实现基础的206 partial content缓存

internal/utils/writers/writer_closer_tee.go

@@ -0,0 +1,53 @@
+// Copyright 2022 Liuxiangchao iwind.liu@gmail.com. All rights reserved.
+
+package writers
+
+import (
+	"io"
+)
+
+type TeeWriterCloser struct {
+	primaryW   io.WriteCloser
+	secondaryW io.WriteCloser
+
+	onFail func(err error)
+}
+
+func NewTeeWriterCloser(primaryW io.WriteCloser, secondaryW io.WriteCloser) *TeeWriterCloser {
+	return &TeeWriterCloser{
+		primaryW:   primaryW,
+		secondaryW: secondaryW,
+	}
+}
+
+func (this *TeeWriterCloser) Write(p []byte) (n int, err error) {
+	{
+		n, err = this.primaryW.Write(p)
+
+		if err != nil {
+			if this.onFail != nil {
+				this.onFail(err)
+			}
+		}
+	}
+
+	{
+		_, err2 := this.secondaryW.Write(p)
+		if err2 != nil {
+			if this.onFail != nil {
+				this.onFail(err2)
+			}
+		}
+	}
+
+	return
+}
+
+func (this *TeeWriterCloser) Close() error {
+	// 这里不关闭secondary
+	return this.primaryW.Close()
+}
+
+func (this *TeeWriterCloser) OnFail(onFail func(err error)) {
+	this.onFail = onFail
+}