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Merged
BobAnkh merged 2 commits into from
Jun 9, 2025
Merged

Adding user defined random generator #22

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9a128c5
Adding support for user chose random generator
maxime-bruno Jun 9, 2025
fd55e9b
Merge branch 'stack-rs:main' into main
maxime-bruno Jun 9, 2025
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8 changes: 4 additions & 4 deletions Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -18,15 +18,15 @@ dyn-clone = { version = "1.0.10", optional = true }
human-bandwidth = { version = "0.1.3", optional = true }
humantime-serde = { version = "1.1.1", optional = true }
itertools = { version = "0.14.0", optional = true }
once_cell = { version = "1.17.0", optional = true }
rand = { version = "0.9.0", optional = true }
rand_distr = { version = "0.5.0", optional = true }
rand = { version = "0.9.1", optional = true }
rand_distr = { version = "0.5.1", optional = true }
serde = { version = "1.0", features = ["derive"], optional = true }
statrs = { version = "0.18.0", optional = true }
typetag = { version = "0.2.5", optional = true }

[dev-dependencies]
figment = { version = "0.10.19", features = ["json"] }
rand_chacha = "0.9"
serde_json = "1.0"

[features]
Expand All @@ -38,7 +38,7 @@ model = [
"loss-model",
"duplicate-model"
]
bw-model = ["dep:rand", "dep:rand_distr", "dep:once_cell", "dep:dyn-clone"]
bw-model = ["dep:rand", "dep:rand_distr", "dep:dyn-clone"]
delay-model = ["dep:dyn-clone"]
delay-per-packet-model = ["dep:dyn-clone"]
loss-model = ["dep:dyn-clone"]
Expand Down
188 changes: 175 additions & 13 deletions src/model/bw.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -57,8 +57,7 @@
//! ```
use crate::{Bandwidth, BwTrace, Duration};
use dyn_clone::DynClone;
use rand::rngs::StdRng;
use rand::SeedableRng;
use rand::{rngs::StdRng, RngCore, SeedableRng};
use rand_distr::{Distribution, Normal};

const DEFAULT_RNG_SEED: u64 = 42;
Expand Down Expand Up @@ -162,15 +161,18 @@ pub struct StaticBwConfig {
/// assert_eq!(normal_bw.next_bw(), Some((Bandwidth::from_bps(12100000), Duration::from_millis(100))));
/// ```
#[derive(Debug, Clone)]
pub struct NormalizedBw {
pub struct NormalizedBw<Rng = StdRng>
where
Rng: RngCore,
{
pub mean: Bandwidth,
pub std_dev: Bandwidth,
pub upper_bound: Option<Bandwidth>,
pub lower_bound: Option<Bandwidth>,
pub duration: Duration,
pub step: Duration,
pub seed: u64,
rng: StdRng,
rng: Rng,
normal: Normal<f64>,
}

Expand Down Expand Up @@ -317,7 +319,10 @@ pub struct NormalizedBwConfig {
/// );
/// ```
#[derive(Debug, Clone)]
pub struct SawtoothBw {
pub struct SawtoothBw<Rng = StdRng>
where
Rng: RngCore,
{
pub bottom: Bandwidth,
pub top: Bandwidth,
pub interval: Duration,
Expand All @@ -329,7 +334,7 @@ pub struct SawtoothBw {
pub upper_noise_bound: Option<Bandwidth>,
pub lower_noise_bound: Option<Bandwidth>,
current: Duration,
rng: StdRng,
rng: Rng,
noise: Normal<f64>,
}

