org.glassfish.weld.ACLSingletonProvider Maven / Gradle / Ivy
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package org.glassfish.weld;
import org.glassfish.web.loader.WebappClassLoader;
import org.jboss.weld.bootstrap.api.SingletonProvider;
import org.jboss.weld.bootstrap.api.Singleton;
import org.glassfish.internal.api.Globals;
import org.glassfish.internal.api.ClassLoaderHierarchy;
import java.util.Map;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.concurrent.ConcurrentHashMap;
/**
* Singleton provider that uses Application ClassLoader to differentiate
* between applications. It is different from
* {@link org.jboss.weld.bootstrap.api.helpers.TCCLSingletonProvider}.
* We can't use TCCLSingletonProvider because thread's context class loader can
* be different for different modules of a single application (ear).
* To support Application Scoped beans, Weld needs to be bootstrapped
* per application as opposed to per module. We rely on the fact that
* all these module class loaders have a common parent which is per application.
* We use that parent ApplicationClassLoader to identify the singleton scope.
*
* @author [email protected]
*/
public class ACLSingletonProvider extends SingletonProvider
{
/*
* See https://glassfish.dev.java.net/issues/show_bug.cgi?id=10192
* for more details about this class.
*
* IMPLEMENTATION NOTE:
* This class assumes a certain delegation hierarchy of application
* class loaders. So, deployment team should be aware of this class
* and change it if application class loader hierarchy changes.
*/
@Override
public ACLSingleton create(Class expectedType) {
return new ACLSingleton();
}
private static class ACLSingleton implements Singleton {
private final Map store = new ConcurrentHashMap<>();
private final Map storeById = new ConcurrentHashMap<>();
private ClassLoader ccl = Globals.get(ClassLoaderHierarchy.class).getCommonClassLoader();
// Can't assume bootstrap loader as null. That's more of a convention.
// I think either android or IBM JVM does not use null for bootstap loader
private static ClassLoader bootstrapCL;
static {
SecurityManager sm = System.getSecurityManager();
bootstrapCL = (sm != null) ?
AccessController.doPrivileged(new PrivilegedAction() {
@Override
public ClassLoader run()
{
return Object.class.getClassLoader();
}
}) : Object.class.getClassLoader();
}
@Override
public T get( String id )
{
ClassLoader acl = getClassLoader();
T instance = store.get(acl);
if (instance == null)
{
instance = storeById.get(id);
if (instance == null) {
throw new IllegalStateException("Singleton not set for " + acl);
}
}
return instance;
}
/**
* This is the most significant method of this class. This is what
* distingushes it from TCCLSIngleton. It tries to obtain a class loader
* that's common to all modules of an application (ear). Since it runs
* in the context of Java EE, it can assume that Thread's context
* class loader is always set as application class loader. In GlassFish,
* the class loader can vary for each module of an Ear. Thread's
* context class loader is set depending on which module is handling
* the request. But, fortunately all those embedded module class loaders
* have a common parent in their delegation chain. That parent
* is of type EarLibClassLoader. So, this code walks up the delegation
* chain until it hits either a EarLibClassLoader type of parent or
* bootstrapClassLoader. If former is the case, it returns that
* instance of EarLibClassLoader. If latter is the case, it assumes
* that this is a standalone module and hence it returns the thread's
* context class loader.
*
* @return a class loader that's common to all modules of a Java EE app
*/
private ClassLoader getClassLoader()
{
SecurityManager sm = System.getSecurityManager();
final ClassLoader tccl = (sm != null) ?
AccessController.doPrivileged(new PrivilegedAction()
{
public ClassLoader run() {
return Thread.currentThread().getContextClassLoader();
}
}) : Thread.currentThread().getContextClassLoader();
if (tccl == null) {
throw new RuntimeException("Thread's context class loader is null");
}
ClassLoader cl = tccl;
ClassLoader appClassLoader = tccl;
// most of the time, class loader of application (whether it is a
// standalone module or an ear) has common class loader in their
// delegation chain. So, we can break the loop early for them.
// There are exceptions like hybrid app to this rule.
// So, we have to walk upto bootstrapCL in worst case.
while (cl != ccl && cl != bootstrapCL) {
if (cl.getClass().getName().equals("org.glassfish.javaee.full.deployment.EarLibClassLoader")) {
return cl;
} else {
if (cl instanceof WebappClassLoader) {
// we do this because it's possible for an app to change the thread's context class loader
appClassLoader = cl;
}
}
cl = getParent(cl);
}
return appClassLoader;
}
private ClassLoader getParent(final ClassLoader cl)
{
SecurityManager sm = System.getSecurityManager();
return sm != null ?
AccessController.doPrivileged(new PrivilegedAction() {
@Override
public ClassLoader run()
{
return cl.getParent();
}
}) : cl.getParent();
}
@Override
public boolean isSet(String id) {
return store.containsKey(getClassLoader()) || storeById.containsKey(id);
}
@Override
public void set(String id, T object) {
store.put(getClassLoader(), object);
storeById.put(id, object);
}
@Override
public void clear(String id) {
store.remove(getClassLoader());
storeById.remove(id);
}
}
}