RE: [aspectj-users] Why does every Aspect (pertarget(..)) add fieldsand

["Jody Brownell" <jody.brownell@xxxxxxxxxx>]

OK - Here is one of the aspects which I see littering EVERY class in the
same eclipse project.

>From my understanding the association indicates I only want to crosscut
on classes which are annotated with @Lock on the type AND @Lock.Read or
@Lock.Write on one or more methods.

	pertarget(fair(Lock) && (readLock() || writeLock()))

However - As I said - every class is being instrumented with fields and
interfaces.


import java.util.concurrent.locks.ReentrantReadWriteLock;

public abstract aspect LockAspect pertarget(fair(Lock) && (readLock() ||
writeLock()))
{
	declare error: execution(@Lock.Read * * (..)) && !@within(Lock):

		"@Lock.Read and @Lock.Write cannot be used unless the
Class/Interface is annotated with @Lock"; 
	
	private ReentrantReadWriteLock.ReadLock read;
	private ReentrantReadWriteLock.WriteLock write;
	private ReentrantReadWriteLock lock;

	public LockAspect(boolean fair)
	{
		lock = new ReentrantReadWriteLock(fair);
		
		read = lock.readLock();
		write = lock.writeLock();
	}
	
	abstract pointcut fair(Lock lock);
	
	pointcut readLock(): execution(@Lock.Read * * (..));
	pointcut writeLock(): execution(@Lock.Write * * (..));
	
	Object around(): readLock()
	{
		Object o = null;

		try
		{
			read.lock();
			o = proceed();
		}
		finally
		{
			read.unlock();
		}

		return o;
	}

	Object around(): writeLock()
	{
		Object o = null;

		try
		{
			write.lock();
			o = proceed();
		}
		finally
		{
			write.unlock();
		}

		return o;
	}
}

aspect UnfairLockAspect extends LockAspect
{
	pointcut fair(Lock lock): @within(lock) && if(lock.isFair() ==
false);
	
	public UnfairLockAspect()
	{
		super(false);
	}
}

aspect FairLockAspect extends LockAspect
{
	pointcut fair(Lock lock): @within(lock) && if(lock.isFair() ==
true);
	
	public FairLockAspect()
	{
		super(true);
	}
}




-----Original Message-----
From: aspectj-users-bounces@xxxxxxxxxxx
[mailto:aspectj-users-bounces@xxxxxxxxxxx] On Behalf Of Andy Clement
Sent: Thursday, February 09, 2006 7:18 AM
To: aspectj-users@xxxxxxxxxxx
Subject: Re: [aspectj-users] Why does every Aspect (pertarget(..)) add
fieldsand interfaces to classes which are not targeted??

On 08/02/06, Jody Brownell <jody.brownell@xxxxxxxxxx> wrote:
> Hello.
>
> I am writing a series of small POC Aspects which revolve around
various
> annotations. I just noticed while debugging that classes not annotated
with
> the designated annotations have some extraneous fields/interfaces
injected
> during the weaving process.
>
> I was hoping someone could explain what it is, why they are there and
how I
> can trim the resulting class files during weaving to be as nimble as
> possible - i.e. remove all the extra fields / interfaces from classes
which
> *SHOULD* not be effected by aspects in the first place. Don't get me
wrong -
> I understand the need for injecting fields, methods and such to
support the
> runtime - but why on classes which have explicitly not been targeted
with an
> aspect. Looking at the name (interface
FairLockAspect$ajcMightHaveAspect )
> implies this is a forward compatibility feature. Is there a quick way
to
> turn this off? I tried the "not reweavable" option in eclipse
preferences -
> but that did not help J (I am grabbing at straws)

The interface is there because instances of the object in question may
have an aspect instance associated with them according to the
pointcuts and pertarget clause used by your aspects.  Under bug number
75442 we did some work to reduce the set of types that are marked
through some extra analysis of the pointcuts/perclause - that was
shipped in AspectJ1.5.0M3.  However, there are certain patterns of
usage (some combination of call and pertarget I think) that make it
very tough to work out what may or may not have an aspect instance at
runtime.

You can't turn this off - the best you can do is alter your
pointcut/perclause definition to limit the effects of it - reducing
the set of types that might have an aspect instance at runtime.  The
interface is attached so that code in the aspect that needs to
determine the aspect instance can rely on certain methods being
implemented by types and so easily manipulate them.

> Thanks for the Help!!!! Sorry if I am on crack and have missed
something
> real obvious J

Can you supply concrete examples of the pointcuts and perclause for a
typical case where you observe this happening?

Andy.