⚡ Bolt: [performance improvement] Optimize string splitting and avoid intermediate allocations in Python SDK build stdout logging

.jules/bolt.md

@@ -0,0 +1,3 @@
+## 2024-05-24 - Iterator Splitting Performance and Scratch Artifacts
+**Learning:** In Rust, chained intermediate `Vec` allocations (`.collect::<Vec<_>>().into_iter()`) for operations like string splitting can be up to 2-3x slower than direct iteration. Replacing string splits with character splits (`.split('\n')`) provides an additional marginal boost. Additionally, using standalone scratch files (e.g. `test_perf.rs`) to verify performance claims locally is helpful due to network environment constraints, but the compiled binaries and scripts *must* be removed to avoid polluting the workspace repository prior to PR submission.
+**Action:** Always prefer direct iteration over intermediate `Vec` collections. Always clean up local scratch files after validating hypotheses.

xdk-build/src/python.rs

@@ -159,16 +159,15 @@ fn run_formatter(output_dir: &Path, venv_python_path: &Path, script_path: &Path)
     let stdout = String::from_utf8_lossy(&output.stdout);
     if !stdout.trim().is_empty() {
         println!();
-        stdout
-            .split("\n")
-            .collect::<Vec<&str>>()
-            .into_iter()
-            .for_each(|line| {
-                let parts = line.split(" ").collect::<Vec<&str>>();
-                if parts.len() == 2 {
-                    log_info!("{} {}", parts[0], parts[1].magenta());
-                }
-            });
+        // ⚡ Bolt: Eliminate intermediate Vec allocations by using iterators directly
+        // and using character-based splitting instead of string-based splitting.
+        stdout.split('\n').for_each(|line| {
+            let mut parts = line.split(' ');
+            // Ensure exactly two parts
+            if let (Some(part0), Some(part1), None) = (parts.next(), parts.next(), parts.next()) {
+                log_info!("{} {}", part0, part1.magenta());
+            }
+        });
         println!();
     }