k8s client-go 源码分析 informer 源码分析(2)-初始化与启动分析
前面一篇文章对 k8s informer 做了概要分析,本篇文章将对 informer 的初始化与启动进行分析。
informer 架构
先来回忆一下 informer 的架构。
k8s client-go informer 主要包括以下部件:
(1)Reflector:Reflector 从 kube-apiserver 中 list&watch 资源对象,然后调用 DeltaFIFO 的 Add/Update/Delete/Replace 方法将资源对象及其变化包装成 Delta 并将其丢到 DeltaFIFO 中;
(2)DeltaFIFO:DeltaFIFO 中存储着一个 map 和一个 queue,即 map[object key]Deltas 以及 object key 的 queue,Deltas 为 Delta 的切片类型,Delta 装有对象及对象的变化类型(Added/Updated/Deleted/Sync) ,Reflector 负责 DeltaFIFO 的输入,Controller 负责处理 DeltaFIFO 的输出;
(3)Controller:Controller 从 DeltaFIFO 的 queue 中 pop 一个 object key 出来,并获取其关联的 Deltas 出来进行处理,遍历 Deltas,根据对象的变化更新 Indexer 中的本地内存缓存,并通知 Processor,相关对象有变化事件发生;
(4)Processor:Processor 根据对象的变化事件类型,调用相应的 ResourceEventHandler 来处理对象的变化;
(5)Indexer:Indexer 中有 informer 维护的指定资源对象的相对于 etcd 数据的一份本地内存缓存,可通过该缓存获取资源对象,以减少对 apiserver、对 etcd 的请求压力;
(6)ResourceEventHandler:用户根据自身处理逻辑需要,注册自定义的的 ResourceEventHandler,当对象发生变化时,将触发调用对应类型的 ResourceEventHandler 来做处理。
概述
...
factory := informers.NewSharedInformerFactory(client, 30*time.Second)
podInformer := factory.Core().V1().Pods()
informer := podInformer.Informer()
...
go factory.Start(stopper)
...
if !cache.WaitForCacheSync(stopper, informer.HasSynced) {
runtime.HandleError(fmt.Errorf("Timed out waiting for caches to sync"))
return
}
...
复制代码
上一节有列举了 informer 的使用代码,注意看到示例代码中的下面这段代码,做了 informer 初始化与启动,其中包括:
(1)informers.NewSharedInformerFactory
:初始化 informer factory;
(2)podInformer.Informer
:初始化 pod informer;
(3)factory.Start
:启动 informer factory;
(4)cache.WaitForCacheSync
:等待 list 操作获取到的对象都同步到 informer 本地缓存 Indexer 中;
下面也将根据这四部分进行 informer 的初始化与启动分析。
基于 k8s v1.17.4 版本依赖的 client-go
1.SharedInformerFactory 的初始化
1.1 sharedInformerFactory 结构体
先来看下 sharedInformerFactory 结构体,看下里面有哪些属性。
看到几个比较重要的属性:
(1)client:连接 k8s 的 clientSet;
(2)informers:是个 map,可以装各个对象的 informer;
(3)startedInformers:记录已经启动的 informer;
// staging/src/k8s.io/client-go/informers/factory.go
type sharedInformerFactory struct {
client kubernetes.Interface
namespace string
tweakListOptions internalinterfaces.TweakListOptionsFunc
lock sync.Mutex
defaultResync time.Duration
customResync map[reflect.Type]time.Duration
informers map[reflect.Type]cache.SharedIndexInformer
// startedInformers is used for tracking which informers have been started.
