RFR 8199868: Support JNI critical functions in object pinning API

[Aleksey Shipilev]

On 04/04/2018 07:47 PM, Zhengyu Gu wrote:
> Please review this patch that adds JNI critical native support to object pinning.
> 
> Shenandoah does not block GC while JNI critical session is in progress. This patch allows it to pin
> all incoming array objects before critical native call, and unpin them after call completes.
> 
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8199868
> Webrev: http://cr.openjdk.java.net/~zgu/8199868/webrev.00/

Looks good to me, but somebody more savvy with runtime stub generation should take a closer look.

*) Should probably be "Why we are here?"

2867   assert(Universe::heap()->supports_object_pinning(), "Why we here?");

2876   assert(Universe::heap()->supports_object_pinning(), "Why we here?");


Thanks,
-Aleksey