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package com.sun.enterprise.v3.server;
import java.io.IOException;
import java.net.URL;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.inject.Inject;
import org.glassfish.hk2.api.PostConstruct;
import org.jvnet.hk2.annotations.Service;
import com.sun.enterprise.module.Module;
import com.sun.enterprise.module.ModuleLifecycleListener;
import com.sun.enterprise.module.ModuleState;
import com.sun.enterprise.module.ModulesRegistry;
import com.sun.enterprise.module.common_impl.CompositeEnumeration;
import com.sun.logging.LogDomains;
/**
* This class is responsible for creating a ClassLoader that can
* load classes exported by the system for public use. We call those classes public APIs and
* the corresponding class loader is called APIClassLoader.
* Such classes include Java EE API, AMX API, appserv-ext API, etc.
* CommonClassLoader delegates to this class loader.
* This class has a punch-in mechanism to do special handling of META-INF/mailcap and META-INF/services resources.
*
* @author Sanjeeb.Sahoo@Sun.COM
*/
@Service
public class APIClassLoaderServiceImpl implements PostConstruct {
/*
* Implementation Note:
* 1. This class currently depends on a special which is configured such that it can load all public APIs.
* The APIClassLoader is a wrapper around such a module's loader. This is how we are indepdendent of
* actual module system like OSGi. So far it has worked when we run in OSGi mode as well as when we run
* in a single classpath mode.
* 2. APIClassLoader maintains a blacklist, i.e., classes and resources that could not be loaded to avoid
* unnecessary delegation. It flushes that list everytime a new bundle is installed in the system.
* This takes care of performance problem in typical production use of GlassFish.
*
* TODO:
* 1. We need to add an upper threshold for blacklist to avoid excessive use of memory.
* 2. Externalize punch-in facility. We don't want to know about things like MAILCAP file in this class.
*/
private ClassLoader theAPIClassLoader;
@Inject
ModulesRegistry mr;
/**
* This is the module that we delegate to.
*/
private static final String APIExporterModuleName =
"GlassFish-Application-Common-Module"; // NOI18N
private static final String MAILCAP = "META-INF/mailcap";
private static final String META_INF_SERVICES = "META-INF/services/"; // NOI18N
private static final String PUNCHIN_MODULE_STATE_PROP =
"glassfish.kernel.apicl.punchin.module.state"; // NOI18N
// set to NEW to maintain backward compatibility. We should change it to RESOLVED after we have
// done enough testing to make susre there are no regressions.
public final ModuleState PUNCHIN_MODULE_STATE_DEFAULT_VALUE = ModuleState.NEW;
private static final Enumeration<URL> EMPTY_URLS = new Enumeration<URL>() {
public boolean hasMoreElements() {
return false;
}
public URL nextElement() {
throw new NoSuchElementException();
}
};
final static Logger logger = LogDomains.getLogger(APIClassLoaderServiceImpl.class, LogDomains.LOADER_LOGGER);
private Module APIModule;
public void postConstruct() {
try {
createAPIClassLoader();
} catch (IOException e) {
throw new RuntimeException(e);
}
}
private void createAPIClassLoader() throws IOException {
APIModule = mr.getModules(APIExporterModuleName).iterator().next();
assert (APIModule != null);
final ClassLoader apiModuleLoader = APIModule.getClassLoader();
/*
* We don't directly retrun APIModule's class loader, because
* that class loader does not delegate to the parent. Instead, it
* relies on OSGi bundle or some such module implementation to load the classes. That behavior is
* fine if we want to mimic underlying module system's classloading semantics. But, APIClassLoader has a
* slightly different requirement. It has to use classic delegation model as well so that
* deployed applications can use classes made available via extension class loader.
* Since the parent of bundle classloader will have glassfish launching classes, felix or any other
* OSGi framework classes and their dependencies, we don't want to delegate to such a class loader.
* Instead, we delegate to JRE's extension class loader if we don't find any class via APIModuleLoader.
* With this, user can actually embed a different version of Felix as part of their app.
