Improve darwin tun performance

internal/stopfd_darwin/stopfd.go

@@ -0,0 +1,61 @@
+package stopfd
+
+import (
+	"fmt"
+
+	"golang.org/x/sys/unix"
+)
+
+type StopFD struct {
+	ReadFD  int
+	WriteFD int
+}
+
+func New() (StopFD, error) {
+	fds := make([]int, 2)
+	err := unix.Pipe(fds)
+	if err != nil {
+		return StopFD{ReadFD: -1, WriteFD: -1}, fmt.Errorf("failed to create pipe: %w", err)
+	}
+
+	if err := unix.SetNonblock(fds[0], true); err != nil {
+		unix.Close(fds[0])
+		unix.Close(fds[1])
+		return StopFD{ReadFD: -1, WriteFD: -1}, fmt.Errorf("failed to set read end non-blocking: %w", err)
+	}
+
+	if err := unix.SetNonblock(fds[1], true); err != nil {
+		unix.Close(fds[0])
+		unix.Close(fds[1])
+		return StopFD{ReadFD: -1, WriteFD: -1}, fmt.Errorf("failed to set write end non-blocking: %w", err)
+	}
+
+	return StopFD{ReadFD: fds[0], WriteFD: fds[1]}, nil
+}
+
+func (sf *StopFD) Stop() {
+	signal := []byte{1}
+	if n, err := unix.Write(sf.WriteFD, signal); n != len(signal) || err != nil {
+		panic(fmt.Sprintf("write(WriteFD) = (%d, %s), want (%d, nil)", n, err, len(signal)))
+	}
+}
+
+func (sf *StopFD) Close() error {
+	var err1, err2 error
+	if sf.ReadFD != -1 {
+		err1 = unix.Close(sf.ReadFD)
+		sf.ReadFD = -1
+	}
+	if sf.WriteFD != -1 {
+		err2 = unix.Close(sf.WriteFD)
+		sf.WriteFD = -1
+	}
+	if err1 != nil {
+		return err1
+	}
+	return err2
+}
+
+func (sf *StopFD) EFD() int {
+	return sf.ReadFD
+}