Merge pull request #961 from sharkdp/codex/uom-quantities

Use uom quantities for benchmark measurements

Cargo.lock

@@ -394,6 +394,7 @@ dependencies = [
  "shell-words",
  "tempfile",
  "thiserror",
+ "uom",
  "windows-sys 0.61.2",
 ]
 
@@ -932,6 +933,12 @@ dependencies = [
  "winnow",
 ]
 
+[[package]]
+name = "typenum"
+version = "1.20.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b6f5e870be6c3b371b77fe0ee0bafb859fa4964b4404c27de1d380043c4dda20"
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.26"
@@ -950,6 +957,16 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b4ac048d71ede7ee76d585517add45da530660ef4390e49b098733c6e897f254"
 
+[[package]]
+name = "uom"
+version = "0.36.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ffd36e5350a65d112584053ee91843955826bf9e56ec0d1351214e01f6d7cd9c"
+dependencies = [
+ "num-traits",
+ "typenum",
+]
+
 [[package]]
 name = "utf8parse"
 version = "0.2.2"

Cargo.toml

@@ -28,6 +28,7 @@ rand = "0.10"
 shell-words = "1.1"
 thiserror = "2.0"
 anyhow = "1.0"
+uom = { version = "0.36.0", default-features = false, features = ["std", "si", "f64"] }
 
 [target.'cfg(not(windows))'.dependencies]
 libc = "0.2"

src/benchmark/executor.rs

@@ -7,9 +7,9 @@ use crate::options::{
     CmdFailureAction, CommandInputPolicy, CommandOutputPolicy, Options, OutputStyleOption, Shell,
 };
 use crate::output::progress_bar::get_progress_bar;
+use crate::quantity::{second, Information, Time, Zero};
 use crate::timer::execute_and_measure;
 use crate::util::randomized_environment_offset;
-use crate::util::units::Second;
 
 use super::measurement::{Measurement, Measurements};
 
@@ -51,7 +51,7 @@ pub trait Executor {
     /// performing a measurement. This should return the time
     /// that is being used in addition to the actual runtime
     /// of the command.
-    fn time_overhead(&self) -> Second;
+    fn time_overhead(&self) -> Time;
 }
 
 fn run_command_and_measure_common(
@@ -150,8 +150,8 @@ impl Executor for RawExecutor<'_> {
         Ok(())
     }
 
-    fn time_overhead(&self) -> Second {
-        0.0
+    fn time_overhead(&self) -> Time {
+        Time::zero()
     }
 }
 
@@ -203,9 +203,9 @@ impl Executor for ShellExecutor<'_> {
         // Subtract shell spawning time
         if let Some(spawning_time) = self.shell_spawning_time {
             result.time_wall_clock =
-                (result.time_wall_clock - spawning_time.time_wall_clock).max(0.0);
-            result.time_user = (result.time_user - spawning_time.time_user).max(0.0);
-            result.time_system = (result.time_system - spawning_time.time_system).max(0.0);
+                (result.time_wall_clock - spawning_time.time_wall_clock).max(Time::zero());
+            result.time_user = (result.time_user - spawning_time.time_user).max(Time::zero());
+            result.time_system = (result.time_system - spawning_time.time_system).max(Time::zero());
         }
 
         Ok(result)
@@ -266,14 +266,14 @@ impl Executor for ShellExecutor<'_> {
             time_wall_clock: measurements.time_wall_clock_mean(),
             time_user: measurements.time_user_mean(),
             time_system: measurements.time_system_mean(),
-            peak_memory_usage: 0,
+            peak_memory_usage: Information::zero(),
             exit_status: ExitStatus::default(),
         });
 
         Ok(())
     }
 
-    fn time_overhead(&self) -> Second {
+    fn time_overhead(&self) -> Time {
         self.shell_spawning_time.unwrap().time_wall_clock
     }
 }
@@ -288,13 +288,15 @@ impl MockExecutor {
         MockExecutor { shell }
     }
 
