Re: [aspectj-users] Re:

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

> I also found that AspectJ puts an instance variable and interface on
> EVERY class, regardless of whether the class actually contains a
> @ReadLock or @WriteLock annotated method. It should be able to
> statically identify the classes that can possibly be affected, and
> only weave those classes.

Aspectj seems to need some extra help forcing proper discrimination of which 
classes to weave.... See

http://dev.eclipse.org/mhonarc/lists/aspectj-users/msg05419.html

For me - do the following worked. I had a class level @Lock with method level 
@Lock.Read or @Lock.Write annotations. The key was using the class level Lock 
to perform proper discrimination.

Change

  pointcut readLock(): execution(@Lock.Read * * (..));
  pointcut writeLock(): execution(@Lock.Write * * (..));

to

  pointcut readLock(): execution(@Lock.Read * (@Lock *).*(..));
  pointcut writeLock(): execution(@Lock.Write * (@Lock *).*(..));


hope this helps.

On Monday 24 April 2006 14:03, Howard Lewis Ship wrote:
> FYI: using my aspect as is, and it does look proper, I get
> IllegalMonitorStateException inside my tests. Pulling out the aspect
> and putting the same code in place manually does not. To me, this
> means that something is going on inside AspectJ-generated code that is
> not correct.
>
> I also found that AspectJ puts an instance variable and interface on
> EVERY class, regardless of whether the class actually contains a
> @ReadLock or @WriteLock annotated method. It should be able to
> statically identify the classes that can possibly be affected, and
> only weave those classes.
>
> On 4/24/06, Howard Lewis Ship <hlship@xxxxxxxxx> wrote:
> > I'm writing some synchronization aspects now.
> >
> > I want to annotation methods with @ReadLock or @WriteLock and have the
> > annotation manage the lock.
> >
> > So far, so good:
> >
> > package org.apache.tapestry.internal.aspects;
> >
> > import java.util.concurrent.locks.ReadWriteLock;
> > import java.util.concurrent.locks.ReentrantReadWriteLock;
> >
> > import org.apache.tapestry.internal.annotations.ReadLock;
> > import org.apache.tapestry.internal.annotations.WriteLock;
> >
> > /**
> >  * Associates a {@link java.util.concurrent.locks.ReadWriteLock} with
> > an object instance; the
> >  * {@link ReadLock} and {@link WriteLock} annotations drive this.
> > Methods that have the ReadLock
> >  * annotation witll be advised to obtain and release the read lock
> > around their execution. Methods
> >  * with the WriteLock annotation will obtain and release the write
> > lock around their execution.
> >  * Methods with ReadLock that call a WriteLock-ed method (within the
> > same instance) will release the
> >  * read lock before invoking the WriteLock-ed method.
> >  * <p>
> >  * This aspect also enforces that the annotations are only applied to
> > instance (not static) methods.
> >  *
> >  * @author Howard M. Lewis Ship
> >  */
> > public abstract aspect Synchronization extends AbstractClassTargetting
> > perthis(readLockMethods() || writeLockMethods())
> > {
> >     private final ReadWriteLock _lock = new ReentrantReadWriteLock();
> >
> >     declare error :
> >         targetClasses() &&
> >         execution(@(ReadLock || WriteLock) static * *(..)) :
> >             "ReadLock and WriteLock annotations may only be applied to
> > instance methods.";
> >
> >     declare error :
> >         targetClasses() &&
> >         execution(@ReadLock @WriteLock * *(..)) :
> >             "A method may be annotated with ReadLock or with WriteLock
> > but not both.";
> >
> >     pointcut readLockMethods() :
> >         targetClasses() &&
> >         execution(@ReadLock * *(..));
> >
> >     pointcut writeLockMethods() :
> >         targetClasses() &&
> >         execution(@WriteLock * *(..));
> >
> >     /** Before read lock methods, acquire the read lock. */
> >     before() : readLockMethods()
> >     {
> >         _lock.readLock().lock();
> >     }
> >
> >     /** After read lock methods (including thrown exceptions), release
> > the read lock. */
> >     after() : readLockMethods()
> >     {
> >         _lock.readLock().unlock();
> >     }
> >
> >     /**
> >      * Before write lock methods, acquire the write lock. Note that
> > obtaining the write lock will
> >      * block indefinately if the current thread has a read lock, but
> > we handle that as a special
> >      * case.
> >      */
> >
> >     before(): writeLockMethods()
> >     {
> >         _lock.writeLock().lock();
> >     }
> >
> >     /** And release the write lock after the method completes
> > (successfully, or with an exception). */
> >     after() : writeLockMethods()
> >     {
> >         _lock.writeLock().unlock();
> >     }
> >
> > }
> >
> >
> > Here's my new issues:
> >
> > 1. Using perthis() creates the aspect instance dynamically, but I'm
> > worried that it uses a synchronized block that will serialize my
> > methods after all the effort I've put in to make them highly parallel
> > (using the readwrite lock).
> >
> > 2. One very important case is not coverred:
> >
> > If a method with @ReadLock invokes a method OF THE SAME INSTANCE with
> > @WriteLock, then we need to release the read lock before we invoke the
> > write lock method, then re-obtain the read lock afterwards.  This
> > feels like something you would do with cflow(), but I can't figure out
> > how to bind to an instance, rather than a type.
> >
> > BTW, I'm finding the combintation of Aspects and Annotations to be
> > very powerful.
> > Using annotations to mark types or methods works well in combintaion
> > with a base aspect that defines an abstract targetClasses() pointcut.
> > Concrete aspects provide a specific set of classes for targetClasses()
> > and the annotation matching does the rest.
> >
> > Thanks in advance!
> > --
> > Howard M. Lewis Ship
> > Independent J2EE / Open-Source Java Consultant
> > Creator, Jakarta Tapestry
> > Creator, Jakarta HiveMind
> >
> > Professional Tapestry training, mentoring, support
> > and project work.  http://howardlewisship.com
>
> --
> Howard M. Lewis Ship
> Independent J2EE / Open-Source Java Consultant
> Creator, Jakarta Tapestry
> Creator, Jakarta HiveMind
>
> Professional Tapestry training, mentoring, support
> and project work.  http://howardlewisship.com
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