diff options
Diffstat (limited to 'core/src/main/scala/org/apache/spark/util/MutableURLClassLoader.scala')
-rw-r--r-- | core/src/main/scala/org/apache/spark/util/MutableURLClassLoader.scala | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/core/src/main/scala/org/apache/spark/util/MutableURLClassLoader.scala b/core/src/main/scala/org/apache/spark/util/MutableURLClassLoader.scala new file mode 100644 index 0000000000..d9c7103b2f --- /dev/null +++ b/core/src/main/scala/org/apache/spark/util/MutableURLClassLoader.scala @@ -0,0 +1,103 @@ +/* + * 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.spark.util + +import java.net.{URLClassLoader, URL} +import java.util.Enumeration +import java.util.concurrent.ConcurrentHashMap + +import scala.collection.JavaConversions._ + +import org.apache.spark.util.ParentClassLoader + +/** + * URL class loader that exposes the `addURL` and `getURLs` methods in URLClassLoader. + */ +private[spark] class MutableURLClassLoader(urls: Array[URL], parent: ClassLoader) + extends URLClassLoader(urls, parent) { + + override def addURL(url: URL): Unit = { + super.addURL(url) + } + + override def getURLs(): Array[URL] = { + super.getURLs() + } + +} + +/** + * A mutable class loader that gives preference to its own URLs over the parent class loader + * when loading classes and resources. + */ +private[spark] class ChildFirstURLClassLoader(urls: Array[URL], parent: ClassLoader) + extends MutableURLClassLoader(urls, null) { + + private val parentClassLoader = new ParentClassLoader(parent) + + /** + * Used to implement fine-grained class loading locks similar to what is done by Java 7. This + * prevents deadlock issues when using non-hierarchical class loaders. + * + * Note that due to Java 6 compatibility (and some issues with implementing class loaders in + * Scala), Java 7's `ClassLoader.registerAsParallelCapable` method is not called. + */ + private val locks = new ConcurrentHashMap[String, Object]() + + override def loadClass(name: String, resolve: Boolean): Class[_] = { + var lock = locks.get(name) + if (lock == null) { + val newLock = new Object() + lock = locks.putIfAbsent(name, newLock) + if (lock == null) { + lock = newLock + } + } + + lock.synchronized { + try { + super.loadClass(name, resolve) + } catch { + case e: ClassNotFoundException => + parentClassLoader.loadClass(name, resolve) + } + } + } + + override def getResource(name: String): URL = { + val url = super.findResource(name) + val res = if (url != null) url else parentClassLoader.getResource(name) + res + } + + override def getResources(name: String): Enumeration[URL] = { + val urls = super.findResources(name) + val res = + if (urls != null && urls.hasMoreElements()) { + urls + } else { + parentClassLoader.getResources(name) + } + res + } + + override def addURL(url: URL) { + super.addURL(url) + } + +} |