Stream-decode msgpack responses instead of waiting for read timeout

lib/client/client.go

@@ -42,15 +42,10 @@ func (c *Client) send(msg any) (uint32, error) {
 }
 
 func (c *Client) receive(expectedID uint32) (any, error) {
-	data, err := c.transport.Receive(c.timeout)
-	if err != nil {
-		return nil, fmt.Errorf("receive: %w", err)
-	}
-	if len(data) == 0 {
-		return nil, fmt.Errorf("no response")
-	}
+	c.transport.SetReadTimeout(c.timeout)
+	dec := msgpack.NewDecoder(c.transport.Reader())
 	var env Envelope
-	if err := msgpack.Unmarshal(data, &env); err != nil {
+	if err := dec.Decode(&env); err != nil {
 		return nil, fmt.Errorf("decode envelope: %w", err)
 	}
 	if env.MessageID != expectedID {

lib/picoserial/picoserial.go

@@ -2,6 +2,7 @@ package picoserial
 
 import (
 	"fmt"
+	"io"
 	"time"
 
 	"go.bug.st/serial"
@@ -38,20 +39,12 @@ func (t *SerialTransport) Send(data []byte) error {
 	return err
 }
 
-func (t *SerialTransport) Receive(timeout time.Duration) ([]byte, error) {
+func (t *SerialTransport) SetReadTimeout(timeout time.Duration) {
 	t.port.SetReadTimeout(timeout)
-	var resp []byte
-	buf := make([]byte, 256)
-	for {
-		n, err := t.port.Read(buf)
-		if n > 0 {
-			resp = append(resp, buf[:n]...)
-		}
-		if err != nil || n == 0 {
-			break
-		}
-	}
-	return resp, nil
+}
+
+func (t *SerialTransport) Reader() io.Reader {
+	return t.port
 }
 
 func (t *SerialTransport) Close() error {

lib/transport/transport.go

@@ -1,9 +1,13 @@
 package transport
 
-import "time"
+import (
+	"io"
+	"time"
+)
 
 type Transport interface {
 	Send(data []byte) error
-	Receive(timeout time.Duration) ([]byte, error)
+	SetReadTimeout(timeout time.Duration)
+	Reader() io.Reader
 	Close() error
 }