1/* 2Copyright 2015 The Kubernetes Authors. 3 4Licensed under the Apache License, Version 2.0 (the "License"); 5you may not use this file except in compliance with the License. 6You may obtain a copy of the License at 7 8 http://www.apache.org/licenses/LICENSE-2.0 9 10Unless required by applicable law or agreed to in writing, software 11distributed under the License is distributed on an "AS IS" BASIS, 12WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13See the License for the specific language governing permissions and 14limitations under the License. 15*/ 16 17package flowcontrol 18 19import ( 20 "sync" 21 "time" 22 23 "k8s.io/apimachinery/pkg/util/clock" 24 "k8s.io/utils/integer" 25) 26 27type backoffEntry struct { 28 backoff time.Duration 29 lastUpdate time.Time 30} 31 32type Backoff struct { 33 sync.RWMutex 34 Clock clock.Clock 35 defaultDuration time.Duration 36 maxDuration time.Duration 37 perItemBackoff map[string]*backoffEntry 38} 39 40func NewFakeBackOff(initial, max time.Duration, tc *clock.FakeClock) *Backoff { 41 return &Backoff{ 42 perItemBackoff: map[string]*backoffEntry{}, 43 Clock: tc, 44 defaultDuration: initial, 45 maxDuration: max, 46 } 47} 48 49func NewBackOff(initial, max time.Duration) *Backoff { 50 return &Backoff{ 51 perItemBackoff: map[string]*backoffEntry{}, 52 Clock: clock.RealClock{}, 53 defaultDuration: initial, 54 maxDuration: max, 55 } 56} 57 58// Get the current backoff Duration 59func (p *Backoff) Get(id string) time.Duration { 60 p.RLock() 61 defer p.RUnlock() 62 var delay time.Duration 63 entry, ok := p.perItemBackoff[id] 64 if ok { 65 delay = entry.backoff 66 } 67 return delay 68} 69 70// move backoff to the next mark, capping at maxDuration 71func (p *Backoff) Next(id string, eventTime time.Time) { 72 p.Lock() 73 defer p.Unlock() 74 entry, ok := p.perItemBackoff[id] 75 if !ok || hasExpired(eventTime, entry.lastUpdate, p.maxDuration) { 76 entry = p.initEntryUnsafe(id) 77 } else { 78 delay := entry.backoff * 2 // exponential 79 entry.backoff = time.Duration(integer.Int64Min(int64(delay), int64(p.maxDuration))) 80 } 81 entry.lastUpdate = p.Clock.Now() 82} 83 84// Reset forces clearing of all backoff data for a given key. 85func (p *Backoff) Reset(id string) { 86 p.Lock() 87 defer p.Unlock() 88 delete(p.perItemBackoff, id) 89} 90 91// Returns True if the elapsed time since eventTime is smaller than the current backoff window 92func (p *Backoff) IsInBackOffSince(id string, eventTime time.Time) bool { 93 p.RLock() 94 defer p.RUnlock() 95 entry, ok := p.perItemBackoff[id] 96 if !ok { 97 return false 98 } 99 if hasExpired(eventTime, entry.lastUpdate, p.maxDuration) { 100 return false 101 } 102 return p.Clock.Since(eventTime) < entry.backoff 103} 104 105// Returns True if time since lastupdate is less than the current backoff window. 106func (p *Backoff) IsInBackOffSinceUpdate(id string, eventTime time.Time) bool { 107 p.RLock() 108 defer p.RUnlock() 109 entry, ok := p.perItemBackoff[id] 110 if !ok { 111 return false 112 } 113 if hasExpired(eventTime, entry.lastUpdate, p.maxDuration) { 114 return false 115 } 116 return eventTime.Sub(entry.lastUpdate) < entry.backoff 117} 118 119// Garbage collect records that have aged past maxDuration. Backoff users are expected 120// to invoke this periodically. 121func (p *Backoff) GC() { 122 p.Lock() 123 defer p.Unlock() 124 now := p.Clock.Now() 125 for id, entry := range p.perItemBackoff { 126 if now.Sub(entry.lastUpdate) > p.maxDuration*2 { 127 // GC when entry has not been updated for 2*maxDuration 128 delete(p.perItemBackoff, id) 129 } 130 } 131} 132 133func (p *Backoff) DeleteEntry(id string) { 134 p.Lock() 135 defer p.Unlock() 136 delete(p.perItemBackoff, id) 137} 138 139// Take a lock on *Backoff, before calling initEntryUnsafe 140func (p *Backoff) initEntryUnsafe(id string) *backoffEntry { 141 entry := &backoffEntry{backoff: p.defaultDuration} 142 p.perItemBackoff[id] = entry 143 return entry 144} 145 146// After 2*maxDuration we restart the backoff factor to the beginning 147func hasExpired(eventTime time.Time, lastUpdate time.Time, maxDuration time.Duration) bool { 148 return eventTime.Sub(lastUpdate) > maxDuration*2 // consider stable if it's ok for twice the maxDuration 149} 150