-    fn extract_time<S: AsRef<str>>(sleep_command: S) -> Second {
+    fn extract_time<S: AsRef<str>>(sleep_command: S) -> Time {
         assert!(sleep_command.as_ref().starts_with("sleep "));
-        sleep_command
-            .as_ref()
-            .trim_start_matches("sleep ")
-            .parse::<Second>()
-            .unwrap()
+        Time::new::<second>(
+            sleep_command
+                .as_ref()
+                .trim_start_matches("sleep ")
+                .parse::<f64>()
+                .unwrap(),
+        )
     }
 }
 
@@ -320,9 +322,9 @@ impl Executor for MockExecutor {
 
         Ok(Measurement {
             time_wall_clock: Self::extract_time(command.get_command_line()),
-            time_user: 0.0,
-            time_system: 0.0,
-            peak_memory_usage: 0,
+            time_user: Time::zero(),
+            time_system: Time::zero(),
+            peak_memory_usage: Information::zero(),
             exit_status,
         })
     }
@@ -331,9 +333,9 @@ impl Executor for MockExecutor {
         Ok(())
     }
 
-    fn time_overhead(&self) -> Second {
+    fn time_overhead(&self) -> Time {
         match &self.shell {
-            None => 0.0,
+            None => Time::zero(),
             Some(shell) => Self::extract_time(shell),
         }
     }
@@ -341,5 +343,8 @@ impl Executor for MockExecutor {
 
 #[test]
 fn test_mock_executor_extract_time() {
-    assert_eq!(MockExecutor::extract_time("sleep 0.1"), 0.1);
+    assert_eq!(
+        MockExecutor::extract_time("sleep 0.1"),
+        Time::new::<second>(0.1)
+    );
 }

src/benchmark/measurement.rs

@@ -1,23 +1,23 @@
 use std::process::ExitStatus;
 
 use crate::outlier_detection::modified_zscores;
+use crate::quantity::{second, Information, Time};
 use crate::util::statistics::{max, mean, median, min, standard_deviation};
-use crate::util::units::Second;
 
 /// Performance measurements and exit status from running a single command
 #[derive(Debug, Default, Copy, Clone)]
 pub struct Measurement {
     /// Wall clock time
-    pub time_wall_clock: Second,
+    pub time_wall_clock: Time,
 
     /// Time spent in user mode
-    pub time_user: Second,
+    pub time_user: Time,
 
     /// Time spent in kernel mode
-    pub time_system: Second,
+    pub time_system: Time,
 
-    /// Maximum amount of memory used, in bytes
-    pub peak_memory_usage: u64,
+    /// Maximum amount of memory used
+    pub peak_memory_usage: Information,
 
     /// The exit status of the process
     pub exit_status: ExitStatus,
@@ -42,17 +42,17 @@ impl Measurements {
         self.measurements.push(measurement);
     }
 
-    pub fn wall_clock_times(&self) -> impl Iterator<Item = Second> + '_ {
+    pub fn wall_clock_times(&self) -> impl Iterator<Item = Time> + '_ {
         self.measurements.iter().map(|m| m.time_wall_clock)
     }
 
     /// The average wall clock time.
-    pub fn time_wall_clock_mean(&self) -> Second {
+    pub fn time_wall_clock_mean(&self) -> Time {
         mean(self.wall_clock_times())
     }
 
     /// The standard deviation of wall clock times, if at least two runs were measured.
-    pub fn stddev(&self) -> Option<Second> {
+    pub fn stddev(&self) -> Option<Time> {
         if self.len() < 2 {
             None
         } else {
@@ -62,32 +62,37 @@ impl Measurements {
     }
 
     /// The median wall clock time.
-    pub fn median(&self) -> Second {
-        median(&self.wall_clock_times().collect::<Vec<_>>())
+    pub fn median(&self) -> Time {
+        median(self.wall_clock_times())
     }
 
     /// The minimum wall clock time.
-    pub fn min(&self) -> Second {
+    pub fn min(&self) -> Time {
         min(self.wall_clock_times())
     }
 
     /// The maximum wall clock time.
-    pub fn max(&self) -> Second {
+    pub fn max(&self) -> Time {
         max(self.wall_clock_times())
     }
 
     /// Compute modified Z-scores for the wall clock times.
     pub fn modified_zscores(&self) -> Vec<f64> {
-        modified_zscores(&self.wall_clock_times().collect::<Vec<_>>())
+        modified_zscores(
+            &self
+                .wall_clock_times()
+                .map(|t| t.get::<second>())
+                .collect::<Vec<_>>(),
+        )
     }
 
