From 12d1abab9aa4f09bf9c0f7b5628c50155f2aaf4e Mon Sep 17 00:00:00 2001
From: kercylan98 <kercylan@gmail.com>
Date: Mon, 18 Sep 2023 10:28:23 +0800
Subject: [PATCH] =?UTF-8?q?feat:=20=E6=96=B0=E5=A2=9E=20buffer=20=E5=8C=85?=
 =?UTF-8?q?=EF=BC=8C=E5=86=85=E7=BD=AE=E4=BA=86=E4=B8=80=E4=B8=AA=E7=8E=AF?=
 =?UTF-8?q?=E5=BD=A2=E7=BC=93=E5=86=B2=E5=8C=BA=E7=9A=84=E5=AE=9E=E7=8E=B0?=
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---
 utils/buffer/errors.go |   7 +++
 utils/buffer/ring.go   | 113 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 120 insertions(+)
 create mode 100644 utils/buffer/errors.go
 create mode 100644 utils/buffer/ring.go

diff --git a/utils/buffer/errors.go b/utils/buffer/errors.go
new file mode 100644
index 0000000..0ea881e
--- /dev/null
+++ b/utils/buffer/errors.go
@@ -0,0 +1,7 @@
+package buffer
+
+import "errors"
+
+var (
+	ErrBufferIsEmpty = errors.New("buffer is empty")
+)
diff --git a/utils/buffer/ring.go b/utils/buffer/ring.go
new file mode 100644
index 0000000..8c4b3df
--- /dev/null
+++ b/utils/buffer/ring.go
@@ -0,0 +1,113 @@
+package buffer
+
+// NewRing 创建一个环形缓冲区
+func NewRing[T any](initSize int) *Ring[T] {
+	if initSize <= 1 {
+		panic("initial size must be great than one")
+	}
+
+	return &Ring[T]{
+		buf:      make([]T, initSize),
+		initSize: initSize,
+		size:     initSize,
+	}
+}
+
+// Ring 环形缓冲区
+type Ring[T any] struct {
+	buf      []T
+	initSize int
+	size     int
+	r        int
+	w        int
+}
+
+// Read 读取数据
+func (slf *Ring[T]) Read() (T, error) {
+	var t T
+	if slf.r == slf.w {
+		return t, ErrBufferIsEmpty
+	}
+
+	v := slf.buf[slf.r]
+	slf.r++
+	if slf.r == slf.size {
+		slf.r = 0
+	}
+
+	return v, nil
+}
+
+// Peek 查看数据
+func (slf *Ring[T]) Peek() (t T, err error) {
+	if slf.r == slf.w {
+		return t, ErrBufferIsEmpty
+	}
+
+	return slf.buf[slf.r], nil
+}
+
+// Write 写入数据
+func (slf *Ring[T]) Write(v T) {
+	slf.buf[slf.w] = v
+	slf.w++
+
+	if slf.w == slf.size {
+		slf.w = 0
+	}
+
+	if slf.w == slf.r {
+		slf.grow()
+	}
+}
+
+// grow 扩容
+func (slf *Ring[T]) grow() {
+	var size int
+	if slf.size < 1024 {
+		size = slf.size * 2
+	} else {
+		size = slf.size + slf.size/4
+	}
+
+	buf := make([]T, size)
+
+	copy(buf[0:], slf.buf[slf.r:])
+	copy(buf[slf.size-slf.r:], slf.buf[0:slf.r])
+
+	slf.r = 0
+	slf.w = slf.size
+	slf.size = size
+	slf.buf = buf
+}
+
+// IsEmpty 是否为空
+func (slf *Ring[T]) IsEmpty() bool {
+	return slf.r == slf.w
+}
+
+// Cap 返回缓冲区容量
+func (slf *Ring[T]) Cap() int {
+	return slf.size
+}
+
+// Len 返回缓冲区长度
+func (slf *Ring[T]) Len() int {
+	if slf.r == slf.w {
+		return 0
+	}
+
+	if slf.w > slf.r {
+		return slf.w - slf.r
+	}
+
+	return slf.size - slf.r + slf.w
+}
+
+// Reset 重置缓冲区
+func (slf *Ring[T]) Reset() {
+	slf.r = 0
+	slf.w = 0
+	slf.size = slf.initSize
+	slf.buf = make([]T, slf.initSize)
+}