com.fitbur.glassfish.hk2.osgiresourcelocator.ServiceLoaderImpl Maven / Gradle / Ivy
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package com.fitbur.glassfish.hk2.osgiresourcelocator;
import com.fitbur.osgi.framework.*;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.*;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
/**
* @author [email protected]
*/
public final class ServiceLoaderImpl extends com.fitbur.glassfish.hk2.osgiresourcelocator.ServiceLoader {
private ReadWriteLock rwLock = new ReentrantReadWriteLock();
private BundleListener bundleTracker;
private BundleContext bundleContext;
private ProvidersList providersList = new ProvidersList();
// /**
// * Map of service type to bundles providing the service
// */
// private Map> serviceToProvidersMap = new HashMap>();
public ServiceLoaderImpl() {
ClassLoader cl = getClass().getClassLoader();
if (cl instanceof BundleReference) {
bundleContext = getBundleContextSecured(BundleReference.class.cast(cl).getBundle());
}
if (bundleContext == null) {
throw new RuntimeException("There is no bundle context available yet. " +
"Instatiate this class in STARTING or ACTIVE state only");
}
}
private BundleContext getBundleContextSecured(final Bundle bundle) {
if (System.getSecurityManager() != null) {
return AccessController.doPrivileged(new PrivilegedAction() {
public BundleContext run() {
return bundle.getBundleContext();
}
});
} else {
return bundle.getBundleContext();
}
}
public void trackBundles() {
assert (bundleTracker == null);
/*
* The reason for separating this code from constructor is that we don't want to
* leak a partially constructed this reference via inner class called BundleTracker.
* That would be a problem since BundleTracker receives callbacks from other threads.
*/
// First register a listener and then iterate over existing bundles
bundleTracker = new BundleTracker();
bundleContext.addBundleListener(bundleTracker);
for (Bundle bundle : bundleContext.getBundles()) {
addProviders(bundle);
}
}
/*package*/ Iterable lookupProviderInstances1(Class serviceClass, ProviderFactory factory) {
if (factory == null) {
factory = new DefaultFactory();
}
List providers = new ArrayList();
for (Class c : lookupProviderClasses1(serviceClass)) {
try {
final T providerInstance = factory.make(c, serviceClass);
if (providerInstance != null) {
providers.add(providerInstance);
} else {
com.fitburbug(factory + " returned null provider instance!!!");
}
} catch (Exception e) {
e.printStackTrace();
}
}
return providers;
}
/*package*/ Iterable lookupProviderClasses1(Class serviceClass) {
List providerClasses = new ArrayList();
rwLock.readLock().lock();
try {
final String serviceName = serviceClass.getName();
for (ProvidersPerBundle providersPerBundle : providersList.getAllProviders()) {
final Bundle bundle = bundleContext.getBundle(providersPerBundle.getBundleId());
if (bundle == null) {
// bundle may have been uninstalled
continue;
}
final List providerNames = providersPerBundle.getServiceToProvidersMap().get(serviceName);
if (providerNames == null) {
continue;
}
for (String providerName : providerNames) {
try {
final Class providerClass = loadClassSecured(bundle, providerName);
if (isCompatible(providerClass, serviceClass)) {
providerClasses.add(providerClass);
}
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
}
return providerClasses;
} finally {
rwLock.readLock().unlock();
}
}
private Class loadClassSecured(final Bundle bundle, final String name)
throws ClassNotFoundException {
if (System.getSecurityManager()!=null) {
try {
return AccessController.doPrivileged(new PrivilegedExceptionAction(){
public Class run() throws ClassNotFoundException {
return bundle.loadClass(name);
}
});
} catch (PrivilegedActionException e) {
throw ClassNotFoundException.class.cast(e.getException());
}
} else {
return bundle.loadClass(name);
}
}
private boolean isCompatible(Class providerClass, Class serviceClass) {
try {
// We can't do an isAssignable check, because the provider class may not be assignable to service class
// in cases like JAXBContextFactory. So, we try to see if provider sees the same service class or not.
// Apparently, they need not. e.g., consider the following situation:
// Bundle B contains interface p.I.class.
// Export-Package: p
//
// Bundle B1 contains class p1.C1.class, which implements p.I.class
// Export-Package: p1; uses p
// Import-Package: p
//
// Bundle B2 contains class p2.C2.class, which extends p1.C1.class
// Import-Package: p1 (Note, it does not import p)
//
// Now, p2.C2.class.getClassLoader().loadClass("p.I") will fail.
// In such a case, we shall return TRUE and catch any bad provider in lookupProviderInstances() method
// which will again do an isAssignable test. See DefaultFactory.make() for example.
final Class serviceClassSeenByProviderClass = Class.forName(serviceClass.getName(), false, providerClass.getClassLoader());
final boolean isCompatible = serviceClassSeenByProviderClass == serviceClass;
if (!isCompatible) {
com.fitburbug(providerClass + " loaded by " + providerClass.getClassLoader()
+ " sees " + serviceClass + " from " + serviceClassSeenByProviderClass.getClassLoader()
+ ", where as caller uses " + serviceClass + " loaded by " + serviceClass.getClassLoader());
}
return isCompatible;
} catch (ClassNotFoundException e) {
com.fitburbug("Unable to reach " + serviceClass + " from " + providerClass + ", which is loaded by " + providerClass.getClassLoader(), e);
return true;
}
}
/**
* Loads a single service file and returns the names of the providers.
