fs: add v8 fast api to existsSync

Author: anonrig

benchmark/fs/bench-existsSync.js

@@ -0,0 +1,25 @@
+'use strict';
+
+const common = require('../common');
+const fs = require('fs');
+const tmpdir = require('../../test/common/tmpdir');
+tmpdir.refresh();
+
+const paths = [
+  __filename,
+  tmpdir.resolve(`.non-existing-file-${process.pid}`),
+];
+
+const bench = common.createBenchmark(main, {
+  n: [1e6],
+});
+
+function main({ n }) {
+  bench.start();
+  for (let i = 0; i < n; i++) {
+    for (let j = 0; j < paths.length; j++) {
+      fs.existsSync(paths[j]);
+    }
+  }
+  bench.end(n);
+}

lib/fs.js

@@ -141,7 +141,7 @@ const {
   validateObject,
   validateString,
 } = require('internal/validators');
-const { readFileSyncUtf8 } = require('internal/fs/read/utf8');
+const syncFs = require('internal/fs/sync');
 
 let truncateWarn = true;
 let fs;
@@ -290,23 +290,7 @@ ObjectDefineProperty(exists, kCustomPromisifiedSymbol, {
  * @returns {boolean}
  */
 function existsSync(path) {
-  try {
-    path = getValidatedPath(path);
-  } catch {
-    return false;
-  }
-  const ctx = { path };
-  const nPath = pathModule.toNamespacedPath(path);
-  binding.access(nPath, F_OK, undefined, ctx);
-
-  // In case of an invalid symlink, `binding.access()` on win32
-  // will **not** return an error and is therefore not enough.
-  // Double check with `binding.stat()`.
-  if (isWindows && ctx.errno === undefined) {
-    binding.stat(nPath, false, undefined, ctx);
-  }
-
-  return ctx.errno === undefined;
+  return syncFs.exists(path);
 }
 
 function readFileAfterOpen(err, fd) {
@@ -462,8 +446,7 @@ function readFileSync(path, options) {
 
   // TODO(@anonrig): Do not handle file descriptor ownership for now.
   if (!isUserFd && (options.encoding === 'utf8' || options.encoding === 'utf-8')) {
-    path = getValidatedPath(path);
-    return readFileSyncUtf8(pathModule.toNamespacedPath(path), stringToFlags(options.flag));
+    return syncFs.readFileUtf8(path, options.flag);
   }
 
   const fd = isUserFd ? path : fs.openSync(path, options.flag, 0o666);

lib/internal/fs/read/utf8.js

@@ -0,0 +1,38 @@
+'use strict';
+
+const pathModule = require('path');
+const { handleErrorFromBinding, getValidatedPath, stringToFlags } = require('internal/fs/utils');
+
+const syncBinding = internalBinding('fs_sync');
+
+/**
+ * @param {string} path
+ * @param {number} flag
+ * @return {string}
+ */
+function readFileUtf8(path, flag) {
+  path = pathModule.toNamespacedPath(getValidatedPath(path));
+  const response = syncBinding.readFileUtf8(path, stringToFlags(flag));
+
+  if (typeof response === 'string') {
+    return response;
+  }
+
+  const { 0: errno, 1: syscall } = response;
+  handleErrorFromBinding({ errno, syscall, path });
+}
+
+function exists(path) {
+  try {
+    path = getValidatedPath(path);
+  } catch {
+    return false;
+  }
+
+  return syncBinding.exists(pathModule.toNamespacedPath(path));
+}
+
+module.exports = {
+  readFileUtf8,
+  exists,
+};

lib/internal/fs/sync.js

@@ -1,3 +1,4 @@
+#include "node_constants.h"
 #include "node_file_sync.h"
 #include "memory_tracker-inl.h"
 #include "node_buffer.h"
@@ -16,16 +17,22 @@
 
 #include <fcntl.h>
 
+#if !defined(_MSC_VER)
+#include <unistd.h>
+#endif
+
 namespace node {
 namespace fs_sync {
 
 using v8::Array;
+using v8::CFunction;
 using v8::Context;
 using v8::FunctionCallbackInfo;
 using v8::HandleScope;
 using v8::Int32;
 using v8::Integer;
 using v8::Isolate;
+using v8::FastOneByteString;
 using v8::JustVoid;
 using v8::Local;
 using v8::Maybe;
@@ -115,6 +122,50 @@ void BindingData::Deserialize(v8::Local<v8::Context> context,
   CHECK_NOT_NULL(binding);
 }
 
