(tested) add hooks check when ping http route called

middleware/hooks.go

@@ -18,6 +18,16 @@ type Hook interface {
 	HandleScrape(context.Context, *bittorrent.ScrapeRequest, *bittorrent.ScrapeResponse) (context.Context, error)
 }
 
+// Pinger is an optional interface that may be implemented by a pre Hook
+// to check if it is operational. Used in frontend.TrackerLogic.
+//
+// It may be useful in cases when Hook performs foreign requests to
+// some external resources (i.e. storage) and `ping` request should
+// also check resource availability.
+type Pinger interface {
+	Ping(ctx context.Context) error
+}
+
 type skipSwarmInteraction struct{}
 
 // SkipSwarmInteractionKey is a key for the context of an Announce to control
@@ -205,3 +215,7 @@ func (h *responseHook) HandleScrape(ctx context.Context, req *bittorrent.ScrapeR
 
 	return ctx, nil
 }
+
+func (h *responseHook) Ping(_ context.Context) error {
+	return h.store.Ping()
+}

middleware/logic.go

@@ -19,12 +19,19 @@ var (
 // NewLogic creates a new instance of a TrackerLogic that executes the provided
 // middleware hooks.
 func NewLogic(annInterval, minAnnInterval time.Duration, peerStore storage.PeerStorage, preHooks, postHooks []Hook) *Logic {
-	return &Logic{
+	l := &Logic{
 		announceInterval:    annInterval,
 		minAnnounceInterval: minAnnInterval,
 		preHooks:            append(preHooks, &responseHook{store: peerStore}),
 		postHooks:           append(postHooks, &swarmInteractionHook{store: peerStore}),
+		pingers:             make([]Pinger, 0, 1),
 	}
+	for _, h := range l.preHooks {
+		if ph, isOk := h.(Pinger); isOk {
+			l.pingers = append(l.pingers, ph)
+		}
+	}
+	return l
 }
 
 // Logic is an implementation of the TrackerLogic that functions by
@@ -34,6 +41,7 @@ type Logic struct {
 	minAnnounceInterval time.Duration
 	preHooks            []Hook
 	postHooks           []Hook
+	pingers             []Pinger
 }
 
 // HandleAnnounce generates a response for an Announce.
@@ -101,6 +109,16 @@ func (l *Logic) AfterScrape(ctx context.Context, req *bittorrent.ScrapeRequest,
 	}
 }
 
+// Ping performs check if all Hook-s are operational
+func (l *Logic) Ping(ctx context.Context) (err error) {
+	for _, p := range l.pingers {
+		if err = p.Ping(ctx); err != nil {
+			break
+		}
+	}
+	return
+}
+
 // Stop stops the Logic.
 //
 // This stops any hooks that implement stop.Stopper.