Add export of bootstrap tracing to Chrome events

Author: Kobzol

src/bootstrap/Cargo.lock

@@ -59,6 +59,7 @@ dependencies = [
  "termcolor",
  "toml",
  "tracing",
+ "tracing-chrome",
  "tracing-subscriber",
  "tracing-tree",
  "walkdir",
@@ -727,6 +728,17 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "tracing-chrome"
+version = "0.7.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bf0a738ed5d6450a9fb96e86a23ad808de2b727fd1394585da5cdd6788ffe724"
+dependencies = [
+ "serde_json",
+ "tracing-core",
+ "tracing-subscriber",
+]
+
 [[package]]
 name = "tracing-core"
 version = "0.1.33"

src/bootstrap/Cargo.toml

@@ -7,7 +7,7 @@ default-run = "bootstrap"
 
 [features]
 build-metrics = ["sysinfo"]
-tracing = ["dep:tracing", "dep:tracing-subscriber", "dep:tracing-tree"]
+tracing = ["dep:tracing", "dep:tracing-chrome", "dep:tracing-subscriber", "dep:tracing-tree"]
 
 [lib]
 path = "src/lib.rs"
@@ -67,6 +67,7 @@ sysinfo = { version = "0.33.0", default-features = false, optional = true, featu
 
 # Dependencies needed by the `tracing` feature
 tracing = { version = "0.1", optional = true, features = ["attributes"] }
+tracing-chrome = { version = "0.7", optional = true }
 tracing-subscriber = { version = "0.3", optional = true, features = ["env-filter", "fmt", "registry", "std"] }
 tracing-tree = { version = "0.4.0", optional = true }
 

src/bootstrap/src/bin/main.rs

@@ -21,7 +21,7 @@ use tracing::instrument;
 #[cfg_attr(feature = "tracing", instrument(level = "trace", name = "main"))]
 fn main() {
     #[cfg(feature = "tracing")]
-    setup_tracing();
+    let _guard = setup_tracing();
 
     let args = env::args().skip(1).collect::<Vec<_>>();
 
@@ -210,15 +210,25 @@ fn check_version(config: &Config) -> Option<String> {
 // - `tracing`'s `#[instrument(..)]` macro will need to be gated like `#![cfg_attr(feature =
 //   "tracing", instrument(..))]`.
 #[cfg(feature = "tracing")]
-fn setup_tracing() {
+fn setup_tracing() -> impl Drop {
     use tracing_subscriber::EnvFilter;
     use tracing_subscriber::layer::SubscriberExt;
 
     let filter = EnvFilter::from_env("BOOTSTRAP_TRACING");
     // cf. <https://docs.rs/tracing-tree/latest/tracing_tree/struct.HierarchicalLayer.html>.
     let layer = tracing_tree::HierarchicalLayer::default().with_targets(true).with_indent_amount(2);
 
-    let registry = tracing_subscriber::registry().with(filter).with(layer);
+    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") {
+        chrome_layer = chrome_layer.writer(io::sink());
+    }
+
+    let (chrome_layer, _guard) = chrome_layer.build();
+
+    let registry = tracing_subscriber::registry().with(filter).with(layer).with(chrome_layer);
 
     tracing::subscriber::set_global_default(registry).unwrap();
+    _guard
 }