/
backoff.go
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/
backoff.go
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/*
Copyright 2015 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 backoff
import (
"math/rand"
"sync"
"time"
log "github.com/golang/glog"
)
type clock interface {
Now() time.Time
}
type realClock struct{}
func (realClock) Now() time.Time {
return time.Now()
}
type backoffEntry struct {
backoff time.Duration
lastUpdate time.Time
}
type Backoff struct {
perItemBackoff map[string]*backoffEntry
lock sync.Mutex
clock clock
defaultDuration time.Duration
maxDuration time.Duration
}
func New(initial, max time.Duration) *Backoff {
return &Backoff{
perItemBackoff: map[string]*backoffEntry{},
clock: realClock{},
defaultDuration: initial,
maxDuration: max,
}
}
func (p *Backoff) getEntry(id string) *backoffEntry {
p.lock.Lock()
defer p.lock.Unlock()
entry, ok := p.perItemBackoff[id]
if !ok {
entry = &backoffEntry{backoff: p.defaultDuration}
p.perItemBackoff[id] = entry
}
entry.lastUpdate = p.clock.Now()
return entry
}
func (p *Backoff) Get(id string) time.Duration {
entry := p.getEntry(id)
duration := entry.backoff
entry.backoff *= 2
if entry.backoff > p.maxDuration {
entry.backoff = p.maxDuration
}
//TODO(jdef) parameterize use of jitter?
// add jitter, get better backoff distribution
duration = time.Duration(rand.Int63n(int64(duration)))
log.V(3).Infof("Backing off %v for pod %s", duration, id)
return duration
}
// Garbage collect records that have aged past maxDuration. Backoff users are expected
// to invoke this periodically.
func (p *Backoff) GC() {
p.lock.Lock()
defer p.lock.Unlock()
now := p.clock.Now()
for id, entry := range p.perItemBackoff {
if now.Sub(entry.lastUpdate) > p.maxDuration {
delete(p.perItemBackoff, id)
}
}
}