Refine buffer

common/rw/buffer.go

@@ -0,0 +1,133 @@
+package rw
+
+import (
+	"io"
+
+	"github.com/sagernet/sing/common"
+	"github.com/sagernet/sing/common/buf"
+)
+
+type BufferedWriter struct {
+	Writer io.Writer
+	Buffer *buf.Buffer
+}
+
+func (w *BufferedWriter) Upstream() io.Writer {
+	return w.Writer
+}
+
+func (w *BufferedWriter) Replaceable() bool {
+	return w.Buffer == nil
+}
+
+func (w *BufferedWriter) Write(p []byte) (n int, err error) {
+	if w.Buffer == nil {
+		return w.Writer.Write(p)
+	}
+	n, err = w.Buffer.Write(p)
+	if n == len(p) {
+		return
+	}
+	fd, err := common.TryFileDescriptor(w.Writer)
+	if err == nil {
+		_, err = WriteV(fd, w.Buffer.Bytes(), p[n:])
+		if err != nil {
+			return
+		}
+		w.Buffer.Release()
+		w.Buffer = nil
+		return len(p), nil
+	}
+	_, err = w.Writer.Write(w.Buffer.Bytes())
+	if err != nil {
+		return
+	}
+	err = w.Flush()
+	if err != nil {
+		return
+	}
+	_, err = w.Writer.Write(p[n:])
+	if err != nil {
+		return
+	}
+	return len(p), nil
+}
+
+func (w *BufferedWriter) Flush() error {
+	if w.Buffer == nil {
+		return nil
+	}
+	if w.Buffer.IsEmpty() {
+		w.Buffer.Release()
+		w.Buffer = nil
+		return nil
+	}
+	_, err := w.Writer.Write(w.Buffer.Bytes())
+	if err != nil {
+		return err
+	}
+	w.Buffer.Release()
+	w.Buffer = nil
+	return nil
+}
+
+func (w *BufferedWriter) Close() error {
+	buffer := w.Buffer
+	if buffer != nil {
+		w.Buffer = nil
+		buffer.Release()
+	}
+	return nil
+}
+
+type HeaderWriter struct {
+	Writer io.Writer
+	Header *buf.Buffer
+}
+
+func (w *HeaderWriter) Upstream() io.Writer {
+	return w.Writer
+}
+
+func (w *HeaderWriter) Replaceable() bool {
+	return w.Header == nil
+}
+
+func (w *HeaderWriter) Write(p []byte) (n int, err error) {
+	if w.Header == nil {
+		return w.Writer.Write(p)
+	}
+	fd, err := common.TryFileDescriptor(w.Writer)
+	if err == nil {
+		_, err = WriteV(fd, w.Header.Bytes(), p)
+		if err != nil {
+			return
+		}
+		w.Header.Release()
+		w.Header = nil
+		return len(p), nil
+	}
+	cachedN, _ := w.Header.Write(p)
+	_, err = w.Writer.Write(w.Header.Bytes())
+	if err != nil {
+		return
+	}
+	w.Header.Release()
+	w.Header = nil
+	if cachedN < len(p) {
+		_, err = w.Writer.Write(p[cachedN:])
+		if err != nil {
+			return
+		}
+	}
+	return len(p), nil
+}
+
+func (w *HeaderWriter) Close() error {
+	buffer := w.Header
+	if buffer != nil {
+		w.Header = nil
+		buffer.Release()
+	}
+	return nil
+}