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Cache

store

// Store 是一个对象存储和处理接口，一个storage握着一个从key到累计器的map，具有基于个一个key对于对象的增加，修改和删除接口。
// Reflector 知道如何监控服务器，并更新对象。这个package提供了各种各样的storage实现。
type Store interface {

	// Add adds the given object to the accumulator associated with the given object's key
	Add(obj interface{}) error

	// Update updates the given object in the accumulator associated with the given object's key
	Update(obj interface{}) error

	// Delete deletes the given object from the accumulator associated with the given object's key
	Delete(obj interface{}) error

	// List returns a list of all the currently non-empty accumulators
	List() []interface{}

	// ListKeys returns a list of all the keys currently associated with non-empty accumulators
	ListKeys() []string

	// Get returns the accumulator associated with the given object's key
	Get(obj interface{}) (item interface{}, exists bool, err error)

	// GetByKey returns the accumulator associated with the given key
	GetByKey(key string) (item interface{}, exists bool, err error)

	// Replace will delete the contents of the store, using instead the
	// given list. Store takes ownership of the list, you should not reference
	// it after calling this function.
	Replace([]interface{}, string) error

	// Resync is meaningless in the terms appearing here but has
	// meaning in some implementations that have non-trivial
	// additional behavior (e.g., DeltaFIFO).
	Resync() error
}

基于Store 新建了Index接口

type Indexer interface {
	Store
	// Index returns the stored objects whose set of indexed values
	// intersects the set of indexed values of the given object, for
	// the named index
	Index(indexName string, obj interface{}) ([]interface{}, error)
	// IndexKeys returns the storage keys of the stored objects whose
	// set of indexed values for the named index includes the given
	// indexed value
	IndexKeys(indexName, indexedValue string) ([]string, error)
	// ListIndexFuncValues returns all the indexed values of the given index
	ListIndexFuncValues(indexName string) []string
	// ByIndex returns the stored objects whose set of indexed values
	// for the named index includes the given indexed value
	ByIndex(indexName, indexedValue string) ([]interface{}, error)
	// GetIndexer return the indexers
	GetIndexers() Indexers

	// AddIndexers adds more indexers to this store.  If you call this after you already have data
	// in the store, the results are undefined.
	AddIndexers(newIndexers Indexers) error
}

// IndexFunc knows how to compute the set of indexed values for an object.
type IndexFunc func(obj interface{}) ([]string, error)

由于Store只有基于对象的存储，因此需要一个将对象映射为string的function，并基于此存储。为了实现store和Index ，因此有了ThreadSafeStore。

// ThreadSafeStore is an interface that allows concurrent indexed
// access to a storage backend.  It is like Indexer but does not
// (necessarily) know how to extract the Store key from a given
// object.
//
// TL;DR caveats: you must not modify anything returned by Get or List as it will break
// the indexing feature in addition to not being thread safe.
//
// The guarantees of thread safety provided by List/Get are only valid if the caller
// treats returned items as read-only. For example, a pointer inserted in the store
// through `Add` will be returned as is by `Get`. Multiple clients might invoke `Get`
// on the same key and modify the pointer in a non-thread-safe way. Also note that
// modifying objects stored by the indexers (if any) will *not* automatically lead
// to a re-index. So it's not a good idea to directly modify the objects returned by
// Get/List, in general.

