150 lines
3.9 KiB
Go
150 lines
3.9 KiB
Go
/*
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Copyright 2015 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package flowcontrol
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import (
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"sync"
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"time"
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"k8s.io/apimachinery/pkg/util/clock"
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"k8s.io/utils/integer"
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)
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type backoffEntry struct {
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backoff time.Duration
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lastUpdate time.Time
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}
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type Backoff struct {
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sync.RWMutex
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Clock clock.Clock
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defaultDuration time.Duration
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maxDuration time.Duration
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perItemBackoff map[string]*backoffEntry
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}
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func NewFakeBackOff(initial, max time.Duration, tc *clock.FakeClock) *Backoff {
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return &Backoff{
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perItemBackoff: map[string]*backoffEntry{},
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Clock: tc,
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defaultDuration: initial,
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maxDuration: max,
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}
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}
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func NewBackOff(initial, max time.Duration) *Backoff {
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return &Backoff{
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perItemBackoff: map[string]*backoffEntry{},
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Clock: clock.RealClock{},
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defaultDuration: initial,
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maxDuration: max,
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}
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}
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// Get the current backoff Duration
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func (p *Backoff) Get(id string) time.Duration {
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p.RLock()
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defer p.RUnlock()
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var delay time.Duration
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entry, ok := p.perItemBackoff[id]
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if ok {
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delay = entry.backoff
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}
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return delay
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}
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// move backoff to the next mark, capping at maxDuration
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func (p *Backoff) Next(id string, eventTime time.Time) {
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p.Lock()
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defer p.Unlock()
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entry, ok := p.perItemBackoff[id]
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if !ok || hasExpired(eventTime, entry.lastUpdate, p.maxDuration) {
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entry = p.initEntryUnsafe(id)
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} else {
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delay := entry.backoff * 2 // exponential
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entry.backoff = time.Duration(integer.Int64Min(int64(delay), int64(p.maxDuration)))
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}
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entry.lastUpdate = p.Clock.Now()
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}
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// Reset forces clearing of all backoff data for a given key.
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func (p *Backoff) Reset(id string) {
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p.Lock()
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defer p.Unlock()
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delete(p.perItemBackoff, id)
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}
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// Returns True if the elapsed time since eventTime is smaller than the current backoff window
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func (p *Backoff) IsInBackOffSince(id string, eventTime time.Time) bool {
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p.RLock()
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defer p.RUnlock()
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entry, ok := p.perItemBackoff[id]
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if !ok {
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return false
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}
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if hasExpired(eventTime, entry.lastUpdate, p.maxDuration) {
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return false
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}
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return p.Clock.Since(eventTime) < entry.backoff
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}
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// Returns True if time since lastupdate is less than the current backoff window.
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func (p *Backoff) IsInBackOffSinceUpdate(id string, eventTime time.Time) bool {
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p.RLock()
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defer p.RUnlock()
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entry, ok := p.perItemBackoff[id]
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if !ok {
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return false
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}
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if hasExpired(eventTime, entry.lastUpdate, p.maxDuration) {
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return false
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}
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return eventTime.Sub(entry.lastUpdate) < entry.backoff
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}
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// Garbage collect records that have aged past maxDuration. Backoff users are expected
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// to invoke this periodically.
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func (p *Backoff) GC() {
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p.Lock()
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defer p.Unlock()
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now := p.Clock.Now()
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for id, entry := range p.perItemBackoff {
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if now.Sub(entry.lastUpdate) > p.maxDuration*2 {
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// GC when entry has not been updated for 2*maxDuration
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delete(p.perItemBackoff, id)
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}
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}
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}
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func (p *Backoff) DeleteEntry(id string) {
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p.Lock()
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defer p.Unlock()
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delete(p.perItemBackoff, id)
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}
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// Take a lock on *Backoff, before calling initEntryUnsafe
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func (p *Backoff) initEntryUnsafe(id string) *backoffEntry {
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entry := &backoffEntry{backoff: p.defaultDuration}
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p.perItemBackoff[id] = entry
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return entry
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}
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// After 2*maxDuration we restart the backoff factor to the beginning
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func hasExpired(eventTime time.Time, lastUpdate time.Time, maxDuration time.Duration) bool {
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return eventTime.Sub(lastUpdate) > maxDuration*2 // consider stable if it's ok for twice the maxDuration
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}
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