This branch updates the Hyper dependency to 0.13 (and thus also updates
http/http-body), and updates all uses of AsyncRead and
AsyncWrite and tokio::net types to use the Tokio 0.2 versions.This
also implies updating bytes from 0.4 to 0.5. Unfortunately, this
change is rather massive, but all these dependencies are pretty tightly
coupled. It wasn't really possible to upgrade them incrementally the way
it was for code in Linkerd, at least not without forking and patching the
dependencies, which I wanted to avoid.

Note on Test Support

This branch also makes a great deal of changes to the test support code
in linkerd2-app-integration. This is necessary because this code no
longer compiled after updating Hyper and the IO traits. When practical,
I've tried to make this a direct translation of the existing code.

I think there's a lot of opportunity to improve this code and reduce
complexity. In particular, the test-support clients work by spawning a
background thread with a Tokio runtime on it, and sending work to that
task and responses back over channels. This is so we can present a
synchronous API to the tests themselves, and write straight-line code in
tests rather than nested futures. In an async/await world, that's kind
of unnecessary. We could switch the integration tests to be async
functions written using #[tokio::test], and remove the complexity of
managing multiple background threads and runtimes for each test client
(and server). We would probably still want to isolate the test proxy
in its own runtime as we do currently, but we could run all the test
support code in the main test thread's runtime and not have to do all
this messing around with threads and channels.

However, I didn't do this kind of refactoring in this PR, beyond adding
async versions of some of the existing test support APIs (which still
use channels internally). These were added for use in tests which have
to call into async APIs from other crates and therefore need to be
async fns. I wanted to avoid totally rewriting the test support code
in this branch, however, since it's already a huge change.

Note on IO Trait Changes

The BoxedIo trait used to have a special shutdown_write method that
would call std::net::TcpStream::shutdown(Shutdown::Write). This was
added because Tokio 0.1's <TcpStream as AsyncWrite>::shutdown did
not call this method; it simply returned Ok(()). However, Tokio
0.2's <TcpStream as AsyncWrite>::poll_shutdown does call
std::net's TcpStream::shutdown. Since BoxedIo was ported directly
from the 0.1 code and still called both AsyncWrite::poll_shutdown
and Io::shutdown_write, we would try to shut down the stream twice,
and the second call would fail with a "transport endpoint is not
connected" error. This broke the tls_accept tests, which expected
there to be no error.

This commit removes the Io::shutdown_write method, since Tokio's
TcpStream now does what we want.

Signed-off-by: Eliza Weisman [email protected]