net: introduce split on UnixDatagram

[cssivision]

fix issue #2551

this pr can be closed if this is merged. #1757

[Darksonn]

I only had a quick look, but three things came to mind:

1. What about a by-ref split like in TcpStream?
2. What about naming? TcpStream calls its owned split into_split.
3. The owned tcp split closes the stream when the writer is dropped. Should we also do that here?

We currently have different naming conventions on split/into_split that we can't fix until v0.3 due to backwards compatibility. Still doesn't hurt to choose what we intend to converge on in v0.3 here.

See also the PR for owned split on TCP streams: #2270.

[cssivision]

I only had a quick look, but three things came to mind:

1. What about a by-ref split like in TcpStream?
2. What about naming? TcpStream calls its owned split into_split.
3. The owned tcp split closes the stream when the writer is dropped. Should we also do that here?

We currently have different naming conventions on split/into_split that we can't fix until v0.3 due to backwards compatibility. Still doesn't hurt to choose what we intend to converge on in v0.3 here.

See also the PR for owned split on TCP streams: #2270.

thanks for reviewing this pr. keep consistent with TcpStream's into_split is a good idea.

Is it necessary to add into_split for UdpSocket and UnixStream, and add split for UnixDatagram? if it's yes, i will fire another pr for this.

[Darksonn]

The issue with UdpSocket and UnixStream is that the function they already have called split does what TcpStream's into_split does, and that can only be fixed when we move to v0.3.

[cssivision]

it's ok to fix UnixStream and UdpSocket when reach v0.3. I will add split to UnixDatagram in another pr.

[cssivision]

activate

[Darksonn]

This looks reasonable at a first glance.

[carllerche]

Thanks 👍