src,lib: reducing C++ calls of esm legacy main resolve

Instead of many C++ calls, now we make only one C++ call
to return a enum number that represents the selected state.

benchmark/esm/esm-legacyMainResolve.js

@@ -0,0 +1,53 @@
+// Tests the impact on eager operations required for policies affecting
+// general startup, does not test lazy operations
+'use strict';
+const fs = require('node:fs');
+const path = require('node:path');
+const common = require('../common.js');
+
+const tmpdir = require('../../test/common/tmpdir.js');
+const { pathToFileURL } = require('node:url');
+
+const benchmarkDirectory =
+  path.resolve(tmpdir.path, 'benchmark-import-meta-resolve');
+
+const configs = {
+  n: [1e4],
+  packageJsonUrl: [
+    'node_modules/test/package.json',
+  ],
+  packageConfigMain: ['', './index.js'],
+  resolvedFile: [
+    'node_modules/test/index.js',
+    'node_modules/test/index.json',
+    'node_modules/test/index.node',
+    'node_modules/non-exist',
+  ],
+};
+
+const options = {
+  flags: ['--expose-internals'],
+};
+
+const bench = common.createBenchmark(main, configs, options);
+
+function main(conf) {
+  const { legacyMainResolve } = require('internal/modules/esm/resolve');
+  tmpdir.refresh();
+
+  fs.mkdirSync(path.join(benchmarkDirectory, 'node_modules', 'test'), { recursive: true });
+  fs.writeFileSync(path.join(benchmarkDirectory, conf.resolvedFile), '\n');
+
+  const packageJsonUrl = pathToFileURL(conf.packageJsonUrl);
+  const packageConfigMain = { main: conf.packageConfigMain };
+
+  bench.start();
+
+  for (let i = 0; i < conf.n; i++) {
+    try {
+      legacyMainResolve(packageJsonUrl, packageConfigMain, undefined);
+    } catch { /* empty */ }
+  }
+
+  bench.end(conf.n);
+}

lib/internal/modules/esm/resolve.js

@@ -36,14 +36,16 @@ const preserveSymlinksMain = getOptionValue('--preserve-symlinks-main');
 const experimentalNetworkImports =
   getOptionValue('--experimental-network-imports');
 const typeFlag = getOptionValue('--input-type');
-const { URL, pathToFileURL, fileURLToPath, isURL, toPathIfFileURL } = require('internal/url');
+const { URL, pathToFileURL, fileURLToPath, isURL } = require('internal/url');
 const { canParse: URLCanParse } = internalBinding('url');
+const { legacyMainResolve: URLLegacyMainResolve } = internalBinding('fs');
 const {
   ERR_INPUT_TYPE_NOT_ALLOWED,
   ERR_INVALID_ARG_TYPE,
   ERR_INVALID_MODULE_SPECIFIER,
   ERR_INVALID_PACKAGE_CONFIG,
   ERR_INVALID_PACKAGE_TARGET,
+  ERR_INVALID_URL,
   ERR_MANIFEST_DEPENDENCY_MISSING,
   ERR_MODULE_NOT_FOUND,
   ERR_PACKAGE_IMPORT_NOT_DEFINED,
@@ -132,13 +134,36 @@ function emitLegacyIndexDeprecation(url, packageJSONUrl, base, main) {
 
 const realpathCache = new SafeMap();
 
-/**
- * @param {string | URL} url
- * @returns {boolean}
- */
-function fileExists(url) {
-  return internalModuleStat(toNamespacedPath(toPathIfFileURL(url))) === 0;
-}
+const mainResolveExtensions = [
+  '',
+  '.js',
+  '.json',
+  '.node',
+  '/index.js',
+  '/index.json',
+  '/index.node',
+  './index.js',
+  './index.json',
+  './index.node',
+];
+
+const mainResolveReturnType = {
+  kInvalidUrl: -2,
+  kModuleNotFound: -1,
+  // 0-6: when packageConfig.main is defined
+  kResolvedByMain: 0,
+  kResolvedByMainJs: 1,
+  kResolvedByMainJson: 2,
+  kResolvedByMainNode: 3,
+  kResolvedByMainIndexJs: 4,
+  kResolvedByMainIndexJson: 5,
+  kResolvedByMainIndexNode: 6,
+  // 7-9: when packageConfig.main is NOT defined,
+  //      or when the previous case didn't found the file
+  kResolvedByPackageAndJs: 7,
+  kResolvedByPackageAndJson: 8,
+  kResolvedByPackageAndNode: 9,
+};
 
