From e67ccf8c31f0af7c3c6a591d2cf57bc7e619c8e6 Mon Sep 17 00:00:00 2001
From: pyihe <785131182@qq.com>
Date: Thu, 16 Feb 2023 15:42:44 +0800
Subject: [PATCH] bytes pool

---
 bytespool/pool.go | 62 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 bytespool/pool.go

diff --git a/bytespool/pool.go b/bytespool/pool.go
new file mode 100644
index 0000000..02bb782
--- /dev/null
+++ b/bytespool/pool.go
@@ -0,0 +1,62 @@
+package bytespool
+
+import (
+	"math/bits"
+	"sync"
+)
+
+// copy from github.com/bytedance/gopkg/tree/develop/lang/mcache
+
+const maxSize = 46
+
+var caches [maxSize]sync.Pool
+
+func init() {
+	for i := 0; i < maxSize; i++ {
+		size := 1 << i
+		caches[i].New = func() any {
+			return make([]byte, 0, size)
+		}
+	}
+}
+
+func Get(length int, capacity ...int) []byte {
+	n := len(capacity)
+	if n > 1 {
+		panic("too many arguments")
+	}
+	c := length
+	if n > 0 && capacity[0] > length {
+		c = capacity[0]
+	}
+	buf := caches[locatePool(c)].Get().([]byte)
+	buf = buf[:length]
+	return buf
+}
+
+func Put(buf []byte) {
+	size := cap(buf)
+	if !validSize(size) {
+		return
+	}
+	buf = buf[:0]
+	caches[bsr(size)].Put(buf)
+}
+
+func locatePool(size int) int {
+	if size <= 0 {
+		return 0
+	}
+	if validSize(size) {
+		return bsr(size)
+	}
+	return bsr(size) + 1
+}
+
+func bsr(x int) int {
+	return bits.Len(uint(x)) - 1
+}
+
+func validSize(size int) bool {
+	return (size & (-size)) == size
+}