l-18

vendor/k8s.io/client-go/tools/cache/reflector.go

@@ -244,7 +244,7 @@ var internalPackages = []string{"client-go/tools/cache/"}
 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 {// 调用了 list & watch
+		if err := r.ListAndWatch(stopCh); err != nil {// 调用了 list & watch，
 			r.watchErrorHandler(r, err)
 		}
 	}, r.backoffManager, true, stopCh)
@@ -280,14 +280,17 @@ func (r *Reflector) resyncChan() (<-chan time.Time, func() bool) {
 func (r *Reflector) ListAndWatch(stopCh <-chan struct{}) error {
 	klog.V(3).Infof("Listing and watching %v from %s", r.expectedTypeName, r.name)
 
+	// 执行list操作
 	err := r.list(stopCh)
 	if err != nil {
 		return err
 	}
 
+	// 执行resync操作
 	resyncerrc := make(chan error, 1)
 	cancelCh := make(chan struct{})
 	defer close(cancelCh)
+	// 启动一个协程来运行 resync
 	go func() {
 		resyncCh, cleanup := r.resyncChan()
 		defer func() {
@@ -313,6 +316,7 @@ func (r *Reflector) ListAndWatch(stopCh <-chan struct{}) error {
 		}
 	}()
 
+	// 执行 watch 操作
 	retry := NewRetryWithDeadline(r.MaxInternalErrorRetryDuration, time.Minute, apierrors.IsInternalError, r.clock)
 	for {
 		// give the stopCh a chance to stop the loop, even in case of continue statements further down on errors
@@ -380,6 +384,8 @@ func (r *Reflector) ListAndWatch(stopCh <-chan struct{}) error {
 // the resource version can be used for further progress notification (aka. watch).
 func (r *Reflector) list(stopCh <-chan struct{}) error {
 	var resourceVersion string
+
+	// 创建 option，主要是确定 resourceVersion
 	options := metav1.ListOptions{ResourceVersion: r.relistResourceVersion()}
 
 	initTrace := trace.New("Reflector ListAndWatch", trace.Field{Key: "name", Value: r.name})
@@ -389,25 +395,34 @@ func (r *Reflector) list(stopCh <-chan struct{}) error {
 	var err error
 	listCh := make(chan struct{}, 1)
 	panicCh := make(chan interface{}, 1)
+	// 启动 goroutine 来执行 list 并接收
 	go func() {
 		defer func() {
 			if r := recover(); r != nil {
 				panicCh <- r
 			}
 		}()
+		// pager 是一个拥有执行了外部list方法结果的对象
 		// Attempt to gather list in chunks, if supported by listerWatcher, if not, the first
 		// list request will return the full response.
-		pager := pager.New(pager.SimplePageFunc(func(opts metav1.ListOptions) (runtime.Object, error) {
+		pager := pager.New(
+			pager.SimplePageFunc(
+				func(opts metav1.ListOptions) (runtime.Object, error) {
+			// 这里执行了外面传进来的对象的 list 方法
 			return r.listerWatcher.List(opts)
 		}))
 		switch {
 		case r.WatchListPageSize != 0:
+			// 设置了分页值，就会让这个值在执行分页的时候生效
 			pager.PageSize = r.WatchListPageSize
 		case r.paginatedResult:
+			// 如果已经使用用分页的结果，就不做任何操作
 			// We got a paginated result initially. Assume this resource and server honor
 			// paging requests (i.e. watch cache is probably disabled) and leave the default
 			// pager size set.
 		case options.ResourceVersion != "" && options.ResourceVersion != "0":
+			// 如果满足这里，说明获取到数据，并且没有分页信息
+			// 如果 PageSize 为 0， 后面会从 cache 中获取数据
 			// User didn't explicitly request pagination.
 			//
 			// With ResourceVersion != "", we have a possibility to list from watch cache,
@@ -436,6 +451,8 @@ func (r *Reflector) list(stopCh <-chan struct{}) error {
 		}
 		close(listCh)
 	}()
+
+	// 控制 goroutine 的运行
 	select {
 	case <-stopCh:
 		return nil
@@ -463,12 +480,15 @@ func (r *Reflector) list(stopCh <-chan struct{}) error {
 		r.paginatedResult = true
 	}
 
+	// 表示list执行成功
 	r.setIsLastSyncResourceVersionUnavailable(false) // list was successful
-	listMetaInterface, err := meta.ListAccessor(list)
+
+	// 处理resourceVersion
+	listMetaInterface, err := meta.ListAccessor(list) // 创建提取器
 	if err != nil {
 		return fmt.Errorf("unable to understand list result %#v: %v", list, err)
 	}
-	resourceVersion = listMetaInterface.GetResourceVersion()
+	resourceVersion = listMetaInterface.GetResourceVersion() // 获取当前数据的 resourceVersion。相当于备份 resourceversion
 	initTrace.Step("Resource version extracted")
 	items, err := meta.ExtractList(list)
 	if err != nil {
@@ -479,7 +499,7 @@ func (r *Reflector) list(stopCh <-chan struct{}) error {
 		return fmt.Errorf("unable to sync list result: %v", err)
 	}
 	initTrace.Step("SyncWith done")
-	r.setLastSyncResourceVersion(resourceVersion)
+	r.setLastSyncResourceVersion(resourceVersion) // 还原 resourceVersion
 	initTrace.Step("Resource version updated")
 	return nil
 }
@@ -598,6 +618,7 @@ func (r *Reflector) setLastSyncResourceVersion(v string) {
 	r.lastSyncResourceVersion = v
 }
 