// This allows Start() to be called multiple times safely.
startedInformers map[reflect.Type]bool
}
复制代码
1.2 NewSharedInformerFactory
NewSharedInformerFactory 方法用于初始化 informer factory,主要是初始化并返回 sharedInformerFactory 结构体。
// staging/src/k8s.io/client-go/informers/factory.go
func NewSharedInformerFactory(client kubernetes.Interface, defaultResync time.Duration) SharedInformerFactory {
return NewSharedInformerFactoryWithOptions(client, defaultResync)
}
func NewFilteredSharedInformerFactory(client kubernetes.Interface, defaultResync time.Duration, namespace string, tweakListOptions internalinterfaces.TweakListOptionsFunc) SharedInformerFactory {
return NewSharedInformerFactoryWithOptions(client, defaultResync, WithNamespace(namespace), WithTweakListOptions(tweakListOptions))
}
func NewSharedInformerFactoryWithOptions(client kubernetes.Interface, defaultResync time.Duration, options ...SharedInformerOption) SharedInformerFactory {
factory := &sharedInformerFactory{
client: client,
namespace: v1.NamespaceAll,
defaultResync: defaultResync,
informers: make(map[reflect.Type]cache.SharedIndexInformer),
startedInformers: make(map[reflect.Type]bool),
customResync: make(map[reflect.Type]time.Duration),
}
// Apply all options
for _, opt := range options {
factory = opt(factory)
}
return factory
}
复制代码
2.对象 informer 的初始化
上一节有列举了 informer 的使用代码,注意看到示例代码中的下面这段代码,这里利用了工厂方法设计模式,podInformer.Informer()
即初始化了 sharedInformerFactory 中的 pod 的 informer,具体调用关系可自行看如下代码,比较简单,这里不再展开分析。
// 初始化informer factory以及pod informer
factory := informers.NewSharedInformerFactory(client, 30*time.Second)
podInformer := factory.Core().V1().Pods()
informer := podInformer.Informer()
复制代码
2.1 podInformer.Informer
Informer 方法中调用了f.factory.InformerFor
方法来做 pod informer 的初始化。
// k8s.io/client-go/informers/core/v1/pod.go
func (f *podInformer) Informer() cache.SharedIndexInformer {
return f.factory.InformerFor(&corev1.Pod{}, f.defaultInformer)
}
复制代码
2.2 f.factory.InformerFor
Informer 方法中调用了f.factory.InformerFor
方法来做 pod informer 的初始化,并传入f.defaultInformer
作为newFunc
,而在f.factory.InformerFor
方法中,调用newFunc
来初始化 informer。
这里也可以看到,其实 informer 初始化后会存储进 map f.informers[informerType]
中,即存储进 sharedInformerFactory 结构体的 informers 属性中,方便共享使用。
// staging/src/k8s.io/client-go/informers/factory.go
func (f *sharedInformerFactory) InformerFor(obj runtime.Object, newFunc internalinterfaces.NewInformerFunc) cache.SharedIndexInformer {
f.lock.Lock()
defer f.lock.Unlock()
informerType := reflect.TypeOf(obj)
informer, exists := f.informers[informerType]
if exists {
return informer
}
resyncPeriod, exists := f.customResync[informerType]
if !exists {
resyncPeriod = f.defaultResync
}
informer = newFunc(f.client, resyncPeriod)
f.informers[informerType] = informer
return informer
}
复制代码
2.3 newFunc/f.defaultInformer
defaultInformer 方法中,调用了NewFilteredPodInformer
方法来初始化 pod informer,最终初始化并返回 sharedIndexInformer 结构体。
// k8s.io/client-go/informers/core/v1/pod.go
func (f *podInformer) defaultInformer(client kubernetes.Interface, resyncPeriod time.Duration) cache.SharedIndexInformer {
return NewFilteredPodInformer(client, f.namespace, resyncPeriod, cache.Indexers{cache.NamespaceIndex: cache.MetaNamespaceIndexFunc}, f.tweakListOptions)
}
func NewFilteredPodInformer(client kubernetes.Interface, namespace string, resyncPeriod time.Duration, indexers cache.Indexers, tweakListOptions internalinterfaces.TweakListOptionsFunc) cache.SharedIndexInformer {
return cache.NewSharedIndexInformer(
&cache.ListWatch{
ListFunc: func(options metav1.ListOptions) (runtime.Object, error) {
if tweakListOptions != nil {
tweakListOptions(&options)
}
return client.CoreV1().Pods(namespace).List(options)
