Rather than consuming `self` and returning `(Self, _)`. This did mean
that a few crates that depended on `Ready` to own the `Service` and
provide it once it was ready had to change to call `poll_ready`
directly. Which in turn meant adding in some PhantomData<Request> so
that the impl blocks wouldn't be under-constrainted. Take, for example:
```
impl<K, S: Service<Req>, Req> Future for UnreadyService<K, S>
```
would fail to compile with
```
error[E0207]: the type parameter `Req` is not constrained by the impl trait, self type, or predicates
```
Calling a method on `Pin<&mut Self>` moves the pin, which means you can't call more methods later. The solution to this is to use `Pin::as_mut`. But it's annoying to have to do that to _every_ call to the `assert_request_eq!` helper macro from `tower-test`, so I made it do it for me.
* update tower-test to std::future
* refactoring tower-test tests
* everything works
* whoops, un-delete the tower dir
* cleanup & update links
* undo changes to tower-filter for this PR
* use pin_utils::unsafe_pinned
* use tokio-test
* Add a note about v0.3.x branch to the readme
Signed-off-by: Lucio Franco <luciofranco14@gmail.com>
* Fix link
Signed-off-by: Lucio Franco <luciofranco14@gmail.com>
Prior to this change, when `Balance` dropped a failing service, `Pool`
would not be notified of this fact. This meant that it never updated
`.services`, and so it might not add a new backing `Service` (e.g., due
to `max_services`) even though no working backing exist.
With this change, dropped services notify the `Pool` so that it knows to
re-check its limits. It also gains some much-needed tests.
Of particular note is that this change lets spans trace requests through `tower::Buffer` by internally carrying the `Span` at the time of `call` along with the request to the worker.
When using a `ServiceBuilder`, it's not possible to obtain the
underlying `Layer` implementation.
Adding a `ServiceBuilder::into_inner` allows callers to retrieve this
field instead of only being able to build a `Service`.
In 03ec4aa, the balancer was changed to make a quick endpoint decision.
This, however, means that the balancer can return NotReady when it does
in fact have a ready endpoint.
This changes the balancer to separate unready endpoints, only
performing p2c over ready endpoints. Unready endpoints are tracked with
a FuturesUnordered that supports eviction via oneshots.
The main downside of this change is that the Balancer must become
generic over the Request type.
As described in #286, `Balance` had a few problems:
- it is responsible for driving all inner services to readiness, making
its `poll_ready` O(n) and not O(1);
- the `choose` abstraction was a hinderance. If a round-robin balancer
is needed it can be implemented separately without much duplicate
code; and
- endpoint errors were considered fatal to the balancer.
This changes replaces `Balance` with `p2c::Balance` and removes the
`choose` module.
Endpoint service failures now cause the service to be removed from the
balancer gracefully.
Endpoint selection is now effectively constant time, though it biases
for availability in the case when random selection does not yield an
available endpoint.
`tower-test` had to be updated so that a mocked service could fail after
advertising readiness.
Lucio Franco
Jon Gjengset
Taiki Endo
John Doneth
Stan Bondi
Gabe Jackson
Oliver Gould