Import of https://github.com/ciena/voltctl at commit 40d61fbf3f910ed4017cf67c9c79e8e1f82a33a5
Change-Id: I8464c59e60d76cb8612891db3303878975b5416c
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 0000000..e671c04
--- /dev/null
+++ b/vendor/k8s.io/client-go/util/flowcontrol/throttle.go
@@ -0,0 +1,143 @@
+/*
+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"
+ "time"
+
+ "golang.org/x/time/rate"
+)
+
+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()
+ // QPS returns QPS of this rate limiter
+ QPS() float32
+}
+
+type tokenBucketRateLimiter struct {
+ limiter *rate.Limiter
+ clock Clock
+ 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 := rate.NewLimiter(rate.Limit(qps), burst)
+ return newTokenBucketRateLimiter(limiter, realClock{}, qps)
+}
+
+// An injectable, mockable clock interface.
+type Clock interface {
+ Now() time.Time
+ Sleep(time.Duration)
+}
+
+type realClock struct{}
+
+func (realClock) Now() time.Time {
+ return time.Now()
+}
+func (realClock) Sleep(d time.Duration) {
+ time.Sleep(d)
+}
+
+// NewTokenBucketRateLimiterWithClock is identical to NewTokenBucketRateLimiter
+// but allows an injectable clock, for testing.
+func NewTokenBucketRateLimiterWithClock(qps float32, burst int, c Clock) RateLimiter {
+ limiter := rate.NewLimiter(rate.Limit(qps), burst)
+ return newTokenBucketRateLimiter(limiter, c, qps)
+}
+
+func newTokenBucketRateLimiter(limiter *rate.Limiter, c Clock, qps float32) RateLimiter {
+ return &tokenBucketRateLimiter{
+ limiter: limiter,
+ clock: c,
+ qps: qps,
+ }
+}
+
+func (t *tokenBucketRateLimiter) TryAccept() bool {
+ return t.limiter.AllowN(t.clock.Now(), 1)
+}
+
+// Accept will block until a token becomes available
+func (t *tokenBucketRateLimiter) Accept() {
+ now := t.clock.Now()
+ t.clock.Sleep(t.limiter.ReserveN(now, 1).DelayFrom(now))
+}
+
+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) 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) Stop() {
+ t.wg.Done()
+}
+
+func (t *fakeNeverRateLimiter) Accept() {
+ t.wg.Wait()
+}
+
+func (t *fakeNeverRateLimiter) QPS() float32 {
+ return 1
+}