various: reduce allocations where available

.github/workflows/hotpath-comment.yml

@@ -0,0 +1,57 @@
+name: Hotpath Comment
+
+on:
+  workflow_run:
+    workflows: ["Hotpath Profile"]
+    types:
+      - completed
+
+permissions:
+  pull-requests: write
+
+jobs:
+  comment:
+    runs-on: ubuntu-latest
+    if: ${{ github.event.workflow_run.conclusion == 'success' }}
+
+    steps:
+      - name: Download profiling results
+        uses: actions/download-artifact@v4
+        with:
+          name: hotpath-results
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          run-id: ${{ github.event.workflow_run.id }}
+
+      - name: Read PR number
+        id: pr
+        run: echo "number=$(cat pr_number.txt)" >> $GITHUB_OUTPUT
+
+      - name: Setup Rust
+        uses: actions-rust-lang/setup-rust-toolchain@v1
+
+      - name: Install hotpath CLI
+        run: cargo install hotpath
+
+      - name: Post timing comparison comment
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          hotpath profile-pr \
+            --repo ${{ github.repository }} \
+            --pr-number ${{ steps.pr.outputs.number }} \
+            --head-json head-timing.json \
+            --base-json base-timing.json \
+            --mode timing \
+            --title "⏱️ Hotpath Timing Profile"
+
+      - name: Post allocation comparison comment
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          hotpath profile-pr \
+            --repo ${{ github.repository }} \
+            --pr-number ${{ steps.pr.outputs.number }} \
+            --head-json head-alloc.json \
+            --base-json base-alloc.json \
+            --mode alloc \
+            --title "📊 Hotpath Allocation Profile"

.github/workflows/hotpath-profile.yml

@@ -0,0 +1,63 @@
+name: Hotpath Profile
+
+on:
+  pull_request:
+    branches: [ "main" ]
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  profile:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout PR HEAD
+        uses: actions/checkout@v4
+
+      - name: Setup Rust
+        uses: actions-rust-lang/setup-rust-toolchain@v1
+
+      - name: Run timing profiling on HEAD
+        env:
+          HOTPATH_JSON: "true"
+        run: |
+          cargo run --features='hotpath' 2>&1 | grep '^{"hotpath_profiling_mode"' > head-timing.json
+
+      - name: Run allocation profiling on HEAD
+        env:
+          HOTPATH_JSON: "true"
+        run: |
+          cargo run --features='hotpath,hotpath-alloc-count-total' 2>&1 | grep '^{"hotpath_profiling_mode"' > head-alloc.json
+
+      - name: Checkout base branch
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.pull_request.base.sha }}
+
+      - name: Run timing profiling on base
+        env:
+          HOTPATH_JSON: "true"
+        run: |
+          cargo run --features='hotpath' 2>&1 | grep '^{"hotpath_profiling_mode"' > base-timing.json
+
+      - name: Run allocation profiling on base
+        env:
+          HOTPATH_JSON: "true"
+        run: |
+          cargo run --features='hotpath,hotpath-alloc-count-total' 2>&1 | grep '^{"hotpath_profiling_mode"' > base-alloc.json
+
+      - name: Save PR number
+        run: echo "${{ github.event.number }}" > pr_number.txt
+
+      - name: Upload profiling results
+        uses: actions/upload-artifact@v4
+        with:
+          name: hotpath-results
+          path: |
+            head-timing.json
+            head-alloc.json
+            base-timing.json
+            base-alloc.json
+            pr_number.txt
+          retention-days: 1

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name    = "microfetch"
-version = "0.4.9"
+version = "0.4.10"
 edition = "2024"
 
 [lib]

src/colors.rs

@@ -37,22 +37,45 @@ impl Colors {
 }
 
 pub static COLORS: LazyLock<Colors> = LazyLock::new(|| {
-  // check for NO_COLOR once at startup
+  // Check for NO_COLOR once at startup
   let is_no_color = env::var("NO_COLOR").is_ok();
   Colors::new(is_no_color)
 });
 
 #[must_use]
 #[cfg_attr(feature = "hotpath", hotpath::measure)]
 pub fn print_dots() -> String {
-  format!(
-    "{}  {}  {}  {}  {}  {}  {}",
-    COLORS.blue,
-    COLORS.cyan,
-    COLORS.green,
-    COLORS.yellow,
-    COLORS.red,
-    COLORS.magenta,
-    COLORS.reset,
-  )
+  // Pre-calculate capacity: 6 color codes + "  " (glyph + 2 spaces) per color
+  const GLYPH: &str = "";
+  let capacity = COLORS.blue.len()
+    + COLORS.cyan.len()
+    + COLORS.green.len()
+    + COLORS.yellow.len()
+    + COLORS.red.len()
+    + COLORS.magenta.len()
+    + COLORS.reset.len()
+    + (GLYPH.len() + 2) * 6;
+
+  let mut result = String::with_capacity(capacity);
+  result.push_str(COLORS.blue);
+  result.push_str(GLYPH);
+  result.push_str("  ");
+  result.push_str(COLORS.cyan);
+  result.push_str(GLYPH);
+  result.push_str("  ");
+  result.push_str(COLORS.green);
+  result.push_str(GLYPH);
+  result.push_str("  ");
+  result.push_str(COLORS.yellow);
+  result.push_str(GLYPH);
+  result.push_str("  ");
+  result.push_str(COLORS.red);
+  result.push_str(GLYPH);
+  result.push_str("  ");
+  result.push_str(COLORS.magenta);
+  result.push_str(GLYPH);
+  result.push_str("  ");
+  result.push_str(COLORS.reset);
+
+  result
 }

