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/// An implementation of [`poll_ready`]() that always signals readiness.
///
/// This should only be used for basic leaf services that have no concept of un-readiness.
/// For wrapper or other service types, use [`forward_ready!`] for simple cases or write a bespoke
/// `poll_ready` implementation.
///
/// [`poll_ready`]: crate::Service::poll_ready
///
/// # Examples
/// ```no_run
/// use actix_service::Service;
/// use futures_util::future::{ready, Ready};
///
/// struct IdentityService;
///
/// impl Service<u32> for IdentityService {
/// type Response = u32;
/// type Error = ();
/// type Future = Ready<Result<Self::Response, Self::Error>>;
///
/// actix_service::always_ready!();
///
/// fn call(&self, req: u32) -> Self::Future {
/// ready(Ok(req))
/// }
/// }
/// ```
#[macro_export]
macro_rules! always_ready {
() => {
#[inline]
fn poll_ready(
&self,
_: &mut ::core::task::Context<'_>,
) -> ::core::task::Poll<Result<(), Self::Error>> {
::core::task::Poll::Ready(Ok(()))
}
};
}
/// An implementation of [`poll_ready`] that forwards readiness checks to a
/// named struct field.
///
/// Tuple structs are not supported.
///
/// [`poll_ready`]: crate::Service::poll_ready
///
/// # Examples
/// ```no_run
/// use actix_service::Service;
/// use futures_util::future::{ready, Ready};
///
/// struct WrapperService<S> {
/// inner: S,
/// }
///
/// impl<S> Service<()> for WrapperService<S>
/// where
/// S: Service<()>,
/// {
/// type Response = S::Response;
/// type Error = S::Error;
/// type Future = S::Future;
///
/// actix_service::forward_ready!(inner);
///
/// fn call(&self, req: ()) -> Self::Future {
/// self.inner.call(req)
/// }
/// }
/// ```
#[macro_export]
macro_rules! forward_ready {
($field:ident) => {
#[inline]
fn poll_ready(
&self,
cx: &mut ::core::task::Context<'_>,
) -> ::core::task::Poll<Result<(), Self::Error>> {
self.$field
.poll_ready(cx)
.map_err(::core::convert::Into::into)
}
};
}
#[cfg(test)]
mod tests {
use core::{
cell::Cell,
convert::Infallible,
task::{self, Context, Poll},
};
use futures_util::{
future::{ready, Ready},
task::noop_waker,
};
use crate::Service;
struct IdentityService;
impl Service<u32> for IdentityService {
type Response = u32;
type Error = Infallible;
type Future = Ready<Result<Self::Response, Self::Error>>;
always_ready!();
fn call(&self, req: u32) -> Self::Future {
ready(Ok(req))
}
}
struct CountdownService(Cell<u32>);
impl Service<()> for CountdownService {
type Response = ();
type Error = Infallible;
type Future = Ready<Result<Self::Response, Self::Error>>;
fn poll_ready(&self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
let count = self.0.get();
if count == 0 {
Poll::Ready(Ok(()))
} else {
self.0.set(count - 1);
cx.waker().wake_by_ref();
Poll::Pending
}
}
fn call(&self, _: ()) -> Self::Future {
ready(Ok(()))
}
}
struct WrapperService<S> {
inner: S,
}
impl<S> Service<()> for WrapperService<S>
where
S: Service<()>,
{
type Response = S::Response;
type Error = S::Error;
type Future = S::Future;
forward_ready!(inner);
fn call(&self, _: ()) -> Self::Future {
self.inner.call(())
}
}
#[test]
fn test_always_ready_macro() {
let waker = noop_waker();
let mut cx = task::Context::from_waker(&waker);
let svc = IdentityService;
assert!(svc.poll_ready(&mut cx).is_ready());
assert!(svc.poll_ready(&mut cx).is_ready());
assert!(svc.poll_ready(&mut cx).is_ready());
}
#[test]
fn test_forward_ready_macro() {
let waker = noop_waker();
let mut cx = task::Context::from_waker(&waker);
let svc = WrapperService {
inner: CountdownService(Cell::new(3)),
};
assert!(svc.poll_ready(&mut cx).is_pending());
assert!(svc.poll_ready(&mut cx).is_pending());
assert!(svc.poll_ready(&mut cx).is_pending());
assert!(svc.poll_ready(&mut cx).is_ready());
}
}