From 0e26d48d6e9e6d51a70a756e9c20a0c91c417a59 Mon Sep 17 00:00:00 2001
From: qydysky <qydysky@foxmail.com>
Date: Mon, 12 Aug 2024 20:06:40 +0800
Subject: [PATCH] 1

---
 slice/Buf.go      | 48 +++++++++++++++++++++++++++++++++++++++++++++++
 slice/Buf_test.go | 34 +++++++++++++++++++++++++++++++++
 2 files changed, 82 insertions(+)
 create mode 100644 slice/Buf.go
 create mode 100644 slice/Buf_test.go

diff --git a/slice/Buf.go b/slice/Buf.go
new file mode 100644
index 0000000..c0549ed
--- /dev/null
+++ b/slice/Buf.go
@@ -0,0 +1,48 @@
+package part
+
+import (
+	"runtime"
+	"sync/atomic"
+)
+
+type BufI[T any] interface {
+	// // eg
+	//
+	//	if tmpbuf, e := buf.Get(); e == nil {
+	//		// do something with tmpbuf
+	//	}
+	Get() []T
+	CacheCount() int64
+}
+
+type bufs[T any] struct {
+	_   noCopy
+	num atomic.Int64
+	buf [][]T
+}
+
+func NewBufs[T any]() BufI[T] {
+	return &bufs[T]{
+		buf: [][]T{},
+	}
+}
+
+func (t *bufs[T]) Get() (b []T) {
+	if len(t.buf) > 0 {
+		b = t.buf[0][:0]
+		t.buf = t.buf[:copy(t.buf, t.buf[1:])]
+		t.num.Add(-1)
+		return
+	} else {
+		b = []T{}
+	}
+	runtime.SetFinalizer(&b, func(objp any) {
+		t.buf = append(t.buf, *objp.(*[]T))
+		t.num.Add(1)
+	})
+	return
+}
+
+func (t *bufs[T]) CacheCount() int64 {
+	return t.num.Load()
+}
diff --git a/slice/Buf_test.go b/slice/Buf_test.go
new file mode 100644
index 0000000..260739c
--- /dev/null
+++ b/slice/Buf_test.go
@@ -0,0 +1,34 @@
+package part
+
+import (
+	"runtime"
+	"testing"
+	"time"
+)
+
+func TestBuf(t *testing.T) {
+	bu := NewBufs[byte]()
+	allocs(bu.Get())
+	runtime.GC()
+	time.Sleep(time.Second)
+	if bu.CacheCount() != 1 {
+		t.Fatal()
+	}
+	b := allocs(bu.Get())
+	runtime.GC()
+	time.Sleep(time.Second)
+	if bu.CacheCount() != 0 {
+		t.Fatal()
+	}
+	allocs(bu.Get())
+	runtime.GC()
+	time.Sleep(time.Second)
+	t.Log(b, bu.CacheCount())
+	if bu.CacheCount() != 1 {
+		t.Fatal()
+	}
+}
+
+func allocs(b []byte) []byte {
+	return append(b, 0x01)
+}
-- 
2.39.2