// ThreadSafeStore是一个支持并行索引`access`后端存储的接口。它很像一个`index`，但是它需要知道将对象转化为key的`keyFunc`
// 使用ThreadSafeStore 应该注意，并不应该修改任何从`Get` ， `List` 返回的任何对象，因为可能会影响到index特性，进而影响线程安全特性。
type ThreadSafeStore interface {
	Add(key string, obj interface{})
	Update(key string, obj interface{})
	Delete(key string)
	Get(key string) (item interface{}, exists bool)
	List() []interface{}
	ListKeys() []string
	Replace(map[string]interface{}, string)
	Index(indexName string, obj interface{}) ([]interface{}, error)
	IndexKeys(indexName, indexKey string) ([]string, error)
	ListIndexFuncValues(name string) []string
	ByIndex(indexName, indexKey string) ([]interface{}, error)
	GetIndexers() Indexers

	// AddIndexers adds more indexers to this store.  If you call this after you already have data
	// in the store, the results are undefined.
	AddIndexers(newIndexers Indexers) error
	// Resync is a no-op and is deprecated
	Resync() error
}

此时可以基于ThreadSafeStore实现Store和Index接口。

// threadSafeMap implements ThreadSafeStore
type threadSafeMap struct {
	lock  sync.RWMutex // 锁
	items map[string]interface{} //对象存储，每个对象的key应该是唯一的，比如uid

	// indexers maps a name to an IndexFunc
	indexers Indexers // 比如namespaceFunc，indexers={"namespace":MetaNamespaceKeyFunc}
	// indices maps a name to an Index
	indices Indices // 比如 Map["namespace"][{realObjectNamespace}]["pod:jsonpath-test"]
}

// associated KeyFunc.
type cache struct {
	// cacheStorage bears the burden of thread safety for the cache
	cacheStorage ThreadSafeStore
	// keyFunc is used to make the key for objects stored in and retrieved from items, and
	// should be deterministic.
	keyFunc KeyFunc
}

// Add inserts an item into the cache.
func (c *cache) Add(obj interface{}) error {
	key, err := c.keyFunc(obj)
	if err != nil {
		return KeyError{obj, err}
	}
	c.cacheStorage.Add(key, obj)
	return nil
}

Queue

基于Store建立了Queue接口。

// Queue扩展Store可以处理存储的Key
// 每个增加，更新，删除都可能增加对象到connection
type Queue interface {
	Store

	// Pop blocks until there is at least one key to process or the
	// Queue is closed.  In the latter case Pop returns with an error.
	// In the former case Pop atomically picks one key to process,
	// removes that (key, accumulator) association from the Store, and
	// processes the accumulator.  Pop returns the accumulator that
	// was processed and the result of processing.  The PopProcessFunc
	// may return an ErrRequeue{inner} and in this case Pop will (a)
	// return that (key, accumulator) association to the Queue as part
	// of the atomic processing and (b) return the inner error from
	// Pop.
	Pop(PopProcessFunc) (interface{}, error)

	// AddIfNotPresent puts the given accumulator into the Queue (in
	// association with the accumulator's key) if and only if that key
	// is not already associated with a non-empty accumulator.
	AddIfNotPresent(interface{}) error

	// HasSynced returns true if the first batch of keys have all been
	// popped.  The first batch of keys are those of the first Replace
	// operation if that happened before any Add, AddIfNotPresent,
	// Update, or Delete; otherwise the first batch is empty.
	HasSynced() bool

	// Close the queue
	Close()
}

// 先入先出的队列，多次对于一个对象的更新可能会被合并为一次操作。
// 解决以下问题：
// - 一个对象处理一次
// - 先入先出处理对象
// - 不想处理删除的对象，删除的对象应该从Queue中删除
// - 不想定时处理重新处理其他对象
// - 其他应用场景可以考虑DeltaFIFO
type FIFO struct {
	lock sync.RWMutex
	cond sync.Cond //基于CondValue降低资源使用
	// We depend on the property that every key in `items` is also in `queue`
	items map[string]interface{}
	//对象名称与顺序
	queue []string

	// populated is true if the first batch of items inserted by Replace() has been populated
	// or Delete/Add/Update was called first.
	// 一开始增加的对象是否被处理完成
	populated bool
	// initialPopulationCount is the number of items inserted by the first call of Replace()
	// 一开始增加对象的个数
	initialPopulationCount int

	// keyFunc is used to make the key used for queued item insertion and retrieval, and
	// should be deterministic.
	// 对象到string的函数
	keyFunc KeyFunc

