RFR: 8220240: Refactor shared dirty card queue

[Kim Barrett]

> On Mar 12, 2019, at 9:30 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
> 
> On Fri, 2019-03-08 at 19:20 -0500, Kim Barrett wrote:
>> 
>> CR:
>> https://bugs.openjdk.java.net/browse/JDK-8220240
>> 
>> Webrev:
>> http://cr.openjdk.java.net/~kbarrett/8220240/open.00/
>> 
>> I'll update copyrights before pushing.
> 
> Some very minor issues:
> 
> - g1DirtyCardQueue.hpp:70:71: superfluous linebreaks
> 
> - please add a sentence/comment what G1SharedDirtyCardQueue is at the
> declaration.
> 
> Looks good otherwise. Do not need to re-review these changes.
> 
> Thanks,
>  Thomas

Thanks.

I added the following comments:

+// A dirty card queue providing thread-safe enqueue.  A shared global
+// instance can be used for cases where a thread-local dirty card can't
+// be used.
 class G1SharedDirtyCardQueue {

and

+  // Thread-safe addition to shared logging buffer.
   void enqueue(void* card_ptr);