Expand Down Expand Up @@ -768,7 +773,7 @@ impl BwTrace for StaticBw {
}
}

impl BwTrace for NormalizedBw {
impl<Rng: RngCore + Send> BwTrace for NormalizedBw<Rng> {
fn next_bw(&mut self) -> Option<(Bandwidth, Duration)> {
if self.duration.is_zero() {
None
Expand All @@ -788,7 +793,7 @@ impl BwTrace for NormalizedBw {
}
}

impl BwTrace for SawtoothBw {
impl<Rng: RngCore + Send> BwTrace for SawtoothBw<Rng> {
fn next_bw(&mut self) -> Option<(Bandwidth, Duration)> {
if self.duration.is_zero() {
None
Expand Down Expand Up @@ -870,7 +875,7 @@ impl BwTrace for TraceBw {
}
}

impl NormalizedBw {
impl<Rng: RngCore> NormalizedBw<Rng> {
pub fn sample(&mut self) -> f64 {
self.normal.sample(&mut self.rng)
}
Expand Down Expand Up @@ -912,6 +917,7 @@ macro_rules! saturating_bandwidth_as_bps_u64 {
}

impl NormalizedBwConfig {
/// Creates an uninitialized config
pub fn new() -> Self {
Self {
mean: None,
Expand All @@ -924,50 +930,127 @@ impl NormalizedBwConfig {
}
}

/// Sets the mean
///
/// If the mean is not set, 12Mbps will be used.
pub fn mean(mut self, mean: Bandwidth) -> Self {
self.mean = Some(mean);
self
}

/// Sets the standard deviation
///
/// If the standard deviation is not set, 0Mbps will be used.
pub fn std_dev(mut self, std_dev: Bandwidth) -> Self {
self.std_dev = Some(std_dev);
self
}

/// Sets the upper bound
///
/// If the upper bound is not set, the upper bound will be the one of [`Bandwidth`].
pub fn upper_bound(mut self, upper_bound: Bandwidth) -> Self {
self.upper_bound = Some(upper_bound);
self
}

/// Sets the lower bound
///
/// If the lower bound is not set, the lower bound will be the one of [`Bandwidth`].
pub fn lower_bound(mut self, lower_bound: Bandwidth) -> Self {
self.lower_bound = Some(lower_bound);
self
}

/// Sets the total duration of the trace
///
/// If the total duration is not set, 1 second will be used.
pub fn duration(mut self, duration: Duration) -> Self {
self.duration = Some(duration);
self
}

/// Sets the duration of each value
///
/// If the step is not set, 1ms will be used.
pub fn step(mut self, step: Duration) -> Self {
self.step = Some(step);
self
}

/// Set the seed for a random generator
///
/// If the seed is not set, `42` will be used.
pub fn seed(mut self, seed: u64) -> Self {
self.seed = Some(seed);
self
}

/// Allows to use a randomly generated seed
///
/// This is equivalent to: `self.seed(rand::random())`
pub fn random_seed(mut self) -> Self {
self.seed = Some(rand::random());
self
}

/// Creates a new [`NormalizedBw`] corresponding to this config.
///
/// The created model will use [`StdRng`] as source of randomness (the call is equivalent to `self.build_with_rng::<StdRng>()`).
/// It should be sufficient for most cases, but [`StdRng`] is not a portable random number generator,
/// so one may want to use a portable random number generator like [`ChaCha`](https://crates.io/crates/rand_chacha),
/// to this end one can use [`build_with_rng`](Self::build_with_rng).
pub fn build(self) -> NormalizedBw {
self.build_with_rng()
}