	// Indication the queue is closed.
	// Used to indicate a queue is closed so a control loop can exit when a queue is empty.
	// Currently, not used to gate any of CRED operations.
	// 是否被关闭
	closed bool
}

// Close the queue.
func (f *FIFO) Close() {
	f.lock.Lock()
	defer f.lock.Unlock()
	f.closed = true
	f.cond.Broadcast() // 通知所有对象，现在可以进一步查看条件了
}

// HasSynced returns true if an Add/Update/Delete/AddIfNotPresent are called first,
// or the first batch of items inserted by Replace() has been popped.
func (f *FIFO) HasSynced() bool {
	f.lock.Lock()
	defer f.lock.Unlock()
	return f.populated && f.initialPopulationCount == 0 //已经被添加过，并且资源已经被消耗完成
}

// Replace will delete the contents of 'f', using instead the given map.
// 'f' takes ownership of the map, you should not reference the map again
// after calling this function. f's queue is reset, too; upon return, it
// will contain the items in the map, in no particular order.
func (f *FIFO) Replace(list []interface{}, resourceVersion string) error {
	items := make(map[string]interface{}, len(list))
	for _, item := range list {
		key, err := f.keyFunc(item)
		if err != nil {
			return KeyError{item, err}
		}
		items[key] = item
	}

	f.lock.Lock()
	defer f.lock.Unlock()

	if !f.populated { //第一次添加，设置flag
		f.populated = true
		f.initialPopulationCount = len(items)
	}

	f.items = items
	f.queue = f.queue[:0]
	for id := range items {
		f.queue = append(f.queue, id)
	}
	if len(f.queue) > 0 {
		f.cond.Broadcast() //通知所有消费者，可以消费了
	}
	return nil
}

// Add inserts an item, and puts it in the queue. The item is only enqueued
// if it doesn't already exist in the set.
func (f *FIFO) Add(obj interface{}) error {
	id, err := f.keyFunc(obj)
	if err != nil {
		return KeyError{obj, err}
	}
	f.lock.Lock()
	defer f.lock.Unlock()
	f.populated = true
	if _, exists := f.items[id]; !exists {
		f.queue = append(f.queue, id)
	}
	f.items[id] = obj
	f.cond.Broadcast() //通知
	return nil
}

// AddIfNotPresent inserts an item, and puts it in the queue. If the item is already
// present in the set, it is neither enqueued nor added to the set.
//
// This is useful in a single producer/consumer scenario so that the consumer can
// safely retry items without contending with the producer and potentially enqueueing
// stale items.
func (f *FIFO) AddIfNotPresent(obj interface{}) error {
	id, err := f.keyFunc(obj)
	if err != nil {
		return KeyError{obj, err}
	}
	f.lock.Lock()
	defer f.lock.Unlock()
	f.addIfNotPresent(id, obj)
	return nil
}

// addIfNotPresent assumes the fifo lock is already held and adds the provided
// item to the queue under id if it does not already exist.
func (f *FIFO) addIfNotPresent(id string, obj interface{}) {
	f.populated = true
	if _, exists := f.items[id]; exists {
		return
	}

	f.queue = append(f.queue, id)
	f.items[id] = obj
	f.cond.Broadcast() //通知
}

// Update is the same as Add in this implementation.
func (f *FIFO) Update(obj interface{}) error {
	return f.Add(obj)
}

// Delete removes an item. It doesn't add it to the queue, because
// this implementation assumes the consumer only cares about the objects,
// not the order in which they were created/added.
func (f *FIFO) Delete(obj interface{}) error {
	id, err := f.keyFunc(obj)
	if err != nil {
		return KeyError{obj, err}
	}
	f.lock.Lock()
	defer f.lock.Unlock()
	f.populated = true
	delete(f.items, id)
	return err
}

