/*
* 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.ranger.plugin.classloader;
import java.io.IOException;
import java.net.URL;
import java.net.URLClassLoader;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.PrivilegedExceptionAction;
import java.util.Enumeration;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class RangerPluginClassLoader extends URLClassLoader {
private static final Logger LOG = LoggerFactory.getLogger(RangerPluginClassLoader.class);
private static volatile RangerPluginClassLoader me = null;
private static MyClassLoader componentClassLoader = null;
public RangerPluginClassLoader(String pluginType, Class<?> pluginClass ) throws Exception {
super(RangerPluginClassLoaderUtil.getInstance().getPluginFilesForServiceTypeAndPluginclass(pluginType, pluginClass), null);
componentClassLoader = AccessController.doPrivileged(
new PrivilegedAction<MyClassLoader>() {
public MyClassLoader run() {
return new MyClassLoader(Thread.currentThread().getContextClassLoader());
}
}
);
}
public static RangerPluginClassLoader getInstance(final String pluginType, final Class<?> pluginClass ) throws Exception {
RangerPluginClassLoader ret = me;
if ( ret == null) {
synchronized(RangerPluginClassLoader.class) {
ret = me;
if ( ret == null){
me = ret = AccessController.doPrivileged(
new PrivilegedExceptionAction<RangerPluginClassLoader>(){
public RangerPluginClassLoader run() throws Exception {
return new RangerPluginClassLoader(pluginType,pluginClass);
}
}
);
}
}
}
return ret;
}
@Override
public Class<?> findClass(String name) throws ClassNotFoundException {
if(LOG.isDebugEnabled()) {
LOG.debug("==> RangerPluginClassLoader.findClass(" + name + ")");
}
Class<?> ret = null;
try {
// first we try to find a class inside the child classloader
if(LOG.isDebugEnabled()) {
LOG.debug("RangerPluginClassLoader.findClass(" + name + "): calling childClassLoader().findClass() ");
}
ret = super.findClass(name);
} catch( Throwable e ) {
// Use the Component ClassLoader findclass to load when childClassLoader fails to find
if(LOG.isDebugEnabled()) {
LOG.debug("RangerPluginClassLoader.findClass(" + name + "): calling componentClassLoader.findClass()");
}
MyClassLoader savedClassLoader = getComponentClassLoader();
if (savedClassLoader != null) {
ret = savedClassLoader.findClass(name);
}
}
if(LOG.isDebugEnabled()) {
LOG.debug("<== RangerPluginClassLoader.findClass(" + name + "): " + ret);
}
return ret;
}
@Override
public synchronized Class<?> loadClass(String name) throws ClassNotFoundException {
if (LOG.isDebugEnabled()) {
LOG.debug("==> RangerPluginClassLoader.loadClass(" + name + ")" );
}
Class<?> ret = null;
try {
// first we try to load a class inside the child classloader
if (LOG.isDebugEnabled()) {
LOG.debug("RangerPluginClassLoader.loadClass(" + name + "): calling childClassLoader.findClass()");
}
ret = super.loadClass(name);
} catch(Throwable e) {
// Use the Component ClassLoader loadClass to load when childClassLoader fails to find
if (LOG.isDebugEnabled()) {
LOG.debug("RangerPluginClassLoader.loadClass(" + name + "): calling componentClassLoader.loadClass()");
}
MyClassLoader savedClassLoader = getComponentClassLoader();
if(savedClassLoader != null) {
ret = savedClassLoader.loadClass(name);
}
}
if(LOG.isDebugEnabled()) {
LOG.debug("<== RangerPluginClassLoader.loadClass" + name + "): " + ret);
}
return ret;
}
@Override
public URL findResource(String name) {
if(LOG.isDebugEnabled()) {
LOG.debug("==> RangerPluginClassLoader.findResource(" + name + ") ");
}
URL ret = super.findResource(name);
if (ret == null) {
if(LOG.isDebugEnabled()) {
LOG.debug("RangerPluginClassLoader.findResource(" + name + "): calling componentClassLoader.getResources()");
}
MyClassLoader savedClassLoader = getComponentClassLoader();
if (savedClassLoader != null) {
