49 lines
1.3 KiB
Rust
49 lines
1.3 KiB
Rust
use super::BalanceMake;
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use rand::{rngs::SmallRng, Rng, SeedableRng};
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use std::{fmt, marker::PhantomData};
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use tower_layer::Layer;
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/// Efficiently distributes requests across an arbitrary number of services
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#[derive(Clone)]
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pub struct BalanceLayer<D, Req> {
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rng: SmallRng,
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_marker: PhantomData<fn(D, Req)>,
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}
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impl<D, Req> BalanceLayer<D, Req> {
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/// Builds a balancer using the system entropy.
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pub fn new() -> Self {
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Self {
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rng: SmallRng::from_entropy(),
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_marker: PhantomData,
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}
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}
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/// Builds a balancer from the provided RNG.
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///
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/// This may be preferrable when many balancers are initialized.
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pub fn from_rng<R: Rng>(rng: &mut R) -> Result<Self, rand::Error> {
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let rng = SmallRng::from_rng(rng)?;
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Ok(Self {
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rng,
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_marker: PhantomData,
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})
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}
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}
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impl<S, Req> Layer<S> for BalanceLayer<S, Req> {
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type Service = BalanceMake<S, Req>;
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fn layer(&self, make_discover: S) -> Self::Service {
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BalanceMake::new(make_discover, self.rng.clone())
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}
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}
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impl<D, Req> fmt::Debug for BalanceLayer<D, Req> {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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f.debug_struct("BalanceLayer")
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.field("rng", &self.rng)
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.finish()
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}
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}
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