fs: improve error performance of readlinkSync

PR-URL: https://github.com/nodejs/node/pull/49962
Refs: https://github.com/nodejs/performance/issues/106
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Stephen Belanger <admin@stephenbelanger.com>
Reviewed-By: Vinícius Lourenço Claro Cardoso <contact@viniciusl.com.br>

benchmark/fs/bench-readlinkSync.js

@@ -0,0 +1,54 @@
+'use strict';
+
+const common = require('../common');
+const fs = require('fs');
+const assert = require('assert');
+const tmpdir = require('../../test/common/tmpdir');
+
+if (process.platform === 'win32') {
+  console.log('Skipping: Windows does not play well with `symlinkSync`');
+  process.exit(0);
+}
+
+const bench = common.createBenchmark(main, {
+  type: ['valid', 'invalid'],
+  n: [1e3],
+});
+
+function main({ n, type }) {
+  switch (type) {
+    case 'valid': {
+      tmpdir.refresh();
+      const tmpfile = tmpdir.resolve(`.readlink-file-${process.pid}`);
+      fs.writeFileSync(tmpfile, 'data', 'utf8');
+      let returnValue;
+      for (let i = 0; i < n; i++) {
+        fs.symlinkSync(tmpfile, tmpdir.resolve(`.readlink-sync-${i}`), 'file');
+      }
+      bench.start();
+      for (let i = 0; i < n; i++) {
+        returnValue = fs.readlinkSync(tmpdir.resolve(`.readlink-sync-${i}`), { encoding: 'utf8' });
+      }
+      bench.end(n);
+      assert(returnValue);
+      break;
+    }
+
+    case 'invalid': {
+      let hasError = false;
+      bench.start();
+      for (let i = 0; i < n; i++) {
+        try {
+          fs.readlinkSync(tmpdir.resolve('.non-existing-file-for-readlinkSync'));
+        } catch {
+          hasError = true;
+        }
+      }
+      bench.end(n);
+      assert(hasError);
+      break;
+    }
+    default:
+      new Error('Invalid type');
+  }
+}

lib/fs.js

@@ -1728,11 +1728,10 @@ function readlink(path, options, callback) {
 function readlinkSync(path, options) {
   options = getOptions(options);
   path = getValidatedPath(path, 'oldPath');
-  const ctx = { path };
-  const result = binding.readlink(pathModule.toNamespacedPath(path),
-                                  options.encoding, undefined, ctx);
-  handleErrorFromBinding(ctx);
-  return result;
+  return binding.readlink(
+    pathModule.toNamespacedPath(path),
+    options.encoding,
+  );
 }
 
 /**
@@ -2714,10 +2713,8 @@ function realpathSync(p, options) {
         }
       }
       if (linkTarget === null) {
-        const ctx = { path: base };
         binding.stat(baseLong, false, undefined, true);
-        linkTarget = binding.readlink(baseLong, undefined, undefined, ctx);
-        handleErrorFromBinding(ctx);
+        linkTarget = binding.readlink(baseLong, undefined);
       }
       resolvedLink = pathModule.resolve(previous, linkTarget);
 

src/node_file.cc

@@ -1383,7 +1383,7 @@ static void ReadLink(const FunctionCallbackInfo<Value>& args) {
   Isolate* isolate = env->isolate();
 
   const int argc = args.Length();
-  CHECK_GE(argc, 3);
+  CHECK_GE(argc, 2);
 
   BufferValue path(isolate, args[0]);
   CHECK_NOT_NULL(*path);
@@ -1392,21 +1392,20 @@ static void ReadLink(const FunctionCallbackInfo<Value>& args) {
 
   const enum encoding encoding = ParseEncoding(isolate, args[1], UTF8);
 
-  FSReqBase* req_wrap_async = GetReqWrap(args, 2);
-  if (req_wrap_async != nullptr) {  // readlink(path, encoding, req)
+  if (argc > 2) {  // readlink(path, encoding, req)
+    FSReqBase* req_wrap_async = GetReqWrap(args, 2);
     FS_ASYNC_TRACE_BEGIN1(
         UV_FS_READLINK, req_wrap_async, "path", TRACE_STR_COPY(*path))
     AsyncCall(env, req_wrap_async, args, "readlink", encoding, AfterStringPtr,
               uv_fs_readlink, *path);
-  } else {
-    CHECK_EQ(argc, 4);
-    FSReqWrapSync req_wrap_sync;
+  } else {  // readlink(path, encoding)
+    FSReqWrapSync req_wrap_sync("readlink", *path);
     FS_SYNC_TRACE_BEGIN(readlink);
-    int err = SyncCall(env, args[3], &req_wrap_sync, "readlink",
-                       uv_fs_readlink, *path);
+    int err =
+        SyncCallAndThrowOnError(env, &req_wrap_sync, uv_fs_readlink, *path);
     FS_SYNC_TRACE_END(readlink);
     if (err < 0) {
-      return;  // syscall failed, no need to continue, error info is in ctx
+      return;
     }
     const char* link_path = static_cast<const char*>(req_wrap_sync.req.ptr);
 
@@ -1416,8 +1415,7 @@ static void ReadLink(const FunctionCallbackInfo<Value>& args) {
                                                encoding,
                                                &error);
     if (rc.IsEmpty()) {
-      Local<Object> ctx = args[3].As<Object>();
-      ctx->Set(env->context(), env->error_string(), error).Check();
+      env->isolate()->ThrowException(error);
       return;
     }
 

typings/internalBinding/fs.d.ts

@@ -178,6 +178,7 @@ declare namespace InternalFSBinding {
   function readlink(path: StringOrBuffer, encoding: unknown, req: FSReqCallback<string | Buffer>): void;
   function readlink(path: StringOrBuffer, encoding: unknown, req: undefined, ctx: FSSyncContext): string | Buffer;
   function readlink(path: StringOrBuffer, encoding: unknown, usePromises: typeof kUsePromises): Promise<string | Buffer>;
+  function readlink(path: StringOrBuffer, encoding: unknown): StringOrBuffer;
 
   function realpath(path: StringOrBuffer, encoding: unknown, req: FSReqCallback<string | Buffer>): void;
   function realpath(path: StringOrBuffer, encoding: unknown, req: undefined, ctx: FSSyncContext): string | Buffer;