THRIFT-5283: add support for Unix Domain Sockets in lib/rs

[tokcum]

Client: rs

The Thrift crate does not support Unix Domain Sockets (UDS). After reviewing and expressing my thoughts on THRIFT-5283, I added support for UDS.

This is not a breaking change. Inspired by how actix_web::HttpServer supports UDS, I added an additional fn to listen to UDS. I reorganized some other existing code to be able to reuse it for UDS. I also had to implement the trait TIoChannel for UnixStream. This went to transport::socket.

As UnixStream is only available on Unix, I tagged the code with #[cfg(unix)]. I also cross compiled lib/rs to Windows with the following cargo targets:

i686-pc-windows-gnu
i686-pc-windows-msvc
x86_64-pc-windows-gnu
x86_64-pc-windows-msvc

Last but not least I ran the rust <-> rust test harnesses as well as the cross test harnesses. This looks good. At least, my contribution didn't introduce new fails.

• Did you create an Apache Jira ticket?
  -> already existed as THRIFT-5283
• If a ticket exists: Does your pull request title follow the pattern "THRIFT-NNNN: describe my issue"?
• Did you squash your changes to a single commit? (not required, but preferred)
• Did you do your best to avoid breaking changes?
  -> not a breaking change.

[tokcum]

I tried to figure out why one of the Travis CI jobs failed. To be honest, I've no clue. I do not see a connection to the PR.

[tokcum]

Actually this PR is a blocker for my osquery-rust crate. I appreciate any feedback on how to bring this PR forward.

[allengeorge]

Looks good! Suggest replacing use of comparison with "" with Option and if let for the UDS usages.

Thank you!

[tokcum]

Looks good! Suggest replacing use of comparison with "" with Option and if let for the UDS usages.

Thank you!

Thanks Allen, will do and update PR.

[tokcum]

Looks good! Suggest replacing use of comparison with "" with Option and if let for the UDS usages.

Thank you!

Surprisingly the linter discouraged me to use if let and pointed me to .is_none() just to complain again and proposing a match statement. This didn't happen when I compiled with cargo build but when I used make to run the tests. It looks like additional rules apply depending on which tools are used.

Just for reference, the two messages I received where:

error: redundant pattern matching, consider using `is_none()`

error: You checked before that `unwrap()` cannot fail. Instead of checking and unwrapping, it's better to use `if let` or `match`.

So I used the match statement.

[allengeorge]

@tokcum Sorry for the delay, and thank you so much for your contribution!