*/
theAPIClassLoader = new APIClassLoader(apiModuleLoader, getExtensionClassLoader());
logger.logp(Level.FINE, "APIClassLoaderService", "createAPIClassLoader",
"APIClassLoader = {0}", new Object[]{theAPIClassLoader});
}
private ClassLoader getExtensionClassLoader() {
if (System.getSecurityManager() != null) {
return AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() {
public ClassLoader run() {
return ClassLoader.getSystemClassLoader().getParent();
}
});
} else {
return ClassLoader.getSystemClassLoader().getParent();
}
}
public ClassLoader getAPIClassLoader() {
return theAPIClassLoader;
}
private class APIClassLoader extends ClassLoader {
// list of not found classes and resources.
// the string represents resource name, so foo/Bar.class for foo.Bar
private Set<String> blacklist;
private final ClassLoader apiModuleLoader;
private ModuleState punchInModuleState = ModuleState.valueOf(System.getProperty(PUNCHIN_MODULE_STATE_PROP,
PUNCHIN_MODULE_STATE_DEFAULT_VALUE.toString()));
/**
* This method takes two classloaders which is unusual. Both the class loaders are consulted,
* so they both are delegates, but depending on the class/resource being requested, one is preferred
* over the other. The second argument is the classic parent class loader, where as the first one
* is the module system gateway classloader. For all java.* names, we consult only the parent loader.
* For any other names, we first consult the gateway loader and then parent. See more comments in
* {@link #loadClass(String)} method implementation of this class.
* @param apiModuleLoader ClassLoader corresponding to the APIModule
* @param parent ClassLoader that's consulted for all java.* classes and for classes
* not found via apiModuleLoader
*/
public APIClassLoader(ClassLoader apiModuleLoader, ClassLoader parent) {
super(parent);
this.apiModuleLoader = apiModuleLoader;
blacklist = new HashSet<String>();
// add a listener to manage blacklist in APIClassLoader
mr.register(new ModuleLifecycleListener() {
public void moduleInstalled(Module module) {
clearBlackList();
}
public void moduleResolved(Module module) {
}
public void moduleStarted(Module module) {
}
public void moduleStopped(Module module) {
}
public void moduleUpdated(Module module) {
clearBlackList();
}
});
}
@Override
public Class<?> loadClass(String name) throws ClassNotFoundException {
return loadClass(name, false);
}
@Override
protected synchronized Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
// First check if we know this can't be loaded
final String resourceName = convertToResourceName(name);
if (isBlackListed(resourceName)) {
throw new ClassNotFoundException(name);
}
// Then check if the class has already been loaded
Class c = findLoadedClass(name);
if (c == null) {
if (!name.startsWith("java.")) { // java classes always come from parent
try {
c = apiModuleLoader.loadClass(name); // we ignore the resolution flag
} catch (ClassNotFoundException cnfe) {
// punch in. find the provider class, no matter where we are.
Module m = mr.getProvidingModule(name);
if (m != null) {
if(select(m)) {
return m.getClassLoader().loadClass(name); // abort search if we fail to load.
} else {
logger.logp(Level.FINE, "APIClassLoaderServiceImpl$APIClassLoader", "loadClass",
"Skipping loading {0} from module {1} as this module is not yet resolved.",
new Object[]{name, m});
}
}
}
}
if (c == null) {
// Call super class implementation which takes care of
// delegating to parent.
try {
c = super.loadClass(name, resolve);
} catch (ClassNotFoundException e) {
addToBlackList(resourceName);
throw e;
}
}
}
return c;
}
/**
* Select this module if it meets punch-in criteria. At this point of implementation, the criteria is
* very simple. It checks to see if the module's state is greater than equal to what is configured in
* {@link #punchInModuleState}.
*
* @param m
* @return
*/
private boolean select(Module m) {
ModuleState state = m.getState();
return state.compareTo(punchInModuleState) >= 0 && state != ModuleState.ERROR;
}
@Override
public URL getResource(String name) {
if (isBlackListed(name)) return null;
URL url = null;
if (!name.startsWith("java/")) {
url = apiModuleLoader.getResource(name);
if (url != null) {
return url;
}
// now punch-ins for various cases that require special handling
if (name.equals(MAILCAP)) {
// punch in for META-INF/mailcap files.
