RFR 8245194: Unix domain socket channel implementation

[Bernd Eckenfels]

I like the protocolFamily addition. Should it allow to differentiate between IPv6 socket bound to ipv4 address or in case of wildcard bound dual stack? (I sometimes had the desire in the path to see what the prefer Option and network libraries closed to use, so you can for example know if the listening shows up in socketstat as v4 or v6 address.


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http://bernd.eckenfels.net
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Von: nio-dev <nio-dev-retn at openjdk.java.net> im Auftrag von Michael McMahon <michael.x.mcmahon at oracle.com>
Gesendet: Friday, July 10, 2020 12:25:56 PM
An: Chris Hegarty <chris.hegarty at oracle.com>
Cc: nio-dev <nio-dev at openjdk.java.net>
Betreff: Re: RFR 8245194: Unix domain socket channel implementation



On 09/07/2020 15:14, Chris Hegarty wrote:


On 8 Jul 2020, at 11:07, Michael McMahon <michael.x.mcmahon at oracle.com<mailto:michael.x.mcmahon at oracle.com>> wrote:

...

My initial reaction to seeing verbiage like "Internet protocol socket” and “unix domain socket”, is how does one know what type of socket channel one has if passed an unbound channel? I wonder if a SocketChannel::protocolFamily method is worth adding? It could be used and linked to from some of the verbiage elsewhere to tighten the spec. There could also be some tie in here with inheritedChannel - if the protocol family is retrievable.
I did consider that question and had concluded that testing the type of the SocketAddress returned by getLocalAddress() would suffice for this. But, you're right that does not work for unbound channels. I'll add this to the API for now (for SocketChannel and ServerSocketChannel in the sandbox), to see what it looks like. Perhaps, for consistency it should be added to DatagramChannel too?

That works for me.

What is the signature of this method? `Optional<ProtocolFamily> protocolFamily()` - or something else? If not optional ( or null ), then what is the family of a channel created with the no-args open method? We had some offline discussion about UNSPEC, and if we add this method then it could be a reason to add an UNSPEC StandardProtocolFamily.


"public ProtocolFamily getProtocolFamily()"

I think a channel will always have a ProtocolFamily. So, it shouldn't need to be Optional<>

The value on the no-args call depends on the preferIPv4Stack setting. INET if set INET6 if not,
depending on which of IPv4/IPv6 are supported obviously. Do you think all of this would need
to be documented explicitly?

Michael

-Chris.
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