From 7044bf523bab3a6da47150a05823dd6571abfd49 Mon Sep 17 00:00:00 2001
From: Divy Srivastava <dj.srivastava23@gmail.com>
Date: Wed, 16 Mar 2022 19:16:52 +0530
Subject: [PATCH] perf(web): optimize Blob.text and Blob.arrayBuffer (#13981)

---
 cli/bench/deno_common.js |  4 ++--
 ext/web/09_file.js       | 28 ++++++++++++++++++----------
 2 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/cli/bench/deno_common.js b/cli/bench/deno_common.js
index 629ed7669a..284f9d2162 100644
--- a/cli/bench/deno_common.js
+++ b/cli/bench/deno_common.js
@@ -39,7 +39,7 @@ function benchStats(name, n, t1, t2) {
 
 function benchB64RtLong() {
   const input = "long-string".repeat(99999);
-  benchSync("b64_rt_long", 1e2, () => {
+  benchSync("b64_rt_long", 100, () => {
     atob(btoa(input));
   });
 }
@@ -58,7 +58,7 @@ function benchUrlParse() {
 
 function benchLargeBlobText() {
   const input = "long-string".repeat(999_999);
-  benchSync("blob_text_large", 3, () => {
+  benchSync("blob_text_large", 100, () => {
     new Blob([input]).text();
   });
 }
diff --git a/ext/web/09_file.js b/ext/web/09_file.js
index 2117a0835e..50cce9004e 100644
--- a/ext/web/09_file.js
+++ b/ext/web/09_file.js
@@ -340,8 +340,22 @@
      */
     async text() {
       webidl.assertBranded(this, BlobPrototype);
-      const buffer = await this.arrayBuffer();
-      return core.decode(new Uint8Array(buffer));
+      const buffer = await this.#u8Array(this.size);
+      return core.decode(buffer);
+    }
+
+    async #u8Array(size) {
+      const bytes = new Uint8Array(size);
+      const partIterator = toIterator(this[_parts]);
+      let offset = 0;
+      for await (const chunk of partIterator) {
+        const byteLength = chunk.byteLength;
+        if (byteLength > 0) {
+          TypedArrayPrototypeSet(bytes, chunk, offset);
+          offset += byteLength;
+        }
+      }
+      return bytes;
     }
 
     /**
@@ -349,14 +363,8 @@
      */
     async arrayBuffer() {
       webidl.assertBranded(this, BlobPrototype);
-      const stream = this.stream();
-      const bytes = new Uint8Array(this.size);
-      let offset = 0;
-      for await (const chunk of stream) {
-        TypedArrayPrototypeSet(bytes, chunk, offset);
-        offset += chunk.byteLength;
-      }
-      return bytes.buffer;
+      const buf = await this.#u8Array(this.size);
+      return buf.buffer;
     }
 
     [SymbolFor("Deno.customInspect")](inspect) {