src/desktop.rs

@@ -1,30 +1,37 @@
+use std::fmt::Write;
+
 #[must_use]
 #[cfg_attr(feature = "hotpath", hotpath::measure)]
 pub fn get_desktop_info() -> String {
   // Retrieve the environment variables and handle Result types
   let desktop_env = std::env::var("XDG_CURRENT_DESKTOP");
-  let display_backend_result = std::env::var("XDG_SESSION_TYPE");
+  let display_backend = std::env::var("XDG_SESSION_TYPE");
 
-  // Capitalize the first letter of the display backend value
-  let mut display_backend = display_backend_result.unwrap_or_default();
-  if let Some(c) = display_backend.as_mut_str().get_mut(0..1) {
-    c.make_ascii_uppercase();
-  }
+  let desktop_str = match desktop_env {
+    Err(_) => "Unknown",
+    Ok(ref s) if s.starts_with("none+") => &s[5..],
+    Ok(ref s) => s.as_str(),
+  };
 
-  // Trim "none+" from the start of desktop_env if present
-  // Use "Unknown" if desktop_env is empty or has an error
-  let desktop_env = match desktop_env {
-    Err(_) => "Unknown".to_owned(),
-    Ok(s) => s.trim_start_matches("none+").to_owned(),
+  let backend_str = match display_backend {
+    Err(_) => "Unknown",
+    Ok(ref s) if s.is_empty() => "Unknown",
+    Ok(ref s) => s.as_str(),
   };
 
-  // Handle the case where display_backend might be empty after capitalization
-  let display_backend = if display_backend.is_empty() {
-    "Unknown"
-  } else {
-    &display_backend
+  // Pre-calculate capacity: desktop_len + " (" + backend_len + ")"
+  // Capitalize first char needs temporary allocation only if backend exists
+  let mut result =
+    String::with_capacity(desktop_str.len() + backend_str.len() + 3);
+  result.push_str(desktop_str);
+  result.push_str(" (");
+
+  // Capitalize first character of backend
+  if let Some(first_char) = backend_str.chars().next() {
+    let _ = write!(result, "{}", first_char.to_ascii_uppercase());
+    result.push_str(&backend_str[first_char.len_utf8()..]);
   }
-  .to_owned();
 
-  format!("{desktop_env} ({display_backend})")
+  result.push(')');
+  result
 }

src/release.rs

@@ -1,28 +1,39 @@
 use std::{
+  fmt::Write as _,
   fs::File,
-  io::{self, BufRead, BufReader},
+  io::{self, Read},
 };
 
 use nix::sys::utsname::UtsName;
 
 #[must_use]
 #[cfg_attr(feature = "hotpath", hotpath::measure)]
 pub fn get_system_info(utsname: &UtsName) -> String {
-  format!(
-    "{} {} ({})",
-    utsname.sysname().to_str().unwrap_or("Unknown"),
-    utsname.release().to_str().unwrap_or("Unknown"),
-    utsname.machine().to_str().unwrap_or("Unknown")
-  )
+  let sysname = utsname.sysname().to_str().unwrap_or("Unknown");
+  let release = utsname.release().to_str().unwrap_or("Unknown");
+  let machine = utsname.machine().to_str().unwrap_or("Unknown");
+
+  // Pre-allocate capacity: sysname + " " + release + " (" + machine + ")"
+  let capacity = sysname.len() + 1 + release.len() + 2 + machine.len() + 1;
+  let mut result = String::with_capacity(capacity);
+
+  write!(result, "{sysname} {release} ({machine})").unwrap();
+  result
 }
 
+/// Gets the pretty name of the OS from `/etc/os-release`.
+///
+/// # Errors
+///
+/// Returns an error if `/etc/os-release` cannot be read.
 #[cfg_attr(feature = "hotpath", hotpath::measure)]
 pub fn get_os_pretty_name() -> Result<String, io::Error> {
-  let file = File::open("/etc/os-release")?;
-  let reader = BufReader::new(file);
+  // We use a stack-allocated buffer here, which seems to perform MUCH better
+  // than `BufReader`. In hindsight, I should've seen this coming.
+  let mut buffer = String::with_capacity(1024);
+  File::open("/etc/os-release")?.read_to_string(&mut buffer)?;
 
-  for line in reader.lines() {
-    let line = line?;
+  for line in buffer.lines() {
     if let Some(pretty_name) = line.strip_prefix("PRETTY_NAME=") {
       if let Some(trimmed) = pretty_name
         .strip_prefix('"')