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Issue #3018 addressing code review comments

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This commit is contained in:
Nate Jensen 2014-04-17 09:28:47 -05:00
parent 8851b335fc
commit 88231d9166
3 changed files with 131 additions and 38 deletions
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44
cave/com.raytheon.uf.viz.core/src/com/raytheon/uf/viz/core/reflect/BundleReflections.java
View file

@ -20,15 +20,12 @@
package com.raytheon.uf.viz.core.reflect;
import java.io.IOException;
import java.lang.reflect.Field;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import org.eclipse.core.runtime.FileLocator;
import org.eclipse.osgi.framework.internal.core.AbstractBundle;
import org.eclipse.osgi.framework.internal.core.BundleRepository;
import org.eclipse.osgi.framework.internal.core.Framework;
import org.osgi.framework.Bundle;
import org.osgi.framework.wiring.BundleWiring;
import org.reflections.Reflections;
@ -67,40 +64,8 @@ public class BundleReflections {
public BundleReflections(Bundle bundle, Scanner scanner) throws IOException {
ConfigurationBuilder cb = new ConfigurationBuilder();
BundleWiring bundleWiring = bundle.adapt(BundleWiring.class);
/*
* If BundleReflection's constructor is invoked on a thread other than
* main/UI thread, then there is a possible deadlock if the application
* shuts down while the bundleWiring.getClassloader() call below is
* still going. The BundleRepository of the Framework is the primary
* resource that is in contention in this deadlock scenario, due to the
* BundleRepository being used as a synchronization lock both deep in
* bundleWiring.getClassloader() and in Framework shutdown code.
*
* Therefore to avoid this deadlock, we attempt to get the
* BundleRepository and synchronize against it, ensuring the call to
* getClassLoader() can finish and then release synchronization locks.
*
* If we fail to get the BundleRepository due to access restrictions,
* then we proceed onwards anyway because the odds of the application
* shutting down at the same time as this is still running is low, and
* even if that occurs, the odds are further reduced that the two
* threads will synchronize against the BundleRepository at the same
* time and deadlock.
*/
BundleRepository bundleRepo = null;
if (bundle instanceof AbstractBundle) {
try {
AbstractBundle ab = (AbstractBundle) bundle;
Field bundleRepoField = Framework.getField(Framework.class,
BundleRepository.class, true);
bundleRepo = (BundleRepository) bundleRepoField.get(ab
.getFramework());
} catch (Throwable t) {
// intentionally log to console and proceed anyway
t.printStackTrace();
}
}
BundleRepository bundleRepo = BundleRepositoryGetter
.getFrameworkBundleRepository(bundle);
if (bundleWiring != null) {
if (bundleRepo != null) {
@ -108,6 +73,11 @@ public class BundleReflections {
cb.addClassLoader(bundleWiring.getClassLoader());
}
} else {
/*
* even if we couldn't get the bundle repository to sync
* against, it's probably safe, see BundleRepositoryGetter
* javadoc
*/
cb.addClassLoader(bundleWiring.getClassLoader());
}
cb.addUrls(FileLocator.getBundleFile(bundle).toURI().toURL());

