refactor: add idle watchgod to transport

transport/watchdog.go

@@ -0,0 +1,45 @@
+package transport
+
+import (
+	"context"
+	"time"
+)
+
+func IdleWatchdog(
+	ctx context.Context,
+	activity <-chan struct{},
+	timeout time.Duration,
+	onTimeout func(),
+) {
+	// disable watchdog timeout if not configured
+	if timeout <= 0 {
+		for {
+			select {
+			case <-activity:
+			case <-ctx.Done():
+				return
+			}
+		}
+	}
+
+	timer := time.NewTimer(timeout)
+	defer timer.Stop()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-activity:
+			if !timer.Stop() {
+				select {
+				case <-timer.C:
+				default:
+				}
+			}
+			timer.Reset(timeout)
+		case <-timer.C:
+			onTimeout()
+			return
+		}
+	}
+}