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From mattf-horton <...@git.apache.org>
Subject [GitHub] metron pull request #530: METRON-777 Metron Extension System and Parser Exte...
Date Tue, 08 Aug 2017 07:16:23 GMT
Github user mattf-horton commented on a diff in the pull request:

    https://github.com/apache/metron/pull/530#discussion_r131831881
  
    --- 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 --
    
    specified bundle file, no?


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