nodejs
diff --git a/‎lib/internal/modules/package_json_reader.js‎
Lines changed: 49 additions & 19 deletions b/‎lib/internal/modules/package_json_reader.js‎
Lines changed: 49 additions & 19 deletions
diff --git a/‎test/parallel/test-module-nearest-parent-package-json-cache.js‎
Lines changed: 57 additions & 0 deletions b/‎test/parallel/test-module-nearest-parent-package-json-cache.js‎
Lines changed: 57 additions & 0 deletions
@@ -23,7 +23,8 @@ const {
     ERR_MODULE_NOT_FOUND,
   },
 } = require('internal/errors');
-const { kEmptyObject } = require('internal/util');
+const { kEmptyObject, isWindows } = require('internal/util');
+const permission = require('internal/process/permission');
 const modulesBinding = internalBinding('modules');
 const path = require('path');
 const { validateString } = require('internal/validators');
@@ -140,10 +141,18 @@ function read(jsonPath, { base, specifier, isESM } = kEmptyObject) {
 }
 
 /**
- * A cache mapping a module's path to its parent `package.json` file's path.
- * This is used in concert with `deserializedPackageJSONCache` to improve
- * the performance of `getNearestParentPackageJSON` when called repeatedly
- * on the same module paths.
+ * A cache mapping a directory to the path of the nearest `package.json` at or
+ * above it (`null` when there is none). The native traversal for a module
+ * starts at the module's directory, so every module in a directory shares one
+ * entry and one native call. Used in concert with
+ * `deserializedPackageJSONCache`.
+ */
+const directoryToParentPackageJSONPathCache = new SafeMap();
+
+/**
+ * When the permission model is enabled the native traversal also depends on
+ * the read permissions in effect at the time of the call, so results are only
+ * remembered per exact module path, as before.
  */
 const moduleToParentPackageJSONCache = new SafeMap();
 
@@ -158,30 +167,51 @@ const moduleToParentPackageJSONCache = new SafeMap();
  */
 const deserializedPackageJSONCache = new SafeMap();
 
+/**
+ * The directory the native nearest-parent traversal starts from for `checkPath`
+ * (see BindingData::NormalizePath/TraverseParent): the path itself when it has
+ * a trailing separator, its dirname otherwise.
+ * @param {string} checkPath
+ * @returns {string}
+ */
+function getTraversalStartDirectory(checkPath) {
+  const last = checkPath[checkPath.length - 1];
+  if (last === '/' || (isWindows && last === '\\')) {
+    return StringPrototypeSlice(checkPath, 0, -1);
+  }
+  return path.dirname(checkPath);
+}
+
 /**
  * Get the nearest parent package.json file from a given path.
  * Return the package.json data and the path to the package.json file, or undefined.
  * @param {string} checkPath The path to start searching from.
  * @returns {undefined | DeserializedPackageConfig}
  */
 function getNearestParentPackageJSON(checkPath) {
-  const parentPackageJSONPath = moduleToParentPackageJSONCache.get(checkPath);
-  if (parentPackageJSONPath !== undefined) {
-    return deserializedPackageJSONCache.get(parentPackageJSONPath);
+  const permissionEnabled = permission.isEnabled();
+  const cache = permissionEnabled ? moduleToParentPackageJSONCache : directoryToParentPackageJSONPathCache;
+  const key = permissionEnabled ? checkPath : getTraversalStartDirectory(checkPath);
+  let parentPackageJSONPath = cache.get(key);
+  if (parentPackageJSONPath === undefined) {
+    const result = modulesBinding.getNearestParentPackageJSON(checkPath);
+    if (result === undefined) {
+      parentPackageJSONPath = null;
+    } else {
+      const packageConfig = deserializePackageJSON(checkPath, result);
+      parentPackageJSONPath = packageConfig.path;
+      if (!deserializedPackageJSONCache.has(parentPackageJSONPath)) {
+        deserializedPackageJSONCache.set(parentPackageJSONPath, packageConfig);
+      }
+    }
+    cache.set(key, parentPackageJSONPath);
   }
 
-  const result = modulesBinding.getNearestParentPackageJSON(checkPath);
-  const packageConfig = deserializePackageJSON(checkPath, result);
-
-  moduleToParentPackageJSONCache.set(checkPath, packageConfig.path);
-
-  const maybeCachedPackageConfig = deserializedPackageJSONCache.get(packageConfig.path);
-  if (maybeCachedPackageConfig !== undefined) {
-    return maybeCachedPackageConfig;
+  if (parentPackageJSONPath === null) {
+    // No package.json above this path: same shape as before, carrying the queried path.
+    return deserializePackageJSON(checkPath, undefined);
   }
-
-  deserializedPackageJSONCache.set(packageConfig.path, packageConfig);
-  return packageConfig;
+  return deserializedPackageJSONCache.get(parentPackageJSONPath);
 }
 
 /**
 
@@ -0,0 +1,57 @@
+'use strict';
+// Flags: --expose-internals
+// The nearest parent package.json lookup that every CommonJS module load
+// performs is answered once per directory, not once per file.
+const common = require('../common');
+const tmpdir = require('../common/tmpdir');
+const assert = require('assert');
+const fs = require('fs');
+const path = require('path');
+const { internalBinding } = require('internal/test/binding');
+const packageJsonReader = require('internal/modules/package_json_reader');
+
+tmpdir.refresh();
+const root = tmpdir.resolve('pkg');
+const sub = path.join(root, 'lib', 'sub');
+fs.mkdirSync(sub, { recursive: true });
+fs.writeFileSync(path.join(root, 'package.json'), JSON.stringify({ name: 'pkg', type: 'commonjs' }));
+const files = [];
+for (const dir of [path.join(root, 'lib'), sub]) {
+  for (let i = 0; i < 5; i++) {
+    const file = path.join(dir, `m${i}.js`);
+    fs.writeFileSync(file, 'module.exports = __filename;');
+    files.push(file);
+  }
+}
+
+const modulesBinding = internalBinding('modules');
+const original = modulesBinding.getNearestParentPackageJSON;
+const calls = [];
+modulesBinding.getNearestParentPackageJSON = common.mustCallAtLeast((checkPath) => {
+  calls.push(checkPath);
+  return original(checkPath);
+}, 1);
+
+for (const file of files) {
+  assert.strictEqual(require(file), file);
+}
+// Ten modules in two directories: two lookups reach the binding.
+assert.strictEqual(calls.length, 2, `binding called for: ${calls.join(', ')}`);
+
+// Same answer (and the same object) for every file of a directory, and for
+// the directory itself when asked with a trailing separator.
+const viaFile = packageJsonReader.getNearestParentPackageJSON(files[0]);
+assert.strictEqual(viaFile.data.name, 'pkg');
+assert.strictEqual(packageJsonReader.getNearestParentPackageJSON(files[1]), viaFile);
+assert.strictEqual(packageJsonReader.getNearestParentPackageJSON(path.join(root, 'lib') + path.sep), viaFile);
+assert.strictEqual(calls.length, 2);
+
+// A directory that has not been seen yet is looked up once more.
+const other = path.join(root, 'other');
+fs.mkdirSync(other);
+fs.writeFileSync(path.join(other, 'x.js'), '');
+assert.strictEqual(packageJsonReader.getNearestParentPackageJSON(path.join(other, 'x.js')).data.name, 'pkg');
+assert.strictEqual(packageJsonReader.getNearestParentPackageJSON(path.join(other, 'y.js')).data.name, 'pkg');
+assert.strictEqual(calls.length, 3);
+
+modulesBinding.getNearestParentPackageJSON = original;