controller: fix limiter cannot work well in high concurrency scenario

Signed-off-by: nolouch <nolouch@gmail.com>

client/resource_group/controller/limiter.go

@@ -406,7 +406,9 @@ func (lim *Limiter) reserveN(now time.Time, n float64, maxFutureReserve time.Dur
 	}
 	// Update state
 	if ok {
-		lim.last = now
+		if lim.last.Before(now) {
+			lim.last = now
+		}
 		lim.tokens = tokens
 		lim.maybeNotify()
 	} else {
@@ -424,7 +426,9 @@ func (lim *Limiter) reserveN(now time.Time, n float64, maxFutureReserve time.Dur
 				zap.Int("remaining-notify-times", lim.remainingNotifyTimes),
 				zap.String("name", lim.name))
 		}
-		lim.last = last
+		if lim.last.Before(now) {
+			lim.last = last
+		}
 		if lim.limit == 0 {
 			lim.notify()
 		} else if lim.remainingNotifyTimes > 0 {

client/resource_group/controller/limiter_test.go

@@ -220,28 +220,27 @@ func TestQPS(t *testing.T) {
 	cases := []struct {
 		concurrency int
 		reserveN    int64
-		RU_PER_SEC  int64
+		ruPerSec    int64
 	}{
-		{10000, 10, 400000},
+		{1000, 10, 400000},
 	}
 
 	for _, tc := range cases {
-		t.Run(fmt.Sprintf("concurrency=%d,reserveN=%d,limit=%d", tc.concurrency, tc.reserveN, tc.RU_PER_SEC), func(t *testing.T) {
-			qps, ruSec, waitTime := testQPSCase(tc.concurrency, tc.reserveN, tc.RU_PER_SEC)
+		t.Run(fmt.Sprintf("concurrency=%d,reserveN=%d,limit=%d", tc.concurrency, tc.reserveN, tc.ruPerSec), func(t *testing.T) {
+			qps, ruSec, waitTime := testQPSCase(tc.concurrency, tc.reserveN, tc.ruPerSec)
 			t.Log(fmt.Printf("QPS: %.2f, RU: %.2f, new request need wait  %s\n", qps, ruSec, waitTime))
-			re.LessOrEqual(math.Abs(float64(tc.RU_PER_SEC)-ruSec), float64(1))
-			re.LessOrEqual(math.Abs(float64(tc.RU_PER_SEC)/float64(tc.reserveN)-qps), float64(1))
+			re.LessOrEqual(math.Abs(float64(tc.ruPerSec)-ruSec), float64(10)*float64(tc.reserveN))
+			re.LessOrEqual(math.Abs(float64(tc.ruPerSec)/float64(tc.reserveN)-qps), float64(10))
 		})
 	}
 }
 
-const testCaseRunTime = 3 * time.Second
+const testCaseRunTime = 4 * time.Second
 
-func testQPSCase(concurrency int, reserveN int64, limit int64) (float64, float64, time.Duration) {
+func testQPSCase(concurrency int, reserveN int64, limit int64) (qps float64, ru float64, needWait time.Duration) {
 	nc := make(chan notifyMsg, 1)
 	lim := NewLimiter(time.Now(), Limit(limit), limit, float64(limit), nc)
 	ctx, cancel := context.WithCancel(context.Background())
-	// defer cancel()
 
 	var wg sync.WaitGroup
 	var totalRequests int64
@@ -268,7 +267,7 @@ func testQPSCase(concurrency int, reserveN int64, limit int64) (float64, float64
 			}
 		}()
 	}
-	qps := float64(0)
+	var vQPS atomic.Value
 	var wait time.Duration
 	ch := make(chan struct{})
 	go func() {
@@ -280,15 +279,15 @@ func testQPSCase(concurrency int, reserveN int64, limit int64) (float64, float64
 				break
 			}
 			windowRequests = atomic.SwapInt64(&totalRequests, 0)
-			qps = float64(windowRequests)
+			vQPS.Store(float64(windowRequests))
 			r := lim.Reserve(ctx, 30*time.Second, time.Now(), float64(reserveN))
-			fmt.Printf("%s: QPS: %.2f, RU: %.2f, new request need wait %s\n", time.Now(), qps, qps*float64(reserveN), wait)
 			wait = r.Delay()
 			time.Sleep(1 * time.Second)
 		}
 	}()
 	<-ch
 	cancel()
 	wg.Wait()
+	qps = vQPS.Load().(float64)
 	return qps, qps * float64(reserveN), wait
 }