Now the defaults are:
+ org.aspectj.apache.bcel.useSingleRepositoryInstance (default: false)
+ org.aspectj.apache.bcel.useUnavailableClassesCache (default: false)
+ org.aspectj.apache.bcel.ignoreCacheClearRequests (default: false)

I.e. the new caching optimisations are opt-in instead of opt-out as
originally designed. This might change in the future, but for now
without any additional tests and experience with the new feature let us
be conservative and make the build green first.

I also added a few more code review findings concerning backward
compatibility, which was less than 100% even with all three flags
deactivated.

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>

In our project we found out that during the build up of the spring context
the class loading takes a very long time.
Root cause is the huge amount of file I/O during pointcut class loading.
We are taking about ~250k file loads.

With these changes we managed to cut down the starting time by around 50%.

What we found out is that IMHO - the clear method of the ClassLoaderRepository
is called far too often -> in our settings this resulted in not a single cache
hit as the cache got cleared permanently.
Therefore we de-actived the cache clear calls inside the ClassLoaderRepository.

Secondly we changed the Java15AnnotationFinder in a way to not always create
new objects for the ClassLoaderRepository but re-use one static instance.
Otherwise we experienced >100k objects being created.

Last but not least we introduced a cache for unavailable classes so that
they do not have to be looked up using file I/O over and over again.

The whole behavior is configurable via
+ org.aspectj.apache.bcel.useSingleRepositoryInstance (default: true)
+ org.aspectj.apache.bcel.useUnavailableClassesCache (default: true)
+ org.aspectj.apache.bcel.ignoreCacheClearRequests (default: true)

Signed-off-by: Stefan Starke <stefan@starkeweb.org>
Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>

Trailing whitespaces are useless. Most of code-styles forbids them. Most of editors always trim them on save.
I propose to clean up project from trailing whitespaces in all java files at once.

StringBuffer is a legacy synchronized class. StringBuilder is a direct replacement to StringBuffer which generally have better performance.

Signed-off-by: Lars Grefer <eclipse@larsgrefer.de>

Multiple changes here:
- annotation unpacking is smarter and if it only needs runtime
  retention annotations it uses reflection and doesn't unpack the
  bytes to discover class level retention annotations.
- Reflection worlds are shared if for the same classloader.

The ANT targets in build.xml will still enable transformation of the packaging from org.aspectj.apache to org.apache for diffing with a new BCEL version, should one ever appear.