test: inspect proxy drain state

internal/perfcheck/main.go

@@ -46,6 +46,7 @@ type snapshot struct {
 	Goroutines      int    `json:"goroutines"`
 	Connections     int64  `json:"connections"`
 	Accepted        int64  `json:"accepted"`
+	ActiveRequests  int64  `json:"activeRequests,omitempty"`
 	FileDescriptors int    `json:"fileDescriptors,omitempty"`
 }
 
@@ -193,12 +194,14 @@ func serve(adapter string, tlsEnabled bool) error {
 	})
 	done := make(chan error, 1)
 	var shutdown func(context.Context) error
+	var stats func() native.Stats
 	switch adapter {
 	case "native":
 		server := native.New(application)
 		server.MaxConnections = 8192
 		server.MaxConcurrentRequests = 4096
 		shutdown = server.Shutdown
+		stats = server.Stats
 		go func() { done <- server.Serve(context.Background(), serveListener) }()
 	case "nethttp":
 		server := &http.Server{
@@ -246,11 +249,16 @@ func serve(adapter string, tlsEnabled bool) error {
 		}
 		var memory runtime.MemStats
 		runtime.ReadMemStats(&memory)
+		connections, accepted, activeRequests := tracked.active.Load(), tracked.accepted.Load(), int64(0)
+		if stats != nil {
+			value := stats()
+			connections, accepted, activeRequests = value.ActiveConnections, int64(value.AcceptedConnections), value.ActiveRequests
+		}
 		if err := encoder.Encode(snapshot{
 			HeapAlloc: memory.HeapAlloc, HeapInuse: memory.HeapInuse,
 			StackInuse: memory.StackInuse, TotalAlloc: memory.TotalAlloc,
 			Mallocs: memory.Mallocs, NumGC: memory.NumGC,
-			Goroutines: runtime.NumGoroutine(), Connections: tracked.active.Load(), Accepted: tracked.accepted.Load(),
+			Goroutines: runtime.NumGoroutine(), Connections: connections, Accepted: accepted, ActiveRequests: activeRequests,
 			FileDescriptors: openFileDescriptorCount(),
 		}); err != nil {
 			return err