     /// The average user time.
-    pub fn time_user_mean(&self) -> Second {
+    pub fn time_user_mean(&self) -> Time {
         mean(self.measurements.iter().map(|m| m.time_user))
     }
 
     /// The average system time.
-    pub fn time_system_mean(&self) -> Second {
+    pub fn time_system_mean(&self) -> Time {
         mean(self.measurements.iter().map(|m| m.time_system))
     }
 }

src/benchmark/mod.rs

@@ -18,8 +18,8 @@ use crate::output::format::{format_duration, format_duration_unit};
 use crate::output::progress_bar::get_progress_bar;
 use crate::output::warnings::{OutlierWarningOptions, Warnings};
 use crate::parameter::ParameterNameAndValue;
+use crate::quantity::{byte, const_time_from_seconds, ratio, second, Time, Zero};
 use crate::util::exit_code::extract_exit_code;
-use crate::util::units::Second;
 use benchmark_result::BenchmarkResult;
 use measurement::{Measurement, Measurements};
 
@@ -29,7 +29,7 @@ use colored::*;
 use self::executor::Executor;
 
 /// Threshold for warning about fast execution time
-pub const MIN_EXECUTION_TIME: Second = 5e-3;
+pub const MIN_EXECUTION_TIME: Time = const_time_from_seconds(5e-3);
 
 pub struct Benchmark<'a> {
     number: usize,
@@ -236,7 +236,7 @@ impl<'a> Benchmark<'a> {
         };
 
         let preparation_result = run_preparation_command()?;
-        let preparation_overhead = preparation_result.map_or(0.0, |res| {
+        let preparation_overhead = preparation_result.map_or(Time::zero(), |res| {
             res.time_wall_clock + self.executor.time_overhead()
         });
 
@@ -250,7 +250,7 @@ impl<'a> Benchmark<'a> {
         let success = res.exit_status.success();
 
         let conclusion_result = run_conclusion_command()?;
-        let conclusion_overhead = conclusion_result.map_or(0.0, |res| {
+        let conclusion_overhead = conclusion_result.map_or(Time::zero(), |res| {
             res.time_wall_clock + self.executor.time_overhead()
         });
 
@@ -259,7 +259,8 @@ impl<'a> Benchmark<'a> {
             / (res.time_wall_clock
                 + self.executor.time_overhead()
                 + preparation_overhead
-                + conclusion_overhead)) as u64;
+                + conclusion_overhead))
+            .get::<ratio>() as u64;
 
         let count = {
             let min = cmp::max(runs_in_min_time, self.options.run_bounds.min);
@@ -292,8 +293,10 @@ impl<'a> Benchmark<'a> {
             run_preparation_command()?;
 
             let msg = {
-                let mean =
-                    format_duration(measurements.time_wall_clock_mean(), self.options.time_unit);
+                let mean = format_duration(
+                    measurements.time_wall_clock_mean().get::<second>(),
+                    self.options.time_unit,
+                );
                 format!("Current estimate: {}", mean.to_string().green())
             };
 
@@ -336,13 +339,14 @@ impl<'a> Benchmark<'a> {
         let system_mean = measurements.time_system_mean();
 
         // Formatting and console output
-        let (mean_str, time_unit) = format_duration_unit(t_mean, self.options.time_unit);
-        let min_str = format_duration(t_min, Some(time_unit));
-        let max_str = format_duration(t_max, Some(time_unit));
+        let (mean_str, time_unit) =
+            format_duration_unit(t_mean.get::<second>(), self.options.time_unit);
+        let min_str = format_duration(t_min.get::<second>(), Some(time_unit));
+        let max_str = format_duration(t_max.get::<second>(), Some(time_unit));
         let num_str = format!("{t_num} runs");
 
