| /* |
| * 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.drill.exec.compile; |
| |
| import java.net.URL; |
| import java.net.URLClassLoader; |
| import java.util.Map; |
| import java.util.concurrent.ConcurrentMap; |
| |
| import org.apache.drill.shaded.guava.com.google.common.collect.Maps; |
| |
| /** |
| * Class loader for "plain-old Java" generated classes. |
| * Very basic implementation: allows defining a class from |
| * byte codes and finding the loaded classes. Delegates |
| * all other class requests to the thread context class |
| * loader. This structure ensures that a generated class can |
| * find both its own inner classes as well as all the standard |
| * Drill implementation classes. |
| */ |
| |
| public class CachedClassLoader extends URLClassLoader { |
| |
| /** |
| * Cache of generated classes. Semantics: a single thread defines |
| * the classes, many threads may access the classes. |
| */ |
| |
| private ConcurrentMap<String, Class<?>> cache = Maps.newConcurrentMap(); |
| |
| public CachedClassLoader() { |
| super(new URL[0], Thread.currentThread().getContextClassLoader()); |
| } |
| |
| public void addClass(String fqcn, byte[] byteCodes) { |
| Class<?> newClass = defineClass(fqcn, byteCodes, 0, byteCodes.length); |
| cache.put(fqcn, newClass); |
| } |
| |
| @Override |
| public Class<?> findClass(String className) throws ClassNotFoundException { |
| Class<?> theClass = cache.get(className); |
| if (theClass != null) { |
| return theClass; |
| } |
| return super.findClass(className); |
| } |
| |
| public void addClasses(Map<String, byte[]> results) { |
| for (Map.Entry<String, byte[]> result : results.entrySet()) { |
| addClass(result.getKey(), result.getValue()); |
| } |
| } |
| } |