pre refactor

src/download_pb.rs

@@ -1,17 +1,29 @@
-use std::{cell::RefCell, rc::Rc};
+use std::{cell::RefCell, rc::Rc, sync::LazyLock, time::Instant};
 
-use indicatif::{MultiProgress, ProgressBar};
+use console::style;
+use indicatif::{HumanBytes, MultiProgress, ProgressBar};
 
-use crate::multibar::{BarSegment, MultiBar};
+use crate::{
+    estimator::Estimator,
+    multibar::{BarSegment, MultiBar},
+};
+
+static DOWNLOAD_CHAR: LazyLock<String> = LazyLock::new(|| style("#").blue().bold().to_string());
+static DONE_CHAR: LazyLock<String> = LazyLock::new(|| style("#").green().bold().to_string());
+
+const INFO_WIDTH: usize = 12;
 
 #[derive(Debug, Clone)]
 pub struct DownloadBar {
+    pub download_estimator: Rc<RefCell<Estimator>>,
+    pub extract_estimator: Rc<RefCell<Estimator>>,
     pub bar: ProgressBar,
     pub name: String,
     pub download_expected: Rc<RefCell<u64>>,
     pub download_done: Rc<RefCell<u64>>,
     pub extract_expected: Rc<RefCell<u64>>,
     pub extract_done: Rc<RefCell<u64>>,
+    pub started_at: Instant,
 }
 
 impl DownloadBar {
@@ -20,10 +32,13 @@ impl DownloadBar {
         let new_self = Self {
             name,
             bar,
+            download_estimator: Rc::new(RefCell::new(Estimator::new(Instant::now()))),
+            extract_estimator: Rc::new(RefCell::new(Estimator::new(Instant::now()))),
             download_expected: Rc::new(RefCell::new(0)),
             download_done: Rc::new(RefCell::new(0)),
             extract_expected: Rc::new(RefCell::new(0)),
             extract_done: Rc::new(RefCell::new(0)),
+            started_at: Instant::now(),
         };
         new_self.update(width);
         new_self
@@ -35,9 +50,20 @@ impl DownloadBar {
         let extract_done = *self.extract_done.borrow();
         let extract_expected = *self.extract_expected.borrow();
 
-        let name = pad_string(&self.name, 20);
+        self.download_estimator
+            .borrow_mut()
+            .record(download_done, Instant::now());
+        self.extract_estimator
+            .borrow_mut()
+            .record(extract_done, Instant::now());
+
+        let name = pad_string(&self.name, (width / 4) as usize);
+        let status = format!("Download {} |", style(name).magenta().bold());
+        let status_len = (width / 4) as usize + 10;
+
         if download_expected == 0 || extract_expected == 0 {
-            self.bar.set_message(format!("Download {}", name));
+            let text = pad_string("Pending...", width as usize / 3);
+            self.bar.set_message(format!("{status}"));
             return;
         }
 
@@ -47,6 +73,42 @@ impl DownloadBar {
         let dl_percent = ((download_done as f64 / download_expected as f64) * 100.0) as u64;
         let ex_percent = ((extract_done as f64 / extract_expected as f64) * 100.0) as u64;
 
+        let download_per_sec = HumanBytes(
+            self.download_estimator
+                .borrow()
+                .steps_per_second(Instant::now()) as u64,
+        )
+        .to_string();
+        let download_done_human = HumanBytes(download_done).to_string();
+        let download_done_human = style(pad_string(&download_done_human, INFO_WIDTH))
+            .blue()
+            .bold()
+            .to_string();
+        let extract_done_human = HumanBytes(extract_done).to_string();
+        let extract_done_human = style(pad_string(&extract_done_human, INFO_WIDTH))
+            .green()
+            .bold()
+            .to_string();
+        let download_per_sec = style(pad_string(&format!("{download_per_sec}/s"), INFO_WIDTH))
+            .blue()
+            .bold()
+            .to_string();
+
+        let display = format!("{download_per_sec} | {download_done_human} | {extract_done_human} ");
+        let display_length = (INFO_WIDTH * 3) + 9;
+
+        // + 6 to account for final format
+        let total_length = status_len + display_length + 4;
+
+        let min = dl_percent.min(ex_percent);
+        let dl = dl_percent.saturating_sub(min);
+        let bar = MultiBar([
+            BarSegment::Dynamic(&DONE_CHAR, min),
+            BarSegment::Dynamic(&DOWNLOAD_CHAR, dl),
+            BarSegment::Dynamic(" ", 100 - min - dl),
+        ])
+        .scale((width - total_length as u16) as u64);
+
         let msg = match width {
             0..50 => {
                 format!(
@@ -61,17 +123,7 @@ impl DownloadBar {
                 )
             }
             _ => {
-                let bar_dl = MultiBar([
+                format!("{status} {display} [{bar}]",)
-                    BarSegment::Dynamic("=", download_done),
-                    BarSegment::Dynamic(" ", download_expected.saturating_sub(download_done)),
-                ])
-                .scale((width / 6) as u64);
-                let bar_ex = MultiBar([
-                    BarSegment::Dynamic("=", extract_done),
-                    BarSegment::Dynamic(" ", extract_expected.saturating_sub(extract_done)),
-                ])
-                .scale((width / 6) as u64);
-                format!("Download {name} [{bar_dl}] {dl_percent:3}% [{bar_ex}] {ex_percent:3}%",)
             }
         };
         self.bar.set_message(msg);
@@ -79,6 +131,12 @@ impl DownloadBar {
     }
 }
 
