fixing up pending logic

internal/wire/client.go

@@ -19,17 +19,17 @@ type Client struct {
 	lastSeq int
 	conn    *websocket.Conn
 
-	// outbox is the set of requests that we'd like to send. The send loop will
+	outbox   chan *pending
-	// read off of this channel and write these values to the underlying
+	resolved chan Response
-	// websocket connection.
-	outbox chan Request
 }
 
 // Dial dials the server specified by the client. The returned read-only
 // channel is a channel of responses from the server that are not replies to a
 // request sent by the client.
 func (c *Client) Dial() (<-chan Response, error) {
-	c.outbox = make(chan Request)
+	c.outbox = make(chan *pending)
+	c.resolved = make(chan Response)
+
 	dialer := websocket.Dialer{
 		HandshakeTimeout: 3 * time.Second,
 		ReadBufferSize:   32 * 1024,
@@ -58,15 +58,25 @@ func (c *Client) Dial() (<-chan Response, error) {
 	return notifications, nil
 }
 
-func (c *Client) Send(v Value) {
+func (c *Client) Send(v Value) (Response, error) {
-	c.lastSeq++
 	d := 3 * time.Second
 	timeout := time.NewTimer(d)
+
+	done := make(chan struct{})
+	p := pending{v: v, done: done}
+
 	select {
-	case c.outbox <- NewRequest(c.lastSeq, v):
+	case c.outbox <- &p:
 		timeout.Stop()
 	case <-timeout.C:
-		c.Error("send timed out after %v", d)
+		return Response{}, fmt.Errorf("send timed out after %v", d)
+	}
+
+	select {
+	case <-done:
+		return p.res, p.err
+	case <-timeout.C:
+		return Response{}, fmt.Errorf("send timed out (2) after %v", d)
 	}
 }
 
@@ -92,33 +102,55 @@ func (c *Client) readLoop(notifications chan<- Response) {
 		c.Child("read-frame").Info(string(b))
 		if res.Re <= 0 {
 			notifications <- res
+		} else {
+			c.resolved <- res
 		}
 	}
 }
 
 func (c *Client) writeLoop(done chan bool) {
+	sent := make(map[int]*pending)
+
 	for {
 		select {
-		case req := <-c.outbox:
+		case p := <-c.outbox:
+			c.lastSeq++
+			req := NewRequest(c.lastSeq, p.v)
+
 			w, err := c.conn.NextWriter(websocket.TextMessage)
 			if err != nil {
-				c.Error("unable to get a writer frame: %v", err)
+				p.err = fmt.Errorf("unable to get a writer frame: %w", err)
+				close(p.done)
 				return
 			}
 			b, err := json.Marshal(req)
 			if err != nil {
-				c.Error("unable to marshal outgoing response: %v", err)
+				p.err = fmt.Errorf("unable to marshal outgoing response: %w", err)
+				close(p.done)
 				break
 			}
 			if _, err := w.Write(b); err != nil {
-				c.Error("failed to write payload: %v", err)
+				p.err = fmt.Errorf("failed to write payload: %w", err)
+				close(p.done)
 				break
 			}
 			if err := w.Close(); err != nil {
-				c.Error("failed to close write frame: %v", err)
+				p.err = fmt.Errorf("failed to close write frame: %w", err)
+				close(p.done)
 				break
 			}
 			c.Child("write-frame").Info(string(b))
+			sent[c.lastSeq] = p
+
+		case res := <-c.resolved:
+			p, ok := sent[res.Re]
+			if !ok {
+				c.Error("saw response for unknown seq %d")
+				break
+			}
+			p.res = res
+			close(p.done)
+
 		case shouldClose := <-done:
 			if shouldClose {
 				msg := websocket.FormatCloseMessage(websocket.CloseNormalClosure, "")
@@ -136,5 +168,11 @@ func (c *Client) writeLoop(done chan bool) {
 			}
 		}
 	}
+}
 
+type pending struct {
+	v    Value
+	res  Response
+	err  error
+	done chan struct{}
 }