Remove Saturation() from rate limiter interface

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()

pkg/util/metrics/BUILD

@@ -13,7 +13,6 @@ go_library(
     deps = [
         "//vendor/github.com/golang/glog:go_default_library",
         "//vendor/github.com/prometheus/client_golang/prometheus:go_default_library",
-        "//vendor/k8s.io/apimachinery/pkg/util/wait:go_default_library",
         "//vendor/k8s.io/client-go/util/flowcontrol:go_default_library",
     ],
 )

pkg/util/metrics/util.go

@@ -21,7 +21,6 @@ import (
 	"sync"
 	"time"
 
-	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/client-go/util/flowcontrol"
 
 	"github.com/golang/glog"
@@ -71,11 +70,13 @@ func RegisterMetricAndTrackRateLimiterUsage(ownerName string, rateLimiter flowco
 	if err := registerRateLimiterMetric(ownerName); err != nil {
 		return err
 	}
-	go wait.Until(func() {
-		metricsLock.Lock()
-		defer metricsLock.Unlock()
-		rateLimiterMetrics[ownerName].metric.Set(rateLimiter.Saturation())
-	}, updatePeriod, rateLimiterMetrics[ownerName].stopCh)
+	// TODO: determine how to track rate limiter saturation
+	// See discussion at https://go-review.googlesource.com/c/time/+/29958#message-4caffc11669cadd90e2da4c05122cfec50ea6a22
+	// go wait.Until(func() {
+	//   metricsLock.Lock()
+	//   defer metricsLock.Unlock()
+	//   rateLimiterMetrics[ownerName].metric.Set()
+	// }, updatePeriod, rateLimiterMetrics[ownerName].stopCh)
 	return nil
 }
 

staging/src/k8s.io/client-go/util/flowcontrol/throttle.go

@@ -30,11 +30,6 @@ type RateLimiter interface {
 	Accept()
 	// Stop stops the rate limiter, subsequent calls to CanAccept will return false
 	Stop()
-	// Saturation returns a percentage number which describes how saturated
-	// this rate limiter is.
-	// Usually we use token bucket rate limiter. In that case,
-	// 1.0 means no tokens are available; 0.0 means we have a full bucket of tokens to use.
-	Saturation() float64
 	// QPS returns QPS of this rate limiter
 	QPS() float32
 }
@@ -77,12 +72,6 @@ func (t *tokenBucketRateLimiter) TryAccept() bool {
 	return t.limiter.TakeAvailable(1) == 1
 }
 
-func (t *tokenBucketRateLimiter) Saturation() float64 {
-	capacity := t.limiter.Capacity()
-	avail := t.limiter.Available()
-	return float64(capacity-avail) / float64(capacity)
-}
-
 // Accept will block until a token becomes available
 func (t *tokenBucketRateLimiter) Accept() {
 	t.limiter.Wait(1)
@@ -105,10 +94,6 @@ func (t *fakeAlwaysRateLimiter) TryAccept() bool {
 	return true
 }
 
-func (t *fakeAlwaysRateLimiter) Saturation() float64 {
-	return 0
-}
-
 func (t *fakeAlwaysRateLimiter) Stop() {}
 
 func (t *fakeAlwaysRateLimiter) Accept() {}
@@ -131,10 +116,6 @@ func (t *fakeNeverRateLimiter) TryAccept() bool {
 	return false
 }
 
-func (t *fakeNeverRateLimiter) Saturation() float64 {
-	return 1
-}
-
 func (t *fakeNeverRateLimiter) Stop() {
 	t.wg.Done()
 }

staging/src/k8s.io/client-go/util/flowcontrol/throttle_test.go

@@ -17,7 +17,6 @@ limitations under the License.
 package flowcontrol
 
 import (
-	"math"
 	"sync"
 	"testing"
 	"time"
@@ -116,29 +115,6 @@ func TestThrottle(t *testing.T) {
 	}
 }
 
-func TestRateLimiterSaturation(t *testing.T) {
-	const e = 0.000001
-	tests := []struct {
-		capacity int
-		take     int
-
-		expectedSaturation float64
-	}{
-		{1, 1, 1},
-		{10, 3, 0.3},
-	}
-	for i, tt := range tests {
-		rl := NewTokenBucketRateLimiter(1, tt.capacity)
-		for i := 0; i < tt.take; i++ {
-			rl.Accept()
-		}
-		if math.Abs(rl.Saturation()-tt.expectedSaturation) > e {
-			t.Fatalf("#%d: Saturation rate difference isn't within tolerable range\n want=%f, get=%f",
-				i, tt.expectedSaturation, rl.Saturation())
-		}
-	}
-}
-
 func TestAlwaysFake(t *testing.T) {
 	rl := NewFakeAlwaysRateLimiter()
 	if !rl.TryAccept() {