+fn str_len(s: &str) -> usize {
+    s.chars()
+        .filter(|x| x.is_alphanumeric() || x.is_whitespace())
+        .count()
+}
+
 fn pad_string(s: &str, width: usize) -> String {
     if s.len() >= width {
         s.to_string()

src/estimator.rs

@@ -0,0 +1,145 @@
+use std::time::{Duration, Instant};
+
+/// Estimator borrowed from https://github.com/console-rs/indicatif/blob/main/src/state.rs#L421
+/// Double-smoothed exponentially weighted estimator
+///
+/// This uses an exponentially weighted *time-based* estimator, meaning that it exponentially
+/// downweights old data based on its age. The rate at which this occurs is currently a constant
+/// value of 15 seconds for 90% weighting. This means that all data older than 15 seconds has a
+/// collective weight of 0.1 in the estimate, and all data older than 30 seconds has a collective
+/// weight of 0.01, and so on.
+///
+/// The primary value exposed by `Estimator` is `steps_per_second`. This value is doubly-smoothed,
+/// meaning that is the result of using an exponentially weighted estimator (as described above) to
+/// estimate the value of another exponentially weighted estimator, which estimates the value of
+/// the raw data.
+///
+/// The purpose of this extra smoothing step is to reduce instantaneous fluctations in the estimate
+/// when large updates are received. Without this, estimates might have a large spike followed by a
+/// slow asymptotic approach to zero (until the next spike).
+#[derive(Debug)]
+pub struct Estimator {
+    smoothed_steps_per_sec: f64,
+    double_smoothed_steps_per_sec: f64,
+    prev_steps: u64,
+    prev_time: Instant,
+    start_time: Instant,
+}
+
+impl Estimator {
+    pub fn new(now: Instant) -> Self {
+        Self {
+            smoothed_steps_per_sec: 0.0,
+            double_smoothed_steps_per_sec: 0.0,
+            prev_steps: 0,
+            prev_time: now,
+            start_time: now,
+        }
+    }
+
+    pub fn record(&mut self, new_steps: u64, now: Instant) {
+        // sanity check: don't record data if time or steps have not advanced
+        if new_steps <= self.prev_steps || now <= self.prev_time {
+            // Reset on backwards seek to prevent breakage from seeking to the end for length determination
+            // See https://github.com/console-rs/indicatif/issues/480
+            if new_steps < self.prev_steps {
+                self.prev_steps = new_steps;
+                self.reset(now);
+            }
+            return;
+        }
+
+        let delta_steps = new_steps - self.prev_steps;
+        let delta_t = duration_to_secs(now - self.prev_time);
+
+        // the rate of steps we saw in this update
+        let new_steps_per_second = delta_steps as f64 / delta_t;
+
+        // update the estimate: a weighted average of the old estimate and new data
+        let weight = estimator_weight(delta_t);
+        self.smoothed_steps_per_sec =
+            self.smoothed_steps_per_sec * weight + new_steps_per_second * (1.0 - weight);
+
+        // An iterative estimate like `smoothed_steps_per_sec` is supposed to be an exponentially
+        // weighted average from t=0 back to t=-inf; Since we initialize it to 0, we neglect the
+        // (non-existent) samples in the weighted average prior to the first one, so the resulting
+        // average must be normalized. We normalize the single estimate here in order to use it as
+        // a source for the double smoothed estimate. See comment on normalization in
+        // `steps_per_second` for details.
+        let delta_t_start = duration_to_secs(now - self.start_time);
+        let total_weight = 1.0 - estimator_weight(delta_t_start);
+        let normalized_smoothed_steps_per_sec = self.smoothed_steps_per_sec / total_weight;
+
+        // determine the double smoothed value (EWA smoothing of the single EWA)
+        self.double_smoothed_steps_per_sec = self.double_smoothed_steps_per_sec * weight
+            + normalized_smoothed_steps_per_sec * (1.0 - weight);
+
+        self.prev_steps = new_steps;
+        self.prev_time = now;
+    }
+
