feat(cli): Add CPU profiling support

Profiling can be enabled via the `UI5_CLI_PROFILE` environment variable.

Author: matz3

packages/cli/bin/ui5.cjs

@@ -94,8 +94,19 @@ const ui5 = {
 	},
 
 	async invokeCLI(pkg) {
+		let profile;
+		if (process.env.UI5_CLI_PROFILE) {
+			profile = await import("../lib/utils/profile.js");
+			await profile.start();
+		}
 		const {default: cli} = await import("../lib/cli/cli.js");
-		await cli(pkg);
+		const {command} = await cli(pkg);
+
+		// Stop profiling after CLI finished execution
+		// Except for "serve" command, which continues running and only stops on sigint (see profile.js)
+		if (profile && command !== "serve") {
+			await profile.stop();
+		}
 	},
 
 	async main() {

packages/cli/lib/cli/cli.js

@@ -68,7 +68,8 @@ export default async (pkg) => {
 	// Format terminal output to full available width
 	cli.wrap(cli.terminalWidth());
 
-	// yargs registers a get method on the argv property.
-	// The property needs to be accessed to initialize everything.
-	cli.argv;
+	const {_} = await cli.argv;
+	return {
+		command: _[0]
+	};
 };

packages/cli/lib/utils/profile.js

@@ -0,0 +1,82 @@
+import {writeFileSync} from "node:fs";
+import {Session} from "node:inspector/promises";
+
+let session;
+let processSignals;
+
+export async function start() {
+	if (session) {
+		return;
+	}
+	session = new Session();
+	session.connect();
+	await session.post("Profiler.enable");
+	await session.post("Profiler.start");
+	console.log(`Recording CPU profile...`);
+	processSignals = registerSigHooks();
+}
+
+async function writeProfile(profile) {
+	const formatter = new Intl.DateTimeFormat("en-GB", {
+		year: "numeric",
+		month: "2-digit",
+		day: "2-digit",
+		hour: "2-digit",
+		minute: "2-digit",
+		second: "2-digit",
+	});
+	const dateParts = Object.create(null);
+	const parts = formatter.formatToParts(new Date());
+	parts.forEach((p) => {
+		dateParts[p.type] = p.value;
+	});
+
+	const fileName = `./ui5_${dateParts.year}-${dateParts.month}-${dateParts.day}_` +
+		`${dateParts.hour}-${dateParts.minute}-${dateParts.second}.cpuprofile`;
+	console.log(`\nSaving CPU profile to ${fileName}...`);
+	writeFileSync(fileName, JSON.stringify(profile));
+}
+
+export async function stop() {
+	if (!session) {
+		return;
+	}
+	const {profile} = await session.post("Profiler.stop");
+	session = null;
+	if (profile) {
+		await writeProfile(profile);
+	}
+	if (processSignals) {
+		deregisterSigHooks(processSignals);
+		processSignals = null;
+	}
+}
+
+function registerSigHooks() {
+	function createListener(exitCode) {
+		return function() {
+			// Gracefully end profiling, then exit
+			stop().then(() => {
+				process.exit(exitCode);
+			});
+		};
+	}
+
+	const processSignals = {
+		"SIGHUP": createListener(128 + 1),
+		"SIGINT": createListener(128 + 2),
+		"SIGTERM": createListener(128 + 15),
+		"SIGBREAK": createListener(128 + 21)
+	};
+
+	for (const signal of Object.keys(processSignals)) {
+		process.on(signal, processSignals[signal]);
+	}
+	return processSignals;
+}
+
+function deregisterSigHooks(signals) {
+	for (const signal of Object.keys(signals)) {
+		process.removeListener(signal, signals[signal]);
+	}
+}