Merge pull request #38320 from liggitt/golang-ratelimit

Automatic merge from submit-queue (batch tested with PRs 59158, 38320, 59059, 55516, 59357). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Switch from juju/ratelimit to golang.org/x/time/rate

Replaces juju/ratelimit with golang.org/x/time/rate
xref https://github.com/kubernetes/steering/issues/21

Requires removing the Saturation() method on the rate limiter. In the process of attempting to contribute it to the `golang.org/x/time/rate` implementation, it became clear that what it was calculating was not very useful when combined with periodic polling. See discussion in https://go-review.googlesource.com/c/time/+/29958#message-4caffc11669cadd90e2da4c05122cfec50ea6a22

```release-note
NONE
```

pkg/controller/certificates/BUILD

@@ -15,7 +15,7 @@ go_library(
     deps = [
         "//pkg/controller:go_default_library",
         "//vendor/github.com/golang/glog:go_default_library",
-        "//vendor/github.com/juju/ratelimit:go_default_library",
+        "//vendor/golang.org/x/time/rate:go_default_library",
         "//vendor/k8s.io/api/certificates/v1beta1:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/api/errors:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/util/runtime:go_default_library",

pkg/controller/certificates/certificate_controller.go

@@ -22,6 +22,9 @@ import (
 	"fmt"
 	"time"
 
+	"github.com/golang/glog"
+	"golang.org/x/time/rate"
+
 	certificates "k8s.io/api/certificates/v1beta1"
 	"k8s.io/apimachinery/pkg/api/errors"
 	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
@@ -34,9 +37,6 @@ import (
 	"k8s.io/client-go/tools/record"
 	"k8s.io/client-go/util/workqueue"
 	"k8s.io/kubernetes/pkg/controller"
-
-	"github.com/golang/glog"
-	"github.com/juju/ratelimit"
 )
 
 type CertificateController struct {
@@ -65,7 +65,7 @@ func NewCertificateController(
 		queue: workqueue.NewNamedRateLimitingQueue(workqueue.NewMaxOfRateLimiter(
 			workqueue.NewItemExponentialFailureRateLimiter(200*time.Millisecond, 1000*time.Second),
 			// 10 qps, 100 bucket size.  This is only for retry speed and its only the overall factor (not per item)
-			&workqueue.BucketRateLimiter{Bucket: ratelimit.NewBucketWithRate(float64(10), int64(100))},
+			&workqueue.BucketRateLimiter{Limiter: rate.NewLimiter(rate.Limit(10), 100)},
 		), "certificate"),
 		handler: handler,
 	}

pkg/controller/nodelifecycle/scheduler/rate_limited_queue.go

@@ -293,20 +293,15 @@ func (q *RateLimitedTimedQueue) SwapLimiter(newQPS float32) {
 		newLimiter = flowcontrol.NewFakeNeverRateLimiter()
 	} else {
 		newLimiter = flowcontrol.NewTokenBucketRateLimiter(newQPS, EvictionRateLimiterBurst)
-	}
-	// If we're currently waiting on limiter, we drain the new one - this is a good approach when Burst value is 1
-	// TODO: figure out if we need to support higher Burst values and decide on the drain logic, should we keep:
-	// - saturation (percentage of used tokens)
-	// - number of used tokens
-	// - number of available tokens
-	// - something else
-	for q.limiter.Saturation() > newLimiter.Saturation() {
-		// Check if we're not using fake limiter
-		previousSaturation := newLimiter.Saturation()
-		newLimiter.TryAccept()
-		// It's a fake limiter
-		if newLimiter.Saturation() == previousSaturation {
-			break
+
+		// If we're currently waiting on limiter, we drain the new one - this is a good approach when Burst value is 1
+		// TODO: figure out if we need to support higher Burst values and decide on the drain logic, should we keep:
+		// - saturation (percentage of used tokens)
+		// - number of used tokens
+		// - number of available tokens
+		// - something else
+		if q.limiter.TryAccept() == false {
+			newLimiter.TryAccept()
 		}
 	}
 	q.limiter.Stop()