 /**
  * Legacy CommonJS main resolution:
@@ -153,44 +178,23 @@ function fileExists(url) {
  * @returns {URL}
  */
 function legacyMainResolve(packageJSONUrl, packageConfig, base) {
-  let guess;
-  if (packageConfig.main !== undefined) {
-    // Note: fs check redundances will be handled by Descriptor cache here.
-    if (fileExists(guess = new URL(`./${packageConfig.main}`,
-                                   packageJSONUrl))) {
-      return guess;
-    } else if (fileExists(guess = new URL(`./${packageConfig.main}.js`,
-                                          packageJSONUrl)));
-    else if (fileExists(guess = new URL(`./${packageConfig.main}.json`,
-                                        packageJSONUrl)));
-    else if (fileExists(guess = new URL(`./${packageConfig.main}.node`,
-                                        packageJSONUrl)));
-    else if (fileExists(guess = new URL(`./${packageConfig.main}/index.js`,
-                                        packageJSONUrl)));
-    else if (fileExists(guess = new URL(`./${packageConfig.main}/index.json`,
-                                        packageJSONUrl)));
-    else if (fileExists(guess = new URL(`./${packageConfig.main}/index.node`,
-                                        packageJSONUrl)));
-    else guess = undefined;
-    if (guess) {
-      emitLegacyIndexDeprecation(guess, packageJSONUrl, base,
-                                 packageConfig.main);
-      return guess;
+  const resolvedOption = URLLegacyMainResolve(packageJSONUrl.href, packageConfig.main);
+
+  if (resolvedOption < mainResolveReturnType.kResolvedByMain) {
+    if (resolvedOption === mainResolveReturnType.kInvalidUrl) {
+      throw new ERR_INVALID_URL(packageConfig.main || './index.js');
+    } else {
+      throw new ERR_MODULE_NOT_FOUND(
+        fileURLToPath(new URL('.', packageJSONUrl)), fileURLToPath(base));
     }
-    // Fallthrough.
-  }
-  if (fileExists(guess = new URL('./index.js', packageJSONUrl)));
-  // So fs.
-  else if (fileExists(guess = new URL('./index.json', packageJSONUrl)));
-  else if (fileExists(guess = new URL('./index.node', packageJSONUrl)));
-  else guess = undefined;
-  if (guess) {
-    emitLegacyIndexDeprecation(guess, packageJSONUrl, base, packageConfig.main);
-    return guess;
   }
-  // Not found.
-  throw new ERR_MODULE_NOT_FOUND(
-    fileURLToPath(new URL('.', packageJSONUrl)), fileURLToPath(base));
+
+  const baseUrl = resolvedOption <= mainResolveReturnType.kResolvedByMainNode ? `./${packageConfig.main}` : '';
+  const guess = new URL(baseUrl + mainResolveExtensions[resolvedOption], packageJSONUrl);
+
+  emitLegacyIndexDeprecation(guess, packageJSONUrl, base, packageConfig.main);
+
+  return guess;
 }
 
 const encodedSepRegEx = /%2F|%5C/i;
@@ -1078,6 +1082,7 @@ module.exports = {
   packageExportsResolve,
   packageImportsResolve,
   throwIfInvalidParentURL,
+  legacyMainResolve,
 };
 
 // cycle

src/node_errors.h

@@ -68,11 +68,14 @@ void AppendExceptionLine(Environment* env,
   V(ERR_INVALID_ARG_VALUE, TypeError)                                          \
   V(ERR_OSSL_EVP_INVALID_DIGEST, Error)                                        \
   V(ERR_INVALID_ARG_TYPE, TypeError)                                           \
+  V(ERR_INVALID_FILE_URL_HOST, TypeError)                                      \
+  V(ERR_INVALID_FILE_URL_PATH, TypeError)                                      \
   V(ERR_INVALID_OBJECT_DEFINE_PROPERTY, TypeError)                             \
   V(ERR_INVALID_MODULE, Error)                                                 \
   V(ERR_INVALID_STATE, Error)                                                  \
   V(ERR_INVALID_THIS, TypeError)                                               \
   V(ERR_INVALID_TRANSFER_OBJECT, TypeError)                                    \
+  V(ERR_INVALID_URL_SCHEME, TypeError)                                         \
   V(ERR_MEMORY_ALLOCATION_FAILED, Error)                                       \
   V(ERR_MESSAGE_TARGET_CONTEXT_UNAVAILABLE, Error)                             \
   V(ERR_MISSING_ARGS, TypeError)                                               \
@@ -163,6 +166,7 @@ ERRORS_WITH_CODE(V)
   V(ERR_INVALID_STATE, "Invalid state")                                        \
   V(ERR_INVALID_THIS, "Value of \"this\" is the wrong type")                   \
   V(ERR_INVALID_TRANSFER_OBJECT, "Found invalid object in transferList")       \
+  V(ERR_INVALID_URL_SCHEME, "The URL must be of scheme file:")                 \
   V(ERR_MEMORY_ALLOCATION_FAILED, "Failed to allocate memory")                 \
   V(ERR_OSSL_EVP_INVALID_DIGEST, "Invalid digest used")                        \
   V(ERR_MESSAGE_TARGET_CONTEXT_UNAVAILABLE,                                    \