From eee87a4d45541e6a232ee4bb8d3c35efb31375de Mon Sep 17 00:00:00 2001
From: Jedrzej Stuczynski <jedrzej.stuczynski@gmail.com>
Date: Fri, 13 Dec 2019 11:23:25 +0000
Subject: [PATCH] Sampling poisson distribution

---
 Cargo.toml           | 4 +++-
 src/utils/mod.rs     | 1 +
 src/utils/poisson.rs | 6 ++++++
 3 files changed, 10 insertions(+), 1 deletion(-)
 create mode 100644 src/utils/poisson.rs

diff --git a/Cargo.toml b/Cargo.toml
index f019dbcb7f..17043400e4 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,12 +11,14 @@ base64 = "0.11.0"
 clap = "2.33.0"
 curve25519-dalek = "1.2.3"
 dirs = "2.0.2"
+futures = "0.3.1"
 pem = "0.7.0"
+rand = "0.7.2"
+rand_distr = "0.2.2"
 reqwest = "0.9.22"
 serde = { version = "1.0", features = ["derive"] }
 sphinx = { path = "../sphinx" }
 sfw-provider-requests = { path = "../nym-sfw-provider/sfw-provider-requests" }
-futures = "0.3.1"
 tokio = { version = "0.2", features = ["full"] }
 
 [dev-dependencies]
diff --git a/src/utils/mod.rs b/src/utils/mod.rs
index ad0049c4c2..2e504a1581 100644
--- a/src/utils/mod.rs
+++ b/src/utils/mod.rs
@@ -1 +1,2 @@
 pub mod bytes;
+pub mod poisson;
diff --git a/src/utils/poisson.rs b/src/utils/poisson.rs
new file mode 100644
index 0000000000..d4991f0dd8
--- /dev/null
+++ b/src/utils/poisson.rs
@@ -0,0 +1,6 @@
+use rand_distr::{Distribution, Exp};
+
+pub fn sample(average_delay: f64) -> f64 {
+    let exp = Exp::new(1.0 / average_delay).unwrap();
+    exp.sample(&mut rand::thread_rng())
+}