[2/n] [update-engine] add ( to the beginning of step indexes in the line displayer (#6447)

This was reported by @wfchandler -- not sure why I missed these
originally.

Also move the step index display logic out into its own displayer -- I need
this (including the padded logic) in a couple of spots.

This can be landed separately from #6444.

Some example output from `cargo run --example update-engine-basic -- -s line`:

```
[00:00:00]   Running (1/7) Downloading component: https://www.example.org
[00:00:00]  Progress (1/7) Downloading component: https://www.example.org: 12.50% ( 131072/1048576 bytes) after 101.22ms
[00:00:00]  Progress (1/7) Downloading component: https://www.example.org: 25.00% ( 262144/1048576 bytes) after 201.49ms
[00:00:00]     Retry (1/7) Downloading component: https://www.example.org: after 302.77ms (at attempt 1) with message: Simulated failure at 25%
[00:00:00]  Progress (1/7) Downloading component: https://www.example.org:  0.00% (      0/1048576 bytes) after 101.37ms
[00:00:00]  Progress (1/7) Downloading component: https://www.example.org: 10.00% ( 104857/1048576 bytes) after 201.61ms
[00:00:00]  Progress (1/7) Downloading component: https://www.example.org: 20.00% ( 209715/1048576 bytes) after 302.86ms
[00:00:00]  Progress (1/7) Downloading component: https://www.example.org: 30.00% ( 314572/1048576 bytes) after 404.14ms
```

Author: sunshowers

update-engine/src/display/group_display.rs

@@ -12,8 +12,9 @@ use swrite::{swrite, SWrite};
 use unicode_width::UnicodeWidthStr;
 
 use crate::{
-    errors::UnknownReportKey, events::EventReport, EventBuffer,
-    ExecutionStatus, ExecutionTerminalInfo, StepSpec, TerminalKind,
+    display::ProgressRatioDisplay, errors::UnknownReportKey,
+    events::EventReport, EventBuffer, ExecutionStatus, ExecutionTerminalInfo,
+    StepSpec, TerminalKind,
 };
 
 use super::{
@@ -309,11 +310,13 @@ impl GroupDisplayStats {
         };
 
         swrite!(line, "{:>HEADER_WIDTH$} ", header.style(header_style));
-        let terminal_count = self.terminal_count();
         swrite!(
             line,
-            "{terminal_count}/{}: {} running, {} {}",
-            self.total,
+            "{}: {} running, {} {}",
+            ProgressRatioDisplay::current_and_total(
+                self.terminal_count(),
+                self.total
+            ),
             self.running.style(formatter.styles().meta_style),
             self.completed.style(formatter.styles().meta_style),
             "completed".style(formatter.styles().progress_style),

update-engine/src/display/line_display_shared.rs

@@ -16,6 +16,7 @@ use owo_colors::OwoColorize;
 use swrite::{swrite, SWrite as _};
 
 use crate::{
+    display::ProgressRatioDisplay,
     events::{
         ProgressCounter, ProgressEvent, ProgressEventKind, StepEvent,
         StepEventKind, StepInfo, StepOutcome,
@@ -633,10 +634,12 @@ fn format_progress_counter(counter: &ProgressCounter) -> String {
             let percent = (counter.current as f64 / total as f64) * 100.0;
             // <12.34> is 5 characters wide.
             let percent_width = 5;
-            let counter_width = total.to_string().len();
             format!(
-                "{:>percent_width$.2}% ({:>counter_width$}/{} {})",
-                percent, counter.current, total, counter.units,
+                "{:>percent_width$.2}% ({} {})",
+                percent,
+                ProgressRatioDisplay::current_and_total(counter.current, total)
+                    .padded(true),
+                counter.units,
             )
         }
         None => format!("{} {}", counter.current, counter.units),
@@ -716,17 +719,16 @@ impl LineDisplayFormatter {
     ) {
         ld_step_info.nest_data.add_prefix(line);
 
-        // Print out "<step index>/<total steps>)". Leave space such that we
-        // print out e.g. "1/8)" and " 3/14)".
-        // Add 1 to the index to make it 1-based.
-        let step_index = ld_step_info.step_info.index + 1;
-        let step_index_width = ld_step_info.total_steps.to_string().len();
+        // Print out "(<current>/<total>)" in a padded way, so that successive
+        // steps are vertically aligned.
         swrite!(
             line,
-            "{:width$}/{:width$}) ",
-            step_index,
-            ld_step_info.total_steps,
-            width = step_index_width
+            "({}) ",
+            ProgressRatioDisplay::index_and_total(
+                ld_step_info.step_info.index,
+                ld_step_info.total_steps
+            )
+            .padded(true),
         );
 
         swrite!(

update-engine/src/display/mod.rs

@@ -11,11 +11,14 @@
 //! * [`LineDisplay`]: a line-oriented display suitable for the command line.
 //! * [`GroupDisplay`]: manages state and shows the results of several
 //!   [`LineDisplay`]s at once.
+//! * Some utility displayers which can be used to build custom displayers.
 