-        let user_str = format_duration(user_mean, Some(time_unit));
-        let system_str = format_duration(system_mean, Some(time_unit));
+        let user_str = format_duration(user_mean.get::<second>(), Some(time_unit));
+        let system_str = format_duration(system_mean.get::<second>(), Some(time_unit));
 
         if self.options.output_style != OutputStyleOption::Disabled {
             let mut stdout = io::stdout().lock();
@@ -357,7 +361,8 @@ impl<'a> Benchmark<'a> {
                     system_str.blue()
                 )?;
             } else {
-                let stddev_str = format_duration(t_stddev.unwrap(), Some(time_unit));
+                let stddev_str =
+                    format_duration(t_stddev.unwrap().get::<second>(), Some(time_unit));
 
                 console_writeln!(
                     stdout,
@@ -440,19 +445,24 @@ impl<'a> Benchmark<'a> {
         Ok(BenchmarkResult {
             command: self.command.get_name(),
             command_with_unused_parameters: self.command.get_name_with_unused_parameters(),
-            mean: t_mean,
-            stddev: t_stddev,
-            median: t_median,
-            user: user_mean,
-            system: system_mean,
-            min: t_min,
-            max: t_max,
-            times: Some(measurements.wall_clock_times().collect()),
+            mean: t_mean.get::<second>(),
+            stddev: t_stddev.map(|t| t.get::<second>()),
+            median: t_median.get::<second>(),
+            user: user_mean.get::<second>(),
+            system: system_mean.get::<second>(),
+            min: t_min.get::<second>(),
+            max: t_max.get::<second>(),
+            times: Some(
+                measurements
+                    .wall_clock_times()
+                    .map(|t| t.get::<second>())
+                    .collect(),
+            ),
             memory_usage_byte: Some(
                 measurements
                     .measurements
                     .iter()
-                    .map(|m| m.peak_memory_usage)
+                    .map(|m| m.peak_memory_usage.get::<byte>() as u64)
                     .collect(),
             ),
             exit_codes: measurements

src/main.rs

@@ -25,6 +25,7 @@ pub mod options;
 pub mod outlier_detection;
 pub mod output;
 pub mod parameter;
+mod quantity;
 pub mod timer;
 pub mod util;
 

src/options.rs

@@ -9,7 +9,8 @@ use clap::ArgMatches;
 
 use crate::command::Commands;
 use crate::error::OptionsError;
-use crate::util::units::{Second, Unit};
+use crate::quantity::{second, Time};
+use crate::util::units::Unit;
 
 use anyhow::Result;
 
@@ -203,7 +204,7 @@ pub struct Options {
     pub warmup_count: u64,
 
     /// Minimum benchmarking time
-    pub min_benchmarking_time: Second,
+    pub min_benchmarking_time: Time,
 
     /// Whether or not to ignore non-zero exit codes
     pub command_failure_action: CmdFailureAction,
@@ -253,7 +254,7 @@ impl Default for Options {
         Options {
             run_bounds: RunBounds::default(),
             warmup_count: 0,
-            min_benchmarking_time: 3.0,
+            min_benchmarking_time: Time::new::<second>(3.0),
             command_failure_action: CmdFailureAction::RaiseError,
             reference_command: None,
             reference_name: None,
@@ -438,9 +439,10 @@ impl Options {
         };
 
         if let Some(time) = matches.get_one::<String>("min-benchmarking-time") {
-            options.min_benchmarking_time = time
-                .parse::<f64>()
-                .map_err(|e| OptionsError::FloatParsingError("min-benchmarking-time", e))?;
+            options.min_benchmarking_time = Time::new::<second>(
+                time.parse::<f64>()
+                    .map_err(|e| OptionsError::FloatParsingError("min-benchmarking-time", e))?,
+            );
         }
 
         options.command_input_policy = if let Some(path_str) = matches.get_one::<String>("input") {

src/outlier_detection.rs

@@ -22,13 +22,13 @@ pub fn modified_zscores(xs: &[f64]) -> Vec<f64> {
     assert!(!xs.is_empty());
 
     // Compute sample median:
-    let x_median = median(xs);
+    let x_median = median(xs.iter().copied());
 
     // Compute the absolute deviations from the median:
     let deviations: Vec<f64> = xs.iter().map(|x| (x - x_median).abs()).collect();
 
     // Compute median absolute deviation:
-    let mad = median(&deviations);
+    let mad = median(deviations.iter().copied());
 
