server.js: Refactor the "opening a profile file" logic in the start s…

…erver code (PR #4656)

profile-server.js

@@ -0,0 +1,32 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+// @noflow
+const http = require('node:http');
+const fs = require('fs');
+const path = require('path');
+
+module.exports = {
+  serveAndOpen(host, profilerUrl, profilePath, openOptions) {
+    // Create a simple http server serving the profile file.
+    const profileServer = http.createServer((req, res) => {
+      res.setHeader('Access-Control-Allow-Origin', profilerUrl);
+      const fileStream = fs.createReadStream(profilePath);
+      fileStream.pipe(res);
+    });
+
+    // Close the profile server on CTRL-C.
+    process.on('SIGINT', () => profileServer.close());
+    process.on('SIGTERM', () => profileServer.close());
+
+    // Spin up the profile server.
+    profileServer.listen(0, host, () => {
+      const profileFromUrl = `${profilerUrl}/from-url/${encodeURIComponent(
+        `http://${host}:${profileServer.address().port}/${encodeURIComponent(
+          path.basename(profilePath)
+        )}`
+      )}`;
+      import('open').then((open) => open.default(profileFromUrl, openOptions));
+    });
+  },
+};

server.js

@@ -4,7 +4,7 @@
 // @noflow
 const webpack = require('webpack');
 const WebpackDevServer = require('webpack-dev-server');
-const http = require('node:http');
+const profileServer = require('./profile-server');
 const config = require('./webpack.config');
 const { oneLine, stripIndent } = require('common-tags');
 const port = process.env.FX_PROFILER_PORT || 4242;
@@ -102,17 +102,6 @@ if (argv.profile) {
   // Needed because of a later working directory change.
   argv.profile = path.resolve(argv.profile);
 
-  // Spin up a simple http server serving the profile file.
-  const profileServer = http.createServer((req, res) => {
-    res.setHeader('Access-Control-Allow-Origin', profilerUrl);
-    const fileStream = fs.createReadStream(argv.profile);
-    fileStream.pipe(res);
-  });
-
-  // Close the profile server on CTRL-C.
-  process.on('SIGINT', () => profileServer.close());
-  process.on('SIGTERM', () => profileServer.close());
-
   // Delete "open" target (if any) in serverConfig.
   if (
     typeof serverConfig.open === 'object' &&
@@ -129,15 +118,8 @@ if (argv.profile) {
   const openOptions = serverConfig.open;
   delete serverConfig.open;
 
-  // Open on profile.
-  profileServer.listen(0, host, () => {
-    const profileFromUrl = `${profilerUrl}/from-url/${encodeURIComponent(
-      `http://${host}:${profileServer.address().port}/${encodeURIComponent(
-        path.basename(argv.profile)
-      )}`
-    )}`;
-    import('open').then((open) => open.default(profileFromUrl, openOptions));
-  });
+  // Start profile server and open on profile.
+  profileServer.serveAndOpen(host, profilerUrl, argv.profile, openOptions);
 }
 
 process.chdir(__dirname); // Allow server.js to be run from anywhere.