+bool BindingData::ExistsInternal(const std::string_view path) {
+  uv_fs_t req;
+  auto make  = OnScopeLeave([&req]() { uv_fs_req_cleanup(&req); });
+  FS_SYNC_TRACE_BEGIN(access);
+  int err = uv_fs_access(nullptr, &req, path.data(), F_OK, nullptr);
+  FS_SYNC_TRACE_END(access);
+
+#ifdef _WIN32
+    // In case of an invalid symlink, `binding.access()` on win32
+    // will **not** return an error and is therefore not enough.
+    // Double check with `stat()`.
+    if (err != 0) {
+        FS_SYNC_TRACE_BEGIN(stat);
+        err = uv_fs_stat(nullptr, &req, path.data, nullptr);
+        FS_SYNC_TRACE_END(stat);
+    }
+#endif // _WIN32
+
+  return err == 0;
+}
+
+void BindingData::Exists(const FunctionCallbackInfo<Value>& args) {
+  Environment* env = Environment::GetCurrent(args);
+  Isolate* isolate = env->isolate();
+
+  const int argc = args.Length();
+  CHECK_GE(argc, 1);
+
+  BufferValue path(isolate, args[0]);
+  CHECK_NOT_NULL(*path);
+  THROW_IF_INSUFFICIENT_PERMISSIONS(
+      env, permission::PermissionScope::kFileSystemRead, path.ToStringView());
+
+  return ExistsInternal(path.ToStringView());
+}
+
+bool BindingData::FastExists(Local<Value> receiver,
+                               const FastOneByteString& path) {
+  // TODO(@anonrig): Add "THROW_IF_INSUFFICIENT_PERMISSIONS"
+  return ExistsInternal(std::string_view(path.data, path.length));
+}
+
+CFunction BindingData::fast_exists_(CFunction::Make(FastExists));
+
 void BindingData::ReadFileUtf8(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
   auto isolate = env->isolate();
@@ -186,6 +237,7 @@ void BindingData::ReadFileUtf8(const FunctionCallbackInfo<Value>& args) {
 void BindingData::CreatePerIsolateProperties(IsolateData* isolate_data,
                                              Local<ObjectTemplate> target) {
   Isolate* isolate = isolate_data->isolate();
+  SetFastMethodNoSideEffect(isolate, target, "exists", Exists, &fast_exists_);
   SetMethodNoSideEffect(isolate, target, "readFileUtf8", ReadFileUtf8);
 }
 
@@ -199,6 +251,9 @@ void BindingData::CreatePerContextProperties(Local<Object> target,
 
 void BindingData::RegisterExternalReferences(
     ExternalReferenceRegistry* registry) {
+  registry->Register(Exists);
+  registry->Register(FastExists);
+  registry->Register(fast_exists_.GetTypeInfo());
   registry->Register(ReadFileUtf8);
 }
 

src/node_file_sync.cc

@@ -31,6 +31,9 @@ class BindingData : public SnapshotableObject {
   SET_SELF_SIZE(BindingData)
   SET_MEMORY_INFO_NAME(BindingData)
 
+  static void Exists(const v8::FunctionCallbackInfo<v8::Value>& args);
+  static bool FastExists(v8::Local<v8::Value> receiver, const v8::FastOneByteString& path);
+
   static void ReadFileUtf8(const v8::FunctionCallbackInfo<v8::Value>& args);
 
   static void CreatePerIsolateProperties(IsolateData* isolate_data,
@@ -40,6 +43,11 @@ class BindingData : public SnapshotableObject {
                                          v8::Local<v8::Context> context,
                                          void* priv);
   static void RegisterExternalReferences(ExternalReferenceRegistry* registry);
+
+ private:
+  static v8::CFunction fast_exists_;
+
+  static bool BindingData::ExistsInternal(const std::string_view path);
 };
 
 }  // namespace fs_sync

src/node_file_sync.h

@@ -75,7 +75,7 @@ const expectedModules = new Set([
   'NativeModule internal/webstreams/queuingstrategies',
   'NativeModule internal/blob',
   'NativeModule internal/fs/utils',
-  'NativeModule internal/fs/read/utf8',
+  'NativeModule internal/fs/sync',
   'NativeModule fs',
   'Internal Binding options',
   'NativeModule internal/options',