mirror of
https://github.com/prometheus/prometheus.git
synced 2024-12-29 07:29:42 -08:00
133 lines
3.2 KiB
Go
133 lines
3.2 KiB
Go
/*
|
|
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 &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
|
|
}
|