RFR[8239355]: '(dc) Initial value of SO_SNDBUF should allow sending large datagrams (macOS)'

[Patrick Concannon]

Hi,

I've included those additional changes, and they can be found in the new 
webrev below.

http://cr.openjdk.java.net/~pconcannon/8239355/webrevs/webrev.03/


Kind regards,

Patrick

On 11/03/2020 12:27, Daniel Fuchs wrote:
> Hi Alan,
>
> On 11/03/2020 12:08, Alan Bateman wrote:
>>> Do we really? I am not sure we do.
>>> We just want to verify that we don't get the "packet too large"
>>> exception caused by the SO_SNDBUF buffer being too small.
>> It would be great if we had a test to send large datagrams on the 
>> network as that is the only way to properly test that they can be 
>> re-assembled and received. I don't mind if it's a separate test, I 
>> agree it can be tricky on systems that have unusual configurations. 
>> I'm just pointing out that testing that the send doesn't fail and 
>> that the datagram can be received through the loopback may not be 
>> enough here.
> Our test doesn't even try to receive the datagram. It just sends it.
> We can write a new test that does the full roundtrip if you think
> it's worthwile.
>
>>> Yes and no - and the test is there to verify that it doesn't have any
>>> unexpected side effects (we know it shouldn't).
>> My preference would be to drop these so the test only runs twice. The 
>> reason is that the effect of setting java.net.preferIPv6Addresses is 
>> not widely known and it will confuse anyone that needs to maintain 
>> this test in the future.
>
> OK - then we can remove the preferIPv6Addresses property and replace:
>
>  114         populateDataProvider(testcases, datagramChannel, 
> MAX_PAYLOAD,
>  117                 null);
>
> with
>
>       if (hasIPv4())
>           populateDataProvider(testcases, datagramChannel, IPV4_SNDBUF,
>                      StandardProtocolFamily.INET);
>       if (hasIPv6() && !preferIPv4Stack())
>           populateDataProvider(testcases, datagramChannel, IPV6_SNDBUF,
>                      StandardProtocolFamily.INET6);
>
>
> to verify that the channel opened with the no-arg DatagramChannel.open()
> can be used to send both IPv4 and IPv6 datagrams.
>
> cheers,
>
> -- daniel