Created
July 7, 2014 18:10
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Migrated attachment for Guice issue 288, comment 69
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import java.lang.ref.PhantomReference; | |
import java.lang.reflect.Field; | |
import java.lang.reflect.Method; | |
import java.util.Timer; | |
import javax.servlet.ServletContextEvent; | |
import javax.servlet.ServletContextListener; | |
public class GuiceLifecycleListener implements ServletContextListener { | |
private static final org.apache.juli.logging.Log log = org.apache.juli.logging.LogFactory.getLog( GuiceLifecycleListener.class ); | |
public void contextInitialized(ServletContextEvent event) {} | |
public void contextDestroyed(ServletContextEvent event) { | |
Thread[] threads = getThreads(); | |
String[] guicePrefixes = { | |
"com.google.inject.internal.", // google guice 2.0 | |
"com.google.inject.internal.util.$" // google guice 3.0 | |
}; | |
for (String guicePrefix : guicePrefixes) { | |
for (Thread thread : threads) { | |
if (thread == null) continue; | |
// Try to shutdown the Finalizer Thread | |
try { | |
if (thread.getClass().getName().equals(guicePrefix + "Finalizer")) { | |
Class mapMakerClass = Class.forName(guicePrefix + "MapMaker"); | |
Class[] classes = mapMakerClass.getDeclaredClasses(); | |
for (Class clazz: classes) { | |
if (clazz.getName().equals(guicePrefix + "MapMaker$QueueHolder")) { | |
Object finalizableReferenceQueue = getFieldInstance(null, clazz, "queue"); | |
Object referenceQueue = getFieldInstance(finalizableReferenceQueue, finalizableReferenceQueue.getClass(), "queue"); | |
Object finalizerQueue = getFieldInstance(thread, thread.getClass(), "queue"); | |
// Check that the thread is our instance | |
if (referenceQueue == finalizerQueue) | |
{ | |
PhantomReference frqReference = (PhantomReference) getFieldInstance(thread, thread.getClass(), "frqReference"); | |
// Notify the finalizer it can stop | |
Method enqueue = finalizerQueue.getClass().getDeclaredMethod("enqueue", new Class[] { java.lang.ref.Reference.class }); | |
enqueue.setAccessible(true); | |
enqueue.invoke(finalizerQueue, new Object[] { frqReference }); | |
log.info(thread.getClass().getName() + " successfully notified to shutdown."); | |
} | |
} | |
} | |
} | |
} catch (Exception e) { | |
log.warn(thread.getClass().getName() + " couldn't be notified to shutdown !", e); | |
} | |
// Try to cancel the Expiration Timer | |
try { | |
if (thread.getClass().getName().equals("java.util.TimerThread")) { | |
Class expirationTimerClass = null; | |
try { | |
expirationTimerClass = Class.forName(guicePrefix + "ExpirationTimer"); | |
} catch (Exception e) { | |
// Silently fail | |
} | |
if (expirationTimerClass != null) { | |
Timer instance = (Timer) getFieldInstance(null, expirationTimerClass, "instance"); | |
Thread instanceThread = (Thread) getFieldInstance(instance, instance.getClass(), "thread"); | |
// Check that the thread is our instance | |
if (instanceThread == thread) { | |
instance.cancel(); | |
log.info(expirationTimerClass.getName() + " successfully cancelled."); | |
} | |
} | |
} | |
} catch (Exception e) { | |
log.warn(thread.getClass().getName() + " couldn't be cancelled !", e); | |
} | |
} | |
} | |
} | |
private Object getFieldInstance(Object instance, Class clazz, String name) { | |
try { | |
Field field = clazz.getDeclaredField(name); | |
field.setAccessible(true); | |
return field.get(instance); | |
} catch (Exception e) { | |
return null; | |
} | |
} | |
/* Code from apache tomcat 6.0.32 */ | |
private Thread[] getThreads() { | |
// Get the current thread group | |
ThreadGroup tg = Thread.currentThread( ).getThreadGroup(); | |
// Find the root thread group | |
while (tg.getParent() != null) { | |
tg = tg.getParent(); | |
} | |
int threadCountGuess = tg.activeCount() + 50; | |
Thread[] threads = new Thread[threadCountGuess]; | |
int threadCountActual = tg.enumerate(threads); | |
// Make sure we don't miss any threads | |
while (threadCountActual == threadCountGuess) { | |
threadCountGuess *=2; | |
threads = new Thread[threadCountGuess]; | |
// Note tg.enumerate(Thread[]) silently ignores any threads that | |
// can't fit into the array | |
threadCountActual = tg.enumerate(threads); | |
} | |
return threads; | |
} | |
} |
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