// List returns a list of all the items.
func (f *FIFO) List() []interface{} {
	f.lock.RLock()
	defer f.lock.RUnlock()
	list := make([]interface{}, 0, len(f.items))
	for _, item := range f.items {
		list = append(list, item)
	}
	return list
}

// ListKeys returns a list of all the keys of the objects currently
// in the FIFO.
func (f *FIFO) ListKeys() []string {
	f.lock.RLock()
	defer f.lock.RUnlock()
	list := make([]string, 0, len(f.items))
	for key := range f.items {
		list = append(list, key)
	}
	return list
}

// Get returns the requested item, or sets exists=false.
func (f *FIFO) Get(obj interface{}) (item interface{}, exists bool, err error) {
	key, err := f.keyFunc(obj)
	if err != nil {
		return nil, false, KeyError{obj, err}
	}
	return f.GetByKey(key)
}

// GetByKey returns the requested item, or sets exists=false.
func (f *FIFO) GetByKey(key string) (item interface{}, exists bool, err error) {
	f.lock.RLock()
	defer f.lock.RUnlock()
	item, exists = f.items[key]
	return item, exists, nil
}

// IsClosed checks if the queue is closed
func (f *FIFO) IsClosed() bool {
	f.lock.Lock()
	defer f.lock.Unlock()
	if f.closed {
		return true
	}
	return false
}

// Pop waits until an item is ready and processes it. If multiple items are
// ready, they are returned in the order in which they were added/updated.
// The item is removed from the queue (and the store) before it is processed,
// so if you don't successfully process it, it should be added back with
// AddIfNotPresent(). process function is called under lock, so it is safe
// update data structures in it that need to be in sync with the queue.
//POP 是Queue独有的函数，可以从底层的存储中获取数据，当没有数据时会发生阻塞
func (f *FIFO) Pop(process PopProcessFunc) (interface{}, error) {
	f.lock.Lock()
	defer f.lock.Unlock()
	for {
		for len(f.queue) == 0 { //直到获取到数据
			// When the queue is empty, invocation of Pop() is blocked until new item is enqueued.
			// When Close() is called, the f.closed is set and the condition is broadcasted.
			// Which causes this loop to continue and return from the Pop().
			if f.closed {
				return nil, ErrFIFOClosed
			}

			f.cond.Wait() //如果以上条件都检查过了，发现没有符合条件则继续阻塞go-routine
		}
		id := f.queue[0]
		f.queue = f.queue[1:]
		if f.initialPopulationCount > 0 {
			f.initialPopulationCount--
		}
		item, ok := f.items[id]
		if !ok { //对象被删除了
			// Item may have been deleted subsequently.
			continue
		}
		delete(f.items, id)
		err := process(item)
		if e, ok := err.(ErrRequeue); ok {
			f.addIfNotPresent(id, item)
			err = e.Err
		}
		return item, err
	}
}

ListWatcher

// Interface can be implemented by anything that knows how to watch and report changes.
type watch.Interface interface {
	// Stops watching. Will close the channel returned by ResultChan(). Releases
	// any resources used by the watch.
	Stop()

	// Returns a chan which will receive all the events. If an error occurs
	// or Stop() is called, the implementation will close this channel and
	// release any resources used by the watch.
	ResultChan() <-chan Event
}

// Lister is any object that knows how to perform an initial list.
type Lister interface {
	// List should return a list type object; the Items field will be extracted, and the
	// ResourceVersion field will be used to start the watch in the right place.
	List(options metav1.ListOptions) (runtime.Object, error)
}
// Watcher is any object that knows how to start a watch on a resource.
type Watcher interface {
	// Watch should begin a watch at the specified version.
	Watch(options metav1.ListOptions) (watch.Interface, error)
}

// ListerWatcher is any object that knows how to perform an initial list and start a watch on a resource.
type ListerWatcher interface {
	Lister
	Watcher
}

