Hey all.
I've been working on
https://issues.jboss.org/browse/WELD-1162 and need
your opinion.
Say we have:
public interface Foo<T> {
void doSomething(T t);
}
public interface StringFoo extends Foo<String> {}
public class StringFooImpl implements StringFoo {}
and
@Inject StringFoo stringFoo;
The proxy created by Weld is a subclass of StringFooImpl and therefore
has two declared methods:
void doSomething(Object o) { doSomething((String) o); }
void doSomething(String) {...}
However, when StringFooImpl is a session bean, with StringFoo as its
local interface, the proxy is a subclass of Object and therefore the
proxy only has the following declared method:
void doSomething(Object o);
In both cases, when a client invokes stringFoo.doSomething("foo"), the
method doSomething(Object) is invoked. But there's a difference in what
happens next:
* In the non-ejb version, the bridge method then immediately invokes
doSomething(String) and only then is the proxy's method handler
invoked. The handler is therefore dealing with the method
doSomething(*String*)
* in the EJB version, doSomething(Object) is not a bridge method, and
so the method handler is invoked directly and it (the handler) is
operating on doSomething(*Object*).
In the second case, this ultimately means that Weld will check whether
doSomething(Object) is intercepted. It isn't, since
Beans.getInterceptableMethods() is ignoring bridge methods. The
interceptor will not be invoked. On the other hand, in the first case,
the interceptor _will_ be invoked, since Weld will be checking whether
doSomething(String) is intercepted.
My initial solution was to make Beans.getInterceptableMethods() also
return bridge methods, but now I'm thinking the actual problem is in the
proxy itself. IMO, when creating a proxy based on an interface, we
should also generate bridge methods on the proxy (this should be either
done by Weld or by Javassist directly). These bridge methods should be
perfectly normal bridge methods and should not invoke the method handler
directly. They should simply invoke the non-bridge method and the
non-bridge method should then invoke the method handler.
The java compiler can't add bridge methods directly to interfaces which
require them, so it adds them to all the classes implementing the
interface (StringFooImpl in our case). Since we are creating
StringFoo$Proxy, which is also a class implementing an interface which
requires bridge methods, we should add the bridge methods
to it - exactly as the java compiler would.
This would solve the interceptor problem and possibly other similar
problems as well.
What do you think?
Marko