/// Creates a new [`NormalizedBw`] corresponding to this config.
///
/// Unlike [`build`](Self::build), this method let you choose the random generator.
///
/// # Example
/// ```rust
/// # use netem_trace::model::NormalizedBwConfig;
/// # use netem_trace::{Bandwidth, BwTrace};
/// # use std::time::Duration;
/// # use rand::rngs::StdRng;
/// # use rand_chacha::ChaCha20Rng;
///
/// let normal_bw = NormalizedBwConfig::new()
/// .mean(Bandwidth::from_mbps(12))
/// .std_dev(Bandwidth::from_mbps(1))
/// .duration(Duration::from_millis(3))
/// .seed(42);
///
/// let mut default_build = normal_bw.clone().build();
/// let mut std_build = normal_bw.clone().build_with_rng::<StdRng>();
/// // ChaCha is deterministic and portable, unlike StdRng
/// let mut chacha_build = normal_bw.clone().build_with_rng::<ChaCha20Rng>();
///
/// for cha in [12044676, 11754367, 11253775] {
/// let default = default_build.next_bw();
/// let std = std_build.next_bw();
/// let chacha = chacha_build.next_bw();
///
/// assert!(default.is_some());
/// assert_eq!(default, std);
/// assert_ne!(default, chacha);
/// assert_eq!(chacha, Some((Bandwidth::from_bps(cha), Duration::from_millis(1))));
/// }
///
/// assert_eq!(default_build.next_bw(), None);
/// assert_eq!(std_build.next_bw(), None);
/// assert_eq!(chacha_build.next_bw(), None);
/// ```
pub fn build_with_rng<Rng: SeedableRng + RngCore>(self) -> NormalizedBw<Rng> {
let mean = self.mean.unwrap_or_else(|| Bandwidth::from_mbps(12));
let std_dev = self.std_dev.unwrap_or_else(|| Bandwidth::from_mbps(0));
let upper_bound = self.upper_bound;
let lower_bound = self.lower_bound;
let duration = self.duration.unwrap_or_else(|| Duration::from_secs(1));
let step = self.step.unwrap_or_else(|| Duration::from_millis(1));
let seed = self.seed.unwrap_or(DEFAULT_RNG_SEED);
let rng = StdRng::seed_from_u64(seed);
let rng = Rng::seed_from_u64(seed);
let bw_mean = saturating_bandwidth_as_bps_u64!(mean) as f64;
let bw_std_dev = saturating_bandwidth_as_bps_u64!(std_dev) as f64;
let normal: Normal<f64> = Normal::new(bw_mean, bw_std_dev).unwrap();
Expand Down Expand Up @@ -1034,7 +1117,14 @@ impl NormalizedBwConfig {
/// assert_eq!(avg_mbps(truncate_build), 11.978819427569897);
///
/// ```
pub fn build_truncated(mut self) -> NormalizedBw {
pub fn build_truncated(self) -> NormalizedBw {
self.build_truncated_with_rng()
}

/// Similar to [`build_truncated`](Self::build_truncated) but let you choose the random generator.
///
/// See [`build`](Self::build) for details about the reason for using another random number generator than [`StdRng`].
pub fn build_truncated_with_rng<Rng: SeedableRng + RngCore>(mut self) -> NormalizedBw<Rng> {
let mean = self
.mean
.unwrap_or_else(|| Bandwidth::from_mbps(12))
Expand All @@ -1052,11 +1142,12 @@ impl NormalizedBwConfig {
let upper = self.upper_bound.map(|upper| upper.as_gbps_f64() / mean);
let new_mean = mean * solve(1f64, sigma, Some(lower), upper).unwrap_or(1f64);
self.mean = Some(Bandwidth::from_gbps_f64(new_mean));
self.build()
self.build_with_rng()
}
}

impl SawtoothBwConfig {
/// Creates an uninitialized config
pub fn new() -> Self {
Self {
bottom: None,
Expand Down Expand Up @@ -1092,21 +1183,41 @@ impl SawtoothBwConfig {
self
}

/// Sets the total duration of the trace
///
/// If the total duration is not set, 1 second will be used.
pub fn duration(mut self, duration: Duration) -> Self {
self.duration = Some(duration);
self
}

/// Sets the duration of each value
///
/// If the step is not set, 1ms will be used.
pub fn step(mut self, step: Duration) -> Self {
self.step = Some(step);
self
}

/// Set the seed for a random generator
///
/// If the seed is not set, `42` will be used.
pub fn seed(mut self, seed: u64) -> Self {
self.seed = Some(seed);
self
}

