Wednesday, May 17, 2017

OSGI bundle/plugin class loading

Being a programmer, I would ask you to take a look at this class.



Below 2 methods will give lot of understanding:

Class<?> findClass(String name, boolean checkParent) throws ClassNotFoundException {
if (checkParent && parent != null && name.startsWith(JAVA_PACKAGE))
// 1) if startsWith "java." delegate to parent and terminate search
// we want to throw ClassNotFoundExceptions if a java.* class cannot be loaded from the parent.
return parent.loadClass(name);
return findClassInternal(name, checkParent);

private Class<?> findClassInternal(String name, boolean checkParent) throws ClassNotFoundException {
if (debug.DEBUG_LOADER)
Debug.println("BundleLoader[" + this + "].findClassInternal(" + name + ")"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
String pkgName = getPackageName(name);
boolean bootDelegation = false;
// follow the OSGi delegation model
if (checkParent && parent != null && container.isBootDelegationPackage(pkgName))
// 2) if part of the bootdelegation list then delegate to parent and continue of failure
try {
return parent.loadClass(name);
} catch (ClassNotFoundException cnfe) {
// we want to continue
bootDelegation = true;
Class<?> result = null;
try {
result = (Class<?>) searchHooks(name, PRE_CLASS);
} catch (ClassNotFoundException e) {
throw e;
} catch (FileNotFoundException e) {
// will not happen
if (result != null)
return result;
// 3) search the imported packages
PackageSource source = findImportedSource(pkgName, null);
if (source != null) {
if (debug.DEBUG_LOADER) {
Debug.println("BundleLoader[" + this + "] loading from import package: " + source); //$NON-NLS-1$ //$NON-NLS-2$
// 3) found import source terminate search at the source
result = source.loadClass(name);
if (result != null)
return result;
throw new ClassNotFoundException(name + " cannot be found by " + this); //$NON-NLS-1$
// 4) search the required bundles
source = findRequiredSource(pkgName, null);
if (source != null) {
if (debug.DEBUG_LOADER) {
Debug.println("BundleLoader[" + this + "] loading from required bundle package: " + source); //$NON-NLS-1$ //$NON-NLS-2$
// 4) attempt to load from source but continue on failure
result = source.loadClass(name);
// 5) search the local bundle
if (result == null)
result = findLocalClass(name);
if (result != null)
return result;
// 6) attempt to find a dynamic import source; only do this if a required source was not found
if (source == null) {
source = findDynamicSource(pkgName);
if (source != null) {
result = source.loadClass(name);
if (result != null)
return result;
// must throw CNFE if dynamic import source does not have the class
throw new ClassNotFoundException(name + " cannot be found by " + this); //$NON-NLS-1$

if (result == null)
try {
result = (Class<?>) searchHooks(name, POST_CLASS);
} catch (ClassNotFoundException e) {
throw e;
} catch (FileNotFoundException e) {
// will not happen
// do buddy policy loading
if (result == null && policy != null)
result = policy.doBuddyClassLoading(name);
if (result != null)
return result;
// hack to support backwards compatibility for bootdelegation
// or last resort; do class context trick to work around VM bugs
if (parent != null && !bootDelegation && ((checkParent && container.getConfiguration().compatibilityBootDelegation) || isRequestFromVM()))
// we don't need to continue if a CNFE is thrown here.
try {
return parent.loadClass(name);
} catch (ClassNotFoundException e) {
// we want to generate our own exception below
throw new ClassNotFoundException(name + " cannot be found by " + this); //$NON-NLS-1$



Tuesday, May 16, 2017

Debugging options for org.eclipse.osgi

#### Debugging options for org.eclipse.osgi

# Turn on general debugging for org.eclipse.osgi
# Prints out class loading debug information
# Prints out event (FrameworkEvent/BundleEvent/ServiceEvent) and listener debug information
# Prints out OSGi service debug information (registration/getting/ungetting etc.)
# Prints out bundle manifest parsing debug information
# Prints out LDAP filter debug information
# Prints out security (PermissionAdmin service) debug information
# Prints out start level service debug information
# Prints out package admin service debug information
# Prints out timing information for bundle activation
# Debug the loading of message bundles
# Debug the object pool additions
# Debug the object pool duplications

# Eclipse adaptor options
org.eclipse.osgi/eclipseadaptor/debug = false
org.eclipse.osgi/eclipseadaptor/debug/location = false
org.eclipse.osgi/eclipseadaptor/debug/cachedmanifest = false
org.eclipse.osgi/eclipseadaptor/converter/debug = false

