Update example echo - ready to merge

[liufuyang]

I tried to update this as well but not sure how to deal with that req.into_body().map(....

Perhaps you have some example to how me how to update this example?

[liufuyang]

how to deal with concat2 above, it also seems to be a function that is missing

"no method named concat2 found for type hyper::Body in the current scope"

[seanmonstar]

It looks like that was renamed to TryStreamExt::try_concat.

[liufuyang]

hmmm.. I tried to go with it, but not really sure how :P
Got some errors like this with my last commit c04d92f

error[E0277]: `(dyn hyper::rt::Stream<Item = std::result::Result<hyper::Chunk, std::boxed::Box<(dyn std::error::Error + std::marker::Send + std::marker::Sync + 'static)>>> + std::marker::Send + 'static)` cannot be shared between threads safely
  --> examples/echo.rs:78:10
   |
78 |         .serve(service);
   |          ^^^^^ `(dyn hyper::rt::Stream<Item = std::result::Result<hyper::Chunk, std::boxed::Box<(dyn std::error::Error + std::marker::Send + std::marker::Sync + 'static)>>> + std::marker::Send + 'static)` cannot be shared between threads safely
   |

[seanmonstar]

Okay, I checked out the branch, and finally understand the giant error messages. They're very confusing, but ultimately, since there was an await inside the match req.uri(), the await was forcing one of the state machine steps to own a borrow of &Request. Because of that, it was noticing the &Request is not Sync, thanks to the wrapped stream variant inside Body.

This will be very easy for users to bump into, and so probably I'll need to fix Body to require Sync...

[seanmonstar]

For reference, here's the issue in the rust-lang repo: rust-lang/rust#57017

[liufuyang]

Well that sounds complicated. Not sure how much I could really understand but it's nice that you helping to solve it out :)

I rebased onto master, now I seem to have this issue:

error[E0599]: no method named `into_future` found for type `tokio_sync::mpsc::bounded::Receiver<_>` in the current scope
   --> src/client/connect/dns.rs:134:14
    |
134 |             .into_future()
    |              ^^^^^^^^^^^
    |
    = note: the method `into_future` exists but the following trait bounds were not satisfied:
            `&mut tokio_sync::mpsc::bounded::Receiver<_> : futures_util::stream::StreamExt`
            `&tokio_sync::mpsc::bounded::Receiver<_> : futures_util::stream::StreamExt`
            `tokio_sync::mpsc::bounded::Receiver<_> : futures_util::stream::StreamExt`

error: aborting due to previous error

[seanmonstar]

You may need to run cargo update to get the latest changes to tokio.

[liufuyang]

Hmmm... did that then I got this 😄

error[E0277]: `dyn std::error::Error` cannot be sent between threads safely
  --> examples/echo.rs:67:1
   |
67 | #[tokio::main]
   | ^^^^^^^^^^^^^^ `dyn std::error::Error` cannot be sent between threads safely
   |
   = help: the trait `std::marker::Send` is not implemented for `dyn std::error::Error`
   = note: required because of the requirements on the impl of `std::marker::Send` for `std::ptr::Unique<dyn std::error::Error>`
   = note: required because it appears within the type `std::boxed::Box<dyn std::error::Error>`
   = note: required because it appears within the type `std::result::Result<(), std::boxed::Box<dyn std::error::Error>>`

[liufuyang]

Oh cool, looks like I just need to add
async fn main() -> Result<(), Box<dyn std::error::Error + Send + Sync>> on the main. Nice.

[liufuyang]

looks like it is working now, let me tide up the PR a bit. Thanks for the help 😄

[liufuyang]

@seanmonstar Hey Sean, I have made this example work and cleanup the code a bit. Would you like take a look at it again? :)

[seanmonstar]

Thanks for continuing despite the difficulties!