104
cave/com.raytheon.uf.viz.core/src/com/raytheon/uf/viz/core/reflect/BundleRepositoryGetter.java Normal file
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@ -0,0 +1,104 @@
/**
* This software was developed and / or modified by Raytheon Company,
* pursuant to Contract DG133W-05-CQ-1067 with the US Government.
*
* U.S. EXPORT CONTROLLED TECHNICAL DATA
* This software product contains export-restricted data whose
* export/transfer/disclosure is restricted by U.S. law. Dissemination
* to non-U.S. persons whether in the United States or abroad requires
* an export license or other authorization.
*
* Contractor Name: Raytheon Company
* Contractor Address: 6825 Pine Street, Suite 340
* Mail Stop B8
* Omaha, NE 68106
* 402.291.0100
*
* See the AWIPS II Master Rights File ("Master Rights File.pdf") for
* further licensing information.
**/
package com.raytheon.uf.viz.core.reflect;
import java.lang.reflect.Field;
import org.eclipse.osgi.framework.internal.core.AbstractBundle;
import org.eclipse.osgi.framework.internal.core.BundleRepository;
import org.eclipse.osgi.framework.internal.core.Framework;
import org.osgi.framework.Bundle;
/**
* Utility class to get the BundleRepository object associated with a Bundle, to
* potentially synchronize against that object.
*
* Specifically if a call to BundleWiring.getClassLoader() is invoked on a
* thread other than main/UI thread, then there is a possible deadlock if the
* application shuts down while the BundleWiring.getClassLoader() call is still
* going. The BundleRepository of the Framework is the primary resource that is
* in contention in this deadlock scenario, due to the BundleRepository being
* used as a synchronization lock both deep in bundleWiring.getClassloader() and
* in Framework shutdown code. The other resource used as a synchronization lock
* and causing the deadlock is the BundleLoader associated with the bundle.
*
* Therefore to avoid this deadlock, if you are going to call
* BundleWiring.getClassLoader() you should attempt to get the BundleRepository
* and synchronize against it. This will ensure the call to getClassLoader() can
* finish and then release synchronization locks of both the BundleRepository
* and BundleLoader.
*
* If we fail to get the BundleRepository due to access restrictions, then you
* should proceed onwards anyway because the odds of the application shutting
* down at the same time as the call to BundleWiring.getClassLoader() is still
* running is low. Even if that occurs, the odds are further reduced that the
* two threads will synchronize against the BundleRepository at the same time
* and deadlock.
*
*
* <pre>
*
* SOFTWARE HISTORY
*
* Date Ticket# Engineer Description
* ------------ ---------- ----------- --------------------------
* Apr 17, 2014 njensen Initial creation
*
* </pre>
*
* @author njensen
* @version 1.0
*/
public class BundleRepositoryGetter {
private BundleRepositoryGetter() {
}
/**
* Attempts to retrieve the BundleRepository associated with the bundle's
* framework. Returns the BundleRepository or null if it could not be
* retrieved.
*
* @param bundle
* the bundle to retrieve the associated BundleRepository for
* @return the BundleRepository or null
*/
@SuppressWarnings("restriction")
protected static BundleRepository getFrameworkBundleRepository(Bundle bundle) {
BundleRepository bundleRepo = null;
if (bundle instanceof AbstractBundle) {
try {
AbstractBundle ab = (AbstractBundle) bundle;
Field bundleRepoField = Framework.getField(Framework.class,
BundleRepository.class, true);
bundleRepo = (BundleRepository) bundleRepoField.get(ab
.getFramework());
} catch (Throwable t) {
// intentionally log to console and proceed anyway
t.printStackTrace();
}
}
return bundleRepo;
}
}

21
cave/com.raytheon.uf.viz.core/src/com/raytheon/uf/viz/core/reflect/SubClassLocator.java
View file

@ -28,6 +28,7 @@ import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import org.eclipse.osgi.framework.internal.core.BundleRepository;
import org.osgi.framework.Bundle;
import org.osgi.framework.namespace.BundleNamespace;
import org.osgi.framework.namespace.PackageNamespace;
@ -56,6 +57,7 @@ import com.raytheon.uf.viz.core.Activator;
* Dec 10, 2013 2602 bsteffen Add null checks to detect unloaded
* bundles.
* Feb 03, 2013 2764 bsteffen Use OSGi API to get dependencies.
* Apr 17, 2014 3018 njensen Synchronize against BundleRepository
*
* </pre>
*
@ -95,6 +97,7 @@ public class SubClassLocator implements ISubClassLocator {
* @param base
* @return
*/
@Override
public Collection<Class<?>> locateSubClasses(Class<?> base) {
Map<String, Set<Class<?>>> recursiveClasses = new HashMap<String, Set<Class<?>>>(
bundleLookup.size(), 1.0f);
@ -109,6 +112,7 @@ public class SubClassLocator implements ISubClassLocator {
/**
* Store the cache to disk.
*/
@Override
public void save() {
cache.save();
}
@ -265,10 +269,25 @@ public class SubClassLocator implements ISubClassLocator {
if (bundleWiring == null) {
return Collections.emptySet();
}
ClassLoader loader = bundleWiring.getClassLoader();
BundleRepository bundleRepo = BundleRepositoryGetter
.getFrameworkBundleRepository(bundle);
ClassLoader loader = null;
if (bundleRepo != null) {
synchronized (bundleRepo) {
loader = bundleWiring.getClassLoader();
}
} else {
/*
* even if we couldn't get the bundle repository to sync against,
* it's probably safe, see BundleRepositoryGetter javadoc
*/
loader = bundleWiring.getClassLoader();
}
if (loader == null) {
return Collections.emptySet();
}
HashSet<Class<?>> result = new HashSet<Class<?>>(classNames.size(),
1.0f);
for (String className : classNames) {