/// Allows to use a randomly generated seed
///
/// This is equivalent to: `self.seed(rand::random())`
pub fn random_seed(mut self) -> Self {
self.seed = Some(rand::random());
self
}

/// Sets the standard deviation
///
/// If the standard deviation is not set, 0Mbps will be used.
pub fn std_dev(mut self, std_dev: Bandwidth) -> Self {
self.std_dev = Some(std_dev);
self
Expand All @@ -1122,7 +1233,58 @@ impl SawtoothBwConfig {
self
}

/// Creates a new [`SawtoothBw`] corresponding to this config.
///
/// The created model will use [`StdRng`] as source of randomness (the call is equivalent to `self.build_with_rng::<StdRng>()`).
/// It should be sufficient for most cases, but [`StdRng`] is not a portable random number generator,
/// so one may want to use a portable random number generator like [`ChaCha`](https://crates.io/crates/rand_chacha),
/// to this end one can use [`build_with_rng`](Self::build_with_rng).
pub fn build(self) -> SawtoothBw {
self.build_with_rng()
}

/// Creates a new [`SawtoothBw`] corresponding to this config.
///
/// Unlike [`build`](Self::build), this method let you choose the random generator.
///
/// # Example
/// ```rust
/// # use netem_trace::model::SawtoothBwConfig;
/// # use netem_trace::{Bandwidth, BwTrace};
/// # use std::time::Duration;
/// # use rand::rngs::StdRng;
/// # use rand_chacha::ChaCha20Rng;
///
/// let sawtooth_bw = SawtoothBwConfig::new()
/// .bottom(Bandwidth::from_mbps(12))
/// .top(Bandwidth::from_mbps(16))
/// .std_dev(Bandwidth::from_mbps(1))
/// .duration(Duration::from_millis(3))
/// .interval(Duration::from_millis(5))
/// .duty_ratio(0.8)
/// .seed(42);
///
/// let mut default_build = sawtooth_bw.clone().build();
/// let mut std_build = sawtooth_bw.clone().build_with_rng::<StdRng>();
/// // ChaCha is deterministic and portable, unlike StdRng
/// let mut chacha_build = sawtooth_bw.clone().build_with_rng::<ChaCha20Rng>();
///
/// for cha in [12044676, 12754367, 13253775] {
/// let default = default_build.next_bw();
/// let std = std_build.next_bw();
/// let chacha = chacha_build.next_bw();
///
/// assert!(default.is_some());
/// assert_eq!(default, std);
/// assert_ne!(default, chacha);
/// assert_eq!(chacha, Some((Bandwidth::from_bps(cha), Duration::from_millis(1))));
/// }
///
/// assert_eq!(default_build.next_bw(), None);
/// assert_eq!(std_build.next_bw(), None);
/// assert_eq!(chacha_build.next_bw(), None);
/// ```
pub fn build_with_rng<Rng: RngCore + SeedableRng>(self) -> SawtoothBw<Rng> {
let bottom = self.bottom.unwrap_or_else(|| Bandwidth::from_mbps(0));
let top = self.top.unwrap_or_else(|| Bandwidth::from_mbps(12));
if bottom > top {
Expand All @@ -1133,7 +1295,7 @@ impl SawtoothBwConfig {
let duration = self.duration.unwrap_or_else(|| Duration::from_secs(1));
let step = self.step.unwrap_or_else(|| Duration::from_millis(1));
let seed = self.seed.unwrap_or(DEFAULT_RNG_SEED);
let rng = StdRng::seed_from_u64(seed);
let rng = Rng::seed_from_u64(seed);
let std_dev = self.std_dev.unwrap_or_else(|| Bandwidth::from_mbps(0));
let upper_noise_bound = self.upper_noise_bound;
let lower_noise_bound = self.lower_noise_bound;
Expand Down
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