Slight optimization and docs

ntex-service/src/apply.rs

@@ -1,7 +1,8 @@
 #![allow(clippy::type_complexity)]
-use std::{cell::RefCell, future::Future, marker, pin::Pin, rc::Rc, task, task::Poll};
+use std::{future::Future, marker, pin::Pin, rc::Rc, task, task::Poll};
 
-use super::{Ctx, IntoService, IntoServiceFactory, Service, ServiceCall, ServiceFactory};
+use super::ctx::{Ctx, ServiceCall, Waiters};
+use super::{IntoService, IntoServiceFactory, Service, ServiceFactory};
 
 /// Apply transform function to a service.
 pub fn apply_fn<T, Req, F, R, In, Out, Err, U>(
@@ -10,7 +11,7 @@ pub fn apply_fn<T, Req, F, R, In, Out, Err, U>(
 ) -> Apply<T, Req, F, R, In, Out, Err>
 where
     T: Service<Req, Error = Err>,
-    F: Fn(In, ApplyService<T>) -> R,
+    for<'r> F: Fn(In, ApplyService<T>) -> R,
     R: Future<Output = Result<Out, Err>>,
     U: IntoService<T, Req>,
 {
@@ -74,8 +75,7 @@ where
 
 pub struct ApplyService<S> {
     svc: Rc<S>,
-    index: usize,
+    waiters: Waiters,
-    waiters: Rc<RefCell<slab::Slab<Option<task::Waker>>>>,
 }
 
 impl<S> ApplyService<S> {
@@ -83,7 +83,7 @@ impl<S> ApplyService<S> {
     where
         S: Service<R>,
     {
-        Ctx::<S>::new(self.index, &self.waiters).call(&self.svc, req)
+        Ctx::<S>::new(&self.waiters).call(&self.svc, req)
     }
 }
 
@@ -102,11 +102,9 @@ where
 
     #[inline]
     fn call<'a>(&'a self, req: In, ctx: Ctx<'a, Self>) -> Self::Future<'a> {
-        let (index, waiters) = ctx.into_inner();
         let svc = ApplyService {
-            index,
-            waiters: waiters.clone(),
             svc: self.service.clone(),
+            waiters: ctx.waiters().clone(),
         };
         (self.f)(req, svc)
     }
@@ -161,7 +159,7 @@ impl<T, Req, Cfg, F, R, In, Out, Err> ServiceFactory<In, Cfg>
 where
     T: ServiceFactory<Req, Cfg, Error = Err>,
     F: Fn(In, ApplyService<T::Service>) -> R + Clone,
-    R: Future<Output = Result<Out, Err>>,
+    for<'r> R: Future<Output = Result<Out, Err>> + 'r,
 {
     type Response = Out;
     type Error = Err;
@@ -186,6 +184,7 @@ pin_project_lite::pin_project! {
         T: ServiceFactory<Req, Cfg, Error = Err>,
         T: 'f,
         F: Fn(In, ApplyService<T::Service>) -> R,
+        T::Service: 'f,
         R: Future<Output = Result<Out, Err>>,
         Cfg: 'f,
     {

ntex-service/src/boxed.rs

@@ -1,7 +1,6 @@
-use std::task::{Context, Poll, Waker};
+use std::{future::Future, pin::Pin, task::Context, task::Poll};
-use std::{cell::RefCell, future::Future, pin::Pin, rc::Rc};
 
-use crate::Ctx;
+use crate::ctx::{Ctx, Waiters};
 
 pub type BoxFuture<'a, I, E> = Pin<Box<dyn Future<Output = Result<I, E>> + 'a>>;
 
@@ -44,8 +43,7 @@ trait ServiceObj<Req> {
     fn call<'a>(
         &'a self,
         req: Req,
-        idx: usize,
+        waiters: &'a Waiters,
-        waiters: &'a Rc<RefCell<slab::Slab<Option<Waker>>>>,
     ) -> BoxFuture<'a, Self::Response, Self::Error>;
 }
 
@@ -71,10 +69,9 @@ where
     fn call<'a>(
         &'a self,
         req: Req,
-        idx: usize,
+        waiters: &'a Waiters,
-        waiters: &'a Rc<RefCell<slab::Slab<Option<Waker>>>>,
     ) -> BoxFuture<'a, Self::Response, Self::Error> {
-        Box::pin(Ctx::<'a, S>::new(idx, waiters).call_nowait(self, req))
+        Box::pin(Ctx::<'a, S>::new(waiters).call_nowait(self, req))
     }
 }
 
@@ -135,8 +132,7 @@ where
 
     #[inline]
     fn call<'a>(&'a self, req: Req, ctx: Ctx<'a, Self>) -> Self::Future<'a> {
-        let (index, waiters) = ctx.into_inner();
+        self.0.call(req, ctx.waiters())
-        self.0.call(req, index, waiters)
     }
 }
 

ntex-service/src/ctx.rs

@@ -1,22 +1,75 @@
-use std::{cell::RefCell, future::Future, marker, ops, pin::Pin, rc::Rc, task, task::Poll};
+use std::{
+    cell::UnsafeCell, future::Future, marker, ops, pin::Pin, rc::Rc, task, task::Poll,
+};
 
 use crate::{Service, ServiceFactory};
 
