Repository: denoland/deno
Pull request: fix(ext/node): implement TCP.setNoDelay

Fixes https://github.com/denoland/deno/issues/26177

The significant delay was caused by Nagel's algorithm + delayed ACKs in Linux kernels. Here's the [kernel patch](https://lwn.net/Articles/502585/) which added 40ms `tcp_default_delack_min`

```
$ deno run -A pg-bench.mjs # main
Tue Oct 15 2024 12:27:22 GMT+0530 (India Standard Time): 42ms

$ target/release/deno run -A pg-bench.mjs # this patch
Tue Oct 15 2024 12:28:02 GMT+0530 (India Standard Time): 1ms
```

```js
import { Buffer } from "node:buffer";

import pg from 'pg'
const { Client } = pg
const client = new Client({
    connectionString: 'postgresql://postgres:postgres@127.0.0.1:5432/postgres'
})
await client.connect()

async function fetch() {
    const startPerf = performance.now();
    const res = await client.query(`select
        $1::int as int,
        $2 as string,
        $3::timestamp with time zone as timestamp,
        $4 as null,
        $5::bool as boolean,
        $6::bytea as bytea,
        $7::jsonb as json
      `, [
        1337,
        'wat',
        new Date().toISOString(),
        null,
        false,
        Buffer.from('awesome'),
        JSON.stringify([{ some: 'json' }, { array: 'object' }])
    ])
    console.log(`${new Date()}: ${Math.round(performance.now() - startPerf)}ms`)
}

for(;;) await fetch();
```

Changed files:
filename: ext/node/polyfills/internal_binding/tcp_wrap.ts
patch: @@ -299,8 +299,8 @@ export class TCP extends ConnectionWrap {
    * @param noDelay
    * @return An error status code.
    */
-  setNoDelay(_noDelay: boolean): number {
-    // TODO(bnoordhuis) https://github.com/denoland/deno/pull/13103
+  setNoDelay(noDelay: boolean): number {
+    this[kStreamBaseField].setNoDelay(noDelay);
     return 0;
   }
 

filename: tests/node_compat/config.jsonc
patch: @@ -439,6 +439,7 @@
       "test-net-server-unref.js",
       "test-net-socket-destroy-twice.js",
       "test-net-socket-no-halfopen-enforcer.js",
+      "test-net-socket-setnodelay.js",
       "test-net-timeout-no-handle.js",
       "test-net-write-arguments.js",
       "test-next-tick-doesnt-hang.js",

filename: tests/node_compat/runner/TODO.md
patch: @@ -1851,7 +1851,6 @@ NOTE: This file should not be manually edited. Please edit `tests/node_compat/co
 - [parallel/test-net-socket-ready-without-cb.js](https://github.com/nodejs/node/tree/v18.12.1/test/parallel/test-net-socket-ready-without-cb.js)
 - [parallel/test-net-socket-reset-send.js](https://github.com/nodejs/node/tree/v18.12.1/test/parallel/test-net-socket-reset-send.js)
 - [parallel/test-net-socket-reset-twice.js](https://github.com/nodejs/node/tree/v18.12.1/test/parallel/test-net-socket-reset-twice.js)
-- [parallel/test-net-socket-setnodelay.js](https://github.com/nodejs/node/tree/v18.12.1/test/parallel/test-net-socket-setnodelay.js)
 - [parallel/test-net-socket-timeout-unref.js](https://github.com/nodejs/node/tree/v18.12.1/test/parallel/test-net-socket-timeout-unref.js)
 - [parallel/test-net-socket-timeout.js](https://github.com/nodejs/node/tree/v18.12.1/test/parallel/test-net-socket-timeout.js)
 - [parallel/test-net-socket-write-after-close.js](https://github.com/nodejs/node/tree/v18.12.1/test/parallel/test-net-socket-write-after-close.js)

filename: tests/node_compat/test/parallel/test-net-socket-setnodelay.js
patch: @@ -0,0 +1,63 @@
+// deno-fmt-ignore-file
+// deno-lint-ignore-file
+
+// Copyright Joyent and Node contributors. All rights reserved. MIT license.
+// Taken from Node 18.12.1
+// This file is automatically generated by `tests/node_compat/runner/setup.ts`. Do not modify this file manually.
+
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const net = require('net');
+
+const truthyValues = [true, 1, 'true', {}, []];
+const falseyValues = [false, 0, ''];
+const genSetNoDelay = (desiredArg) => (enable) => {
+  assert.strictEqual(enable, desiredArg);
+};
+
+// setNoDelay should default to true
+let socket = new net.Socket({
+  handle: {
+    setNoDelay: common.mustCall(genSetNoDelay(true)),
+    readStart() {}
+  }
+});
+socket.setNoDelay();
+
+socket = new net.Socket({
+  handle: {
+    setNoDelay: common.mustCall(genSetNoDelay(true), 1),
+    readStart() {}
+  }
+});
+truthyValues.forEach((testVal) => socket.setNoDelay(testVal));
+
+socket = new net.Socket({
+  handle: {
+    setNoDelay: common.mustNotCall(),
+    readStart() {}
+  }
+});
+falseyValues.forEach((testVal) => socket.setNoDelay(testVal));
+
+socket = new net.Socket({
+  handle: {
+    setNoDelay: common.mustCall(3),
+    readStart() {}
+  }
+});
+truthyValues.concat(falseyValues).concat(truthyValues)
+  .forEach((testVal) => socket.setNoDelay(testVal));
+
+// If a handler doesn't have a setNoDelay function it shouldn't be called.
+// In the case below, if it is called an exception will be thrown
+socket = new net.Socket({
+  handle: {
+    setNoDelay: null,
+    readStart() {}
+  }
+});
+const returned = socket.setNoDelay(true);
+assert.ok(returned instanceof net.Socket);