     // Handle MAD == 0 case
     let mad = if mad > 0.0 { mad } else { f64::EPSILON };

src/output/warnings.rs

@@ -2,7 +2,7 @@ use std::fmt;
 
 use crate::benchmark::MIN_EXECUTION_TIME;
 use crate::output::format::format_duration;
-use crate::util::units::Second;
+use crate::quantity::{second, Time};
 
 pub struct OutlierWarningOptions {
     pub warmup_in_use: bool,
@@ -13,7 +13,7 @@ pub struct OutlierWarningOptions {
 pub enum Warnings {
     FastExecutionTime,
     NonZeroExitCode,
-    SlowInitialRun(Second, OutlierWarningOptions),
+    SlowInitialRun(Time, OutlierWarningOptions),
     OutliersDetected(OutlierWarningOptions),
 }
 
@@ -26,7 +26,7 @@ impl fmt::Display for Warnings {
                 inaccurate because hyperfine can not calibrate the shell startup time much \
                 more precise than this limit. You can try to use the `-N`/`--shell=none` \
                 option to disable the shell completely.",
-                MIN_EXECUTION_TIME * 1e3
+                MIN_EXECUTION_TIME.get::<second>() * 1e3
             ),
             Warnings::NonZeroExitCode => write!(f, "Ignoring non-zero exit code."),
             Warnings::SlowInitialRun(time_first_run, ref options) => write!(
@@ -34,7 +34,7 @@ impl fmt::Display for Warnings {
                 "The first benchmarking run for this command was significantly slower than the \
                  rest ({time}). This could be caused by (filesystem) caches that were not filled until \
                  after the first run. {hints}",
-                time=format_duration(time_first_run, None),
+                time=format_duration(time_first_run.get::<second>(), None),
                 hints=match (options.warmup_in_use, options.prepare_in_use) {
                     (true, true) => "You are already using both the '--warmup' option as well \
                     as the '--prepare' option. Consider re-running the benchmark on a quiet system. \

src/quantity.rs

@@ -0,0 +1,45 @@
+use std::marker::PhantomData;
+
+pub use uom::num_traits::Zero;
+pub use uom::si::f64::{Information, Ratio, Time};
+pub use uom::si::information::byte;
+pub use uom::si::ratio::ratio;
+pub use uom::si::time::{microsecond, nanosecond, second};
+
+pub const fn const_time_from_seconds(value: f64) -> Time {
+    // Quantity::new in uom is not yet const: https://docs.rs/uom/0.36.0/uom/si/struct.Quantity.html
+    Time {
+        dimension: PhantomData,
+        units: PhantomData,
+        value,
+    }
+}
+
+#[cfg(test)]
+use uom::si::{information::kibibyte, time::millisecond};
+
+#[test]
+fn test_time() {
+    let time = Time::new::<millisecond>(123.4);
+    assert_eq!(time.get::<millisecond>(), 123.4);
+
+    let time_s = time.get::<second>();
+    approx::assert_relative_eq!(time_s, 0.1234);
+
+    let time_us = time.get::<microsecond>();
+    approx::assert_relative_eq!(time_us, 123400.0);
+}
+
+#[test]
+fn test_information() {
+    use uom::si::information::pebibyte;
+
+    let information = Information::new::<kibibyte>(8.);
+    assert_eq!(information.get::<byte>(), 8192.);
+
+    let information_kib = information.get::<kibibyte>();
+    assert_eq!(information_kib, 8.);
+
+    let largest_exactly_representable = Information::new::<byte>(9_007_199_254_740_992.);
+    assert_eq!(largest_exactly_representable.get::<pebibyte>(), 8.);
+}

src/timer/unix_timer.rs

@@ -3,16 +3,16 @@
 use std::convert::TryFrom;
 use std::mem;
 
+use crate::quantity::{byte, microsecond, Information, Time};
 use crate::timer::CPUTimes;
-use crate::util::units::Second;
 
 #[derive(Debug, Copy, Clone)]
 pub struct CPUInterval {
     /// Total amount of time spent executing in user mode
-    pub user: Second,
+    pub user: Time,
 
