It's possible that there's a memory leak in the Tokio 0.2 version of
`tokio::sync::watch`. This commit updates the service-profiles code to
use Tokio 0.3's version of watch, whose internals are significantly
different.

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

discovery::buffer also needs this
Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

turns out tower-rs/tower-http@926a64f
made it more or less impossible for us to use the
`tower-request-modifier` crate. it now returns services with `impl
FnOnce` in their types, so we can't return it from `NewService` or
`MakeService` impls.

i'll fix this upstream eventually but for now let's just pin to the
revision before it got that way.

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

this fixes error types not downcasting since different versions of h2
are in tree

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

tests and metrics also rely on h2 error downcasting

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

This branch updates the `linkerd2-drain` crate to use Tokio 0.3's
synchronization primitives, and replace the `oneshot` channel with
`watch` (removing the weird `future::Shared` nonsense).

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

…nto eliza/tokio-0.3

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

This tracks the change that added an `instrument` combinator in the main
`tracing` crate.

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

This branch updates `linkerd2-buffer`, and `linkerd2-proxy-discover`'s
`buffer` module to use Tokio 0.3's MPSC channel rather than Tokio 0.2's.
The rest of the proxy still uses Tokio 0.2, including the 0.2 runtime.

Most of the Tokio synchronization primitives lost their `poll`-based
interfaces in 0.3 as part of the move to intrusive lists of wakers for
synchronization primitives (see tokio-rs/tokio#2325,
tokio-rs/tokio#2509, and tokio-rs/tokio#2861). This change takes
advantage of the inherently pinned nature of `async fn` and `async`
blocks to avoid needing a separate heap allocation to store the waiter
state for a task waiting on a synchronization primitive. However, it
means that a synchronization primitive can _only_ be waited on when the
future that waits on it is pinned --- otherwise, there is a potential
dangling pointer. The `poll`-based APIs allowed waiting on
synchronization primitives from unpinned contexts, so they were removed.

To wait on the synchronization primitives from contexts that may not be
pinned, such as `poll_ready`, it's necessary to add a `Pin<Box<...>>`
around the future that's waiting on the synchronization primitive. This
ensures that the future will not move while it's part of the wait list.
It's important to note that this isn't an _additional_ allocation per
waiter versus Tokio 0.2; instead, it's the same allocation that would
have _always_ happened internally to the synchronization primitive in
the 0.2 API. Now, it's moved outside of the `tokio::sync` type so that
it can be avoided when used with `async`/`await` syntax, and added by
the user when polling the sync primitives.

Because we need to poll channel senders in `tower::Service`
implementations' `poll_ready` functions, it was necessary to introduce
our own bounded MPSC channel type that exposes a polling-based API. When
the buffer's channel is full, we want to exert backpressure in
`poll_ready`, so that callers such as load balancers could choose to
call another service rather than waiting for buffer capacity. This
branch adds a new `linkerd2-channel` crate that implements a pollable
bounded channel, wrapping `tokio::sync`'s unbounded MPSC and using a
`tokio::sync::Semaphore` to implement bounding. It's worth noting that
this is, essentially, how `tokio::sync::mpsc`'s bounded channel is
implemented --- it also uses the semaphore. However, our implementation
exposes a `poll_ready` method by boxing the future that waits to acquire
a semaphore permit, which the Tokio channel does not expose.

This was factored out of PR #732.

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

This branch updates the proxy to use Tokio 0.3 and the Tokio 0.3
versions of various ecosystem crates. This includes `tower` 0.4 and
`bytes` 0.6, as well as the Tokio 0.3 versions of `tokio-util`, `hyper`,
`tonic`, etc. Due to API changes in Tokio and in other dependencies, it
was necessary to make some code changes as well as updating
dependencies, but there should be no functional change.

In particular:
* Tokio's support for vectored IO changed significantly in 0.3, so this
  branch updates our use of `AsyncWrite` to participate in the new
  vectored write APIs
* Hyper's HTTP/1.1 upgrade API changed in 0.14, so this branch changes the
  proxy's code for handling CONNECT to use the new API
* Tokio removed support for some socket options, which now need to be
  set using `socket2`
* Tokio removed the `poll_ready` method was removed from the bounded
  MPSC channel, so the proxy's buffers (`linkerd2-buffer` and the
  `buffer` module in `linkerd2-proxy-discover`) had to be switched to
  our own implementation (this merged separately, in PR #759).

Several ecosystem crates have yet to be released, so we depend on them
via Git dependencies for now. The patches in Cargo.toml can be
removed as other dependencies publish their Tokio 0.3 versions.