fix: 积压时等本帧写出再断开并让 Shutdown 等待 0x8B

internal/broker/broker.go

@@ -141,9 +141,14 @@ type connState struct {
 	downStop       chan struct{}
 	downDone       chan struct{}
 	downBytes      atomic.Int64
-	sentPub        atomic.Int64
+	wirePending    atomic.Int64 // Publish 入 mochi outbound 后、OnPacketSent 前
 	mu             sync.Mutex
 
+	// 带断开的下行帧：只等本帧 OnPacketSent，不用连接级计数。
+	writeWaitCh      chan struct{}
+	writeWaitPayload []byte
+	writeWaitPID     uint16 // 非 0 时优先按 packet id 匹配
+
 	handshakeTimer *time.Timer
 }
 
@@ -232,28 +237,105 @@ func (b *Broker) Close() error {
 }
 
 // Shutdown 向所有连接发 MQTT 5 0x8B 后关闭。完整 HTTP 停机顺序见 L-03。
+// ctx 未取消时先等下行队列与 wirePending 排空，再 DisconnectClient（此时 outbound 空，
+// 0x8B 直写套接字），并在截止前等连接拆掉；ctx 已取消则发完即 Close，不等待。
 func (b *Broker) Shutdown(ctx context.Context) error {
 	if b.closed.Load() {
 		return nil
 	}
+	if ctx == nil {
+		ctx = context.Background()
+	}
+
 	b.connsMu.RLock()
+	states := make([]*connState, 0, len(b.byClient))
 	clients := make([]*mqtt.Client, 0, len(b.byClient))
-	for cl := range b.byClient {
+	for cl, st := range b.byClient {
 		if cl != nil {
 			clients = append(clients, cl)
 		}
+		if st != nil {
+			states = append(states, st)
+		}
 	}
 	b.connsMu.RUnlock()
+
+	for _, st := range states {
+		st.mu.Lock()
+		st.closing = true
+		st.mu.Unlock()
+	}
+
+	alreadyCancelled := false
+	select {
+	case <-ctx.Done():
+		alreadyCancelled = true
+	default:
+	}
+
+	var waitErr error
+	if !alreadyCancelled {
+		if !b.waitConnsQuiet(ctx, states) {
+			waitErr = ctx.Err()
+		}
+	}
+
 	for _, cl := range clients {
 		_ = b.server.DisconnectClient(cl, packets.ErrServerShuttingDown)
 	}
-	if ctx != nil {
+
+	if !alreadyCancelled && waitErr == nil {
+		waitErr = b.waitConnsGone(ctx)
+	}
+
+	closeErr := b.Close()
+	if waitErr != nil {
+		return waitErr
+	}
+	return closeErr
+}
+
+func (b *Broker) waitConnsQuiet(ctx context.Context, states []*connState) bool {
+	for {
+		quiet := true
+		for _, st := range states {
+			if st.wirePending.Load() > 0 {
+				quiet = false
+				break
+			}
+			st.mu.Lock()
+			ch := st.downCh
+			st.mu.Unlock()
+			if ch != nil && len(ch) > 0 {
+				quiet = false
+				break
+			}
+		}
+		if quiet {
+			return true
+		}
 		select {
 		case <-ctx.Done():
-		default:
+			return false
+		case <-time.After(2 * time.Millisecond):
+		}
+	}
+}
+
+func (b *Broker) waitConnsGone(ctx context.Context) error {
+	for {
+		b.connsMu.RLock()
+		n := len(b.byClient)
+		b.connsMu.RUnlock()
+		if n == 0 {
+			return nil
+		}
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		case <-time.After(2 * time.Millisecond):
 		}
 	}
-	return b.Close()
 }
 
 // AttachTCP 把裸 TCP/TLS 连接交给 mochi；阻塞到连接结束。