+/// Container for a service.
+///
+/// Container allows to call enclosed service and adds support of shared readiness.
 pub struct Container<S> {
     svc: Rc<S>,
+    waiters: Waiters,
+}
+
+pub struct Ctx<'a, S: ?Sized> {
+    waiters: &'a Waiters,
+    _t: marker::PhantomData<Rc<S>>,
+}
+
+pub(crate) struct Waiters {
     index: usize,
-    waiters: Rc<RefCell<slab::Slab<Option<task::Waker>>>>,
+    waiters: Rc<UnsafeCell<slab::Slab<Option<task::Waker>>>>,
+}
+
+impl Waiters {
+    #[allow(clippy::mut_from_ref)]
+    fn get(&self) -> &mut slab::Slab<Option<task::Waker>> {
+        unsafe { &mut *self.waiters.as_ref().get() }
+    }
+
+    fn notify(&self) {
+        for (_, waker) in self.get().iter_mut() {
+            if let Some(waker) = waker.take() {
+                waker.wake();
+            }
+        }
+    }
+
+    fn register(&self, cx: &mut task::Context<'_>) {
+        self.get()[self.index] = Some(cx.waker().clone());
+    }
+}
+
+impl Clone for Waiters {
+    fn clone(&self) -> Self {
+        Waiters {
+            index: self.get().insert(None),
+            waiters: self.waiters.clone(),
+        }
+    }
+}
+
+impl Drop for Waiters {
+    #[inline]
+    fn drop(&mut self) {
+        self.get().remove(self.index);
+        self.notify();
+    }
 }
 
 impl<S> Container<S> {
     #[inline]
+    /// Construct new container instance.
     pub fn new(svc: S) -> Self {
         let mut waiters = slab::Slab::new();
         let index = waiters.insert(None);
         Container {
-            index,
             svc: Rc::new(svc),
-            waiters: Rc::new(RefCell::new(waiters)),
+            waiters: Waiters {
+                index,
+                waiters: Rc::new(UnsafeCell::new(waiters)),
+            },
         }
     }
 
@@ -27,9 +80,10 @@ impl<S> Container<S> {
         S: Service<R>,
     {
         let res = self.svc.poll_ready(cx);
-
         if res.is_pending() {
-            self.waiters.borrow_mut()[self.index] = Some(cx.waker().clone());
+            self.waiters.register(cx)
+        } else {
+            self.waiters.notify()
         }
         res
     }
@@ -50,7 +104,6 @@ impl<S> Container<S> {
         S: Service<R>,
     {
         let ctx = Ctx::<'a, S> {
-            index: self.index,
             waiters: &self.waiters,
             _t: marker::PhantomData,
         };
@@ -61,12 +114,10 @@ impl<S> Container<S> {
         f: &F,
         cfg: C,
     ) -> ContainerFactory<'_, F, R, C> {
-        ContainerFactory {
+        ContainerFactory { fut: f.create(cfg) }
-            fut: f.create(cfg),
-            _t: marker::PhantomData,
-        }
     }
 
+    /// Extract service if container hadnt been cloned before.
     pub fn into_service(self) -> Option<S> {
         let svc = self.svc.clone();
         drop(self);
@@ -75,11 +126,9 @@ impl<S> Container<S> {
 }
 
 impl<S> Clone for Container<S> {
+    #[inline]
     fn clone(&self) -> Self {
-        let index = self.waiters.borrow_mut().insert(None);
-
         Self {
-            index,
             svc: self.svc.clone(),
             waiters: self.waiters.clone(),
         }
@@ -87,6 +136,7 @@ impl<S> Clone for Container<S> {
 }
 
 impl<S> From<S> for Container<S> {
+    #[inline]
     fn from(svc: S) -> Self {
         Container::new(svc)
     }
@@ -101,41 +151,16 @@ impl<S> ops::Deref for Container<S> {
     }
 }
 
-impl<S> Drop for Container<S> {
-    fn drop(&mut self) {
-        let mut waiters = self.waiters.borrow_mut();
-
-        waiters.remove(self.index);
-        for (_, waker) in &mut *waiters {
-            if let Some(waker) = waker.take() {
-                waker.wake();
-            }
-        }
-    }
-}
-
-pub struct Ctx<'a, S: ?Sized> {
-    index: usize,
-    waiters: &'a Rc<RefCell<slab::Slab<Option<task::Waker>>>>,
-    _t: marker::PhantomData<Rc<S>>,
-}
-
 impl<'a, S: ?Sized> Ctx<'a, S> {
-    pub(crate) fn new(
+    pub(crate) fn new(waiters: &'a Waiters) -> Self {
-        index: usize,
-        waiters: &'a Rc<RefCell<slab::Slab<Option<task::Waker>>>>,
-    ) -> Self {
         Self {
-            index,
             waiters,
             _t: marker::PhantomData,
         }
     }
 
