fix: 接线 Prometheus 指标到连接与投递事件

internal/broker/broker.go

@@ -12,6 +12,7 @@ import (
 	"time"
 
 	"git.asio.asia/nixevol/NixMsg/internal/app/port"
+	"git.asio.asia/nixevol/NixMsg/internal/metrics"
 	mqtt "github.com/mochi-mqtt/server/v2"
 	"github.com/mochi-mqtt/server/v2/packets"
 )
@@ -68,15 +69,18 @@ type Options struct {
 	Logger        *slog.Logger
 	// OnPublishDropped 可选；nil 时仅打 debug 日志。
 	OnPublishDropped PublishDroppedFunc
+	// Metrics 可选；会话建立/断开时更新 nixmsg_connections。
+	Metrics *metrics.Registry
 }
 
 // Broker 内置 mochi，不自带监听端口。
 type Broker struct {
-	server *mqtt.Server
-	auth   Authenticator
-	uplink port.UplinkHandler
-	log    *slog.Logger
-	onDrop PublishDroppedFunc
+	server  *mqtt.Server
+	auth    Authenticator
+	uplink  port.UplinkHandler
+	log     *slog.Logger
+	onDrop  PublishDroppedFunc
+	metrics *metrics.Registry
 
 	hook *nixHook
 
@@ -105,6 +109,7 @@ type connState struct {
 	handshook      bool
 	subscribedDown bool
 	largeHeld      int
+	metricsCounted bool
 	mu             sync.Mutex
 
 	handshakeTimer *time.Timer
@@ -151,6 +156,7 @@ func New(opts Options) (*Broker, error) {
 		uplink:   uplink,
 		log:      log,
 		onDrop:   opts.OnPublishDropped,
+		metrics:  opts.Metrics,
 		current:  make(map[string]*connState),
 		byClient: make(map[*mqtt.Client]*connState),
 		queues:   make(map[string]*uplinkQueue),