Reflector

// Reflector watch指定资源，并将所有变更都加入到存储中
type Reflector struct {
	// name identifies this reflector. By default it will be a file:line if possible.
	name string

	// The name of the type we expect to place in the store. The name
	// will be the stringification of expectedGVK if provided, and the
	// stringification of expectedType otherwise. It is for display
	// only, and should not be used for parsing or comparison.
	// 期望名称，只用做显示只用
	expectedTypeName string
	// An example object of the type we expect to place in the store.
	// Only the type needs to be right, except that when that is
	// `unstructured.Unstructured` the object's `"apiVersion"` and
	// `"kind"` must also be right.
	// 期望的类型
	expectedType reflect.Type
	// GVK
	expectedGVK *schema.GroupVersionKind
	// 存储
	store Store
	// ListWatch
	listerWatcher ListerWatcher

	// backoff manages backoff of ListWatch
	//ListWatch失败的backoff
	backoffManager wait.BackoffManager
	// initConnBackoffManager manages backoff the initial connection with the Watch calll of ListAndWatch.
	// 开始建立连接时使用的backoff
	initConnBackoffManager wait.BackoffManager

   //何时检查Resync
	resyncPeriod time.Duration
	// ShouldResync is invoked periodically and whenever it returns `true` the Store's Resync operation is invoked
	// 检查结果
	ShouldResync func() bool
	// clock allows tests to manipulate time
	clock clock.Clock
	// paginatedResult defines whether pagination should be forced for list calls.
	// It is set based on the result of the initial list call.
	// 是否分页
	paginatedResult bool
	// lastSyncResourceVersion is the resource version token last
	// observed when doing a sync with the underlying store
	// it is thread safe, but not synchronized with the underlying store
	// 最后 同步resouceVersion
	lastSyncResourceVersion string
	// isLastSyncResourceVersionUnavailable is true if the previous list or watch request with
	// lastSyncResourceVersion failed with an "expired" or "too large resource version" error.
	// 如果为false，则需要从新同步resouceVersion
	isLastSyncResourceVersionUnavailable bool
	// lastSyncResourceVersionMutex guards read/write access to lastSyncResourceVersion
	// 锁
	lastSyncResourceVersionMutex sync.RWMutex
	// WatchListPageSize is the requested chunk size of initial and resync watch lists.
	// If unset, for consistent reads (RV="") or reads that opt-into arbitrarily old data
	// (RV="0") it will default to pager.PageSize, for the rest (RV != "" && RV != "0")
	// it will turn off pagination to allow serving them from watch cache.
	// NOTE: It should be used carefully as paginated lists are always served directly from
	// etcd, which is significantly less efficient and may lead to serious performance and
	// scalability problems.
	// 分页大小
	WatchListPageSize int64
	// Called whenever the ListAndWatch drops the connection with an error.
	// Watch连接错误时，handler
	watchErrorHandler WatchErrorHandler
}

// NewReflector creates a new Reflector object which will keep the
// given store up to date with the server's contents for the given
// resource. Reflector promises to only put things in the store that
// have the type of expectedType, unless expectedType is nil. If
// resyncPeriod is non-zero, then the reflector will periodically
// consult its ShouldResync function to determine whether to invoke
// the Store's Resync operation; `ShouldResync==nil` means always
// "yes".  This enables you to use reflectors to periodically process
// everything as well as incrementally processing the things that
// change.
func NewReflector(lw ListerWatcher, expectedType interface{}, store Store, resyncPeriod time.Duration) *Reflector {
	return NewNamedReflector(naming.GetNameFromCallsite(internalPackages...), lw, expectedType, store, resyncPeriod)
}

