[PATCH 0/2] Class- and class loader-local storage (Bug ID #6493635)

[David M. Lloyd]

After running into the problem described in this bug for the umpteenth 
time, I decided to get off my duff and do something about it.

Following are two patches.  The first one adds the notion of class-local 
storage, and the second adds class loader-local storage; both mechanisms 
work basically the same way.  There's a map on the Class or ClassLoader 
that's lazily created, weakly keyed by an object which is private to the 
ClassLocal or ClassLoaderLocal instance.  The *Local instance itself has 
operations to read and write the values with operations similar to what one 
might find on Map and ConcurrentMap.

A possible future optimization might be to replace the simple 
synchronization I am using with a more complex mechanism (like one of the 
concurrent reference map implementations floating out there).

References:

   http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6493635
   http://crazybob.org/2006/12/caching-class-related-information.html
   http://weblogs.java.net/blog/jhook/archive/2006/12/class_metadata.html
   http://dmlloyd.blogspot.com/2009/02/class-local-data.html

- DML