},
WatchFunc: func(options metav1.ListOptions) (watch.Interface, error) {
if tweakListOptions != nil {
tweakListOptions(&options)
}
return client.CoreV1().Pods(namespace).Watch(options)
},
},
&corev1.Pod{},
resyncPeriod,
indexers,
)
}
func NewSharedIndexInformer(lw ListerWatcher, objType runtime.Object, defaultEventHandlerResyncPeriod time.Duration, indexers Indexers) SharedIndexInformer {
realClock := &clock.RealClock{}
sharedIndexInformer := &sharedIndexInformer{
processor: &sharedProcessor{clock: realClock},
indexer: NewIndexer(DeletionHandlingMetaNamespaceKeyFunc, indexers),
listerWatcher: lw,
objectType: objType,
resyncCheckPeriod: defaultEventHandlerResyncPeriod,
defaultEventHandlerResyncPeriod: defaultEventHandlerResyncPeriod,
cacheMutationDetector: NewCacheMutationDetector(fmt.Sprintf("%T", objType)),
clock: realClock,
}
return sharedIndexInformer
}
复制代码
2.4 sharedIndexInformer 结构体
sharedIndexInformer 结构体中重点看到以下几个属性:
(1)indexer:对应着 informer 中的部件 Indexer,Indexer 中有 informer 维护的指定资源对象的相对于 etcd 数据的一份本地内存缓存,可通过该缓存获取资源对象,以减少对 apiserver、对 etcd 的请求压力;
(2)controller:对应着 informer 中的部件 Controller,Controller 从 DeltaFIFO 中 pop Deltas 出来处理,根据对象的变化更新 Indexer 中的本地内存缓存,并通知 Processor,相关对象有变化事件发生;
(3)processor:对应着 informer 中的部件 Processor,Processor 根据对象的变化事件类型,调用相应的 ResourceEventHandler 来处理对象的变化;
// staging/src/k8s.io/client-go/tools/cache/shared_informer.go
type sharedIndexInformer struct {
indexer Indexer
controller Controller
processor *sharedProcessor
cacheMutationDetector CacheMutationDetector
// This block is tracked to handle late initialization of the controller
listerWatcher ListerWatcher
objectType runtime.Object
// resyncCheckPeriod is how often we want the reflector's resync timer to fire so it can call
// shouldResync to check if any of our listeners need a resync.
resyncCheckPeriod time.Duration
// defaultEventHandlerResyncPeriod is the default resync period for any handlers added via
// AddEventHandler (i.e. they don't specify one and just want to use the shared informer's default
// value).
defaultEventHandlerResyncPeriod time.Duration
// clock allows for testability
clock clock.Clock
started, stopped bool
startedLock sync.Mutex
// blockDeltas gives a way to stop all event distribution so that a late event handler
// can safely join the shared informer.
blockDeltas sync.Mutex
}
复制代码
Indexer 接口与 cache 结构体
cache 结构体为 Indexer 接口的实现;
// staging/src/k8s.io/client-go/tools/cache/store.go
type cache struct {
cacheStorage ThreadSafeStore
keyFunc KeyFunc
}
复制代码
threadSafeMap struct 是 ThreadSafeStore 接口的一个实现,其最重要的一个属性便是 items 了,items 是用 map 构建的键值对,资源对象都存在 items 这个 map 中,key 根据资源对象来算出,value 为资源对象本身,这里的 items 即为 informer 的本地缓存了,而 indexers 与 indices 属性则与索引功能有关。
// staging/src/k8s.io/client-go/tools/cache/thread_safe_store.go
type threadSafeMap struct {
lock sync.RWMutex
items map[string]interface{}
// indexers maps a name to an IndexFunc
indexers Indexers
// indices maps a name to an Index
indices Indices
}
复制代码
关于 Indexer 的详细分析会在后续有专门的文章做分析,这里不展开分析;
controller 结构体
而 controller 结构体则包含了 informer 中的主要部件 Reflector 以及 DeltaFIFO;
(1)Reflector:Reflector 从 kube-apiserver 中 list&watch 资源对象,然后将对象的变化包装成 Delta 并将其丢到 DeltaFIFO 中;
(2)DeltaFIFO:DeltaFIFO 存储着 map[object key]Deltas 以及 object key 的 queue,Delta 装有对象及对象的变化类型 ,Reflector 负责 DeltaFIFO 的输入,Controller 负责处理 DeltaFIFO 的输出;
// staging/src/k8s.io/client-go/tools/cache/controller.go
type controller struct {
config Config
reflector *Reflector
reflectorMutex sync.RWMutex
clock clock.Clock
}
type Config struct {
// The queue for your objects; either a FIFO or
// a DeltaFIFO. Your Process() function should accept
// the output of this Queue's Pop() method.
