add command profiler

Author: Shourya742

src/bootstrap/src/utils/exec.rs

@@ -72,6 +72,65 @@ pub struct CommandCacheKey {
     cwd: Option<PathBuf>,
 }
 
+#[derive(Default, Clone)]
+pub struct CommandProfile {
+    pub count: usize,
+    pub total_duration: Duration,
+}
+
+#[derive(Default)]
+pub struct CommandProfiler {
+    stats: Mutex<HashMap<CommandCacheKey, CommandProfile>>,
+}
+
+
+impl CommandProfiler {
+    pub fn record(&self, key: CommandCacheKey, duration: Duration) {
+        let mut stats = self.stats.lock().unwrap();
+        let entry = stats.entry(key).or_default();
+        entry.count += 1;
+        entry.total_duration += duration;
+    }
+
+    pub fn report_slowest(&self, top_n: usize) {
+        let stats = self.stats.lock().unwrap();
+        let mut entries: Vec<_> = stats.iter().collect();
+        entries.sort_by_key(|(_, stat)| std::cmp::Reverse(stat.total_duration));
+
+        println!("\nTop {top_n} slowest commands:");
+        for (key, profile) in entries.into_iter().take(top_n) {
+            println!(
+                "- {:?} (count: {}, total: {:.2?}, avg: {:.2?})",
+                key.program,
+                profile.count,
+                profile.total_duration,
+                profile.total_duration / profile.count as u32
+            );
+        }
+    }
+
+    pub fn to_json(&self) -> serde_json::Value {
+        use serde_json::json;
+
+        let stats = self.stats.lock().unwrap();
+        let entries: Vec<_> = stats
+            .iter()
+            .map(|(key, profile)| {
+                json!({
+                    "program": key.program,
+                    "args": key.args,
+                    "envs": key.envs,
+                    "cwd": key.cwd,
+                    "count": profile.count,
+                    "total_duration_ms": profile.total_duration.as_millis(),
+                })
+            })
+            .collect();
+
+        json!({ "commands": entries })
+    }
+}
+
 /// Wrapper around `std::process::Command`.
 ///
 /// By default, the command will exit bootstrap if it fails.