RFR: 8238665: Add JFR event for direct memory statistics

[Alan Bateman]

On 05/03/2020 15:19, Denghui Dong wrote:
> Hi Alan and Erik,
>
> Sorry, I'm not sure if I fully understand what you mean.
> For this feature, I still think exporting jdk.internal.access to jdk.jfr is a good solutionsince there are
> some other packages has already exported to jdk.jfr in this module.
I think it would be cleaner to put a helper in jdk.internal.misc so that 
JFR has access to the counters for each of the buffer pools. That would 
avoid additional plumbing when you extend it to mapped buffers. As I 
mentioned in one of the other mails, 
ManagementFactoryHelper.getBufferPoolMXBeans() could be changed to use 
it too. From the perspective of java.base then it's a lot nicer as 
anyone touching the buffer code doesn't need to have to concerned with 
direct access from code in java.management and jdk.jfr.

-Alan