Queue
...
}
复制代码
3.启动 sharedInformerFactory
sharedInformerFactory.Start 为 informer factory 的启动方法,其主要逻辑为循环遍历 informers,然后跑 goroutine 调用informer.Run
来启动sharedInformerFactory
中存储的各个 informer。
// staging/src/k8s.io/client-go/informers/factory.go
func (f *sharedInformerFactory) Start(stopCh <-chan struct{}) {
f.lock.Lock()
defer f.lock.Unlock()
for informerType, informer := range f.informers {
if !f.startedInformers[informerType] {
go informer.Run(stopCh)
f.startedInformers[informerType] = true
}
}
}
复制代码
sharedIndexInformer.Run
sharedIndexInformer.Run 用于启动 informer,主要逻辑为:
(1)调用 NewDeltaFIFO,初始化 DeltaFIFO;
(2)构建 Config 结构体,这里留意下 Process 属性,赋值了 s.HandleDeltas,后面会分析到该方法;
(3)调用 New,利用 Config 结构体来初始化 controller;
(4)调用 s.processor.run,启动 processor;
(5)调用 s.controller.Run,启动 controller;
// staging/src/k8s.io/client-go/tools/cache/shared_informer.go
func (s *sharedIndexInformer) Run(stopCh <-chan struct{}) {
defer utilruntime.HandleCrash()
// 初始化DeltaFIFO
fifo := NewDeltaFIFO(MetaNamespaceKeyFunc, s.indexer)
// 构建Config结构体
cfg := &Config{
Queue: fifo,
ListerWatcher: s.listerWatcher,
ObjectType: s.objectType,
FullResyncPeriod: s.resyncCheckPeriod,
RetryOnError: false,
ShouldResync: s.processor.shouldResync,
Process: s.HandleDeltas,
}
func() {
s.startedLock.Lock()
defer s.startedLock.Unlock()
// 初始化controller
s.controller = New(cfg)
s.controller.(*controller).clock = s.clock
s.started = true
}()
// Separate stop channel because Processor should be stopped strictly after controller
processorStopCh := make(chan struct{})
var wg wait.Group
defer wg.Wait() // Wait for Processor to stop
defer close(processorStopCh) // Tell Processor to stop
wg.StartWithChannel(processorStopCh, s.cacheMutationDetector.Run)
// 启动processor
wg.StartWithChannel(processorStopCh, s.processor.run)
defer func() {
s.startedLock.Lock()
defer s.startedLock.Unlock()
s.stopped = true // Don't want any new listeners
}()
// 启动controller
s.controller.Run(stopCh)
}
复制代码
3.1 New
New 函数初始化了 controller 并 return。
// staging/src/k8s.io/client-go/tools/cache/controller.go
func New(c *Config) Controller {
ctlr := &controller{
config: *c,
clock: &clock.RealClock{},
}
return ctlr
}
复制代码
3.2 s.processor.run
s.processor.run 启动了 processor,其中注意到 listener.run 与 listener.pop 两个核心方法即可,暂时没有用到,等下面用到他们的时候再做分析。
// staging/src/k8s.io/client-go/tools/cache/shared_informer.go
func (p *sharedProcessor) run(stopCh <-chan struct{}) {
func() {
p.listenersLock.RLock()
