tower_balance/p2c/
make.rs

1use super::Balance;
2use crate::error;
3use futures_core::ready;
4use pin_project::pin_project;
5use rand::{rngs::SmallRng, SeedableRng};
6use std::marker::PhantomData;
7use std::{
8    future::Future,
9    pin::Pin,
10    task::{Context, Poll},
11};
12use tower_discover::Discover;
13use tower_service::Service;
14
15/// Makes `Balancer`s given an inner service that makes `Discover`s.
16#[derive(Clone, Debug)]
17pub struct BalanceMake<S, Req> {
18    inner: S,
19    rng: SmallRng,
20    _marker: PhantomData<fn(Req)>,
21}
22
23/// Makes a balancer instance.
24#[pin_project]
25#[derive(Debug)]
26pub struct MakeFuture<F, Req> {
27    #[pin]
28    inner: F,
29    rng: SmallRng,
30    _marker: PhantomData<fn(Req)>,
31}
32
33impl<S, Req> BalanceMake<S, Req> {
34    pub(crate) fn new(inner: S, rng: SmallRng) -> Self {
35        Self {
36            inner,
37            rng,
38            _marker: PhantomData,
39        }
40    }
41
42    /// Initializes a P2C load balancer from the OS's entropy source.
43    pub fn from_entropy(make_discover: S) -> Self {
44        Self::new(make_discover, SmallRng::from_entropy())
45    }
46}
47
48impl<S, Target, Req> Service<Target> for BalanceMake<S, Req>
49where
50    S: Service<Target>,
51    S::Response: Discover,
52    <S::Response as Discover>::Service: Service<Req>,
53    <<S::Response as Discover>::Service as Service<Req>>::Error: Into<error::Error>,
54{
55    type Response = Balance<S::Response, Req>;
56    type Error = S::Error;
57    type Future = MakeFuture<S::Future, Req>;
58
59    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
60        self.inner.poll_ready(cx)
61    }
62
63    fn call(&mut self, target: Target) -> Self::Future {
64        MakeFuture {
65            inner: self.inner.call(target),
66            rng: self.rng.clone(),
67            _marker: PhantomData,
68        }
69    }
70}
71
72impl<F, T, E, Req> Future for MakeFuture<F, Req>
73where
74    F: Future<Output = Result<T, E>>,
75    T: Discover,
76    <T as Discover>::Service: Service<Req>,
77    <<T as Discover>::Service as Service<Req>>::Error: Into<error::Error>,
78{
79    type Output = Result<Balance<T, Req>, E>;
80
81    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
82        let this = self.project();
83        let inner = ready!(this.inner.poll(cx))?;
84        let svc = Balance::new(inner, this.rng.clone());
85        Poll::Ready(Ok(svc))
86    }
87}
tower_balance/p2c/make.rs

tower_balance/p2c/
make.rs