 mod group_display;
 mod line_display;
 mod line_display_shared;
+mod utils;
 
 pub use group_display::GroupDisplay;
 pub use line_display::{LineDisplay, LineDisplayStyles};
 use line_display_shared::*;
+pub use utils::*;

update-engine/src/display/utils.rs

@@ -0,0 +1,108 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+//! Utility displayers.
+
+use std::fmt;
+
+/// Given current and total, displays `{current}/{total}`.
+///
+/// * If the `index_and_total` constructor is called, then `current` is `index
+///   + 1`.
+/// * If `padded` is `true`, `current` is right-aligned and padded with spaces
+///   to the width of `total`.
+///
+/// # Examples
+///
+/// ```
+/// use update_engine::display::ProgressRatioDisplay;
+///
+/// // 0-based index and total.
+/// let display = ProgressRatioDisplay::index_and_total(0 as u64, 8 as u64);
+/// assert_eq!(display.to_string(), "1/8");
+///
+/// // 1-based current and total.
+/// let display = ProgressRatioDisplay::current_and_total(82 as u64, 230 as u64);
+/// assert_eq!(display.to_string(), "82/230");
+///
+/// // With padding.
+/// let display = display.padded(true);
+/// assert_eq!(display.to_string(), " 82/230");
+/// ```
+#[derive(Debug)]
+pub struct ProgressRatioDisplay {
+    current: u64,
+    total: u64,
+    padded: bool,
+}
+
+impl ProgressRatioDisplay {
+    /// Create a new `ProgressRatioDisplay` with current and total values.
+    ///
+    /// `current` is considered to be 1-based. For example, "20/80 jobs done".
+    pub fn current_and_total<T: ToU64>(current: T, total: T) -> Self {
+        Self { current: current.to_u64(), total: total.to_u64(), padded: false }
+    }
+
+    /// Create a new `ProgressRatioDisplay` with index and total values.
+    ///
+    /// The index is 0-based (i.e. 1 is added to it). For example, step index 0
+    /// out of 8 total steps is shown as "1/8".
+    pub fn index_and_total<T: ToU64>(index: T, total: T) -> Self {
+        Self {
+            current: index
+                .to_u64()
+                .checked_add(1)
+                .expect("index can't be u64::MAX"),
+            total: total.to_u64(),
+            padded: false,
+        }
+    }
+
+    /// If set to true, the current value is padded to the same width as the
+    /// total.
+    pub fn padded(self, padded: bool) -> Self {
+        Self { padded, ..self }
+    }
+}
+
+impl fmt::Display for ProgressRatioDisplay {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        if self.padded {
+            let width = self.total.to_string().len();
+            write!(f, "{:>width$}/{}", self.current, self.total)
+        } else {
+            write!(f, "{}/{}", self.current, self.total)
+        }
+    }
+}
+
+/// Trait that abstracts over `usize` and `u64`.
+///
+/// There are no `From` implementations between `usize` and `u64`, but we
+/// assert below that all the architectures we support are 64-bit.
+pub trait ToU64 {
+    fn to_u64(self) -> u64;
+}
+
+const _: () = {
+    assert!(
+        std::mem::size_of::<usize>() == std::mem::size_of::<u64>(),
+        "usize and u64 are the same size"
+    );
+};
+
+impl ToU64 for usize {
+    #[inline]
+    fn to_u64(self) -> u64 {
+        self as u64
+    }
+}
+
+impl ToU64 for u64 {
+    #[inline]
+    fn to_u64(self) -> u64 {
+        self
+    }
+}

wicket/src/ui/panes/update.rs

@@ -29,6 +29,7 @@ use ratatui::widgets::{
 use ratatui::Frame;
 use slog::{info, o, Logger};
 use tui_tree_widget::{Tree, TreeItem, TreeState};
+use update_engine::display::ProgressRatioDisplay;
 use update_engine::{
     AbortReason, CompletionReason, ExecutionStatus, FailureReason, StepKey,
     TerminalKind, WillNotBeRunReason,
@@ -1984,9 +1985,11 @@ impl ComponentUpdateListState {
                     ));
                     status_text.push(Span::styled(
                         format!(
-                            " (step {}/{})",
-                            step_key.index + 1,
-                            summary.total_steps,
+                            " (step {})",
+                            ProgressRatioDisplay::index_and_total(
+                                step_key.index,
+                                summary.total_steps,
+                            )
                         ),
                         style::plain_text(),
                     ));
@@ -2015,9 +2018,11 @@ impl ComponentUpdateListState {
                             ));
                             status_text.push(Span::styled(
                                 format!(
-                                    " at step {}/{}",
-                                    info.step_key.index + 1,
-                                    summary.total_steps,
+                                    " at step {}",
+                                    ProgressRatioDisplay::index_and_total(
+                                        info.step_key.index,
+                                        summary.total_steps,
+                                    )
                                 ),
                                 style::plain_text(),
                             ));
@@ -2033,9 +2038,11 @@ impl ComponentUpdateListState {
                             ));
                             status_text.push(Span::styled(
                                 format!(
-                                    " at step {}/{}",
-                                    info.step_key.index + 1,
-                                    summary.total_steps,
+                                    " at step {}",
+                                    ProgressRatioDisplay::index_and_total(
+                                        info.step_key.index,
+                                        summary.total_steps,
+                                    )
                                 ),
                                 style::plain_text(),
                             ));