policy: minor perf opts and cleanup

PR-URL: https://github.com/nodejs/node/pull/29322
Reviewed-By: James M Snell <jasnell@gmail.com>

1 files changed, 25 insertions, 19 deletions

diff --git a/lib/internal/modules/cjs/helpers.js b/lib/internal/modules/cjs/helpers.js
index 5e0e1b06ae..7a98700245 100644
--- a/lib/internal/modules/cjs/helpers.js
+++ b/lib/internal/modules/cjs/helpers.js
@@ -1,6 +1,6 @@
 'use strict';
 
-const { Object } = primordials;
+const { Object, SafeMap } = primordials;
 const {
   ERR_MANIFEST_DEPENDENCY_MISSING,
   ERR_UNKNOWN_BUILTIN_MODULE
@@ -28,34 +28,40 @@ function loadNativeModule(filename, request, experimentalModules) {
 // Invoke with makeRequireFunction(module) where |module| is the Module object
 // to use as the context for the require() function.
 // Use redirects to set up a mapping from a policy and restrict dependencies
+const urlToFileCache = new SafeMap();
 function makeRequireFunction(mod, redirects) {
   const Module = mod.constructor;
 
   let require;
   if (redirects) {
-    const { map, reaction } = redirects;
+    const { resolve, reaction } = redirects;
     const id = mod.filename || mod.id;
     require = function require(path) {
       let missing = true;
-      if (map === true) {
+      const destination = resolve(path);
+      if (destination === true) {
         missing = false;
-      } else if (map.has(path)) {
-        const redirect = map.get(path);
-        if (redirect === true) {
-          missing = false;
-        } else if (typeof redirect === 'string') {
-          const parsed = new URL(redirect);
-          if (parsed.protocol === 'node:') {
-            const specifier = parsed.pathname;
-            const mod = loadNativeModule(
-              specifier,
-              redirect,
-              experimentalModules);
-            if (mod && mod.canBeRequiredByUsers) return mod.exports;
-            throw new ERR_UNKNOWN_BUILTIN_MODULE(specifier);
-          } else if (parsed.protocol === 'file:') {
-            return mod.require(fileURLToPath(parsed));
+      } else if (destination) {
+        const href = destination.href;
+        if (destination.protocol === 'node:') {
+          const specifier = destination.pathname;
+          const mod = loadNativeModule(
+            specifier,
+            href,
+            experimentalModules);
+          if (mod && mod.canBeRequiredByUsers) {
+            return mod.exports;
           }
+          throw new ERR_UNKNOWN_BUILTIN_MODULE(specifier);
+        } else if (destination.protocol === 'file:') {
+          let filepath;
+          if (urlToFileCache.has(href)) {
+            filepath = urlToFileCache.get(href);
+          } else {
+            filepath = fileURLToPath(destination);
+            urlToFileCache.set(href, filepath);
+          }
+          return mod.require(filepath);
         }
       }
       if (missing) {