From 1ba88a7892fa1b0d7cf229b0cd5709575901ebd0 Mon Sep 17 00:00:00 2001
From: Divy Srivastava <dj.srivastava23@gmail.com>
Date: Tue, 30 Jul 2024 05:39:55 -0700
Subject: perf(ext/node): improve `Buffer` from string performance (#24567)
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Fixes https://github.com/denoland/deno/issues/24323

- Use a Buffer pool for `fromString`
- Implement fast call base64 writes
- Direct from string `create` method for each encoding op

```
$ deno bench -A bench.mjs # 1.45.1+fee4d3a
cpu: Apple M1 Pro
runtime: deno 1.45.1+fee4d3a (aarch64-apple-darwin)

benchmark                time (avg)             (min … max)       p75       p99      p999
----------------------------------------------------------- -----------------------------
Buffer.from base64      550 ns/iter     (490 ns … 1'265 ns)    572 ns    606 ns  1'265 ns
Buffer#write base64     285 ns/iter       (259 ns … 371 ns)    307 ns    347 ns    360 ns

$ ~/gh/deno/target/release/deno bench -A bench.mjs # this PR
cpu: Apple M1 Pro
runtime: deno dev (aarch64-apple-darwin)

benchmark                time (avg)             (min … max)       p75       p99      p999
----------------------------------------------------------- -----------------------------
Buffer.from base64      151 ns/iter       (145 ns … 770 ns)    148 ns    184 ns    648 ns
Buffer#write base64   62.58 ns/iter     (60.79 ns … 157 ns)  61.65 ns  75.79 ns    141 ns

$ node bench.mjs # v22.4.0
cpu: Apple M1 Pro
runtime: node v22.4.0 (arm64-darwin)

benchmark                time (avg)             (min … max)       p75       p99      p999
----------------------------------------------------------- -----------------------------
Buffer.from base64      163 ns/iter     (96.92 ns … 375 ns)  99.45 ns    127 ns    220 ns
Buffer#write base64   75.48 ns/iter     (74.97 ns … 134 ns)  75.17 ns  81.83 ns  96.84 ns
```
---
 ext/node/polyfills/string_decoder.ts | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

(limited to 'ext/node/polyfills/string_decoder.ts')

diff --git a/ext/node/polyfills/string_decoder.ts b/ext/node/polyfills/string_decoder.ts
index 4a49c2e3e..19aff8124 100644
--- a/ext/node/polyfills/string_decoder.ts
+++ b/ext/node/polyfills/string_decoder.ts
@@ -39,10 +39,15 @@ const {
   Symbol,
   MathMin,
   DataViewPrototypeGetBuffer,
+  DataViewPrototypeGetByteLength,
+  DataViewPrototypeGetByteOffset,
   ObjectPrototypeIsPrototypeOf,
   String,
   TypedArrayPrototypeGetBuffer,
+  TypedArrayPrototypeGetByteLength,
+  TypedArrayPrototypeGetByteOffset,
   StringPrototypeToLowerCase,
+  Uint8Array,
 } = primordials;
 const { isTypedArray } = core;
 
@@ -83,11 +88,21 @@ function normalizeBuffer(buf: Buffer) {
   }
   if (isBufferType(buf)) {
     return buf;
+  } else if (isTypedArray(buf)) {
+    return Buffer.from(
+      new Uint8Array(
+        TypedArrayPrototypeGetBuffer(buf),
+        TypedArrayPrototypeGetByteOffset(buf),
+        TypedArrayPrototypeGetByteLength(buf),
+      ),
+    );
   } else {
     return Buffer.from(
-      isTypedArray(buf)
-        ? TypedArrayPrototypeGetBuffer(buf)
-        : DataViewPrototypeGetBuffer(buf),
+      new Uint8Array(
+        DataViewPrototypeGetBuffer(buf),
+        DataViewPrototypeGetByteOffset(buf),
+        DataViewPrototypeGetByteLength(buf),
+      ),
     );
   }
 }
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