WIP: Rewrite examples with async.

[rubdos]

Motivation

We would love to get community involvement in this work. There is a lot to do. The best way to get involved is to:

The examples should be updated to idiomatic async / await syntax.

The first alpha release will happen once the examples have been updated.

Solution

I started rewriting the examples using the new #[tokio::main] and async and await keywords. I will have every example in it's own commit, such that you can cherry pick what you'd like to keep.

I'm on Gitter and IRC, so feel free to ping me there.

[rubdos]

I think these three examples are as far as it gets right now:

• Anything TCP basically depends on Streams (i.e., incoming feature for tokio-tcp), which is to be decided. Without the incoming feature, you need to manually use the poll_accept method, which is quite counter productive.
• Codecs still seem to be broken, and they also depend on Streams and Sinks.

I'll still have a look at blocking.rs and manual_runtime.rs, but especially the latter is not my personal use case, so I might have no clue :-)

Everything else seems to fall in the above categories.

[rubdos]

blocking.rs depends on a threadpool's block_on_all, which is currently still commented out.

[rubdos]

manual_runtime.rs depends on timer support, but that's soon there.

[carllerche]

Thanks for doing this work.

re: incoming, I would rewrite the examples to not use streaming (which works better with async / await). For example:

let listener = TcpListener::bind(...)?;

loop {
    let (socket, _) = listener.accept().await?;
    // do something with the socket.
}

I'll review the rest shortly. Thanks again.

[blckngm]

I updated the proxy example in the TCP split PR: link, but did not include it eventually. The usage of incoming can be replaced with accept. But it also needs try_join.

[rubdos]

I updated the proxy example in the TCP split PR: link, but did not include it eventually.

Mind recovering that commit and filing a merge request on my merge request? I'm not sure whether I can pull that commit of GH. Commit is 0b1608c

[rubdos]

Hmm, I have the commit now, but there's a lot of things going on that I'm afraid to touch without permission for proxy:

• tokio-tcp requires default = ["incoming"]
• tokio requires futures-preview = "0.3.0-alpha.16"

EDIT: cfr commit 4487254

[rubdos]

Thanks for doing this work.

re: incoming, I would rewrite the examples to not use streaming (which works better with async / await). For example:

let listener = TcpListener::bind(...)?;

loop {
    let (socket, _) = listener.accept().await?;
    // do something with the socket.
}

I'll review the rest shortly. Thanks again.

You didn't mean to rewrite the Tcp examples with fn accept(), right? Because I cannot find any accept() :-)

error[E0599]: no method named `accept` found for type `tokio_tcp::listener::TcpListener` in the current scope
  --> tokio/examples/proxy.rs:48:29
   |
48 |         let stream = socket.accept().await.unwrap()?;
   |                             ^^^^^^

[carllerche]

@rubdos You are correct! I have a branch in progress, but I ended up going into a yak shave as the necessary tooling to write tests weren't in place yet. I will try to get that up today.

[blckngm]

Hmm, I have the commit now, but there's a lot of things going on that I'm afraid to touch without permission for proxy:

* `tokio-tcp` requires `default = ["incoming"]`

* `tokio` requires `futures-preview = "0.3.0-alpha.16"`

EDIT: cfr commit 4487254

Yeah, maybe it's not time yet. It can be adopted once the incoming/accept method is settled, and try_join is implemented or allowed to be imported from futures/futures-utils.

Also, feel free to come up with something entirely different. It's by no means the only way to write this example.

[carllerche]

I have posted #1242.

[rubdos]

Nice! Expect TCP examples coming in tonight!

[carllerche]

Going to move forward with this as is. Follow up work can happen in new PRs. Thanks again 👍