fix: 🐛 同じtokenを5回以上連続で落とさないように

bench/payment/handler.go

@@ -81,22 +81,26 @@ func (s *Server) PostPaymentsHandler(w http.ResponseWriter, r *http.Request) {
 	if failurePercentage > 50 {
 		failurePercentage = 50
 	}
-	if rand.IntN(100) > failurePercentage {
+	failureCount, _ := s.failureCounts.GetOrSetDefault(token, func() int { return 0 })
+	if rand.IntN(100) > failurePercentage || failureCount >= 4 {
 		// lock はここでしか触らない。lock が true の場合は idempotency key が同じリクエストが処理中の場合のみ
 		if p.locked.CompareAndSwap(false, true) {
 			s.processedPayments.Append(&processedPayment{payment: p, processedAt: time.Now()})
 			p.Status = s.verifier.Verify(p)
 			if p.Status.Err != nil {
 				s.errChan <- p.Status.Err
 			}
+			s.failureCounts.Delete(token)
+			switch rand.IntN(2) {
+			case 0:
+				writeRandomError(w)
+			case 1:
+				writeResponse(w, p.Status)
+			}
+			return
 		}
-		switch rand.IntN(2) {
-		case 0:
-			writeRandomError(w)
-		case 1:
-			writeResponse(w, p.Status)
-		}
-		return
+	} else {
+		s.failureCounts.Set(token, failureCount+1)
 	}
 
 	// 不安定なエラーを再現

bench/payment/server.go

@@ -19,6 +19,7 @@ type processedPayment struct {
 type Server struct {
 	mux               *http.ServeMux
 	knownKeys         *concurrent.SimpleMap[string, *Payment]
+	failureCounts     *concurrent.SimpleMap[string, int]
 	processedPayments *concurrent.SimpleSlice[*processedPayment]
 	processTime       time.Duration
 	verifier          Verifier
@@ -30,6 +31,7 @@ func NewServer(verifier Verifier, processTime time.Duration, errChan chan error)
 	s := &Server{
 		mux:               http.NewServeMux(),
 		knownKeys:         concurrent.NewSimpleMap[string, *Payment](),
+		failureCounts:     concurrent.NewSimpleMap[string, int](),
 		processedPayments: concurrent.NewSimpleSlice[*processedPayment](),
 		processTime:       processTime,
 		verifier:          verifier,