     /// Total amount of time spent executing in kernel mode
-    pub system: Second,
+    pub system: Time,
 }
 
 pub struct CPUTimer {
@@ -26,13 +26,13 @@ impl CPUTimer {
         }
     }
 
-    pub fn stop(&self) -> (Second, Second, u64) {
+    pub fn stop(&self) -> (Time, Time, Information) {
         let end_cpu = get_cpu_times();
         let cpu_interval = cpu_time_interval(&self.start_cpu, &end_cpu);
         (
             cpu_interval.user,
             cpu_interval.system,
-            end_cpu.memory_usage_byte,
+            Information::new::<byte>(end_cpu.memory_usage_byte as f64),
         )
     }
 }
@@ -70,11 +70,13 @@ fn get_cpu_times() -> CPUTimes {
 /// Compute the time intervals in between two `CPUTimes` snapshots
 fn cpu_time_interval(start: &CPUTimes, end: &CPUTimes) -> CPUInterval {
     CPUInterval {
-        user: ((end.user_usec - start.user_usec) as f64) * 1e-6,
-        system: ((end.system_usec - start.system_usec) as f64) * 1e-6,
+        user: Time::new::<microsecond>((end.user_usec - start.user_usec) as f64),
+        system: Time::new::<microsecond>((end.system_usec - start.system_usec) as f64),
     }
 }
 
+#[cfg(test)]
+use crate::quantity::second;
 #[cfg(test)]
 use approx::assert_relative_eq;
 
@@ -93,14 +95,14 @@ fn test_cpu_time_interval() {
     };
 
     let t_zero = cpu_time_interval(&t_a, &t_a);
-    assert!(t_zero.user.abs() < f64::EPSILON);
-    assert!(t_zero.system.abs() < f64::EPSILON);
+    assert!(t_zero.user.get::<second>().abs() < f64::EPSILON);
+    assert!(t_zero.system.get::<second>().abs() < f64::EPSILON);
 
     let t_ab = cpu_time_interval(&t_a, &t_b);
-    assert_relative_eq!(0.007655, t_ab.user);
-    assert_relative_eq!(0.015679, t_ab.system);
+    assert_relative_eq!(0.007655, t_ab.user.get::<second>());
+    assert_relative_eq!(0.015679, t_ab.system.get::<second>());
 
     let t_ba = cpu_time_interval(&t_b, &t_a);
-    assert_relative_eq!(-0.007655, t_ba.user);
-    assert_relative_eq!(-0.015679, t_ba.system);
+    assert_relative_eq!(-0.007655, t_ba.user.get::<second>());
+    assert_relative_eq!(-0.015679, t_ba.system.get::<second>());
 }

src/timer/wall_clock_timer.rs

@@ -1,6 +1,6 @@
 use std::time::Instant;
 
-use crate::util::units::Second;
+use crate::quantity::{nanosecond, second, Time};
 
 pub struct WallClockTimer {
     start: Instant,
@@ -13,8 +13,10 @@ impl WallClockTimer {
         }
     }
 
-    pub fn stop(&self) -> Second {
+    pub fn stop(&self) -> Time {
         let duration = self.start.elapsed();
-        duration.as_secs() as f64 + f64::from(duration.subsec_nanos()) * 1e-9
+
+        Time::new::<second>(duration.as_secs() as f64)
+            + Time::new::<nanosecond>(duration.subsec_nanos() as f64)
     }
 }

src/timer/windows_timer.rs

@@ -27,7 +27,7 @@ use windows_sys::{
     },
 };
 
-use crate::util::units::Second;
+use crate::quantity::{microsecond, Information, Time, Zero};
 
 const HUNDRED_NS_PER_MS: i64 = 10;
 
@@ -86,7 +86,7 @@ impl CPUTimer {
         Self { job_object }
     }
 
-    pub fn stop(&self) -> (Second, Second, u64) {
+    pub fn stop(&self) -> (Time, Time, Information) {
         let mut job_object_info =
             mem::MaybeUninit::<JOBOBJECT_BASIC_ACCOUNTING_INFORMATION>::uninit();
 
@@ -114,9 +114,13 @@ impl CPUTimer {
             // for all active processes associated with the job, as well as all terminated
             // processes no longer associated with the job, in 100-nanosecond ticks."
             let kernel: i64 = job_object_info.TotalKernelTime / HUNDRED_NS_PER_MS;
-            (user as f64 * 1e-6, kernel as f64 * 1e-6, 0)
+            (
+                Time::new::<microsecond>(user as f64),
+                Time::new::<microsecond>(kernel as f64),
+                Information::zero(),
+            )
         } else {
-            (0.0, 0.0, 0)
+            (Time::zero(), Time::zero(), Information::zero())
         }
     }
 }

src/util/statistics.rs

@@ -1,5 +1,9 @@
 //! Statistics for non-empty samples of finite measurements.
 
