Auto merge of #143525 - Shourya742:2025-07-06-add-profiler, r=Kobzol

Add profiler to bootstrap command

This PR adds command profiling to the bootstrap command. It tracks the total execution time and records cache hits for each command. It also provides the ability to export execution result to a JSON file. Integrating this with Chrome tracing could further enhance observability.

r? `@Kobzol`

Author: bors

src/bootstrap/src/bin/main.rs

@@ -8,6 +8,7 @@
 use std::fs::{self, OpenOptions};
 use std::io::{self, BufRead, BufReader, IsTerminal, Write};
 use std::str::FromStr;
+use std::time::Instant;
 use std::{env, process};
 
 use bootstrap::{
@@ -17,11 +18,17 @@ use bootstrap::{
 #[cfg(feature = "tracing")]
 use tracing::instrument;
 
+fn is_bootstrap_profiling_enabled() -> bool {
+    env::var("BOOTSTRAP_PROFILE").is_ok_and(|v| v == "1")
+}
+
 #[cfg_attr(feature = "tracing", instrument(level = "trace", name = "main"))]
 fn main() {
     #[cfg(feature = "tracing")]
     let _guard = setup_tracing();
 
+    let start_time = Instant::now();
+
     let args = env::args().skip(1).collect::<Vec<_>>();
 
     if Flags::try_parse_verbose_help(&args) {
@@ -96,7 +103,8 @@ fn main() {
     let out_dir = config.out.clone();
 
     debug!("creating new build based on config");
-    Build::new(config).build();
+    let mut build = Build::new(config);
+    build.build();
 
     if suggest_setup {
         println!("WARNING: you have not made a `bootstrap.toml`");
@@ -147,6 +155,10 @@ fn main() {
             t!(file.write_all(lines.join("\n").as_bytes()));
         }
     }
+
+    if is_bootstrap_profiling_enabled() {
+        build.report_summary(start_time);
+    }
 }
 
 fn check_version(config: &Config) -> Option<String> {
@@ -226,7 +238,7 @@ fn setup_tracing() -> impl Drop {
     let mut chrome_layer = tracing_chrome::ChromeLayerBuilder::new().include_args(true);
 
     // Writes the Chrome profile to trace-<unix-timestamp>.json if enabled
-    if !env::var("BOOTSTRAP_PROFILE").is_ok_and(|v| v == "1") {
+    if !is_bootstrap_profiling_enabled() {
         chrome_layer = chrome_layer.writer(io::sink());
     }
 

src/bootstrap/src/core/build_steps/compile.rs

@@ -2576,7 +2576,7 @@ pub fn stream_cargo(
     }
 
     // Make sure Cargo actually succeeded after we read all of its stdout.
-    let status = t!(streaming_command.wait());
+    let status = t!(streaming_command.wait(&builder.config.exec_ctx));
     if builder.is_verbose() && !status.success() {
         eprintln!(
             "command did not execute successfully: {cmd:?}\n\

src/bootstrap/src/lib.rs

@@ -22,7 +22,7 @@ use std::collections::{BTreeSet, HashMap, HashSet};
 use std::fmt::Display;
 use std::path::{Path, PathBuf};
 use std::sync::OnceLock;
-use std::time::SystemTime;
+use std::time::{Instant, SystemTime};
 use std::{env, fs, io, str};
 
 use build_helper::ci::gha;
@@ -1928,6 +1928,10 @@ to download LLVM rather than building it.
     pub fn exec_ctx(&self) -> &ExecutionContext {
         &self.config.exec_ctx
     }
+
+    pub fn report_summary(&self, start_time: Instant) {
+        self.config.exec_ctx.profiler().report_summary(start_time);
+    }
 }
 
 impl AsRef<ExecutionContext> for Build {