+// 确认 resourceVersion 的方法
 // relistResourceVersion determines the resource version the reflector should list or relist from.
 // Returns either the lastSyncResourceVersion so that this reflector will relist with a resource
 // versions no older than has already been observed in relist results or watch events, or, if the last relist resulted
@@ -608,16 +629,20 @@ func (r *Reflector) relistResourceVersion() string {
 	defer r.lastSyncResourceVersionMutex.RUnlock()
 
 	if r.isLastSyncResourceVersionUnavailable {
+		// 如果最近一次的sync的 resourceVersion 不可用，我们就返回一个空的 resourceVersion
 		// Since this reflector makes paginated list requests, and all paginated list requests skip the watch cache
 		// if the lastSyncResourceVersion is unavailable, we set ResourceVersion="" and list again to re-establish reflector
 		// to the latest available ResourceVersion, using a consistent read from etcd.
 		return ""
 	}
 	if r.lastSyncResourceVersion == "" {
+		// 如果最近一次的sync的 resourceVersion 为字符串 空 ，则返回字符串 “0”
 		// For performance reasons, initial list performed by reflector uses "0" as resource version to allow it to
 		// be served from the watch cache if it is enabled.
 		return "0"
 	}
+
+	// 都不满足直接返回最后一次同步的 resourceVersion
 	return r.lastSyncResourceVersion
 }
 

vendor/k8s.io/client-go/tools/pager/pager.go

@@ -74,12 +74,13 @@ func New(fn ListPageFunc) *ListPager {
 // server to reduce the impact on the server. If the chunk attempt fails, it will load
 // the full list instead. The Limit field on options, if unset, will default to the page size.
 func (p *ListPager) List(ctx context.Context, options metav1.ListOptions) (runtime.Object, bool, error) {
+	// 设置 page size
 	if options.Limit == 0 {
 		options.Limit = p.PageSize
 	}
 	requestedResourceVersion := options.ResourceVersion
 	requestedResourceVersionMatch := options.ResourceVersionMatch
-	var list *metainternalversion.List
+	var list *metainternalversion.List // 用来存储获取的结果
 	paginatedResult := false
 
 	for {
@@ -89,8 +90,10 @@ func (p *ListPager) List(ctx context.Context, options metav1.ListOptions) (runti
 		default:
 		}
 
+		// 真正执行外部传入的，含有list对象的 list 方法
 		obj, err := p.PageFn(ctx, options)
 		if err != nil {
+			// 错误处理
 			// Only fallback to full list if an "Expired" errors is returned, FullListIfExpired is true, and
 			// the "Expired" error occurred in page 2 or later (since full list is intended to prevent a pager.List from
 			// failing when the resource versions is established by the first page request falls out of the compaction
@@ -104,14 +107,18 @@ func (p *ListPager) List(ctx context.Context, options metav1.ListOptions) (runti
 			options.Continue = ""
 			options.ResourceVersion = requestedResourceVersion
 			options.ResourceVersionMatch = requestedResourceVersionMatch
-			result, err := p.PageFn(ctx, options)
+			result, err := p.PageFn(ctx, options) // 失败了，最后还会执行一次
+			// 执行后，不管成功与否，都直接返回
 			return result, paginatedResult, err
 		}
+		// 创建一个提取器
+		// 根据获取的对象类型，来生成提取器
 		m, err := meta.ListAccessor(obj)
 		if err != nil {
 			return nil, paginatedResult, fmt.Errorf("returned object must be a list: %v", err)
 		}
 
+		// 判断结果状态，如果没有更多或者已经为空，则退出
 		// exit early and return the object we got if we haven't processed any pages
 		if len(m.GetContinue()) == 0 && list == nil {
 			return obj, paginatedResult, nil
@@ -119,10 +126,14 @@ func (p *ListPager) List(ctx context.Context, options metav1.ListOptions) (runti
 
 		// initialize the list and fill its contents
 		if list == nil {
+			// 进到这里，表示是第一次执行
+			// 使用创建的提取器初始化 list 对象
 			list = &metainternalversion.List{Items: make([]runtime.Object, 0, options.Limit+1)}
 			list.ResourceVersion = m.GetResourceVersion()
 			list.SelfLink = m.GetSelfLink()
 		}
+
+		// 处理每一个获取的对象，无论是一个列表，还是封装在一个列表对象中的列表
 		if err := meta.EachListItem(obj, func(obj runtime.Object) error {
 			list.Items = append(list.Items, obj)
 			return nil
@@ -130,18 +141,24 @@ func (p *ListPager) List(ctx context.Context, options metav1.ListOptions) (runti
 			return nil, paginatedResult, err
 		}
 
+		// 如果获取完成，就返回
 		// if we have no more items, return the list
 		if len(m.GetContinue()) == 0 {
 			return list, paginatedResult, nil
 		}
 
+		// 开始下一次循环的初始化设置
 		// set the next loop up
-		options.Continue = m.GetContinue()
+		options.Continue = m.GetContinue() // 获取了象一个对象
+
+		// 一些变量的清理工作
 		// Clear the ResourceVersion(Match) on the subsequent List calls to avoid the
 		// `specifying resource version is not allowed when using continue` error.
 		// See https://github.com/kubernetes/kubernetes/issues/85221#issuecomment-553748143.
 		options.ResourceVersion = ""
 		options.ResourceVersionMatch = ""
+
+		// 如果走到这里，自然的，分页就产生了。
 		// At this point, result is already paginated.
 		paginatedResult = true
 	}