spacegate_kernel/helper_layers/
random_pick.rs

1use std::sync::Arc;
2
3use rand::distr::Distribution;
4
5#[derive(Clone)]
6pub struct RandomPick<I, S>
7where
8    I: rand::distr::uniform::SampleUniform + std::cmp::PartialOrd,
9{
10    picker: Arc<rand::distr::weighted::WeightedIndex<I>>,
11    services: Arc<[S]>,
12}
13
14impl<I, S> std::fmt::Debug for RandomPick<I, S>
15where
16    I: rand::distr::uniform::SampleUniform + std::cmp::PartialOrd,
17{
18    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
19        f.debug_struct("RandomPick").finish()
20    }
21}
22
23impl<I, S> RandomPick<I, S>
24where
25    I: rand::distr::uniform::SampleUniform + std::cmp::PartialOrd + Clone + Default + for<'a> std::ops::AddAssign<&'a I> + rand::distr::weighted::Weight,
26{
27    pub fn new(services: impl IntoIterator<Item = (I, S)>) -> Self {
28        let (weights, services): (Vec<_>, Vec<_>) = services.into_iter().unzip();
29        assert!(!services.is_empty(), "services must not be empty");
30        Self {
31            picker: Arc::new(rand::distr::weighted::WeightedIndex::new(weights).expect("invalid weights")),
32            services: services.into(),
33        }
34    }
35}
36
37impl<I, R, S> hyper::service::Service<R> for RandomPick<I, S>
38where
39    S: hyper::service::Service<R>,
40    S::Future: std::marker::Send,
41    I: rand::distr::uniform::SampleUniform + std::cmp::PartialOrd + Clone,
42{
43    type Response = S::Response;
44    type Error = S::Error;
45    type Future = S::Future;
46
47    #[allow(clippy::indexing_slicing)]
48    fn call(&self, req: R) -> Self::Future {
49        if self.services.len() == 1 {
50            self.services[0].call(req)
51        } else {
52            let index = self.picker.sample(&mut rand::rng());
53            self.services[index].call(req)
54        }
55    }
56}
spacegate_kernel/helper_layers/random_pick.rs

spacegate_kernel/helper_layers/
random_pick.rs
