On 01/22/2013 06:08 PM, Joel Borggrén-Franck wrote:
Hi,
On Jan 22, 2013, at 6:01 PM, Peter Levart <peter.lev...@gmail.com> wrote:
On 01/22/2013 01:47 PM, Joel Borggrén-Franck wrote:
Hi Peter,
Thanks for your comments, see inline,
On 01/19/2013 06:11 PM, Peter Levart wrote:
I see, there is a dilema how to cache type annotations. To satisfy
single-annotation-returning methods and repeating annotation logic, a
HashMap would be a logical choice, but it has much bigger footprint than
simple arrays of annotations...
I don't prioritize footprint for classes that have runtime visible type
annotations. Those classes should be very few, and as a user you are making an
explicit choice of adding metadata when you use runtime visible (type)
annotations.
So here is my list of priorities (and by un-annotated I mean without runtime
visible annotations):
- Unannotated classes/fields/methods should have as small as possible extra
footprint, this is most important.
Hello Joel,
I imagine there will be additional places where references to Map<Class<? extends
Annotation>, Annotation> will be added to hold cached annotations. To satisfy your priority #1
I would consistently make sure that when there are no annotations to put into the map, a singleton
Collections.emptyMap() reference is put in place. This is currently not so for regular annotations
(should be corrected). I know of runtime tools that "scan" classes for particular
annotations, just to find out that majority of them are without annotations. If empty instances of
HashMap(16) pop-up as a result of such scan, lots of memory is wasted.
Good suggestion.
- Classes/fields/methods without type annotations should have negligible
footprint over classes/fields/methods with only regular annotations.
You meant "Classes/fields/methods *with* type annotations should have negligible
footprint over classes/fields/methods with only regular annotations", right?
No :)
As I suspect class/filed/methods with runtime visible regular annotations will
be 100x (or 1000x??) more common than with runtime visible type annotations the
most common scenario will be
1) No annotations
2) Only regular annotations
So there should be very little overhead from having no type annotations. IE in
the order of an extra pointer that is null.
Ah, I understand that sentence now ;-).
... extra pointer that is null (not cached yet) or
Collections.emptyMap() (cached but empty)....
Regards, Peter
cheers
/Joel
