RFR: 8224167: Refactor PtrQueue completed buffer processing

[Thomas Schatzl]

Hi,

On Mon, 2019-05-20 at 17:15 -0400, Kim Barrett wrote:
> Please review this change to how PtrQueue handles completed (full)
> buffers.  The code has been refactored to have a new virtual function
> [...]
> 
> Shenandoah is affected by this refactoring, and has been updated
> accordingly, but I've only very lightly tested it.
> 
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8224167
> 
> Webrev:
> http://cr.openjdk.java.net/~kbarrett/8224167/open.00/
> 
> Testing:
> mach5 tier1-5
> Local (linux-x64) hs-tier1 with shenandoah included.
> 

  thanks for this cleanup. Looks good.

Thomas