RFR 8223065: Add jcmd to get the listen address of the debugger

[Chris Plummer]

Hi Ralf,

I think print_debug_listen_address() should have some exception checking 
added after the java calls.

I'm a little unsure why you modified DebugOnCmdStartDCmd to use 
print_debug_listen_address(), but still have a fallback to print the 
specified transport and address. If anything I would have written a 
get_debug_listen_address() and used it to verify that the specified and 
actual addresses end up being the same (and then also make 
print_debug_listen_address() use this API).

I'm also unsure of your ThreadToNativeFromVM change. This is not an area 
I understand well, so best to get someone else to ok it.

You need to update copyright date to 2019.

Can you write a test for this new dcmd. You can probably just extend 
OnJcmdTest.java.

thanks,

Chris

On 4/29/19 8:31 AM, Schmelter, Ralf wrote:
> Thanks for the review.
>
> I've update the webrev to use explicit NULL checks: https://bugs.openjdk.java.net/browse/JDK-8223065
>
> And I now use the pointer to the first byte in the result to split the property value, since I might need the calculate the pointer past the last character (if the prop ends with ':').
>
> I cannot see the SEGV, but I've scheduled the patch to be tested in our nightly build again, so maybe I can reproduce it there.
>
> Best regards,
> Ralf