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jittered_ticker.go
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jittered_ticker.go
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// Copyright (c) 2016-2018 Tigera, Inc. All rights reserved.
//
// 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 jitter
import (
"math/rand"
"time"
log "github.com/sirupsen/logrus"
)
// Ticker tries to emit events on channel C at minDuration intervals plus up to maxJitter.
type Ticker struct {
C <-chan time.Time
stop chan bool
MinDuration time.Duration
MaxJitter time.Duration
}
func NewTicker(minDuration time.Duration, maxJitter time.Duration) *Ticker {
if minDuration < 0 {
log.WithField("duration", minDuration).Panic("Negative duration")
}
if maxJitter < 0 {
log.WithField("jitter", minDuration).Panic("Negative jitter")
}
c := make(chan time.Time, 1)
ticker := &Ticker{
C: c,
stop: make(chan bool),
MinDuration: minDuration,
MaxJitter: maxJitter,
}
go ticker.loop(c)
return ticker
}
func (t *Ticker) loop(c chan time.Time) {
tickLoop:
for {
time.Sleep(t.calculateDelay())
// Send best-effort then go back to sleep.
select {
case <-t.stop:
log.Info("Stopping jittered ticker")
close(c)
break tickLoop
case c <- time.Now():
default:
}
}
}
func (t *Ticker) calculateDelay() time.Duration {
jitter := time.Duration(rand.Int63n(int64(t.MaxJitter)))
delay := t.MinDuration + jitter
return delay
}
func (t *Ticker) Stop() {
t.stop <- true
}