// Run repeatedly uses the reflector's ListAndWatch to fetch all the
// objects and subsequent deltas.
// Run will exit when stopCh is closed.
func (r *Reflector) Run(stopCh <-chan struct{}) {
	klog.V(3).Infof("Starting reflector %s (%s) from %s", r.expectedTypeName, r.resyncPeriod, r.name)
	wait.BackoffUntil(func() {
		if err := r.ListAndWatch(stopCh); err != nil {
			r.watchErrorHandler(r, err)
		}
	}, r.backoffManager, true, stopCh)
	klog.V(3).Infof("Stopping reflector %s (%s) from %s", r.expectedTypeName, r.resyncPeriod, r.name)
}

// ListAndWatch first lists all items and get the resource version at the moment of call,
// and then use the resource version to watch.
// It returns error if ListAndWatch didn't even try to initialize watch.
func (r *Reflector) ListAndWatch(stopCh <-chan struct{}) error {
	klog.V(3).Infof("Listing and watching %v from %s", r.expectedTypeName, r.name)
	var resourceVersion string

	options := metav1.ListOptions{ResourceVersion: r.relistResourceVersion()}

    //连接ListWatch，初始化相关信息
	if err := func() error {
		//.................................
	}(); err != nil {
		return err
	}

	resyncerrc := make(chan error, 1)
	cancelCh := make(chan struct{})
	defer close(cancelCh)

	//定时Sync
	go func() {
	    //................................

	}()

	for {
		// give the stopCh a chance to stop the loop, even in case of continue statements further down on errors
		select {
		case <-stopCh:
			return nil
		default:
		}

		timeoutSeconds := int64(minWatchTimeout.Seconds() * (rand.Float64() + 1.0))
		options = metav1.ListOptions{
			ResourceVersion: resourceVersion,
			// We want to avoid situations of hanging watchers. Stop any wachers that do not
			// receive any events within the timeout window.
			TimeoutSeconds: &timeoutSeconds,
			// To reduce load on kube-apiserver on watch restarts, you may enable watch bookmarks.
			// Reflector doesn't assume bookmarks are returned at all (if the server do not support
			// watch bookmarks, it will ignore this field).
			AllowWatchBookmarks: true,
		}

		// start the clock before sending the request, since some proxies won't flush headers until after the first watch event is sent
		start := r.clock.Now()
		//增加Wathcer
		w, err := r.listerWatcher.Watch(options)
		if err != nil {
			// If this is "connection refused" error, it means that most likely apiserver is not responsive.
			// It doesn't make sense to re-list all objects because most likely we will be able to restart
			// watch where we ended.
			// If that's the case begin exponentially backing off and resend watch request.
			if utilnet.IsConnectionRefused(err) {
				<-r.initConnBackoffManager.Backoff().C()
				continue
			}
			return err
		}
        //处理事件逻辑
		if err := r.watchHandler(start, w, &resourceVersion, resyncerrc, stopCh); err != nil {
			if err != errorStopRequested {
				switch {
				case isExpiredError(err):
					// Don't set LastSyncResourceVersionUnavailable - LIST call with ResourceVersion=RV already
					// has a semantic that it returns data at least as fresh as provided RV.
					// So first try to LIST with setting RV to resource version of last observed object.
					klog.V(4).Infof("%s: watch of %v closed with: %v", r.name, r.expectedTypeName, err)
				default:
					klog.Warningf("%s: watch of %v ended with: %v", r.name, r.expectedTypeName, err)
				}
			}
			return nil
		}
	}
}

// watchHandler watches w and keeps *resourceVersion up to date.
func (r *Reflector) watchHandler(start time.Time, w watch.Interface, resourceVersion *string, errc chan error, stopCh <-chan struct{}) error {
	eventCount := 0

