实现基础的206 partial content缓存

internal/utils/readers/reader_tee.go

@@ -0,0 +1,52 @@
+// Copyright 2022 Liuxiangchao iwind.liu@gmail.com. All rights reserved.
+
+package readers
+
+import (
+	"io"
+)
+
+type TeeReader struct {
+	r io.Reader
+	w io.Writer
+
+	onFail func(err error)
+	onEOF  func()
+}
+
+func NewTeeReader(reader io.Reader, writer io.Writer) *TeeReader {
+	return &TeeReader{
+		r: reader,
+		w: writer,
+	}
+}
+
+func (this *TeeReader) Read(p []byte) (n int, err error) {
+	n, err = this.r.Read(p)
+	if n > 0 {
+		_, wErr := this.w.Write(p[:n])
+		if err == nil && wErr != nil {
+			err = wErr
+		}
+	}
+	if err != nil {
+		if err == io.EOF {
+			if this.onEOF != nil {
+				this.onEOF()
+			}
+		} else {
+			if this.onFail != nil {
+				this.onFail(err)
+			}
+		}
+	}
+	return
+}
+
+func (this *TeeReader) OnFail(onFail func(err error)) {
+	this.onFail = onFail
+}
+
+func (this *TeeReader) OnEOF(onEOF func()) {
+	this.onEOF = onEOF
+}