From 391a390d2c27d4343763d9a5e109b9056302ce3d Mon Sep 17 00:00:00 2001
From: Nick Oliver <Nickolas.Oliver@aexp.com>
Date: Wed, 27 Mar 2024 14:27:12 -0700
Subject: [PATCH] perf(one-app-server-bundler): serve-module read and write the
 module map once (#623)

O(1) rather than O(n)
---
 .../__tests__/bin/serve-module.spec.js        |  8 ++-
 .../bin/serve-module.js                       | 56 ++++++++++---------
 2 files changed, 38 insertions(+), 26 deletions(-)

diff --git a/packages/one-app-server-bundler/__tests__/bin/serve-module.spec.js b/packages/one-app-server-bundler/__tests__/bin/serve-module.spec.js
index cc37e5f1..a2e44c8d 100644
--- a/packages/one-app-server-bundler/__tests__/bin/serve-module.spec.js
+++ b/packages/one-app-server-bundler/__tests__/bin/serve-module.spec.js
@@ -23,7 +23,7 @@ const setup = (modulePath) => {
   jest.resetModules();
   jest.clearAllMocks();
   jest.doMock('node:util', () => ({
-    parseArgs: jest.fn(() => ({ positionals: [modulePath] })),
+    parseArgs: jest.fn(() => ({ positionals: modulePath ? [modulePath] : [] })),
   }));
 
   fs = require('node:fs');
@@ -45,6 +45,12 @@ describe('serve-module', () => {
     setPlatform(originalPlatform);
   });
 
+  it('should throw if no module path is provided', () => {
+    setup();
+    fs._.setFiles({});
+    expect(() => require('../../bin/serve-module')).toThrowErrorMatchingInlineSnapshot('"serve-module(s) requires at least one module path for one-app to serve"');
+  });
+
   it('should throw if the module doesn\'t have a version', () => {
     fs._.setFiles({
       '../my-module-name/package.json': JSON.stringify({ name: 'my-module-name' }),
diff --git a/packages/one-app-server-bundler/bin/serve-module.js b/packages/one-app-server-bundler/bin/serve-module.js
index 13152af2..c880a1a3 100755
--- a/packages/one-app-server-bundler/bin/serve-module.js
+++ b/packages/one-app-server-bundler/bin/serve-module.js
@@ -22,7 +22,21 @@ const symModulesPath = path.join(publicPath, 'modules');
 
 fs.mkdirSync(symModulesPath, { recursive: true });
 
-util.parseArgs({ allowPositionals: true }).positionals.forEach((modulePath) => {
+const modulePaths = util.parseArgs({ allowPositionals: true }).positionals;
+
+if (modulePaths.length === 0) {
+  throw new Error('serve-module(s) requires at least one module path for one-app to serve');
+}
+
+const moduleMapPath = path.join(publicPath, 'module-map.json');
+let moduleMap;
+try {
+  moduleMap = JSON.parse(fs.readFileSync(moduleMapPath));
+} catch (e) {
+  moduleMap = { key: 'not-used-in-development', modules: {} };
+}
+
+modulePaths.forEach((modulePath) => {
   const pkg = JSON.parse(fs.readFileSync(path.join(modulePath, 'package.json')));
   const absoluteModulePath = modulePath.startsWith('/')
     ? modulePath : path.join(process.cwd(), modulePath);
@@ -58,28 +72,20 @@ util.parseArgs({ allowPositionals: true }).positionals.forEach((modulePath) => {
     fs.symlinkSync(sourceBundlePath, symBundlePath, type);
   }
 
-  const moduleMapPath = path.join(publicPath, 'module-map.json');
-  try {
-    fs.accessSync(moduleMapPath);
-  } catch (e) {
-    fs.writeFileSync(moduleMapPath, JSON.stringify({ key: 'not-used-in-development', modules: {} }, null, 2));
-  } finally {
-    const moduleMap = JSON.parse(fs.readFileSync(moduleMapPath));
-    moduleMap.modules[moduleName] = {
-      browser: {
-        integrity: browserSri,
-        url: `[one-app-dev-cdn-url]/static/modules/${moduleName}/${version}/${moduleName}.browser.js`,
-      },
-      node: {
-        integrity: nodeSri,
-        url: `[one-app-dev-cdn-url]/static/modules/${moduleName}/${version}/${moduleName}.node.js`,
-      },
-      legacyBrowser: {
-        integrity: legacyBrowserSri || `[No legacy bundle generated for ${moduleName}. This will 404.]`,
-        url: `[one-app-dev-cdn-url]/static/modules/${moduleName}/${version}/${moduleName}.legacy.browser.js`,
-      },
-    };
-
-    fs.writeFileSync(moduleMapPath, JSON.stringify(moduleMap, null, 2));
-  }
+  moduleMap.modules[moduleName] = {
+    browser: {
+      integrity: browserSri,
+      url: `[one-app-dev-cdn-url]/static/modules/${moduleName}/${version}/${moduleName}.browser.js`,
+    },
+    node: {
+      integrity: nodeSri,
+      url: `[one-app-dev-cdn-url]/static/modules/${moduleName}/${version}/${moduleName}.node.js`,
+    },
+    legacyBrowser: {
+      integrity: legacyBrowserSri || `[No legacy bundle generated for ${moduleName}. This will 404.]`,
+      url: `[one-app-dev-cdn-url]/static/modules/${moduleName}/${version}/${moduleName}.legacy.browser.js`,
+    },
+  };
 });
+
+fs.writeFileSync(moduleMapPath, JSON.stringify(moduleMap, null, 2));