+use std::ops::{Add, AddAssign, Div};
+
+use crate::quantity::{byte, ratio, second, Information, Ratio, Time, Zero};
+
 /// A min function that assumes no NaNs and at least one element
 pub fn min<Q: PartialOrd>(values: impl IntoIterator<Item = Q>) -> Q {
     values
@@ -17,54 +21,97 @@ pub fn max<Q: PartialOrd>(values: impl IntoIterator<Item = Q>) -> Q {
 }
 
 /// Arithmetic mean, summing measurements in their original order.
-pub fn mean(values: impl IntoIterator<Item = f64>) -> f64 {
-    let mut sum = 0.0;
+pub fn mean<Q, P>(values: impl IntoIterator<Item = Q>) -> Q
+where
+    Q: AddAssign + Zero + Div<Ratio, Output = P>,
+    P: Into<Q>,
+{
+    let mut sum = Q::zero();
     let mut count = 0usize;
     for value in values {
         sum += value;
         count += 1;
     }
-    sum / count as f64
+
+    let count = Ratio::new::<ratio>(count as f64);
+    (sum / count).into()
 }
 
 /// Median without modifying the input sample.
-pub fn median(values: &[f64]) -> f64 {
+pub fn median<Q, P>(values: impl IntoIterator<Item = Q>) -> Q
+where
+    Q: Copy + PartialOrd + Add<Output = Q> + Div<Ratio, Output = P>,
+    P: Into<Q>,
+{
+    let mut values = values.into_iter().collect::<Vec<_>>();
     assert!(
         !values.is_empty(),
         "median requires at least one measurement"
     );
-    let mut sorted = values.to_vec();
-    sorted.sort_unstable_by(|a, b| a.partial_cmp(b).expect("No NaN measurements"));
+    values.sort_unstable_by(|a, b| a.partial_cmp(b).expect("No NaN measurements"));
 
-    let mid = sorted.len() / 2;
-    if sorted.len() % 2 == 1 {
-        sorted[mid]
+    let len = values.len();
+    if len % 2 == 0 {
+        let mid = len / 2;
+        let a = &values[mid - 1];
+        let b = &values[mid];
+        ((*b + *a) / Ratio::new::<ratio>(2.)).into()
     } else {
-        (sorted[mid] + sorted[mid - 1]) / 2.0
+        values[len / 2]
+    }
+}
+
+/// This is just sad, but after several hours trying to figure out how to write
+/// a generic `standard_deviation` function using `uom` quantities, I gave up.
+pub trait UnsafeRawValue {
+    fn unsafe_raw_value(&self) -> f64;
+    fn unsafe_from_raw_value(value: f64) -> Self;
+}
+
+impl UnsafeRawValue for Time {
+    fn unsafe_raw_value(&self) -> f64 {
+        self.get::<second>()
+    }
+
+    fn unsafe_from_raw_value(value: f64) -> Self {
+        Time::new::<second>(value)
+    }
+}
+
+impl UnsafeRawValue for Information {
+    fn unsafe_raw_value(&self) -> f64 {
+        self.get::<byte>()
+    }
+
+    fn unsafe_from_raw_value(value: f64) -> Self {
+        Information::new::<byte>(value)
     }
 }
 
 /// Sample standard deviation, using an already computed mean.
-pub fn standard_deviation(values: &[f64], mean: f64) -> f64 {
+pub fn standard_deviation<Q: UnsafeRawValue>(values: &[Q], mean: Q) -> Q {
+    let mean = mean.unsafe_raw_value();
     assert!(
         values.len() > 1,
         "standard deviation requires at least two measurements"
     );
     let sum = values
         .iter()
-        .map(|value| (value - mean) * (value - mean))
+        .map(|value| (value.unsafe_raw_value() - mean) * (value.unsafe_raw_value() - mean))
         .fold(0.0, |sum, deviation| sum + deviation);
     assert!(sum >= 0.0, "invalid sum of squared deviations");
 
