From 65a94a6176e3a76ca52d0666cf882689ac0b5b9c Mon Sep 17 00:00:00 2001
From: Marcos Casagrande <marcos@denode.com>
Date: Fri, 22 Sep 2023 04:06:42 +0200
Subject: [PATCH] perf(ext/fetch): use new instead of createBranded (#20624)
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This PR optimizes `fromInner*` methods of `Request` / `Header` /
`Response` used by `Deno.serve` and `fetch` by using `new` instead of
`ObjectCreate` from `createBranded`.

The "brand" is created by passing `webidl.brand` to the constructor
instead.


https://github.com/denoland/deno/blob/142449ecab20006c5cfd15462814650596bc034d/ext/webidl/00_webidl.js#L1001-L1005

### Benchmark
```js
const createBranded = Symbol("create branded");
const brand = Symbol("brand");
class B {
  constructor(init) {
    if (init === createBranded) {
      this[brand] = brand;
    }
  }
}

Deno.bench("Object.create(protoype)", () => {
  Object.create(B.prototype);
});

Deno.bench("new Class", () => {
  new B(createBranded);
});
```

```
cpu: 13th Gen Intel(R) Core(TM) i9-13900H
runtime: deno 1.37.0 (x86_64-unknown-linux-gnu)

benchmark                    time (avg)        iter/s             (min … max)       p75       p99      p995
----------------------------------------------------------------------------- -----------------------------
Object.create(protoype)       8.74 ns/iter 114,363,610.3    (7.32 ns … 26.02 ns)   8.65 ns  13.39 ns  14.47 ns
new Class                     3.05 ns/iter 328,271,012.2      (2.78 ns … 9.1 ns)   3.06 ns   3.46 ns    3.5 ns
```
---
 ext/fetch/20_headers.js  | 10 ++++++++--
 ext/fetch/23_request.js  | 10 ++++++++--
 ext/fetch/23_response.js | 10 ++++++++--
 3 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/ext/fetch/20_headers.js b/ext/fetch/20_headers.js
index 39127b1ecf2e2b..a004daa897465b 100644
--- a/ext/fetch/20_headers.js
+++ b/ext/fetch/20_headers.js
@@ -40,6 +40,7 @@ const _headerList = Symbol("header list");
 const _iterableHeaders = Symbol("iterable headers");
 const _iterableHeadersCache = Symbol("iterable headers cache");
 const _guard = Symbol("guard");
+const _brand = webidl.brand;
 
 /**
  * @typedef Header
@@ -286,12 +287,17 @@ class Headers {
 
   /** @param {HeadersInit} [init] */
   constructor(init = undefined) {
+    if (init === _brand) {
+      this[_brand] = _brand;
+      return;
+    }
+
     const prefix = "Failed to construct 'Headers'";
     if (init !== undefined) {
       init = webidl.converters["HeadersInit"](init, prefix, "Argument 1");
     }
 
-    this[webidl.brand] = webidl.brand;
+    this[_brand] = _brand;
     this[_guard] = "none";
     if (init !== undefined) {
       fillHeaders(this, init);
@@ -486,7 +492,7 @@ webidl.converters["Headers"] = webidl.createInterfaceConverter(
  * @returns {Headers}
  */
 function headersFromHeaderList(list, guard) {
-  const headers = webidl.createBranded(Headers);
+  const headers = new Headers(_brand);
   headers[_headerList] = list;
   headers[_guard] = guard;
   return headers;
diff --git a/ext/fetch/23_request.js b/ext/fetch/23_request.js
index 5232cc13c96c97..c09bd4880877ab 100644
--- a/ext/fetch/23_request.js
+++ b/ext/fetch/23_request.js
@@ -52,6 +52,7 @@ const _mimeType = Symbol("mime type");
 const _body = Symbol("body");
 const _url = Symbol("url");
 const _method = Symbol("method");
+const _brand = webidl.brand;
 
 /**
  * @param {(() => string)[]} urlList
@@ -275,6 +276,11 @@ class Request {
    * @param {RequestInit} init
    */
   constructor(input, init = {}) {
+    if (input === _brand) {
+      this[_brand] = _brand;
+      return;
+    }
+
     const prefix = "Failed to construct 'Request'";
     webidl.requiredArguments(arguments.length, 1, prefix);
     input = webidl.converters["RequestInfo_DOMString"](
@@ -284,7 +290,7 @@ class Request {
     );
     init = webidl.converters["RequestInit"](init, prefix, "Argument 2");
 
-    this[webidl.brand] = webidl.brand;
+    this[_brand] = _brand;
 
     /** @type {InnerRequest} */
     let request;
@@ -554,7 +560,7 @@ function toInnerRequest(request) {
  * @returns {Request}
  */
 function fromInnerRequest(inner, signal, guard) {
-  const request = webidl.createBranded(Request);
+  const request = new Request(_brand);
   request[_request] = inner;
   request[_signal] = signal;
   request[_getHeaders] = () => headersFromHeaderList(inner.headerList, guard);
diff --git a/ext/fetch/23_response.js b/ext/fetch/23_response.js
index dc4e7543420af5..73a90166d590ac 100644
--- a/ext/fetch/23_response.js
+++ b/ext/fetch/23_response.js
@@ -60,6 +60,7 @@ const _response = Symbol("response");
 const _headers = Symbol("headers");
 const _mimeType = Symbol("mime type");
 const _body = Symbol("body");
+const _brand = webidl.brand;
 
 /**
  * @typedef InnerResponse
@@ -305,6 +306,11 @@ class Response {
    * @param {ResponseInit} init
    */
   constructor(body = null, init = undefined) {
+    if (body === _brand) {
+      this[_brand] = _brand;
+      return;
+    }
+
     const prefix = "Failed to construct 'Response'";
     body = webidl.converters["BodyInit_DOMString?"](body, prefix, "Argument 1");
     init = webidl.converters["ResponseInit_fast"](init, prefix, "Argument 2");
@@ -320,7 +326,7 @@ class Response {
       bodyWithType = extractBody(body);
     }
     initializeAResponse(this, init, bodyWithType);
-    this[webidl.brand] = webidl.brand;
+    this[_brand] = _brand;
   }
 
   /**
@@ -489,7 +495,7 @@ function toInnerResponse(response) {
  * @returns {Response}
  */
 function fromInnerResponse(inner, guard) {
-  const response = webidl.createBranded(Response);
+  const response = new Response(_brand);
   response[_response] = inner;
   response[_headers] = headersFromHeaderList(inner.headerList, guard);
   return response;