RFR (M/L): 8247928: Refactor G1ConcurrentMarkThread for mark abort (JDK-8240556)

[Kim Barrett]

> On Aug 21, 2020, at 9:44 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
> http://cr.openjdk.java.net/~tschatzl/8247928/webrev.0_to_1/ (diff)
> http://cr.openjdk.java.net/~tschatzl/8247928/webrev.1/ (full)

I started to review this, but I’m confused.  The baseline for webrev.1 doesn’t look like what’s
in the repository.  And I don’t see some other RFR that this is based on.  It looks like no other
version that I’ve seen.

One thing I noticed despite that:

It seems backward that the phase functions return true to indicate aborted,
overflow, or whatever, and return false for successful completion. And
there's no mention of what the return values are in the description in the
header file.