ /**
+ * Loads the details for the specified BUNDLE. The details will be
extracted from the manifest
+ * file.
+ *
+ * @param bundleFile the bundle file
+ * @return details about the Bundle
+ * @throws FileSystemException ioe
+ */
+ private static BundleDetails getBundleDetails(final FileObject
bundleFile, BundleProperties props)
+ throws FileSystemException {
+ return BundleUtil.fromBundleFile(bundleFile, props);
+ }
+
+ /**
+ * @param extensionFile the bundle file
+ * @return the bundle for the specified working directory. Returns null
when no bundle exists for
+ * the specified working directory
--- End diff --
nice catch
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