google永远的神

tcpip/buffer/view.go

@@ -0,0 +1,104 @@
+package buffer
+
+type View []byte
+
+func NewView(size int) View {
+	return make(View, size)
+}
+
+func NewViewFromBytes(b []byte) View {
+	return append(View(nil), b...)
+}
+
+func (v *View) TrimFront(count int) {
+	*v = (*v)[count:]
+}
+
+func (v *View) CapLength(length int) {
+	*v = (*v)[:length:length]
+}
+
+func (v View) ToVectorisedView() VectorisedView {
+	return NewVectorisedView(len(v), []View{v})
+}
+
+// VectorisedView 是使用非连续内存的矢量化视图版本。它支持视图支持的所有便捷方法。
+type VectorisedView struct {
+	views []View
+	size  int
+}
+
+func NewVectorisedView(size int, views []View) VectorisedView {
+	return VectorisedView{views: views, size: size}
+}
+
+func (vv *VectorisedView) TrimFront(count int) {
+	for count > 0 && len(vv.views) > 0 {
+		if count < len(vv.views[0]) {
+			vv.size -= count
+			vv.views[0].TrimFront(count)
+			return
+		}
+		count -= len(vv.views[0])
+		vv.RemoveFirst()
+	}
+}
+
+func (vv *VectorisedView) CapLength(length int) {
+	if length < 0 {
+		length = 0
+	}
+	if vv.size < length {
+		return
+	}
+	vv.size = length
+	for i := range vv.views {
+		v := &vv.views[i]
+		if len(*v) >= length {
+			if length == 0 {
+				vv.views = vv.views[:i]
+			} else {
+				v.CapLength(length)
+				vv.views = vv.views[:i+1] // 更新view 这个写法太艹了 底层数组没有共享可以直接修改
+			}
+			return
+		}
+		length -= len(*v)
+	}
+}
+
+// 会把buffer原来的内容覆盖
+func (vv *VectorisedView) Clone(buffer []View) VectorisedView {
+	return VectorisedView{views: append(buffer[:0], vv.views...), size: vv.size}
+}
+
+func (vv *VectorisedView) First() View {
+	if len(vv.views) == 0 {
+		return nil
+	}
+	return vv.views[0]
+}
+
+func (vv *VectorisedView) RemoveFirst() {
+	if len(vv.views) == 0 {
+		return
+	}
+	vv.size -= len(vv.views[0])
+	vv.views = vv.views[1:]
+}
+
+func (vv *VectorisedView) Size() int {
+	return vv.size
+}
+
+func (vv VectorisedView) ToView() View {
+	u := make([]byte, 0, vv.size)
+	for _, v := range vv.views {
+		u = append(u, v...)
+	}
+	return u
+}
+
+func (vv VectorisedView) Views() []View {
+	return vv.views
+}