// see issue #8426
for (Module m : mr.getModules()) {
if (!select(m)) continue;
if ((url = m.getClassLoader().getResource(name)) != null) {
return url;
}
}
} else if(name.startsWith(META_INF_SERVICES)) {
// punch in to find the service loader from any module
// If this is a META-INF/services lookup, search in every
// modules that we know of.
String serviceName = name.substring(
META_INF_SERVICES.length());
for( Module m : mr.getModules() ) {
if (!select(m)) continue;
List<URL> list = m.getMetadata().getDescriptors(
serviceName);
if(!list.isEmpty()) {
return list.get(0);
}
}
}
}
// Either requested resource belongs to java/ namespace or
// it was not found in any of the bundles, so call
// super class implementation which will delegate to parent.
url = super.getResource(name);
if (url == null) {
addToBlackList(name);
}
return url;
}
/**
* This method is required as {@link ClassLoader#getParent} is a privileged method
*/
private ClassLoader getParent_() {
if (System.getSecurityManager() != null) {
return AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() {
public ClassLoader run() {
return getParent();
}
});
} else {
return getParent();
}
}
@Override
public Enumeration<URL> getResources(String name) throws IOException {
List<Enumeration<URL>> enumerators = new ArrayList<Enumeration<URL>>();
enumerators.add(findResources(name));
if (getParent_() != null) {
enumerators.add(getParent_().getResources(name));
}
return new CompositeEnumeration(enumerators);
}
// This method is needed to be compatible with ClassLoader implementation in IBM JRE.
// In IBM JRE, ClassLoader.getResources() does not call parent.getResources(); instead it
// recurssively calls findResources() for all parents in the delegation hierarchy.
// See issue #16364 for details.
@Override
protected Enumeration<URL> findResources(String name) throws IOException {
if (!name.startsWith("java/")) {
List<Enumeration<URL>> enumerations = new ArrayList<Enumeration<URL>>();
Enumeration<URL> apiResources = apiModuleLoader.getResources(name);
if (apiResources.hasMoreElements()) {
enumerations.add(apiResources);
}
// now punch-ins for various cases that require special handling
if (name.equals(MAILCAP)) {
// punch in for META-INF/mailcap files. see issue #8426
for (Module m : mr.getModules()) {
if (!select(m)) continue; // We don't look in unresolved modules
if (m == APIModule) continue; // we have already looked up resources in apiModuleLoader
enumerations.add(m.getClassLoader().getResources(name));
}
} else if (name.startsWith(META_INF_SERVICES)) {
// punch in. find the service loader from any module
String serviceName = name.substring(META_INF_SERVICES.length());
List<URL> punchedInURLs = new ArrayList<URL>();
for (Module m : mr.getModules()) {
if (!select(m)) continue; // We don't look in modules that don't meet punch in criteria
if (m == APIModule) continue; // we have already looked up resources in apiModuleLoader
punchedInURLs.addAll(m.getMetadata().getDescriptors(serviceName));
}
if (!punchedInURLs.isEmpty()) {
enumerations.add(Collections.enumeration(punchedInURLs));
}
}
// now assemble the result and return
switch (enumerations.size()) {
case 0:
return EMPTY_URLS;
case 1:
return enumerations.get(0);
default:
return new CompositeEnumeration(enumerations);
}
}
return EMPTY_URLS;
}
@Override
public String toString() {
return "APIClassLoader";
}
/**
* Takes a class name as used in Class.forName and converts it to a resource name as used in
* ClassLoader.getResource
*
* @param className className to be converted
* @return equivalent resource name
*/
private String convertToResourceName(String className) {
return className.replace('.', '/').concat(".class");
}
private synchronized boolean isBlackListed(String name) {
return blacklist.contains(name);
}
private synchronized void addToBlackList(String name) {
blacklist.add(name);
}
private synchronized void clearBlackList() {
blacklist.clear();
}
}
}