RFR(S): Ensure collection set and cset map are consistent, and a few cleanup

[Aleksey Shipilev]

On 05/31/2017 08:04 PM, Zhengyu Gu wrote:
> Added collection set/cset fast test verification code, and restricting access to
> cset fast test map to ensure they are consistent.
> 
> Also, eliminated unused parameters in ShenandoahPolicy code, plus a few cleanup.
> 
> We might want to get rid of region cache in collection set. instead, just have
> collection set to wrap around cset fast test. I will experiment this later.
> 
> Webrev:
> http://cr.openjdk.java.net/~zgu/shenandoah/cset_cleanup/webrev.00/index.html

Excellent, this always disturbed me.

 *) This looks okay, but chf's partial would trade that "int* connections"
parameter for "ShConnMatrix*". I think that leaving this cleanup alone helps chf
to not to rebase much:

 189   virtual void choose_collection_set(ShenandoahCollectionSet*
collection_set, int* connections=NULL);

 *) Is removal of this branch meaningful? It was supposed to avoid some stores:

 228         if (!r->is_root()) {
 229           r->set_root(true);
 230         }

 *) I don't think looped partial GC belongs in this change. Split it out?

Thanks,
-Aleksey