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Date: Tue, 14 Nov 2006 15:31:07 +0300
From: "Alexei Zakharov" <alexei.zakharov@gmail.com>
To: harmony-dev@incubator.apache.org
Subject: Re: [classlib] Using Aspects for Tracing
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References: <fc2fc95c0611140357h605aa478x1753be21a176ef76@mail.gmail.com>

Sian,

Cool! Thanks for this. Can AspectJ be used for something more
sophisticated than just tracing? For application-level logging for
example?

Thanks,

2006/11/14, Sian January <sianjanuary@googlemail.com>:
> Hello,
>
> Following a recent discussion on this list I have been looking into how
> aspects could be used for tracing in the Harmony class library code.  I have
> been using AspectJ and have written a really simple tracing aspect for the
> math module, adapted the build.xml script and written some instructions on
> how to apply it.  At the moment the aspect just does entry and exit tracing
> and prints to System.out, but this is because it's a first draft - it is
> possible to do more targeted tracing and to use frameworks such as
> java.util.logging with aspects.
>
> Steps to follow:
>
>
> 1. Download AspectJ from
> http://www.eclipse.org/aspectj/downloads.php
>
> 2. Copy aspectjrt.jar to /depends/jars/aspectj/
>
> 3. Copy aspectjtools.jar and aspectjrt.jar to ANT_HOME/lib and if using
> Eclipse add both of these to your ant runtime configuration (Window >
> Preferences > Ant > Runtime > Add...)
>
> 4. Edit build file to use iajc* instead of javac and include aspect class
> files (or apply the buildxmlpatch.txt to build.xml in the math module)
>
> 5. Write a tracing aspect (or copy the one attached to
> modules\math\src\main\java\org\apache\harmony\tracing)
>
> 6. Re-build the module
>
> 7. Make sure to add aspectjrt.jar to the runtime classpath of whatever
> program you are running.
>
>
> * - iajc isn't incremental like javac in ant, it will always do a total
> rebuild.  Also if you switch from using iajc back to javac you will need to
> do a clean before you do a rebuild.
> Please also note that it's not possible to use this kind of tracing for any
> classes that are depended on by the AspectJ runtime or there will be errors
> initializing the classes because of circular dependencies.  However I think
> most modules apart from luni should be safe.  Also it's important to not
> trace methods that are called (directly or indirectly) by your tracing
> methods otherwise you will end up in an endless loop.
>
> If anyone thinks this information might be useful to have available
> somewhere I would be happy to expand it a bit for a web page or a Wiki page.
>
> Regards,
>
> Sian


-- 
Alexei Zakharov,
Intel Enterprise Solutions Software Division