From a031b83a09a8628435317a03f199cdc18b78262f Mon Sep 17 00:00:00 2001
From: Matthew Heon <matthew.heon@gmail.com>
Date: Wed, 1 Nov 2017 11:24:59 -0400
Subject: Initial checkin from CRI-O repo

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>
---
 .../k8s.io/client-go/util/flowcontrol/throttle.go  | 148 +++++++++++++++++++++
 1 file changed, 148 insertions(+)
 create mode 100644 vendor/k8s.io/client-go/util/flowcontrol/throttle.go

(limited to 'vendor/k8s.io/client-go/util/flowcontrol/throttle.go')

diff --git a/vendor/k8s.io/client-go/util/flowcontrol/throttle.go b/vendor/k8s.io/client-go/util/flowcontrol/throttle.go
new file mode 100644
index 000000000..c45169c40
--- /dev/null
+++ b/vendor/k8s.io/client-go/util/flowcontrol/throttle.go
@@ -0,0 +1,148 @@
+/*
+Copyright 2014 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package flowcontrol
+
+import (
+	"sync"
+
+	"github.com/juju/ratelimit"
+)
+
+type RateLimiter interface {
+	// TryAccept returns true if a token is taken immediately. Otherwise,
+	// it returns false.
+	TryAccept() bool
+	// Accept returns once a token becomes available.
+	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
+}
+
+type tokenBucketRateLimiter struct {
+	limiter *ratelimit.Bucket
+	qps     float32
+}
+
+// NewTokenBucketRateLimiter creates a rate limiter which implements a token bucket approach.
+// The rate limiter allows bursts of up to 'burst' to exceed the QPS, while still maintaining a
+// smoothed qps rate of 'qps'.
+// The bucket is initially filled with 'burst' tokens, and refills at a rate of 'qps'.
+// The maximum number of tokens in the bucket is capped at 'burst'.
+func NewTokenBucketRateLimiter(qps float32, burst int) RateLimiter {
+	limiter := ratelimit.NewBucketWithRate(float64(qps), int64(burst))
+	return newTokenBucketRateLimiter(limiter, qps)
+}
+
+// An injectable, mockable clock interface.
+type Clock interface {
+	ratelimit.Clock
+}
+
+// NewTokenBucketRateLimiterWithClock is identical to NewTokenBucketRateLimiter
+// but allows an injectable clock, for testing.
+func NewTokenBucketRateLimiterWithClock(qps float32, burst int, clock Clock) RateLimiter {
+	limiter := ratelimit.NewBucketWithRateAndClock(float64(qps), int64(burst), clock)
+	return newTokenBucketRateLimiter(limiter, qps)
+}
+
+func newTokenBucketRateLimiter(limiter *ratelimit.Bucket, qps float32) RateLimiter {
+	return &tokenBucketRateLimiter{
+		limiter: limiter,
+		qps:     qps,
+	}
+}
+
+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)
+}
+
+func (t *tokenBucketRateLimiter) Stop() {
+}
+
+func (t *tokenBucketRateLimiter) QPS() float32 {
+	return t.qps
+}
+
+type fakeAlwaysRateLimiter struct{}
+
+func NewFakeAlwaysRateLimiter() RateLimiter {
+	return &fakeAlwaysRateLimiter{}
+}
+
+func (t *fakeAlwaysRateLimiter) TryAccept() bool {
+	return true
+}
+
+func (t *fakeAlwaysRateLimiter) Saturation() float64 {
+	return 0
+}
+
+func (t *fakeAlwaysRateLimiter) Stop() {}
+
+func (t *fakeAlwaysRateLimiter) Accept() {}
+
+func (t *fakeAlwaysRateLimiter) QPS() float32 {
+	return 1
+}
+
+type fakeNeverRateLimiter struct {
+	wg sync.WaitGroup
+}
+
+func NewFakeNeverRateLimiter() RateLimiter {
+	rl := fakeNeverRateLimiter{}
+	rl.wg.Add(1)
+	return &rl
+}
+
+func (t *fakeNeverRateLimiter) TryAccept() bool {
+	return false
+}
+
+func (t *fakeNeverRateLimiter) Saturation() float64 {
+	return 1
+}
+
+func (t *fakeNeverRateLimiter) Stop() {
+	t.wg.Done()
+}
+
+func (t *fakeNeverRateLimiter) Accept() {
+	t.wg.Wait()
+}
+
+func (t *fakeNeverRateLimiter) QPS() float32 {
+	return 1
+}
-- 
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