mirror of https://github.com/k3s-io/k3s
145 lines
4.0 KiB
Go
145 lines
4.0 KiB
Go
/*
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Copyright 2017 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 util
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import (
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"fmt"
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"sync"
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"sync/atomic"
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"time"
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ktypes "k8s.io/apimachinery/pkg/types"
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"k8s.io/klog"
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)
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type clock interface {
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Now() time.Time
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}
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type realClock struct{}
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func (realClock) Now() time.Time {
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return time.Now()
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}
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// BackoffEntry is single threaded. in particular, it only allows a single action to be waiting on backoff at a time.
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// It is expected that all users will only use the public TryWait(...) method
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// It is also not safe to copy this object.
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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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reqInFlight int32
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}
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// tryLock attempts to acquire a lock via atomic compare and swap.
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// returns true if the lock was acquired, false otherwise
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func (b *BackoffEntry) tryLock() bool {
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return atomic.CompareAndSwapInt32(&b.reqInFlight, 0, 1)
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}
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// unlock returns the lock. panics if the lock isn't held
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func (b *BackoffEntry) unlock() {
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if !atomic.CompareAndSwapInt32(&b.reqInFlight, 1, 0) {
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panic(fmt.Sprintf("unexpected state on unlocking: %+v", b))
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}
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}
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// TryWait tries to acquire the backoff lock, maxDuration is the maximum allowed period to wait for.
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func (b *BackoffEntry) TryWait(maxDuration time.Duration) bool {
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if !b.tryLock() {
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return false
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}
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defer b.unlock()
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b.wait(maxDuration)
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return true
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}
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func (b *BackoffEntry) getBackoff(maxDuration time.Duration) time.Duration {
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duration := b.backoff
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newDuration := time.Duration(duration) * 2
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if newDuration > maxDuration {
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newDuration = maxDuration
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}
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b.backoff = newDuration
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klog.V(4).Infof("Backing off %s", duration.String())
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return duration
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}
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func (b *BackoffEntry) wait(maxDuration time.Duration) {
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time.Sleep(b.getBackoff(maxDuration))
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}
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// PodBackoff is used to restart a pod with back-off delay.
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type PodBackoff struct {
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perPodBackoff map[ktypes.NamespacedName]*BackoffEntry
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lock sync.Mutex
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clock clock
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defaultDuration time.Duration
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maxDuration time.Duration
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}
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// MaxDuration returns the max time duration of the back-off.
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func (p *PodBackoff) MaxDuration() time.Duration {
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return p.maxDuration
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}
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// CreateDefaultPodBackoff creates a default pod back-off object.
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func CreateDefaultPodBackoff() *PodBackoff {
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return CreatePodBackoff(1*time.Second, 60*time.Second)
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}
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// CreatePodBackoff creates a pod back-off object by default duration and max duration.
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func CreatePodBackoff(defaultDuration, maxDuration time.Duration) *PodBackoff {
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return CreatePodBackoffWithClock(defaultDuration, maxDuration, realClock{})
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}
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// CreatePodBackoffWithClock creates a pod back-off object by default duration, max duration and clock.
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func CreatePodBackoffWithClock(defaultDuration, maxDuration time.Duration, clock clock) *PodBackoff {
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return &PodBackoff{
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perPodBackoff: map[ktypes.NamespacedName]*BackoffEntry{},
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clock: clock,
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defaultDuration: defaultDuration,
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maxDuration: maxDuration,
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}
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}
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// GetEntry returns a back-off entry by Pod ID.
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func (p *PodBackoff) GetEntry(podID ktypes.NamespacedName) *BackoffEntry {
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p.lock.Lock()
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defer p.lock.Unlock()
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entry, ok := p.perPodBackoff[podID]
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if !ok {
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entry = &BackoffEntry{backoff: p.defaultDuration}
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p.perPodBackoff[podID] = entry
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}
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entry.lastUpdate = p.clock.Now()
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return entry
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}
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// Gc execute garbage collection on the pod back-off.
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func (p *PodBackoff) Gc() {
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p.lock.Lock()
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defer p.lock.Unlock()
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now := p.clock.Now()
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for podID, entry := range p.perPodBackoff {
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if now.Sub(entry.lastUpdate) > p.maxDuration {
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delete(p.perPodBackoff, podID)
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}
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}
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}
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