	// Stopping the watcher should be idempotent and if we return from this function there's no way
	// we're coming back in with the same watch interface.
	defer w.Stop()

loop:
	for {
		select {
		case <-stopCh:
			return errorStopRequested
		case err := <-errc:
			return err
		case event, ok := <-w.ResultChan():
		    // 获得结果
		    // 判断返回结果
			if !ok {
				break loop
			}
			if event.Type == watch.Error {
				return apierrors.FromObject(event.Object)
			}
			if r.expectedType != nil {
				if e, a := r.expectedType, reflect.TypeOf(event.Object); e != a {
					utilruntime.HandleError(fmt.Errorf("%s: expected type %v, but watch event object had type %v", r.name, e, a))
					continue
				}
			}
			if r.expectedGVK != nil {
				if e, a := *r.expectedGVK, event.Object.GetObjectKind().GroupVersionKind(); e != a {
					utilruntime.HandleError(fmt.Errorf("%s: expected gvk %v, but watch event object had gvk %v", r.name, e, a))
					continue
				}
			}
			meta, err := meta.Accessor(event.Object)
			if err != nil {
				utilruntime.HandleError(fmt.Errorf("%s: unable to understand watch event %#v", r.name, event))
				continue
			}
			newResourceVersion := meta.GetResourceVersion()
			switch event.Type {
			case watch.Added:
			    //`Store`增加对象
				err := r.store.Add(event.Object)
				if err != nil {
					utilruntime.HandleError(fmt.Errorf("%s: unable to add watch event object (%#v) to store: %v", r.name, event.Object, err))
				}
			//`Store`更新对象
			case watch.Modified:
				err := r.store.Update(event.Object)
				if err != nil {
					utilruntime.HandleError(fmt.Errorf("%s: unable to update watch event object (%#v) to store: %v", r.name, event.Object, err))
				}
			// 删除对象
			case watch.Deleted:
				// TODO: Will any consumers need access to the "last known
				// state", which is passed in event.Object? If so, may need
				// to change this.
				err := r.store.Delete(event.Object)
				if err != nil {
					utilruntime.HandleError(fmt.Errorf("%s: unable to delete watch event object (%#v) from store: %v", r.name, event.Object, err))
				}
			case watch.Bookmark:
				// A `Bookmark` means watch has synced here, just update the resourceVersion
			default:
				utilruntime.HandleError(fmt.Errorf("%s: unable to understand watch event %#v", r.name, event))
			}
			*resourceVersion = newResourceVersion
			r.setLastSyncResourceVersion(newResourceVersion)
			if rvu, ok := r.store.(ResourceVersionUpdater); ok {
				rvu.UpdateResourceVersion(newResourceVersion)
			}
			eventCount++
		}
	}

	watchDuration := r.clock.Since(start)
	if watchDuration < 1*time.Second && eventCount == 0 {
		return fmt.Errorf("very short watch: %s: Unexpected watch close - watch lasted less than a second and no items received", r.name)
	}
	klog.V(4).Infof("%s: Watch close - %v total %v items received", r.name, r.expectedTypeName, eventCount)
	return nil
}

Controller

// Config contains all the settings for one of these low-level controllers.
type Config struct {
	// The queue for your objects - has to be a DeltaFIFO due to
	// assumptions in the implementation. Your Process() function
	// should accept the output of this Queue's Pop() method.
	Queue

	// Something that can list and watch your objects.
	ListerWatcher

	// Something that can process a popped Deltas.
	Process ProcessFunc

	// ObjectType is an example object of the type this controller is
	// expected to handle.  Only the type needs to be right, except
	// that when that is `unstructured.Unstructured` the object's
	// `"apiVersion"` and `"kind"` must also be right.
	ObjectType runtime.Object

	// FullResyncPeriod is the period at which ShouldResync is considered.
	FullResyncPeriod time.Duration

	// ShouldResync is periodically used by the reflector to determine
	// whether to Resync the Queue. If ShouldResync is `nil` or
	// returns true, it means the reflector should proceed with the
	// resync.
	ShouldResync ShouldResyncFunc

	// If true, when Process() returns an error, re-enqueue the object.
	// TODO: add interface to let you inject a delay/backoff or drop
	//       the object completely if desired. Pass the object in
	//       question to this interface as a parameter.  This is probably moot
	//       now that this functionality appears at a higher level.
	RetryOnError bool

