RFR: 8071462: Remove G1ParGCAllocator::alloc_buffer_waste

[Thomas Schatzl]

Hi,

On Fri, 2015-04-17 at 14:23 +0300, Michail Chernov wrote:
> Hi Thomas,
> 
> Thanks for looking!
> 
> On 17.04.2015 14:08, Thomas Schatzl wrote:
> > Hi Michail,
> >
> > On Wed, 2015-04-15 at 21:42 +0300, Michail Chernov wrote:
> >> Hi Thomas,
> >>
> >> I tried to make all what you said.
> >> Webrev: http://cr.openjdk.java.net/~dpochepk/~mchernov/8071462/webrev.02/
> >>
> >> ParGCAllocBuffer::add_undo_waste and
> >> ParGCAllocBuffer::undo_last_allocation were made as protected members.
> >>
> >> ParGCAllocBuffer::undo_allocation now does the same as
> >> ParScanThreadState::undo_alloc_in_to_space and
> >> G1ParGCAllocator::undo_allocation
> >>
> >> G1ParGCAllocator has virtual G1PLABWasteStat wasted() = 0; method which
> >> must be implemented in all heirs.
> >>
> >> Introduced new class G1PLABWasteStat (g1Allocator.hpp) that retrieves
> >> wasted and undo wasted values from allocation buffers. If new class is
> >> not acceptable there, I can add 2 virtual methods to G1ParGCAllocator
> >> for retrieving wasted and undo wasted values.
> >    some comments:
> >
> > - Introduction of G1PLABWasteStat fine with me, although I would not add
> > an extra type just for two values to be returned.
> Should I create 2 separate virtual method to get wasted and undo wasted 
> values? Or I can use Pair template which is from utilities/pair.hpp.

Just two parameters which are passed by reference (we typically use
pointers but I do not mind either) would be fine, that's why I said it
would be preferable to me in this situation :) The struct isn't that
much used (actually only in this place) and seems to add a lot of
unnecessary boiler plate code just for transferring that information in
this single place.

Thanks,
  Thomas