sim-rs: implement constant distribution

Author: SupernaviX

data/simulation/config.d.ts

@@ -65,7 +65,8 @@ export interface Config {
 export type Distribution =
   | NormalDistribution
   | ExpDistribution
-  | LogNormalDistribution;
+  | LogNormalDistribution
+  | ConstantDistribution;
 
 export interface NormalDistribution {
   distribution: "normal";
@@ -85,6 +86,11 @@ export interface LogNormalDistribution {
   sigma: number;
 }
 
+export interface ConstantDistribution {
+  distribution: "constant";
+  value: number;
+}
+
 export enum DiffusionStrategy {
   PeerOrder = "peer-order",
   FreshestFirst = "freshest-first",

data/simulation/config.schema.json

@@ -1,6 +1,18 @@
 {
   "$schema": "http://json-schema.org/draft-07/schema#",
   "definitions": {
+    "ConstantDistribution": {
+      "properties": {
+        "distribution": {
+          "const": "constant",
+          "type": "string"
+        },
+        "value": {
+          "type": "number"
+        }
+      },
+      "type": "object"
+    },
     "DiffusionStrategy": {
       "enum": ["peer-order", "freshest-first"],
       "type": "string"
@@ -15,6 +27,9 @@
         },
         {
           "$ref": "#/definitions/LogNormalDistribution"
+        },
+        {
+          "$ref": "#/definitions/ConstantDistribution"
         }
       ]
     },

sim-rs/sim-core/src/config.rs

@@ -32,6 +32,7 @@ pub enum DistributionConfig {
     Normal { mean: f64, std_dev: f64 },
     Exp { lambda: f64, scale: Option<f64> },
     LogNormal { mu: f64, sigma: f64 },
+    Constant { value: f64 },
 }
 impl From<DistributionConfig> for FloatDistribution {
     fn from(value: DistributionConfig) -> Self {
@@ -43,6 +44,7 @@ impl From<DistributionConfig> for FloatDistribution {
                 FloatDistribution::scaled_exp(lambda, scale.unwrap_or(1.))
             }
             DistributionConfig::LogNormal { mu, sigma } => FloatDistribution::log_normal(mu, sigma),
+            DistributionConfig::Constant { value } => FloatDistribution::constant(value),
         }
     }
 }

sim-rs/sim-core/src/probability.rs

@@ -1,10 +1,13 @@
+use rand::Rng;
 use rand_distr::{Distribution, Exp, LogNormal, Normal};
+use std::fmt::Debug;
 
 #[derive(Debug, Clone, Copy)]
 pub enum FloatDistribution {
     Normal(Normal<f64>),
     ScaledExp(Exp<f64>, f64),
     LogNormal(LogNormal<f64>),
+    Constant(Constant<f64>),
 }
 impl FloatDistribution {
     pub fn normal(mean: f64, std_dev: f64) -> Self {
@@ -16,6 +19,9 @@ impl FloatDistribution {
     pub fn log_normal(mu: f64, sigma: f64) -> Self {
         Self::LogNormal(LogNormal::new(mu, sigma).unwrap())
     }
+    pub fn constant(value: f64) -> Self {
+        Self::Constant(Constant::new(value))
+    }
 }
 
 impl Distribution<f64> for FloatDistribution {
@@ -24,6 +30,22 @@ impl Distribution<f64> for FloatDistribution {
             Self::Normal(d) => d.sample(rng),
             Self::ScaledExp(d, scale) => d.sample(rng) * scale,
             Self::LogNormal(d) => d.sample(rng),
+            Self::Constant(d) => d.sample(rng),
         }
     }
 }
+
+#[derive(Debug, Clone, Copy)]
+pub struct Constant<T>(T);
+impl<T> Constant<T> {
+    pub fn new(value: T) -> Self {
+        Self(value)
+    }
+}
+
+impl<T: Clone> Distribution<T> for Constant<T> {
+    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> T {
+        let _ = rng;
+        self.0.clone()
+    }
+}