Switch BBR RNG to PCG

Author: ww-oai

quinn-proto/Cargo.toml

@@ -50,6 +50,7 @@ lru-slab = { workspace = true }
 qlog = { workspace = true, optional = true }
 rustc-hash = { workspace = true }
 rand = { workspace = true }
+rand_pcg = "0.10"
 ring = { workspace = true, optional = true }
 rustls = { workspace = true, optional = true }
 rustls-platform-verifier = { workspace = true, optional = true }
@@ -69,7 +70,6 @@ web-time = { workspace = true }
 [dev-dependencies]
 assert_matches = { workspace = true }
 hex-literal = { workspace = true  }
-rand_pcg = "0.10"
 rcgen = { workspace = true }
 tracing-subscriber = { workspace = true }
 lazy_static = "1"

quinn-proto/src/congestion/bbr/mod.rs

@@ -2,8 +2,8 @@ use std::any::Any;
 use std::fmt::Debug;
 use std::sync::Arc;
 
-use rand::rngs::{StdRng, SysRng};
-use rand::{Rng, RngExt, SeedableRng};
+use rand::{RngExt, SeedableRng};
+use rand_pcg::Pcg32;
 
 use crate::congestion::ControllerMetrics;
 use crate::congestion::bbr::bw_estimation::BandwidthEstimation;
@@ -57,7 +57,7 @@ pub struct Bbr {
     bw_at_last_round: u64,
     round_wo_bw_gain: u64,
     ack_aggregation: AckAggregationState,
-    random_number_generator: StdRng,
+    random_number_generator: Pcg32,
 }
 
 impl Bbr {
@@ -98,7 +98,7 @@ impl Bbr {
             bw_at_last_round: 0,
             round_wo_bw_gain: 0,
             ack_aggregation: AckAggregationState::default(),
-            random_number_generator: StdRng::try_from_rng(&mut SysRng).unwrap(),
+            random_number_generator: Pcg32::from_rng(&mut rand::rng()),
         }
     }