defer p.listenersLock.RUnlock()
for _, listener := range p.listeners {
p.wg.Start(listener.run)
p.wg.Start(listener.pop)
}
p.listenersStarted = true
}()
<-stopCh
p.listenersLock.RLock()
defer p.listenersLock.RUnlock()
for _, listener := range p.listeners {
close(listener.addCh) // Tell .pop() to stop. .pop() will tell .run() to stop
}
p.wg.Wait() // Wait for all .pop() and .run() to stop
}
复制代码
3.3 controller.Run
controller.Run 为 controller 的启动方法,这里主要看到几个点:
(1)调用 NewReflector,初始化 Reflector;
(2)调用 r.Run,实际上是调用了 Reflector 的启动方法来启动 Reflector;
(3)调用 c.processLoop,开始 controller 的核心处理;
// k8s.io/client-go/tools/cache/controller.go
func (c *controller) Run(stopCh <-chan struct{}) {
defer utilruntime.HandleCrash()
go func() {
<-stopCh
c.config.Queue.Close()
}()
r := NewReflector(
c.config.ListerWatcher,
c.config.ObjectType,
c.config.Queue,
c.config.FullResyncPeriod,
)
r.ShouldResync = c.config.ShouldResync
r.clock = c.clock
c.reflectorMutex.Lock()
c.reflector = r
c.reflectorMutex.Unlock()
var wg wait.Group
defer wg.Wait()
wg.StartWithChannel(stopCh, r.Run)
wait.Until(c.processLoop, time.Second, stopCh)
}
复制代码
3.3.1 Reflector 结构体
先来看到 Reflector 结构体,这里重点看到以下属性:
(1)expectedType:放到 Store 中(即 DeltaFIFO 中)的对象类型;
(2)store:store 会赋值为 DeltaFIFO,具体可以看之前的 informer 初始化与启动分析即可得知,这里不再展开分析;
(3)listerWatcher:存放 list 方法和 watch 方法的 ListerWatcher interface 实现;
// k8s.io/client-go/tools/cache/reflector.go
type Reflector struct {
...
expectedType reflect.Type
store Store
listerWatcher ListerWatcher
...
}
复制代码
3.3.2 r.Run/Reflector.Run
Reflector.Run 方法中启动了 Reflector,而 Reflector 的核心处理逻辑为从 kube-apiserver 处做 list&watch 操作,然后将得到的对象封装存储进 DeltaFIFO 中。
// staging/src/k8s.io/client-go/tools/cache/reflector.go
func (r *Reflector) Run(stopCh <-chan struct{}) {
klog.V(3).Infof("Starting reflector %v (%s) from %s", r.expectedTypeName, r.resyncPeriod, r.name)
wait.Until(func() {
if err := r.ListAndWatch(stopCh); err != nil {
utilruntime.HandleError(err)
}
}, r.period, stopCh)
}
复制代码
3.3.3 controller.processLoop
controller 的核心处理方法 processLoop 中,最重要的逻辑是循环调用 c.config.Queue.Pop 将 DeltaFIFO 中的队头元素给 pop 出来,然后调用 c.config.Process 方法来做处理,当处理出错时,再调用 c.config.Queue.AddIfNotPresent 将对象重新加入到 DeltaFIFO 中去。
// k8s.io/client-go/tools/cache/controller.go
func (c *controller) processLoop() {
for {
obj, err := c.config.Queue.Pop(PopProcessFunc(c.config.Process))
if err != nil {
if err == ErrFIFOClosed {
return
}
if c.config.RetryOnError {
// This is the safe way to re-enqueue.