     // Preserve the operation order of statistical 1.0: dividing by n - 1
     // before taking the square root also preserves exported floating-point values.
-    (sum / (values.len() as f64 - 1.0)).sqrt()
+    Q::unsafe_from_raw_value((sum / (values.len() as f64 - 1.0)).sqrt())
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
     use approx::assert_relative_eq;
+    use uom::si::information::kibibyte;
+    use uom::si::time::{microsecond, millisecond};
 
     #[test]
     fn test_min() {
@@ -74,8 +121,12 @@ mod tests {
         assert_eq!(-1.0, min([-1.0, 1.0]));
         assert_eq!(-1.0, min([1.0, -1.0, 0.0]));
 
-        let values = vec![1024.0, 2.0, 3.0];
-        assert_eq!(*min(&values), 2.0);
+        let values = vec![
+            Information::new::<kibibyte>(1.0),
+            Information::new::<byte>(2.0),
+            Information::new::<byte>(3.0),
+        ];
+        assert_eq!(min(&values).get::<byte>(), 2.0);
     }
 
     #[test]
@@ -86,8 +137,12 @@ mod tests {
         assert_eq!(1.0, max([-1.0, 1.0]));
         assert_eq!(1.0, max([-1.0, 1.0, 0.0]));
 
-        let values = vec![1.0, 2048.0, 3.0];
-        assert_eq!(*max(&values), 2048.0);
+        let values = vec![
+            Information::new::<byte>(1.0),
+            Information::new::<kibibyte>(2.0),
+            Information::new::<byte>(3.0),
+        ];
+        assert_eq!(max(&values).get::<kibibyte>(), 2.0);
     }
 
     #[test]
@@ -95,25 +150,46 @@ mod tests {
         assert_eq!(1.0, mean([1.0]));
         assert_relative_eq!(2.0, mean([1.0, 3.0]));
 
-        let values = [0.1, 0.2, 0.6];
-        assert_relative_eq!(mean(values), 0.3);
+        let values = [
+            Time::new::<millisecond>(100.0),
+            Time::new::<millisecond>(200.0),
+            Time::new::<microsecond>(600_000.0),
+        ];
+        let result = mean(values);
+        assert_relative_eq!(result.get::<millisecond>(), 300.0);
     }
 
     #[test]
     fn test_median() {
-        assert_eq!(1.0, median(&[1.0]));
-        assert_relative_eq!(2.0, median(&[1.0, 3.0]));
+        assert_eq!(1.0, median([1.0]));
+        assert_relative_eq!(2.0, median([1.0, 3.0]));
 
-        let values = [0.1, 0.2, 0.6];
-        assert_relative_eq!(median(&values), 0.2);
+        let values = [
+            Time::new::<millisecond>(100.0),
+            Time::new::<millisecond>(200.0),
+            Time::new::<microsecond>(600_000.0),
+        ];
+        let result = median(values);
+        assert_relative_eq!(result.get::<millisecond>(), 200.0);
 
-        let values = [0.1, 0.2, 0.3, 0.6];
-        assert_relative_eq!(median(&values), 0.25);
+        let values = [
+            Time::new::<millisecond>(100.0),
+            Time::new::<millisecond>(200.0),
+            Time::new::<microsecond>(300_000.0),
+            Time::new::<microsecond>(600_000.0),
+        ];
+        let result = median(values);
+        assert_relative_eq!(result.get::<millisecond>(), 250.0);
     }
 
     #[test]
     fn test_standard_deviation() {
-        let values = [0.1, 0.2, 0.3];
-        assert_relative_eq!(standard_deviation(&values, mean(values)), 0.1);
+        let values = [
+            Time::new::<millisecond>(100.0),
+            Time::new::<millisecond>(200.0),
+            Time::new::<microsecond>(300_000.0),
+        ];
+        let result = standard_deviation(&values, mean(values));
+        assert_relative_eq!(result.get::<millisecond>(), 100.0);
     }
 }