content: package org.apache.cassandra.triggers;
  /*
   *
   * 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.
   *
   */
  import java.io.IOException;
  import java.net.URL;
  import java.net.URLClassLoader;
  import java.nio.file.StandardCopyOption;
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.function.BiPredicate;
  
  import org.apache.cassandra.io.util.File;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import org.apache.cassandra.io.FSWriteError;
  import org.apache.cassandra.io.util.FileUtils;
  
  import static java.nio.file.Files.*;
  
  /**
   * Custom class loader will load the classes from the class path, CCL will load
   * the classes from the URL first, if it cannot find the required class it
   * will let the parent class loader do its job.
   *
   * Note: If the CCL is GC'ed then the associated classes will be unloaded.
   */
  public class CustomClassLoader extends URLClassLoader
  {
      private static final Logger logger = LoggerFactory.getLogger(CustomClassLoader.class);
      private final Map<String, Class<?>> cache = new ConcurrentHashMap<>();
      private final ClassLoader parent;
  
      public CustomClassLoader(ClassLoader parent)
      {
          super(new URL[] {}, parent);
          assert parent != null;
          this.parent = getParent();
      }
  
      public CustomClassLoader(ClassLoader parent, File classPathDir)
      {
          super(new URL[] {}, parent);
          assert parent != null;
          this.parent = getParent();
          addClassPath(classPathDir);
      }
  
      public void addClassPath(File dir)
      {
          if (dir == null || !dir.exists())
              return;
          BiPredicate<File, String> filter = (ignore, name) -> name.endsWith(".jar");
          for (File inputJar : dir.tryList(filter))
          {
              File lib = new File(FileUtils.getTempDir(), "lib");
              if (!lib.exists())
              {
                  lib.tryCreateDirectory();
                  lib.deleteOnExit();
              }
              File out = FileUtils.createTempFile("cassandra-", ".jar", lib);
              out.deleteOnExit();
              logger.info("Loading new jar {}", inputJar.absolutePath());
              try
              {
                  copy(inputJar.toPath(), out.toPath(), StandardCopyOption.REPLACE_EXISTING);
                  addURL(out.toPath().toUri().toURL());
              }
              catch (IOException ex)
              {
                  throw new FSWriteError(ex, out);
              }
          }
      }
  
      @Override
      public Class<?> loadClass(String name) throws ClassNotFoundException
      {
          Class<?> clazz = cache.get(name);
          if (clazz == null)
              return loadClassInternal(name);
          return clazz;
      }
  
      public synchronized Class<?> loadClassInternal(String name) throws ClassNotFoundException
      {
          try
          {
              return parent.loadClass(name);
          }
          catch (ClassNotFoundException ex)
          {
              logger.trace("Class not found using parent class loader,", ex);
              // Don't throw the exception here, try triggers directory.
          }
          Class<?> clazz = this.findClass(name);
          cache.put(name, clazz);
          return clazz;
      }
  }
  