use futures::{Future, IntoFuture, Poll}; mod and_then; mod apply; mod cell; mod fn_service; mod from_err; mod map; mod map_err; mod map_init_err; mod then; pub use self::and_then::{AndThen, AndThenNewService}; pub use self::apply::{Apply, ApplyNewService}; pub use self::fn_service::{FnNewService, FnService}; pub use self::from_err::{FromErr, FromErrNewService}; pub use self::map::{Map, MapNewService}; pub use self::map_err::{MapErr, MapErrNewService}; pub use self::map_init_err::MapInitErr; pub use self::then::{Then, ThenNewService}; /// An asynchronous function from `Request` to a `Response`. pub trait Service { /// Responses given by the service. type Response; /// Errors produced by the service. type Error; /// The future response value. type Future: Future; /// Returns `Ready` when the service is able to process requests. /// /// If the service is at capacity, then `NotReady` is returned and the task /// is notified when the service becomes ready again. This function is /// expected to be called while on a task. /// /// This is a **best effort** implementation. False positives are permitted. /// It is permitted for the service to return `Ready` from a `poll_ready` /// call and the next invocation of `call` results in an error. fn poll_ready(&mut self) -> Poll<(), Self::Error>; /// Process the request and return the response asynchronously. /// /// This function is expected to be callable off task. As such, /// implementations should take care to not call `poll_ready`. If the /// service is at capacity and the request is unable to be handled, the /// returned `Future` should resolve to an error. /// /// Calling `call` without calling `poll_ready` is permitted. The /// implementation must be resilient to this fact. fn call(&mut self, req: Request) -> Self::Future; /// Apply function to specified service and use it as a next service in /// chain. fn apply( self, service: I, f: F, ) -> AndThen> where Self: Sized, T: Service, I: IntoService, F: Fn(Self::Response, &mut T) -> Out, Out: IntoFuture, { self.and_then(Apply::new(service.into_service(), f)) } /// Call another service after call to this one has resolved successfully. /// /// This function can be used to chain two services together and ensure that /// the second service isn't called until call to the fist service have /// finished. Result of the call to the first service is used as an /// input parameter for the second service's call. /// /// Note that this function consumes the receiving service and returns a /// wrapped version of it. fn and_then(self, service: F) -> AndThen where Self: Sized, F: IntoService, B: Service, { AndThen::new(self, service.into_service()) } /// Map this service's error to any error implementing `From` for /// this service`s `Error`. /// /// Note that this function consumes the receiving service and returns a /// wrapped version of it. fn from_err(self) -> FromErr where Self: Sized, E: From, { FromErr::new(self) } /// Chain on a computation for when a call to the service finished, /// passing the result of the call to the next service `B`. /// /// Note that this function consumes the receiving service and returns a /// wrapped version of it. fn then(self, service: B) -> Then where Self: Sized, B: Service, Error = Self::Error>, { Then::new(self, service) } /// Map this service's output to a different type, returning a new service /// of the resulting type. /// /// This function is similar to the `Option::map` or `Iterator::map` where /// it will change the type of the underlying service. /// /// Note that this function consumes the receiving service and returns a /// wrapped version of it, similar to the existing `map` methods in the /// standard library. fn map(self, f: F) -> Map where Self: Sized, F: Fn(Self::Response) -> R, { Map::new(self, f) } /// Map this service's error to a different error, returning a new service. /// /// This function is similar to the `Result::map_err` where it will change /// the error type of the underlying service. This is useful for example to /// ensure that services have the same error type. /// /// Note that this function consumes the receiving service and returns a /// wrapped version of it. fn map_err(self, f: F) -> MapErr where Self: Sized, F: Fn(Self::Error) -> E, { MapErr::new(self, f) } } /// Creates new `Service` values. /// /// Acts as a service factory. This is useful for cases where new `Service` /// values must be produced. One case is a TCP servier listener. The listner /// accepts new TCP streams, obtains a new `Service` value using the /// `NewService` trait, and uses that new `Service` value to process inbound /// requests on that new TCP stream. /// /// Request - request handled by the service pub trait NewService { /// Responses given by the service type Response; /// Errors produced by the service type Error; /// The `Service` value created by this factory type Service: Service; /// Errors produced while building a service. type InitError; /// The future of the `Service` instance. type Future: Future; /// Create and return a new service value asynchronously. fn new_service(&self) -> Self::Future; /// Apply function to specified service and use it as a next service in /// chain. fn apply( self, service: I, f: F, ) -> AndThenNewService> where Self: Sized, T: NewService, I: IntoNewService, F: Fn(Self::Response, &mut T::Service) -> Out + Clone, Out: IntoFuture, { self.and_then(ApplyNewService::new(service, f)) } /// Call another service after call to this one has resolved successfully. fn and_then(self, new_service: F) -> AndThenNewService where Self: Sized, F: IntoNewService, B: NewService, { AndThenNewService::new(self, new_service) } /// `NewService` that create service to map this service's error /// and new service's init error to any error /// implementing `From` for this service`s `Error`. /// /// Note that this function consumes the receiving new service and returns a /// wrapped version of it. fn from_err(self) -> FromErrNewService where Self: Sized, E: From, { FromErrNewService::new(self) } /// Create `NewService` to chain on a computation for when a call to the /// service finished, passing the result of the call to the next /// service `B`. /// /// Note that this function consumes the receiving future and returns a /// wrapped version of it. fn then(self, new_service: F) -> ThenNewService where Self: Sized, F: IntoNewService>, B: NewService< Result, Error = Self::Error, InitError = Self::InitError, >, { ThenNewService::new(self, new_service) } /// Map this service's output to a different type, returning a new service /// of the resulting type. fn map(self, f: F) -> MapNewService where Self: Sized, F: Fn(Self::Response) -> R, { MapNewService::new(self, f) } /// Map this service's error to a different error, returning a new service. fn map_err(self, f: F) -> MapErrNewService where Self: Sized, F: Fn(Self::Error) -> E, { MapErrNewService::new(self, f) } /// Map this service's init error to a different error, returning a new service. fn map_init_err(self, f: F) -> MapInitErr where Self: Sized, F: Fn(Self::InitError) -> E, { MapInitErr::new(self, f) } } impl<'a, S, Request> Service for &'a mut S where S: Service + 'a, { type Response = S::Response; type Error = S::Error; type Future = S::Future; fn poll_ready(&mut self) -> Poll<(), S::Error> { (**self).poll_ready() } fn call(&mut self, request: Request) -> S::Future { (**self).call(request) } } impl Service for Box where S: Service + ?Sized, { type Response = S::Response; type Error = S::Error; type Future = S::Future; fn poll_ready(&mut self) -> Poll<(), S::Error> { (**self).poll_ready() } fn call(&mut self, request: Request) -> S::Future { (**self).call(request) } } impl NewService for F where F: Fn() -> R, R: IntoFuture, S: Service, { type Response = S::Response; type Error = S::Error; type Service = S; type InitError = E; type Future = R::Future; fn new_service(&self) -> Self::Future { (*self)().into_future() } } /// Trait for types that can be converted to a `Service` pub trait IntoService where T: Service, { /// Convert to a `Service` fn into_service(self) -> T; } /// Trait for types that can be converted to a Service pub trait IntoNewService where T: NewService, { /// Convert to an `NewService` fn into_new_service(self) -> T; } impl IntoService for T where T: Service, { fn into_service(self) -> T { self } } impl IntoNewService for T where T: NewService, { fn into_new_service(self) -> T { self } }