c.config.Queue.AddIfNotPresent(obj)
}
}
}
}
复制代码
3.3.4 c.config.Process/sharedIndexInformer.HandleDeltas
根据前面sharedIndexInformer.Run
方法的分析中可以得知,c.config.Process 其实就是 sharedIndexInformer.HandleDeltas。
HandleDeltas 方法中,将从 DeltaFIFO 中 pop 出来的对象以及类型,相应的在 indexer 中做添加、更新、删除操作,并调用 s.processor.distribute 通知自定义的 ResourceEventHandler。
// staging/src/k8s.io/client-go/tools/cache/shared_informer.go
func (s *sharedIndexInformer) HandleDeltas(obj interface{}) error {
s.blockDeltas.Lock()
defer s.blockDeltas.Unlock()
// from oldest to newest
for _, d := range obj.(Deltas) {
switch d.Type {
case Sync, Added, Updated:
isSync := d.Type == Sync
s.cacheMutationDetector.AddObject(d.Object)
if old, exists, err := s.indexer.Get(d.Object); err == nil && exists {
if err := s.indexer.Update(d.Object); err != nil {
return err
}
s.processor.distribute(updateNotification{oldObj: old, newObj: d.Object}, isSync)
} else {
if err := s.indexer.Add(d.Object); err != nil {
return err
}
s.processor.distribute(addNotification{newObj: d.Object}, isSync)
}
case Deleted:
if err := s.indexer.Delete(d.Object); err != nil {
return err
}
s.processor.distribute(deleteNotification{oldObj: d.Object}, false)
}
}
return nil
}
复制代码
怎么通知到自定义的 ResourceEventHandler 呢?继续往下看。
3.3.5 sharedIndexInformer.processor.distribute
可以看到 distribute 方法最终是将构造好的 addNotification、updateNotification、deleteNotification 对象写入到 p.addCh 中。
// staging/src/k8s.io/client-go/tools/cache/shared_informer.go
func (p *sharedProcessor) distribute(obj interface{}, sync bool) {
p.listenersLock.RLock()
defer p.listenersLock.RUnlock()
if sync {
for _, listener := range p.syncingListeners {
listener.add(obj)
}
} else {
for _, listener := range p.listeners {
listener.add(obj)
}
}
}
func (p *processorListener) add(notification interface{}) {
p.addCh <- notification
}
复制代码
到这里,processor 中的 listener.pop 以及 listener.run 方法终于派上了用场,继续往下看。
3.3.6 listener.pop
分析 processorListener 的 pop 方法可以得知,其逻辑实际上就是将 p.addCh 中的对象给拿出来,然后丢进了 p.nextCh 中。那么谁来处理 p.nextCh 呢?继续往下看。
// staging/src/k8s.io/client-go/tools/cache/shared_informer.go
func (p *processorListener) pop() {
defer utilruntime.HandleCrash()
defer close(p.nextCh) // Tell .run() to stop
var nextCh chan<- interface{}
var notification interface{}
for {
select {
case nextCh <- notification:
// Notification dispatched
var ok bool
notification, ok = p.pendingNotifications.ReadOne()
if !ok { // Nothing to pop
nextCh = nil // Disable this select case
}
case notificationToAdd, ok := <-p.addCh:
if !ok {
return
}
if notification == nil { // No notification to pop (and pendingNotifications is empty)
// Optimize the case - skip adding to pendingNotifications
notification = notificationToAdd
nextCh = p.nextCh
} else { // There is already a notification waiting to be dispatched
p.pendingNotifications.WriteOne(notificationToAdd)
}
}
}
}
复制代码
3.3.7 listener.run
在 processorListener 的 run 方法中,将循环读取 p.nextCh,判断对象类型,是 updateNotification 则调用 p.handler.OnUpdate 方法,是 addNotification 则调用 p.handler.OnAdd 方法,是 deleteNotification 则调用 p.handler.OnDelete 方法做处理。
// staging/src/k8s.io/client-go/tools/cache/shared_informer.go
func (p *processorListener) run() {
// this call blocks until the channel is closed. When a panic happens during the notification
// we will catch it, **the offending item will be skipped!**, and after a short delay (one second)
// the next notification will be attempted. This is usually better than the alternative of never
// delivering again.
