8234805: (dc) Remove JNI upcall from DatagramChannel.receive implementation

[Chris Hegarty]

> On 29 Nov 2019, at 07:36, Alan Bateman <Alan.Bateman at oracle.com> wrote:
> 
> On 28/11/2019 12:02, Chris Hegarty wrote:
>> :
>> Just a question. Is the use of ArraysSupport::vectorizedMismatch here
>> guaranteed to never return a tail (of elements to be checked)? If a
>> value other than -1 (no tail) is returned, it will not be seen by the
>> current code. If there is a guarantee of no tail (given the usage), then
>> maybe capture the value returned by vectorizedMismatch, and assert that
>> it is -1?
> That is a good observation and it's probably best that it tests the remaining bytes. I did have this initially it wasn't used due to the sizeof struct sockaddr_in6.
> 
> I've created a webrev, unfortunately I fat fingered the scp location so we copied over the original. The only change is to the method to compare the two SOCKETADDESSS structures and the comment on DCI.socketAddress that Daniel asked to be expanded to say that it guarded by readLock. Daniel asked for the test to print the network configuration but we decided this wasn't necessary, instead the right thing is for the jtreg failure handler to run ifconfig/equivalent to avoid every test needing to do this. Daniel also suggested the test should skip when there are no IPv4 addresses but this isn't necessary as it doesn't require an IPv4 address. The only change to the test is to filter out the wildcard address to avoid surprising configurations on Solaris where network interfaces appear to be plumbed with ::0. This test is only interesting in specific local addresses to make sure that the code in the change gets a bit of a work out (existing tests will exercise it too of course).
> 
> http://cr.openjdk.java.net/~alanb/8234805/webrev/

LGTM.

-Chris.