### OSGi resolver options
# Turns on debugging for the resolver
org.eclipse.osgi/resolver/debug = false
# Prints out wiring information after the resolver has completed the resolve process
org.eclipse.osgi/resolver/wiring = false
# Prints out Import-Package information
org.eclipse.osgi/resolver/imports = false
# Prints out Require-Bundle information
org.eclipse.osgi/resolver/requires = false
# Prints out debug information form the "uses" clause
org.eclipse.osgi/resolver/uses = false
# Prints out cycle information
org.eclipse.osgi/resolver/cycles = false
# Prints out Eclipse-GenericRequire information
org.eclipse.osgi/resolver/generics = false

#### Profile settings
org.eclipse.osgi/profile/startup = false
org.eclipse.osgi/profile/benchmark = false
org.eclipse.osgi/profile/debug = false

# Override the default implemenation 
org.eclipse.osgi/profile/impl = org.eclipse.osgi.internal.profile.DefaultProfileLogger

# Append all profile messages to the filename specified
org.eclipse.osgi/defaultprofile/logfilename = 

# Output all profile log messages synchronously to the jvm console.
# By default, all log messages are cached until the log buffer is
# requested.
org.eclipse.osgi/defaultprofile/logsynchronously = false

# Specify the size of the default profile implementation log buffer.
org.eclipse.osgi/defaultprofile/buffersize = 256

#### Monitoring settings
# monitor class loading

# monitor bundle activation

# monitor resource bundle (*.properties) loading

#### Trace settings
# trace class loading - snapshot the execution stack when a class is loaded

# trace location - file in which execution traces are written

# trace filters - Java properties file defining which classes should 
# be traced (if trace/classLoading is true)
# File format:
# plugins=<comma separated list of plugins whose classes to trace>
# packages=<comma separated list of package prefixes of classes to trace>
# Note that there may be many 'plugins' and 'packages' lines in one file.

# trace bundle activation - snapshot the execution stack when a bundle is activated

Wednesday, April 12, 2017

Setting TLS protocol version for HttpsURLConnection

SSLContext sc = SSLContext.getInstance("TLSv1.2"); //$NON-NLS-1$
sc.init(null, null, new;
HttpsURLConnection con = (HttpsURLConnection) httpsURL.openConnection();


Other way would be setting VM arg to the Java.


Wednesday, January 25, 2017

Adding filter to tree viewer

PatternFilter filter = new PatternFilter();
FilteredTree tree = new FilteredTree(sash, SWT.MULTI | SWT.H_SCROLL | SWT.V_SCROLL, filter, true);
TreeViewer viewer = tree.getViewer();

//go on..

Tuesday, January 10, 2017

Removing unwanted preference pages from eclipse

To remove unwanted preferences from your eclipse rcp app, we can do the following.

As part of your App MyRCPWorkbenchAdvisor#postStartup() method, you need to invoke the following code with the preference page id.

private void removeUnwantedPreferences()
PreferenceManager pm = PlatformUI.getWorkbench().getPreferenceManager();
IPreferenceNode root = getRoot(pm);
if (root != null)

//Identify preference node
private IPreferenceNode getRoot(PreferenceManager pm)
Method m = PreferenceManager.class.getDeclaredMethod("getRoot", (Class[]) null); 
return (IPreferenceNode) m.invoke(pm);
catch (Exception e)
IdeLog.logWarning(TitaniumCorePlugin.getDefault(), e);
return null;

//remove preference id from the preference node
private void removePrefsPage(IPreferenceNode root, String id)
for (IPreferenceNode node : root.getSubNodes())
if (node.getId().equals(id))
removePrefsPage(node, id);


This seems to be work without any issues.

However, I could see other direct approach but that doesn't seem to work well in all scenarios.

PreferenceManager pm = PlatformUI.getWorkbench().getPreferenceManager();

Sunday, January 8, 2017

Tip: Eclipse plugins error - prerequisite build errors

I've faced this issue many times with eclipse.

Even though we have all the plugins and their dependencies defined correctly, still eclipse shows the errors by saying the prerequisite has to be build first.

It's frustrating since I have not made any changes in the project from the last time.

Okay, so the solution for this is:

1. Identify the root prerequisite plugin which eclipse is complaining about.
2. Close that root plugin
3. Re-open it
4. Do clean build for all projects

Thursday, September 15, 2016

How to get your colleague Pull request into your system for testing

For my own reference:

git remote add coworker
git fetch coworker
git checkout --track coworker/TIMOB-23628

If your co-worker has made some more changes, then you pull the latest changes in the below way.

git checkout TIMOB-23628

git pull

To push it back to your colleague branch
git puh coworker TIMOB-23628

Another way would be

To fetch a remote PR into your local repo,
git fetch origin pull/ID/head:BRANCHNAME

where ID is the pull request id and BRANCHNAME is the name of the new branch that you want to create. Once you have created the branch, then simply

git checkout BRANCHNAME