	// Called whenever the ListAndWatch drops the connection with an error.
	WatchErrorHandler WatchErrorHandler

	// WatchListPageSize is the requested chunk size of initial and relist watch lists.
	WatchListPageSize int64
}
// New makes a new Controller from the given Config.
func New(c *Config) Controller {
	ctlr := &controller{
		config: *c,
		clock:  &clock.RealClock{},
	}
	return ctlr
}
// Run begins processing items, and will continue until a value is sent down stopCh or it is closed.
// It's an error to call Run more than once.
// Run blocks; call via go.
func (c *controller) Run(stopCh <-chan struct{}) {
	defer utilruntime.HandleCrash()
	go func() {
		<-stopCh
		c.config.Queue.Close()
	}()
	//新建reflector
	r := NewReflector(
		c.config.ListerWatcher,
		c.config.ObjectType,
		c.config.Queue,
		c.config.FullResyncPeriod,
	)
	r.ShouldResync = c.config.ShouldResync
	r.WatchListPageSize = c.config.WatchListPageSize
	r.clock = c.clock
	if c.config.WatchErrorHandler != nil {
		r.watchErrorHandler = c.config.WatchErrorHandler
	}

	c.reflectorMutex.Lock()
	c.reflector = r
	c.reflectorMutex.Unlock()

	var wg wait.Group

    // reflector跑起来
	wg.StartWithChannel(stopCh, r.Run)

    // 处理loop
	wait.Until(c.processLoop, time.Second, stopCh)
	wg.Wait()
}

// processLoop drains the work queue.
// TODO: Consider doing the processing in parallel. This will require a little thought
// to make sure that we don't end up processing the same object multiple times
// concurrently.
//
// TODO: Plumb through the stopCh here (and down to the queue) so that this can
// actually exit when the controller is stopped. Or just give up on this stuff
// ever being stoppable. Converting this whole package to use Context would
// also be helpful.
func (c *controller) processLoop() {
	for {
	    //没有对象时Pop 会阻塞
		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)
			}
		}
	}
}

func NewInformer(
	lw ListerWatcher,
	objType runtime.Object,
	resyncPeriod time.Duration,
	h ResourceEventHandler,
) (Store, Controller) {
	// This will hold the client state, as we know it.
	clientState := NewStore(DeletionHandlingMetaNamespaceKeyFunc)

	return clientState, newInformer(lw, objType, resyncPeriod, h, clientState)
}

func newInformer(
	lw ListerWatcher,
	objType runtime.Object,
	resyncPeriod time.Duration,
	h ResourceEventHandler,
	clientState Store,
) Controller {
	// This will hold incoming changes. Note how we pass clientState in as a
	// KeyLister, that way resync operations will result in the correct set
	// of update/delete deltas.
	fifo := NewDeltaFIFOWithOptions(DeltaFIFOOptions{
		KnownObjects:          clientState,
		EmitDeltaTypeReplaced: true,
	})

	cfg := &Config{
		Queue:            fifo,
		ListerWatcher:    lw,
		ObjectType:       objType,
		FullResyncPeriod: resyncPeriod,
		RetryOnError:     false,

		Process: func(obj interface{}) error {
			// from oldest to newest
			for _, d := range obj.(Deltas) {
				switch d.Type {
				case Sync, Replaced, Added, Updated:
					if old, exists, err := clientState.Get(d.Object); err == nil && exists {
						if err := clientState.Update(d.Object); err != nil {
							return err
						}
						h.OnUpdate(old, d.Object)
					} else {
						if err := clientState.Add(d.Object); err != nil {
							return err
						}
						h.OnAdd(d.Object)
					}
				case Deleted:
					if err := clientState.Delete(d.Object); err != nil {
						return err
					}
					h.OnDelete(d.Object)
				}
			}
			return nil
		},
	}
	return New(cfg)
}