-    pub(crate) fn into_inner(
+    pub(crate) fn waiters(self) -> &'a Waiters {
-        self,
+        self.waiters
-    ) -> (usize, &'a Rc<RefCell<slab::Slab<Option<task::Waker>>>>) {
-        (self.index, self.waiters)
     }
 
     /// Call service, do not check service readiness
@@ -147,7 +172,6 @@ impl<'a, S: ?Sized> Ctx<'a, S> {
         svc.call(
             req,
             Ctx {
-                index: self.index,
                 waiters: self.waiters,
                 _t: marker::PhantomData,
             },
@@ -165,7 +189,6 @@ impl<'a, S: ?Sized> Ctx<'a, S> {
             state: ServiceCallState::Ready {
                 svc,
                 req: Some(req),
-                index: self.index,
                 waiters: self.waiters,
             },
         }
@@ -175,9 +198,9 @@ impl<'a, S: ?Sized> Ctx<'a, S> {
 impl<'a, S: ?Sized> Copy for Ctx<'a, S> {}
 
 impl<'a, S: ?Sized> Clone for Ctx<'a, S> {
+    #[inline]
     fn clone(&self) -> Self {
         Self {
-            index: self.index,
             waiters: self.waiters,
             _t: marker::PhantomData,
         }
@@ -209,8 +232,7 @@ pin_project_lite::pin_project! {
     {
         Ready { req: Option<Req>,
                 svc: &'a T,
-                index: usize,
+                waiters: &'a Waiters,
-                waiters: &'a Rc<RefCell<slab::Slab<Option<task::Waker>>>>,
         },
         Call { #[pin] fut: T::Future<'a> },
         Empty,
@@ -227,24 +249,15 @@ where
         let mut this = self.as_mut().project();
 
         match this.state.as_mut().project() {
-            ServiceCallStateProject::Ready {
+            ServiceCallStateProject::Ready { req, svc, waiters } => {
-                req,
+                match svc.poll_ready(cx)? {
-                svc,
-                index,
-                waiters,
-            } => match svc.poll_ready(cx)? {
                     Poll::Ready(()) => {
-                    for (_, waker) in &mut *waiters.borrow_mut() {
+                        waiters.notify();
-                        if let Some(waker) = waker.take() {
-                            waker.wake();
-                        }
-                    }
 
                         let fut = svc.call(
                             req.take().unwrap(),
                             Ctx {
                                 waiters,
-                            index: *index,
                                 _t: marker::PhantomData,
                             },
                         );
@@ -252,10 +265,11 @@ where
                         self.poll(cx)
                     }
                     Poll::Pending => {
-                    waiters.borrow_mut()[*index] = Some(cx.waker().clone());
+                        waiters.register(cx);
                         Poll::Pending
                     }
-            },
+                }
+            }
             ServiceCallStateProject::Call { fut } => fut.poll(cx).map(|r| {
                 this.state.set(ServiceCallState::Empty);
                 r
@@ -277,7 +291,6 @@ pin_project_lite::pin_project! {
     {
         #[pin]
         fut: F::Future<'f>,
-        _t: marker::PhantomData<(R, C)>,
     }
 }
 

ntex-service/src/lib.rs

@@ -80,6 +80,10 @@ pub use self::pipeline::{pipeline, pipeline_factory, Pipeline, PipelineFactory};
 /// ```rust,ignore
 /// async fn my_service(req: u8) -> Result<u64, Infallible>;
 /// ```
+///
+/// Service cannot be called directly, it must be wrapped to an instance of [`Container`] or
+/// by using `ctx` argument of the call method in case of chanined services.
+///
 pub trait Service<Req> {
     /// Responses given by the service.
     type Response;
@@ -96,11 +100,9 @@ pub trait Service<Req> {
     /// Process the request and return the response asynchronously.
     ///
     /// This function is expected to be callable off-task. As such, implementations of `call`
-    /// should take care to not call `poll_ready`. If the  service is at capacity and the request
+    /// should take care to not call `poll_ready`. Caller of the service verifies readiness,
-    /// is unable to be handled, the returned `Future` should resolve to an error.
+    /// Only way to make a `call` is to use `ctx` argument, it enforces readiness before calling
-    ///
+    /// service.
-    /// Invoking `call` without first invoking `poll_ready` is permitted. Implementations must be
-    /// resilient to this fact.
     fn call<'a>(&'a self, req: Req, ctx: Ctx<'a, Self>) -> Self::Future<'a>;
 
     #[inline]
@@ -116,7 +118,8 @@ pub trait Service<Req> {
     /// # Notes
     ///
     /// 1. `.poll_ready()` might be called on different task from actual service call.
-    /// 1. In case of chained services, `.poll_ready()` is called for all services at once.
+    /// 2. In case of chained services, `.poll_ready()` is called for all services at once.
+    /// 3. Every `.call()` in chained services enforces readiness.
     fn poll_ready(&self, cx: &mut task::Context<'_>) -> Poll<Result<(), Self::Error>> {
         Poll::Ready(Ok(()))
     }