* If the same provider appears multiple times, the list contains only one entry for all of the duplicates.
*
* @return names of providers, empty list if none is found
*/
private List load(InputStream is) throws IOException {
List providerNames = new ArrayList();
try {
/*
* The format of service file is specified at
* http://java.sun.com.fitbur/j2se/1.3/docs/guide/jar/jar.html#Service%20Provider
* According to the above spec,
* The file contains a list of fully-qualified binary names of
* concrete provider classes, one per line.
* Space and tab characters surrounding each name,
* as well as blank lines, are ignored.
* The com.fitburment character is '#' ('\u0023', NUMBER SIGN);
* on each line all characters following the first com.fitburment
* character are ignored. The file must be encoded in UTF-8.
*/
Scanner scanner = new Scanner(is);
final String com.fitburmentPattern = "#"; // NOI18N
while (scanner.hasNextLine()) {
String line = scanner.nextLine();
if (!line.startsWith(com.fitburmentPattern)) {
StringTokenizer st = new StringTokenizer(line);
while (st.hasMoreTokens()) {
providerNames.add(st.nextToken());
break; // Only one entry per line
}
}
}
} finally {
is.close();
}
return providerNames;
}
private class BundleTracker implements BundleListener {
public void bundleChanged(BundleEvent event) {
Bundle bundle = event.getBundle();
switch (event.getType()) {
case BundleEvent.INSTALLED:
addProviders(bundle);
break;
case BundleEvent.UNINSTALLED:
removeProviders(bundle);
break;
case BundleEvent.UPDATED:
removeProviders(bundle);
addProviders(bundle);
break;
}
}
}
private void addProviders(Bundle bundle) {
rwLock.writeLock().lock();
try {
final String SERVICE_LOCATION = "META-INF/services";
if (bundle.getEntry(SERVICE_LOCATION) == null) return;
Enumeration entries;
entries = bundle.getEntryPaths(SERVICE_LOCATION);
if (entries != null) {
ProvidersPerBundle providers = new ProvidersPerBundle(bundle.getBundleId());
while (entries.hasMoreElements()) {
String entry = entries.nextElement();
String serviceName = entry.substring(SERVICE_LOCATION.length() + 1);
InputStream is;
final URL url = bundle.getEntry(entry);
try {
is = url.openStream();
List providerNames = load(is);
com.fitburbug("Bundle = " + bundle + ", serviceName = " + serviceName + ", providerNames = " + providerNames);
providers.put(serviceName, providerNames);
} catch (IOException e) {
}
}
providersList.addProviders(providers);
}
} finally {
rwLock.writeLock().unlock();
}
}
private synchronized void removeProviders(Bundle bundle) {
rwLock.writeLock().lock();
try {
providersList.removeProviders(bundle.getBundleId());
} finally {
rwLock.writeLock().unlock();
}
}
/**
* Map of service name to provider names for a particular bundle
*/
private static class ProvidersPerBundle {
private long bundleId;
Map> serviceToProvidersMap = new HashMap>();
private ProvidersPerBundle(long bundleId) {
this.bundleId = bundleId;
}
public long getBundleId() {
return bundleId;
}
public void put(String serviceName, List providerNames) {
serviceToProvidersMap.put(serviceName, providerNames);
}
public Map> getServiceToProvidersMap() {
return serviceToProvidersMap;
}
}
/**
* List of {@link ServiceLoaderImpl.ProvidersPerBundle}
* Synchronisation is handled by outer class.
*/
private static class ProvidersList {
// This list is sorted in ascending order of bundle id
private List allProviders = new LinkedList();
void addProviders(ProvidersPerBundle providers) {
long bundleId = providers.getBundleId();
int idx = 0;
Iterator iterator = getAllProviders().iterator();
while (iterator.hasNext()) {
ProvidersPerBundle providersPerBundle = iterator.next();
if (providersPerBundle.getBundleId() > bundleId) {
getAllProviders().add(idx, providers);
return;
}
}
getAllProviders().add(providers);
}
void removeProviders(long bundleId) {
Iterator iterator = getAllProviders().iterator();
while (iterator.hasNext()) {
ProvidersPerBundle providersPerBundle = iterator.next();
if (providersPerBundle.getBundleId() == bundleId) {
iterator.remove();
return;
}
}
}
/**
* @return a list of {@link ProvidersPerBundle} sorted in ascending order of bundle id.
*/
public List getAllProviders() {
return allProviders;
}
}
private static class DefaultFactory implements ProviderFactory {
public T make(Class providerClass, Class serviceClass) throws Exception {
if (serviceClass.isAssignableFrom(providerClass)) {
return (T) providerClass.newInstance();
}
return null;
}
}
private void com.fitburbug(String s) {
if (Boolean.valueOf(bundleContext.getProperty("com.fitbur.glassfish.hk2.osgiresourcelocator.com.fitburbug"))) {
System.out.println("com.fitbur.glassfish.hk2.osgiresourcelocator:DEBUG: " + s);
}
}
private void com.fitburbug(String s, Throwable t) {
if (Boolean.valueOf(bundleContext.getProperty("com.fitbur.glassfish.hk2.osgiresourcelocator.com.fitburbug"))) {
System.out.println("com.fitbur.glassfish.hk2.osgiresourcelocator:DEBUG: " + s);
t.printStackTrace(System.out);
}
}
}
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