/*
* Copyright (c) 1998-2011 Caucho Technology -- all rights reserved
*
* This file is part of Resin(R) Open Source
*
* Each copy or derived work must preserve the copyright notice and this
* notice unmodified.
*
* Resin Open Source is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* Resin Open Source is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
* of NON-INFRINGEMENT. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License
* along with Resin Open Source; if not, write to the
* Free SoftwareFoundation, Inc.
* 59 Temple Place, Suite 330
* Boston, MA 02111-1307 USA
*
* @author Scott Ferguson
*/
package com.caucho.loader;
import java.util.concurrent.atomic.AtomicLong;
/**
* Creates a ClassLoader dependent variable. The value of the ClassLoaderLocal
* variable depends on the context ClassLoader.
*/
public class EnvironmentLocal<E> {
// true on initialization if getting the system classloader is allowed,
// i.e. not forbiggen by the security manager
private static Boolean _isSystemClassLoader;
private static AtomicLong _varCount = new AtomicLong();
private String _varName;
private E _globalValue;
/**
* Creates a new environment local variable with an anonymous identifier.
*/
public EnvironmentLocal()
{
_varName = "resin:var-" + _varCount.incrementAndGet();
}
public EnvironmentLocal(String varName)
{
_varName = varName;
}
public String getVariable()
{
return _varName;
}
/**
* Returns the variable for the context classloader.
*/
@SuppressWarnings("unchecked")
public E get()
{
Thread thread = Thread.currentThread();
ClassLoader loader = thread.getContextClassLoader();
Object value = null;
for (; loader != null; loader = loader.getParent()) {
if (loader instanceof EnvironmentClassLoader) {
EnvironmentClassLoader envLoader = (EnvironmentClassLoader) loader;
value = envLoader.getAttribute(_varName);
if (value != null)
return (E) value;
}
}
return _globalValue;
}
/**
* Returns the variable for the context classloader.
*/
@SuppressWarnings("unchecked")
public E get(ClassLoader loader)
{
Object value = null;
for (; loader != null; loader = loader.getParent()) {
if (loader instanceof EnvironmentClassLoader) {
EnvironmentClassLoader envLoader = (EnvironmentClassLoader) loader;
value = envLoader.getAttribute(_varName);
if (value != null)
return (E) value;
}
}
return _globalValue;
}
/**
* Returns the variable for the context classloader.
*/
@SuppressWarnings("unchecked")
public E getLevel()
{
Thread thread = Thread.currentThread();
ClassLoader loader = thread.getContextClassLoader();
for (; loader != null; loader = loader.getParent()) {
if (loader instanceof EnvironmentClassLoader) {
EnvironmentClassLoader envLoader = (EnvironmentClassLoader) loader;
return (E) envLoader.getAttribute(_varName);
}
}
return _globalValue;
}
/**
* Returns the variable for the context classloader.
*/
@SuppressWarnings("unchecked")
public E getLevel(ClassLoader loader)
{
for (; loader != null; loader = loader.getParent()) {
if (loader instanceof EnvironmentClassLoader) {
EnvironmentClassLoader envLoader = (EnvironmentClassLoader) loader;
return (E) envLoader.getAttribute(_varName);
}
}
return _globalValue;
}
/**
* Sets the variable for the context classloader.
*
* @param value
* the new value
*
* @return the old value
*/
@SuppressWarnings("unchecked")
public final E set(E value)
{
Thread thread = Thread.currentThread();
ClassLoader loader = thread.getContextClassLoader();
for (; loader != null; loader = loader.getParent()) {
if (loader instanceof EnvironmentClassLoader) {
EnvironmentClassLoader envLoader = (EnvironmentClassLoader) loader;
return (E) envLoader.setAttribute(_varName, value);
}
}
return setGlobal(value);
}
/**
* Sets the variable for the context classloader.
*
* @param value
* the new value
*
* @return the old value
*/
@SuppressWarnings("unchecked")
public final E set(E value, ClassLoader loader)
{
for (; loader != null; loader = loader.getParent()) {
if (loader instanceof EnvironmentClassLoader) {
EnvironmentClassLoader envLoader = (EnvironmentClassLoader) loader;
return (E) envLoader.setAttribute(_varName, value);
}
}
return setGlobal(value);
}
/**
* Removes this variable
*
* @return the old value
*/
@SuppressWarnings("unchecked")
public final E remove()
{
Thread thread = Thread.currentThread();
ClassLoader loader = thread.getContextClassLoader();
for (; loader != null; loader = loader.getParent()) {
if (loader instanceof EnvironmentClassLoader) {
EnvironmentClassLoader envLoader = (EnvironmentClassLoader) loader;
return (E) envLoader.removeAttribute(_varName);
}
}
return setGlobal(null);
}
/**
* Removes the variable for the context classloader.
*
* @return the old value
*/
@SuppressWarnings("unchecked")
public final E remove(ClassLoader loader)
{
for (; loader != null; loader = loader.getParent()) {
if (loader instanceof EnvironmentClassLoader) {
EnvironmentClassLoader envLoader = (EnvironmentClassLoader) loader;
return (E) envLoader.removeAttribute(_varName);
}
}
return setGlobal(null);
}
/**
* Sets the global value.
*
* @param value
* the new value
*
* @return the old value
*/
public E setGlobal(E value)
{
E oldValue = _globalValue;
_globalValue = value;
ClassLoader systemLoader = getSystemClassLoader();
if (systemLoader instanceof EnvironmentClassLoader)
((EnvironmentClassLoader) systemLoader).setAttribute(_varName, value);
else
_globalValue = value;
return oldValue;
}
/**
* Returns the global value.
*/
@SuppressWarnings("unchecked")
public E getGlobal()
{
ClassLoader systemLoader = getSystemClassLoader();
if (systemLoader instanceof EnvironmentClassLoader)
return (E) ((EnvironmentClassLoader) systemLoader).getAttribute(_varName);
else
return _globalValue;
}
public static ClassLoader getSystemClassLoader()
{
if (_isSystemClassLoader == null) {
_isSystemClassLoader = false;
try {
ClassLoader.getSystemClassLoader();
_isSystemClassLoader = true;
} catch (Throwable e) {
}
}
if (_isSystemClassLoader)
return ClassLoader.getSystemClassLoader();
else
return null;
}
}