+    /// Reset the state of the estimator. Once reset, estimates will not depend on any data prior
+    /// to `now`. This does not reset the stored position of the progress bar.
+    pub fn reset(&mut self, now: Instant) {
+        self.smoothed_steps_per_sec = 0.0;
+        self.double_smoothed_steps_per_sec = 0.0;
+
+        // only reset prev_time, not prev_steps
+        self.prev_time = now;
+        self.start_time = now;
+    }
+
+    /// Average time per step in seconds, using double exponential smoothing
+    pub fn steps_per_second(&self, now: Instant) -> f64 {
+        // Because the value stored in the Estimator is only updated when the Estimator receives an
+        // update, this value will become stuck if progress stalls. To return an accurate estimate,
+        // we determine how much time has passed since the last update, and treat this as a
+        // pseudo-update with 0 steps.
+        let delta_t = duration_to_secs(now - self.prev_time);
+        let reweight = estimator_weight(delta_t);
+
+        // Normalization of estimates:
+        //
+        // The raw estimate is a single value (smoothed_steps_per_second) that is iteratively
+        // updated. At each update, the previous value of the estimate is downweighted according to
+        // its age, receiving the iterative weight W(t) = 0.1 ^ (t/15).
+        //
+        // Since W(Sum(t_n)) = Prod(W(t_n)), the total weight of a sample after a series of
+        // iterative steps is simply W(t_e) - W(t_b), where t_e is the time since the end of the
+        // sample, and t_b is the time since the beginning. The resulting estimate is therefore a
+        // weighted average with sample weights W(t_e) - W(t_b).
+        //
+        // Notice that the weighting function generates sample weights that sum to 1 only when the
+        // sample times span from t=0 to t=inf; but this is not the case. We have a first sample
+        // with finite, positive t_b = t_f. In the raw estimate, we handle times prior to t_f by
+        // setting an initial value of 0, meaning that these (non-existent) samples have no weight.
+        //
+        // Therefore, the raw estimate must be normalized by dividing it by the sum of the weights
+        // in the weighted average. This sum is just W(0) - W(t_f), where t_f is the time since the
+        // first sample, and W(0) = 1.
+        let delta_t_start = duration_to_secs(now - self.start_time);
+        let total_weight = 1.0 - estimator_weight(delta_t_start);
+
+        // Generate updated values for `smoothed_steps_per_sec` and `double_smoothed_steps_per_sec`
+        // (sps and dsps) without storing them. Note that we normalize sps when using it as a
+        // source to update dsps, and then normalize dsps itself before returning it.
+        let sps = self.smoothed_steps_per_sec * reweight / total_weight;
+        let dsps = self.double_smoothed_steps_per_sec * reweight + sps * (1.0 - reweight);
+        dsps / total_weight
+    }
+}
+
+fn estimator_weight(age: f64) -> f64 {
+    const EXPONENTIAL_WEIGHTING_SECONDS: f64 = 15.0;
+    0.1_f64.powf(age / EXPONENTIAL_WEIGHTING_SECONDS)
+}
+
+fn duration_to_secs(d: Duration) -> f64 {
+    d.as_secs() as f64 + f64::from(d.subsec_nanos()) / 1_000_000_000f64
+}
+
+fn secs_to_duration(s: f64) -> Duration {
+    let secs = s.trunc() as u64;
+    let nanos = (s.fract() * 1_000_000_000f64) as u32;
+    Duration::new(secs, nanos)
+}

src/lib.rs

@@ -1,6 +1,7 @@
 pub mod action;
 pub mod action_raw;
 pub mod download_pb;
+pub mod estimator;
 pub mod multibar;
 pub mod nix_path;
 pub mod state_manager;

src/main.rs

@@ -18,6 +18,7 @@ static LAZY: LazyLock<i32> = LazyLock::new(|| {
 pub mod action;
 pub mod action_raw;
 pub mod download_pb;
+pub mod estimator;
 pub mod multibar;
 pub mod nix_path;
 pub mod state_manager;

src/state_manager.rs

@@ -1,6 +1,6 @@
 use console::{Term, style};
 use indicatif::{MultiProgress, ProgressBar, ProgressFinish, ProgressStyle};
-use std::{borrow::Cow, collections::HashMap, io};
+use std::{borrow::Cow, collections::HashMap, io, time::Instant};
 
 use crate::{action::StartFields, download_pb::DownloadBar, nix_path};