[FELIX-5285] iPojo does not delegate to the right classloader for Nullable Proxy instantiation

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Component/s: iPOJO
• Assignee: Clement Escoffier
• Reporter: Emmanuel Juste
• Created: 24/Jun/16 12:08
• Updated: 31/Aug/16 15:26
• Resolved: 31/Aug/16 15:26

Description

iPojo runtime & api: 1.12.1
Felix framework: 4.2.1
This issue is similar to https://issues.apache.org/jira/browse/FELIX-2093

This interface exist in v1.0 of an api and is exported by the system bundle (felix) A

package com.data.service

public interface DataService
{
    public void search(String condition);
}

A bundle, B, imports com.data.service;version=1.0:

@Requires(optional = true)
private DataServiceImpl dataServiceImpl;

where DataServiceImpl only implements the interface
All is working well at this point.

Then, the api evolves with a new method:

package com.data.service

import com.data.service.conditions.Condition;

public interface DataService
{
    public void search(String condition);

    public void search(Condition condition);
}

still exported by system bundle A but now as version 1.1
The bundle B is not recompiled against this new version and does not import the new package com.data.service.conditions

Now, when bundle B runs with v1.1 of the api, the requires of DataServiceImpl is failing in Dependency.createNullableObject() (http://felix.apache.org/ipojo/api/1.12.1/src-html/org/apache/felix/ipojo/handlers/dependency/Dependency.html line 433) when creating the proxy: the proxy class is created w/o issue but when an instance of this proxy class is done, there is a Class.forName() done that fails to load the class Condition because it is not imported

Since the class Condition is already available and allows to create the proxy class, it would make sense to use it instead of trying to load it thru the bundle classloader
To achieve this, the methods of the specification could be browsed, for each parameters and return types the classloader could be collected and given to the NullableClassLoader. All classloaders could be asked to load the class. At some point, the classloader of Condition would be queried and would return the class

I don't know if this is breaking OSGi principles but I think it can fix this issue

NB: I also tried to export the new api with uses directive:
com.data.service;version=1.1;uses:="com.data.service.conditions"
with no result. If I understand correctly uses directive is not supposed to add implicit package import to bundle B, but are only used by the OSGi framework to help it on the wiring process

Here's the cause exception thrown in java.lang.IllegalStateException: Cannot create the Nullable object, a referenced class cannot be loaded:

java.lang.NoClassDefFoundError: *** Class 'com.data.service.conditions.Condition' was not found because bundle B [5] does not import 'com.data.service.conditions' even though bundle org.apache.felix.framework [0] does export it. Additionally, the class is also available from the system class loader. There are two fixes: 1) Add an import for 'com.data.service.conditions' to bundle B [5]; imports are necessary for each class directly touched by bundle code or indirectly touched, such as super classes if their methods are used. 2) Add package 'com.data.service.conditions' to the 'org.osgi.framework.bootdelegation' property; a library or VM bug can cause classes to be loaded by the wrong class loader. The first approach is preferable for preserving modularity. ***

And the stack trace of the loadClass that fails:

"[iPOJO] pool-1-thread-1@4605" daemon prio=5 tid=0x21 nid=NA runnable 
java.lang.Thread.State: RUNNABLE
	  at org.apache.felix.ipojo.handlers.dependency.Dependency$NullableClassLoader.loadClass(Dependency.java:1072)
	  at java.lang.Class.forName0(Class.java:-1)
	  at java.lang.Class.forName(Class.java:264)
	  at com.sun.proxy.$Proxy154.<clinit>(Unknown Source:-1)
	  at sun.reflect.NativeConstructorAccessorImpl.newInstance0(NativeConstructorAccessorImpl.java:-1)
	  at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	  at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	  at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
	  at java.lang.reflect.Proxy.newProxyInstance(Proxy.java:739)
	  at org.apache.felix.ipojo.handlers.dependency.Dependency.createNullableObject(Dependency.java:434)
	  at org.apache.felix.ipojo.handlers.dependency.Dependency.start(Dependency.java:457)
	  at org.apache.felix.ipojo.handlers.dependency.DependencyHandler.__M_start(DependencyHandler.java:496)
	  at org.apache.felix.ipojo.handlers.dependency.DependencyHandler.start(DependencyHandler.java:-1)
	  at org.apache.felix.ipojo.HandlerManager.start(HandlerManager.java:136)
	  at org.apache.felix.ipojo.InstanceManager.start(InstanceManager.java:421)
	  at org.apache.felix.ipojo.ComponentFactory.createInstance(ComponentFactory.java:179)
	  at org.apache.felix.ipojo.IPojoFactory.createComponentInstance(IPojoFactory.java:319)
	  - locked <0x2a3b> (a org.apache.felix.ipojo.ComponentFactory)
	  at org.apache.felix.ipojo.IPojoFactory.createComponentInstance(IPojoFactory.java:240)
	  at org.apache.felix.ipojo.extender.internal.linker.ManagedType$InstanceSupport$1.call(ManagedType.java:312)
	  at org.apache.felix.ipojo.extender.internal.linker.ManagedType$InstanceSupport$1.call(ManagedType.java:306)
	  at org.apache.felix.ipojo.extender.internal.queue.JobInfoCallable.call(JobInfoCallable.java:114)
	  at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	  at java.lang.Thread.run(Thread.java:745)