stopCh := make(chan struct{})
wait.Until(func() {
// this gives us a few quick retries before a long pause and then a few more quick retries
err := wait.ExponentialBackoff(retry.DefaultRetry, func() (bool, error) {
for next := range p.nextCh {
switch notification := next.(type) {
case updateNotification:
p.handler.OnUpdate(notification.oldObj, notification.newObj)
case addNotification:
p.handler.OnAdd(notification.newObj)
case deleteNotification:
p.handler.OnDelete(notification.oldObj)
default:
utilruntime.HandleError(fmt.Errorf("unrecognized notification: %T", next))
}
}
// the only way to get here is if the p.nextCh is empty and closed
return true, nil
})
// the only way to get here is if the p.nextCh is empty and closed
if err == nil {
close(stopCh)
}
}, 1*time.Minute, stopCh)
}
复制代码
而 p.handler.OnUpdate、p.handler.OnAdd、p.handler.OnDelete 方法实际上就是自定义的的 ResourceEventHandlerFuncs 了。
informer.AddEventHandler(cache.ResourceEventHandlerFuncs{
AddFunc: onAdd,
UpdateFunc: onUpdate,
DeleteFunc: onDelete,
})
复制代码
// staging/src/k8s.io/client-go/tools/cache/controller.go
type ResourceEventHandlerFuncs struct {
AddFunc func(obj interface{})
UpdateFunc func(oldObj, newObj interface{})
DeleteFunc func(obj interface{})
}
func (r ResourceEventHandlerFuncs) OnAdd(obj interface{}) {
if r.AddFunc != nil {
r.AddFunc(obj)
}
}
func (r ResourceEventHandlerFuncs) OnUpdate(oldObj, newObj interface{}) {
if r.UpdateFunc != nil {
r.UpdateFunc(oldObj, newObj)
}
}
func (r ResourceEventHandlerFuncs) OnDelete(obj interface{}) {
if r.DeleteFunc != nil {
r.DeleteFunc(obj)
}
}
复制代码
4.cache.WaitForCacheSync(stopper, informer.HasSynced)
可以看出在 cache.WaitForCacheSync 方法中,实际上是调用方法入参cacheSyncs ...InformerSynced
来判断 cache 是否同步完成(即调用informer.HasSynced
方法),而这里说的 cache 同步完成,意思是等待 informer 从 kube-apiserver 同步资源完成,即 informer 的 list 操作获取的对象都存入到 informer 中的 indexer 本地缓存中;
// staging/src/k8s.io/client-go/tools/cache/shared_informer.go
func WaitForCacheSync(stopCh <-chan struct{}, cacheSyncs ...InformerSynced) bool {
err := wait.PollImmediateUntil(syncedPollPeriod,
func() (bool, error) {
for _, syncFunc := range cacheSyncs {
if !syncFunc() {
return false, nil
}
}
return true, nil
},
stopCh)
if err != nil {
klog.V(2).Infof("stop requested")
return false
}
klog.V(4).Infof("caches populated")
return true
}
复制代码
4.1 informer.HasSynced
HasSynced 方法实际上是调用了 sharedIndexInformer.controller.HasSynced 方法;
// staging/src/k8s.io/client-go/tools/cache/shared_informer.go
func (s *sharedIndexInformer) HasSynced() bool {
s.startedLock.Lock()
defer s.startedLock.Unlock()
if s.controller == nil {
return false
}
return s.controller.HasSynced()
}
复制代码
s.controller.HasSynced
这里的 c.config.Queue.HasSynced()方法,实际上是指 DeltaFIFO 的 HasSynced 方法,会在 DeltaFIFO 的分析中再详细分析,这里只需要知道当 informer 的 list 操作获取的对象都存入到 informer 中的 indexer 本地缓存中则返回 true 即可;
// staging/src/k8s.io/client-go/tools/cache/controller.go
func (c *controller) HasSynced() bool {
return c.config.Queue.HasSynced()
}
复制代码
4.2 sharedInformerFactory.WaitForCacheSync
可以顺带看下 sharedInformerFactory.WaitForCacheSync 方法,其实际上是遍历 factory 中的所有 informer,调用 cache.WaitForCacheSync,然后传入每个 informer 的 HasSynced 方法作为入参;
// staging/src/k8s.io/client-go/informers/factory.go
func (f *sharedInformerFactory) WaitForCacheSync(stopCh <-chan struct{}) map[reflect.Type]bool {
informers := func() map[reflect.Type]cache.SharedIndexInformer {
f.lock.Lock()
defer f.lock.Unlock()
informers := map[reflect.Type]cache.SharedIndexInformer{}
for informerType, informer := range f.informers {
if f.startedInformers[informerType] {
informers[informerType] = informer
}
}
return informers
}()
res := map[reflect.Type]bool{}
for informType, informer := range informers {
res[informType] = cache.WaitForCacheSync(stopCh, informer.HasSynced)
}
return res
}
复制代码
至此,整个 informer 的初始化与启动的分析就结束了,后面会对 informer 中的各个核心部件进行详细分析,敬请期待。
总结
下面用两张图片总结一下 informer 的初始化与启动;
informer 初始化
informer 启动
评论