tower-rs/tower tower-0.4.0

Tower 0.4.0

on GitHub

This is a major breaking release including a large number of changes. In
particular, this release updates tower to depend on Tokio 1.0, and moves all
middleware into the tower crate. In addition, Tower 0.4 reworks several
middleware APIs, as well as introducing new ones.

This release does not change the core Service or Layer traits, so tower
0.4 still depends on tower-service 0.3 and tower-layer 0.3. This means that
tower 0.4 is still compatible with libraries that depend on those crates.

Added

• make: Added MakeService::into_service and MakeService::as_service for
  converting MakeServices into Services (#492)
• steer: Added steer middleware for routing requests to one of a set of
  services (#426)
• util: Added MapRequest middleware and ServiceExt::map_request, for
  applying a function to a request before passing it to the inner service
  (#435)
• util: Added MapResponse middleware and ServiceExt::map_response, for
  applying a function to the Response type of an inner service after its
  future completes (#435)
• util: Added MapErr middleware and ServiceExt::map_err, for
  applying a function to the Error returned by an inner service if it fails
  (#396)
• util: Added MapResult middleware and ServiceExt::map_result, for
  applying a function to the Result returned by an inner service's future
  regardless of whether it succeeds or fails (#499)
• util: Added Then middleware and ServiceExt::then, for chaining another
  future after an inner service's future completes (with a Response or an
  Error) (#500)
• util: Added AndThen middleware and ServiceExt::and_then, for
  chaining another future after an inner service's future completes successfully
  (#485)
• util: Added layer_fn, for constructing a Layer from a function taking
  a Service and returning a different Service (#491)
• util: Added FutureService, which implements Service for a
  Future whose Output type is a Service ([#496])
• util: Added BoxService::layer and UnsyncBoxService::layer, to make
  constructing layers more ergonomic (#503)
• layer: Added Layer impl for &Layer (#446)
• retry: Added Retry::get_ref, Retry::get_mut, and Retry::into_inner
  to access the inner service (#463)
• timeout: Added Timeout::get_ref, Timeout::get_mut, and
  Timeout::into_inner to access the inner service (#463)
• buffer: Added Clone and Copy impls for BufferLayer (#493)
• Several documentation improvements (#442, #444, #445, #449, #487,
  #490, #506])

Changed

• All middleware tower-* crates were merged into tower and placed
  behind feature flags (#432)
• Updated Tokio dependency to 1.0 (#489)
• builder: Make ServiceBuilder::service take self by reference rather
  than by value (#504)
• reconnect: Return errors from MakeService in the response future, rather than
  in poll_ready, allowing the reconnect service to be reused when a reconnect
  fails (#386, #437)
• discover: Changed Discover to be a sealed trait alias for a
  TryStream<Item = Change>. Discover implementations are now written by
  implementing Stream. (#443)
• load: Renamed the Instrument trait to TrackCompletion (#445)
• load: Renamed NoInstrument to CompleteOnResponse (#445)
• balance: Renamed BalanceLayer to MakeBalanceLayer (#449)
• balance: Renamed BalanceMake to MakeBalance (#449)
• ready-cache: Changed ready_cache::error::Failed's fmt::Debug impl to
  require the key type to also implement fmt::Debug (#467)
• filter: Changed Filter and Predicate to use a synchronous function as
  a predicate (#508)
• filter: Renamed the previous Filter and Predicate (where Predicates
  returned a Future) to AsyncFilter and AsyncPredicate (#508)
• filter: Predicates now take a Request type by value and may return a
  new request, potentially of a different type (#508)
• filter: Predicates may now return an error of any type (#508)

Fixed

• limit: Fixed an issue where RateLimit services do not reset the remaining
  count when rate limiting (#438, [#439])
• util: Fixed a bug where oneshot futures panic if the service does not
  immediately become ready (#447)
• ready-cache: Fixed ready_cache::error::Failed not returning inner error types
  via Error::source (#467)
• hedge: Fixed an interaction with buffer where buffer slots were
  eagerly reserved for hedge requests even if they were not sent (#472)
• hedge: Fixed the use of a fixed 10 second bound on the hedge latency
  histogram resulting on errors with longer-lived requests. The latency
  histogram now automatically resizes (#484)
• buffer: Fixed an issue where tasks waiting for buffer capacity were not
  woken when a buffer is dropped, potentially resulting in a task leak (#480)

Removed

• Remove ServiceExt::ready.
• discover: Removed discover::stream module, since Discover is now an
  alias for Stream (#443)
• buffer: Removed MakeBalance::from_rng, which caused all balancers to use
  the same RNG (#497)