From 1fb2aecab3a121d56ae0675e2d73333d169cfd0f Mon Sep 17 00:00:00 2001
From: Trivernis <trivernis@gmail.com>
Date: Fri, 3 Apr 2020 16:03:30 +0200
Subject: [PATCH] Subtract the duration it takes to measure from measurements

---
 Cargo.toml      |  2 +-
 src/benching.rs | 20 +++++++++++++++++++-
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index e4c2ab1..d072ab8 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "benchlib-rs"
-version = "0.2.2"
+version = "0.3.0"
 authors = ["Trivernis <trivernis@gmail.com>"]
 edition = "2018"
 license-file = "LICENSE"
diff --git a/src/benching.rs b/src/benching.rs
index bcdc219..226f62c 100644
--- a/src/benching.rs
+++ b/src/benching.rs
@@ -126,17 +126,29 @@ pub struct Bencher {
     measurements: Vec<BenchVec>,
     iterations: usize,
     max_auto_iterations: usize,
+    bench_duration: Duration,
 }
 
 impl Bencher {
     pub fn new() -> Self {
         Self {
+            bench_duration: Self::calculate_bench_duration(),
             measurements: Vec::new(),
             iterations: 100,
             max_auto_iterations: 10000,
         }
     }
 
+    fn calculate_bench_duration() -> Duration{
+        let mut durations = BenchVec::new();
+        for _ in 0..1000 {
+            let start = Instant::now();
+            durations.push(start.elapsed());
+        }
+
+        durations.average()
+    }
+
     /// Sets the number of iterations a benchmark will be run
     /// If set to 0 it iterates until the standard deviation is below 1%
     pub fn set_iterations(&mut self, iterations: usize) -> &mut Self {
@@ -167,7 +179,12 @@ impl Bencher {
             while count < self.max_auto_iterations {
                 let start = Instant::now();
                 func();
-                durations.push(start.elapsed());
+                let duration = start.elapsed();
+                if duration > self.bench_duration {
+                    durations.push(duration - self.bench_duration);
+                } else {
+                    durations.push(duration);
+                }
                 if (durations.standard_deviation() / durations.average().as_nanos() as f64) < 0.01 && count > 1{
                     break;
                 }
@@ -203,6 +220,7 @@ impl Bencher {
     /// Prints the settings of the Bencher
     pub fn print_settings(&mut self) -> &mut Self {
         println!("\n{}{}Benchmarking Settings{}", color::Fg(color::Green), style::Underline, style::Reset);
+        println!("Benchmarking accuracy delay:\t {:?}", self.bench_duration);
         println!("Number of iterations:\t {}", if self.iterations > 0 {self.iterations.to_string() } else { "auto".to_string() });
         if self.iterations == 0 {
             println!("Maximum number of iterations: {}", self.max_auto_iterations)