mirror of https://github.com/k3s-io/k3s
256 lines
6.9 KiB
Go
256 lines
6.9 KiB
Go
/*
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Copyright 2016 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 workqueue
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import (
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"container/heap"
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"time"
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"k8s.io/apimachinery/pkg/util/clock"
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utilruntime "k8s.io/apimachinery/pkg/util/runtime"
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)
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// DelayingInterface is an Interface that can Add an item at a later time. This makes it easier to
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// requeue items after failures without ending up in a hot-loop.
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type DelayingInterface interface {
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Interface
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// AddAfter adds an item to the workqueue after the indicated duration has passed
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AddAfter(item interface{}, duration time.Duration)
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}
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// NewDelayingQueue constructs a new workqueue with delayed queuing ability
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func NewDelayingQueue() DelayingInterface {
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return newDelayingQueue(clock.RealClock{}, "")
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}
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func NewNamedDelayingQueue(name string) DelayingInterface {
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return newDelayingQueue(clock.RealClock{}, name)
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}
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func newDelayingQueue(clock clock.Clock, name string) DelayingInterface {
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ret := &delayingType{
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Interface: NewNamed(name),
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clock: clock,
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heartbeat: clock.NewTicker(maxWait),
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stopCh: make(chan struct{}),
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waitingForAddCh: make(chan *waitFor, 1000),
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metrics: newRetryMetrics(name),
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}
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go ret.waitingLoop()
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return ret
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}
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// delayingType wraps an Interface and provides delayed re-enquing
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type delayingType struct {
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Interface
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// clock tracks time for delayed firing
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clock clock.Clock
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// stopCh lets us signal a shutdown to the waiting loop
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stopCh chan struct{}
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// heartbeat ensures we wait no more than maxWait before firing
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heartbeat clock.Ticker
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// waitingForAddCh is a buffered channel that feeds waitingForAdd
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waitingForAddCh chan *waitFor
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// metrics counts the number of retries
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metrics retryMetrics
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}
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// waitFor holds the data to add and the time it should be added
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type waitFor struct {
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data t
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readyAt time.Time
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// index in the priority queue (heap)
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index int
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}
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// waitForPriorityQueue implements a priority queue for waitFor items.
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//
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// waitForPriorityQueue implements heap.Interface. The item occurring next in
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// time (i.e., the item with the smallest readyAt) is at the root (index 0).
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// Peek returns this minimum item at index 0. Pop returns the minimum item after
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// it has been removed from the queue and placed at index Len()-1 by
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// container/heap. Push adds an item at index Len(), and container/heap
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// percolates it into the correct location.
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type waitForPriorityQueue []*waitFor
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func (pq waitForPriorityQueue) Len() int {
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return len(pq)
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}
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func (pq waitForPriorityQueue) Less(i, j int) bool {
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return pq[i].readyAt.Before(pq[j].readyAt)
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}
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func (pq waitForPriorityQueue) Swap(i, j int) {
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pq[i], pq[j] = pq[j], pq[i]
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pq[i].index = i
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pq[j].index = j
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}
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// Push adds an item to the queue. Push should not be called directly; instead,
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// use `heap.Push`.
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func (pq *waitForPriorityQueue) Push(x interface{}) {
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n := len(*pq)
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item := x.(*waitFor)
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item.index = n
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*pq = append(*pq, item)
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}
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// Pop removes an item from the queue. Pop should not be called directly;
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// instead, use `heap.Pop`.
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func (pq *waitForPriorityQueue) Pop() interface{} {
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n := len(*pq)
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item := (*pq)[n-1]
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item.index = -1
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*pq = (*pq)[0:(n - 1)]
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return item
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}
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// Peek returns the item at the beginning of the queue, without removing the
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// item or otherwise mutating the queue. It is safe to call directly.
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func (pq waitForPriorityQueue) Peek() interface{} {
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return pq[0]
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}
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// ShutDown gives a way to shut off this queue
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func (q *delayingType) ShutDown() {
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q.Interface.ShutDown()
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close(q.stopCh)
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q.heartbeat.Stop()
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}
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// AddAfter adds the given item to the work queue after the given delay
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func (q *delayingType) AddAfter(item interface{}, duration time.Duration) {
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// don't add if we're already shutting down
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if q.ShuttingDown() {
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return
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}
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q.metrics.retry()
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// immediately add things with no delay
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if duration <= 0 {
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q.Add(item)
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return
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}
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select {
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case <-q.stopCh:
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// unblock if ShutDown() is called
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case q.waitingForAddCh <- &waitFor{data: item, readyAt: q.clock.Now().Add(duration)}:
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}
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}
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// maxWait keeps a max bound on the wait time. It's just insurance against weird things happening.
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// Checking the queue every 10 seconds isn't expensive and we know that we'll never end up with an
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// expired item sitting for more than 10 seconds.
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const maxWait = 10 * time.Second
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// waitingLoop runs until the workqueue is shutdown and keeps a check on the list of items to be added.
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func (q *delayingType) waitingLoop() {
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defer utilruntime.HandleCrash()
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// Make a placeholder channel to use when there are no items in our list
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never := make(<-chan time.Time)
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waitingForQueue := &waitForPriorityQueue{}
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heap.Init(waitingForQueue)
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waitingEntryByData := map[t]*waitFor{}
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for {
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if q.Interface.ShuttingDown() {
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return
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}
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now := q.clock.Now()
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// Add ready entries
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for waitingForQueue.Len() > 0 {
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entry := waitingForQueue.Peek().(*waitFor)
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if entry.readyAt.After(now) {
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break
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}
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entry = heap.Pop(waitingForQueue).(*waitFor)
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q.Add(entry.data)
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delete(waitingEntryByData, entry.data)
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}
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// Set up a wait for the first item's readyAt (if one exists)
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nextReadyAt := never
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if waitingForQueue.Len() > 0 {
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entry := waitingForQueue.Peek().(*waitFor)
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nextReadyAt = q.clock.After(entry.readyAt.Sub(now))
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}
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select {
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case <-q.stopCh:
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return
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case <-q.heartbeat.C():
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// continue the loop, which will add ready items
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case <-nextReadyAt:
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// continue the loop, which will add ready items
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case waitEntry := <-q.waitingForAddCh:
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if waitEntry.readyAt.After(q.clock.Now()) {
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insert(waitingForQueue, waitingEntryByData, waitEntry)
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} else {
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q.Add(waitEntry.data)
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}
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drained := false
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for !drained {
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select {
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case waitEntry := <-q.waitingForAddCh:
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if waitEntry.readyAt.After(q.clock.Now()) {
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insert(waitingForQueue, waitingEntryByData, waitEntry)
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} else {
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q.Add(waitEntry.data)
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}
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default:
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drained = true
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}
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}
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}
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}
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}
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// insert adds the entry to the priority queue, or updates the readyAt if it already exists in the queue
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func insert(q *waitForPriorityQueue, knownEntries map[t]*waitFor, entry *waitFor) {
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// if the entry already exists, update the time only if it would cause the item to be queued sooner
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existing, exists := knownEntries[entry.data]
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if exists {
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if existing.readyAt.After(entry.readyAt) {
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existing.readyAt = entry.readyAt
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heap.Fix(q, existing.index)
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}
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return
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}
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heap.Push(q, entry)
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knownEntries[entry.data] = entry
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}
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