Refactor platform command api

experimental/libbox/command_log.go

@@ -0,0 +1,104 @@
+//go:build darwin
+
+package libbox
+
+import (
+	"context"
+	"encoding/binary"
+	"io"
+	"net"
+)
+
+func (s *CommandServer) WriteMessage(message string) {
+	s.subscriber.Emit(message)
+	s.access.Lock()
+	s.savedLines.PushBack(message)
+	if s.savedLines.Len() > 100 {
+		s.savedLines.Remove(s.savedLines.Front())
+	}
+	s.access.Unlock()
+}
+
+func readLog(reader io.Reader) ([]byte, error) {
+	var messageLength uint16
+	err := binary.Read(reader, binary.BigEndian, &messageLength)
+	if err != nil {
+		return nil, err
+	}
+	data := make([]byte, messageLength)
+	_, err = io.ReadFull(reader, data)
+	if err != nil {
+		return nil, err
+	}
+	return data, nil
+}
+
+func writeLog(writer io.Writer, message []byte) error {
+	err := binary.Write(writer, binary.BigEndian, uint16(len(message)))
+	if err != nil {
+		return err
+	}
+	_, err = writer.Write(message)
+	return err
+}
+
+func (s *CommandServer) handleLogConn(conn net.Conn) error {
+	var savedLines []string
+	s.access.Lock()
+	savedLines = make([]string, 0, s.savedLines.Len())
+	for element := s.savedLines.Front(); element != nil; element = element.Next() {
+		savedLines = append(savedLines, element.Value)
+	}
+	s.access.Unlock()
+	subscription, done, err := s.observer.Subscribe()
+	if err != nil {
+		return err
+	}
+	defer s.observer.UnSubscribe(subscription)
+	for _, line := range savedLines {
+		err = writeLog(conn, []byte(line))
+		if err != nil {
+			return err
+		}
+	}
+	ctx := connKeepAlive(conn)
+	for {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		case message := <-subscription:
+			err = writeLog(conn, []byte(message))
+			if err != nil {
+				return err
+			}
+		case <-done:
+			return nil
+		}
+	}
+}
+
+func (c *CommandClient) handleLogConn(conn net.Conn) {
+	c.handler.Connected()
+	for {
+		message, err := readLog(conn)
+		if err != nil {
+			c.handler.Disconnected(err.Error())
+			return
+		}
+		c.handler.WriteLog(string(message))
+	}
+}
+
+func connKeepAlive(reader io.Reader) context.Context {
+	ctx, cancel := context.WithCancelCause(context.Background())
+	go func() {
+		for {
+			_, err := readLog(reader)
+			if err != nil {
+				cancel(err)
+				return
+			}
+		}
+	}()
+	return ctx
+}