ret = savedClassLoader.getResource(name);
}
}
if(LOG.isDebugEnabled()) {
LOG.debug("<== RangerPluginClassLoader.findResource(" + name + "): " + ret);
}
return ret;
}
@Override
public Enumeration<URL> findResources(String name) throws IOException {
Enumeration<URL> ret = null;
if(LOG.isDebugEnabled()) {
LOG.debug("==> RangerPluginClassLoader.findResources(" + name + ") ");
}
ret = new MergeEnumeration(findResourcesUsingChildClassLoader(name),findResourcesUsingComponentClassLoader(name));
if(LOG.isDebugEnabled()) {
LOG.debug("<== RangerPluginClassLoader.findResources(" + name + ") ");
}
return ret;
}
public Enumeration<URL> findResourcesUsingChildClassLoader(String name) {
Enumeration<URL> ret = null;
try {
if(LOG.isDebugEnabled()) {
LOG.debug("RangerPluginClassLoader.findResourcesUsingChildClassLoader(" + name + "): calling childClassLoader.findResources()");
}
ret = super.findResources(name);
} catch ( Throwable t) {
//Ignore any exceptions. Null / Empty return is handle in following statements
if(LOG.isDebugEnabled()) {
LOG.debug("RangerPluginClassLoader.findResourcesUsingChildClassLoader(" + name + "): class not found in child. Falling back to componentClassLoader", t);
}
}
return ret;
}
public Enumeration<URL> findResourcesUsingComponentClassLoader(String name) {
Enumeration<URL> ret = null;
try {
if(LOG.isDebugEnabled()) {
LOG.debug("RangerPluginClassLoader.findResourcesUsingComponentClassLoader(" + name + "): calling componentClassLoader.getResources()");
}
MyClassLoader savedClassLoader = getComponentClassLoader();
if (savedClassLoader != null) {
ret = savedClassLoader.getResources(name);
}
if(LOG.isDebugEnabled()) {
LOG.debug("<== RangerPluginClassLoader.findResourcesUsingComponentClassLoader(" + name + "): " + ret);
}
} catch( Throwable t) {
if(LOG.isDebugEnabled()) {
LOG.debug("RangerPluginClassLoader.findResourcesUsingComponentClassLoader(" + name + "): class not found in componentClassLoader.", t);
}
}
return ret;
}
public void activate() {
if(LOG.isDebugEnabled()) {
LOG.debug("==> RangerPluginClassLoader.activate()");
}
//componentClassLoader.set(new MyClassLoader(Thread.currentThread().getContextClassLoader()));
Thread.currentThread().setContextClassLoader(this);
if(LOG.isDebugEnabled()) {
LOG.debug("<== RangerPluginClassLoader.activate()");
}
}
public void deactivate() {
if(LOG.isDebugEnabled()) {
LOG.debug("==> RangerPluginClassLoader.deactivate()");
}
MyClassLoader savedClassLoader = getComponentClassLoader();
if(savedClassLoader != null && savedClassLoader.getParent() != null) {
Thread.currentThread().setContextClassLoader(savedClassLoader.getParent());
} else {
LOG.warn("RangerPluginClassLoader.deactivate() was not successful.Couldn't not get the saved componentClassLoader...");
}
if(LOG.isDebugEnabled()) {
LOG.debug("<== RangerPluginClassLoader.deactivate()");
}
}
private MyClassLoader getComponentClassLoader() {
return componentClassLoader;
//return componentClassLoader.get();
}
static class MyClassLoader extends ClassLoader {
public MyClassLoader(ClassLoader realClassLoader) {
super(realClassLoader);
}
@Override
public Class<?> findClass(String name) throws ClassNotFoundException { //NOPMD
return super.findClass(name);
}
}
static class MergeEnumeration implements Enumeration<URL> { //NOPMD
Enumeration<URL> e1 = null;
Enumeration<URL> e2 = null;
public MergeEnumeration(Enumeration<URL> e1, Enumeration<URL> e2 ) {
this.e1 = e1;
this.e2 = e2;
}
@Override
public boolean hasMoreElements() {
return ( (e1 != null && e1.hasMoreElements() ) || ( e2 != null && e2.hasMoreElements()) );
}
@Override
public URL nextElement() {
URL ret = null;
if (e1 != null && e1.hasMoreElements())
ret = e1.nextElement();
else if ( e2 != null && e2.hasMoreElements() ) {
ret = e2.nextElement();
}
return ret;
}
}
}