From b93c0c890c6bf7d64bdb672c89e3d74b4fcb1f44 Mon Sep 17 00:00:00 2001
From: Mateus Veloso <mateusveloso.developer@gmail.com>
Date: Wed, 8 Nov 2023 01:25:13 -0300
Subject: [PATCH] Optimize memory allocation in appendRune function (#1988)

* Optimize memory allocation in appendRune function

* Add benchmark tests for appendRune function memory allocation

* remove function

* remove old
---
 types/append.go      |  4 +++-
 types/append_test.go | 17 +++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)
 create mode 100644 types/append_test.go

diff --git a/types/append.go b/types/append.go
index 05be2a0f..342d478b 100644
--- a/types/append.go
+++ b/types/append.go
@@ -160,7 +160,9 @@ func appendRune(b []byte, r rune) []byte {
 	}
 	l := len(b)
 	if cap(b)-l < utf8.UTFMax {
-		b = append(b, make([]byte, utf8.UTFMax)...)
+		nb := make([]byte, l, 2*l+utf8.UTFMax)
+		copy(nb, b)
+		b = nb
 	}
 	n := utf8.EncodeRune(b[l:l+utf8.UTFMax], r)
 	return b[:l+n]
diff --git a/types/append_test.go b/types/append_test.go
new file mode 100644
index 00000000..5a2df1cc
--- /dev/null
+++ b/types/append_test.go
@@ -0,0 +1,17 @@
+package types
+
+import (
+	"testing"
+)
+
+func BenchmarkAppendRuneNew(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		b.StopTimer()
+		s := make([]byte, 0, 1024)
+		b.StartTimer()
+
+		for j := 0; j < 1000000; j++ {
+			s = appendRune(s, '世')
+		}
+	}
+}