1 files changed, 151 insertions, 0 deletions
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..956285b
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,151 @@
+#[macro_use]
+extern crate clap;
+extern crate num;
+
+use std::path::{Path, PathBuf};
+use std::fs::File;
+use std::io::{self, Read};
+use std::{iter, thread, ops};
+use std::time::Duration;
+
+use clap::{Arg, App, AppSettings, SubCommand};
+
+use num::NumCast;
+
+const SYS_PRESENT: &'static str = "/sys/devices/system/cpu/present";
+static FORMAT: [char; 9] = [' ', '▁', '▂', '▃', '▄', '▅', '▆', '▇', '█'];
+
+const WINDOW_SIZE: usize = 32;
+
+#[derive(Debug, Default)]
+struct Window<T> {
+    data: Vec<T>,
+    idx: usize,
+    size: usize
+}
+
+impl<T> Window<T> where T: for<'a> iter::Sum<&'a T> + ops::Div<Output=T> + NumCast {
+    fn new(size: usize) -> Window<T> {
+        Window { data: Vec::with_capacity(size), idx: 0, size: size }
+    }
+
+    fn sample(&mut self, value: T) {
+        if self.data.len() < self.size { self.data.push(value) }
+        else { self.data[self.idx] = value; }
+        self.idx = (self.idx + 1) % self.size;
+    }
+
+    fn elements(&self) -> (&[T], &[T]) { (&self.data[self.idx..], &self.data[..self.idx]) }
+    fn average(&self) -> T { self.data.iter().sum::<T>() / T::from(self.data.len()).unwrap() }
+}
+
+#[derive(Debug, Default)]
+struct Core {
+    index: u32,
+    min_freq: u32,
+    max_freq: u32,
+    cur_freq: Window<u32>
+}
+
+#[derive(Debug)]
+struct System {
+    cores: Vec<Core>,
+    load: Window<f32>
+}
+
+impl System {
+    fn new() -> System {
+        System {
+            cores: init_cores(),
+            load: Window::new(8)
+        }
+    }
+
+    // Direct printing to avoid allocation
+    fn print_cores(&self) {
+        for c in &self.cores {
+            let load = (c.cur_freq.average() - c.min_freq) as f32 / (c.max_freq - c.min_freq) as f32;
+            print!("{}", FORMAT[(FORMAT.len() as f32 * load) as usize]);
+        }
+        println!("");
+    }
+
+    fn print_system(&self) {
+        let (first, last) = self.load.elements();
+        for load in first.iter().chain(last.iter()) {
+            print!("{}", FORMAT[(FORMAT.len() as f32 * load) as usize]);
+        }
+        println!("");
+    }
+}
+
+fn read_into_string<P: AsRef<Path>>(path: P) -> io::Result<String> {
+    let mut output = String::new();
+    try!(try!(File::open(path)).read_to_string(&mut output));
+    Ok(output)
+}
+
+fn init_cores() -> Vec<Core> {
+    let present = read_into_string(SYS_PRESENT).expect("Can't read kernel interface to query present cores");
+    
+    // a-b
+    let mut parts = present.split('-').flat_map(|s| s.trim().parse::<u32>().ok());
+    let (a, b) = (parts.next().unwrap(), parts.next().unwrap());
+    (a..b + 1).map(|idx| {
+        let cpu_path: PathBuf = format!("/sys/devices/system/cpu/cpu{}/cpufreq", idx).into();
+        Core {
+            index: idx,
+            min_freq: read_into_string(cpu_path.join("scaling_min_freq")).ok()
+                .and_then(|s| s.trim().parse().ok()).expect("Can't read min freq"),
+            max_freq: read_into_string(cpu_path.join("scaling_max_freq")).ok()
+                .and_then(|s| s.trim().parse().ok()).expect("Can't read max frequency"),
+            cur_freq: Window::new(WINDOW_SIZE)
+        }
+    }).collect()
+}
+
+fn update(system: &mut System) {
+    let mut frame_average = 0.;
+    for c in &mut system.cores {
+        let cpu_path: PathBuf = format!("/sys/devices/system/cpu/cpu{}/cpufreq/scaling_cur_freq", c.index).into();
+        let cur_freq = read_into_string(cpu_path).ok()
+                .and_then(|s| s.trim().parse().ok()).expect("Can't read current frequency");
+        c.cur_freq.sample(cur_freq);
+        frame_average += (cur_freq - c.min_freq) as f32 / (c.max_freq - c.min_freq) as f32;
+    }
+    system.load.sample(frame_average / system.cores.len() as f32);
+}
+
+fn main() {
+    let matches = App::new("cpuline")
+        .version(crate_version!())
+        .author(crate_authors!())
+        .about("Display CPU usage per-core or over time (Linux-only)")
+        .setting(AppSettings::SubcommandRequired)
+        .arg(Arg::with_name("interval")
+             .global(true)
+             .short("i")
+             .long("interval")
+             .value_name("MS")
+             .takes_value(true)
+             .default_value("1000"))
+        .subcommand(SubCommand::with_name("cores"))
+        .subcommand(SubCommand::with_name("time"))
+        .get_matches();
+
+    let action = match matches.subcommand_name() {
+        Some("cores") => System::print_cores,
+        Some("time") => System::print_system,
+        _ => unreachable!()
+    };
+
+    let interval = value_t!(matches, "interval", u64).unwrap();
+
+    let mut system = System::new();
+
+    loop {
+        update(&mut system);
+        action(&system);
+        thread::sleep(Duration::from_millis(interval));
+    }
+}