[k8s源码]7.indexer

FIFO

在reflector中定义了一个FIFO的存储。

items: 一个 map，用于存储实际的对象，键是对象的唯一标识符。
queue: 一个字符串切片，保存了对象键的有序列表，维护了插入顺序。
keyFunc: 一个函数，用于从对象生成唯一键。
lock: 用于保护并发访问的读写锁。
cond: 条件变量，用于在队列状态改变时发出通知。

Go 复制代码

func NewFIFO(keyFunc KeyFunc) *FIFO {
	f := &FIFO{
		items:   map[string]interface{}{},
		queue:   []string{},
		keyFunc: keyFunc,
	}
	f.cond.L = &f.lock
	return f
}

FIFO 和 Indexer 都是 Kubernetes 客户端库中的重要组件，但它们服务于不同的目的。FIFO 主要用于保持对象的处理顺序，而 Indexer 提供了更强大的查询和索引能力。在实际应用中，它们常常一起使用：FIFO 用于初始数据接收和排序，而 Indexer 用于后续的高效数据检索和查询。

Go 复制代码

// 创建 Indexer
indexer := cache.NewIndexer(cache.MetaNamespaceKeyFunc, cache.Indexers{
    "namespace": cache.MetaNamespaceIndexFunc,
})

// 创建 DeltaFIFO
fifo := cache.NewDeltaFIFO(cache.MetaNamespaceKeyFunc, indexer)

// 创建 Reflector
reflector := cache.NewReflector(
    listerWatcher,
    &api.Pod{},
    fifo,
    0,
)

// 启动 Reflector
go reflector.Run(stopCh)

// 处理 FIFO 中的项目
for {
    item, shutdown := fifo.Pop(cache.PopProcessFunc(func(obj interface{}) error {
        // 处理逻辑
        indexer.Update(obj)
        return nil
    }))
    if shutdown {
        break
    }
}

Reflector 持续监听 API 服务器的变更。

变更被推送到 DeltaFIFO。

DeltaFIFO 保持这些变更的顺序。

处理函数从 DeltaFIFO 取出变更，更新 Indexer。

Indexer 维护最新的对象状态，并提供查询能力。

indexer demo

indexer提供存储和索引的能力。Indexer 使用 MetaNamespaceKeyFunc 为每个对象生成一个唯一的键。同时，Indexer 使用索引函数（如 "namespace" 和 "nodeName"）来创建额外的索引。

Go 复制代码

package main

import (
	"fmt"

	v1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/client-go/tools/cache"
)

func main() {
	// 创建 Indexer
	indexer := cache.NewIndexer(
		cache.MetaNamespaceKeyFunc,
		cache.Indexers{
			"namespace": func(obj interface{}) ([]string, error) {
				pod, ok := obj.(*v1.Pod)
				if !ok {
					return []string{}, nil
				}
				return []string{pod.Namespace}, nil
			},
		},
	)

	// 添加 nodeName 索引
	err := indexer.AddIndexers(cache.Indexers{
		"nodeName": func(obj interface{}) ([]string, error) {
			pod, ok := obj.(*v1.Pod)
			if !ok {
				return []string{}, nil
			}
			return []string{pod.Spec.NodeName}, nil
		},
	})
	if err != nil {
		panic(err)
	}

	// 添加一些 Pod
	pods := []*v1.Pod{
		{
			ObjectMeta: metav1.ObjectMeta{Name: "pod1", Namespace: "default"},
			Spec:       v1.PodSpec{NodeName: "node1"},
		},
		{
			ObjectMeta: metav1.ObjectMeta{Name: "pod2", Namespace: "kube-system"},
			Spec:       v1.PodSpec{NodeName: "node1"},
		},
		{
			ObjectMeta: metav1.ObjectMeta{Name: "pod3", Namespace: "default"},
			Spec:       v1.PodSpec{NodeName: "node2"},
		},
	}

	for _, pod := range pods {
		err := indexer.Add(pod)
		if err != nil {
			fmt.Printf("Error adding pod: %v\n", err)
		}
	}

	// 使用 namespace 索引
	defaultPods, err := indexer.ByIndex("namespace", "default")
	if err != nil {
		panic(err)
	}
	fmt.Printf("Pods in default namespace: %d\n", len(defaultPods))

	// 使用 nodeName 索引
	node1Pods, err := indexer.ByIndex("nodeName", "node1")
	if err != nil {
		panic(err)
	}
	fmt.Printf("Pods on node1: %d\n", len(node1Pods))

	// 获取所有索引器
	allIndexers := indexer.GetIndexers()
	for indexName := range allIndexers {
		fmt.Printf("Index: %s\n", indexName)
	}
}

这里创建的就是indexer（索引器），加入的"namespace"和"NodeName"就是索引index。

Go 复制代码

Store {
    // 主存储
    MainStorage: {
        "default/pod-1": Pod-1对象,
        "kube-system/pod-2": Pod-2对象,
        "default/pod-3": Pod-3对象
    },

    // Indices（索引集）
    Indices: {
        "namespace": {
            // Index（命名空间索引）
            "default": ["default/pod-1", "default/pod-3"],
            "kube-system": ["kube-system/pod-2"]
        },
        "nodeName": {
            // Index（节点名索引）
            "node-A": ["default/pod-1", "kube-system/pod-2"],
            "node-B": ["default/pod-3"]
        }
    }
}

library indexer demo

Go 复制代码

package main

import (
	"fmt"
)

type Book struct {
	ID     string
	Title  string
	Author string
	Genre  string
}
type IndexFunc func(Book) []string
type Index map[string][]string
type Indexers map[string]IndexFunc
type Indices map[string]Index

type Library struct {
	books    map[string]Book
	indexers Indexers
	indices  Indices
}

func authorIndexFunc(book Book) []string {
	return []string{book.Author}
}
func genreIndexFunc(book Book) []string {
	return []string{book.Genre}
}
func NewLibrary() *Library {
	return &Library{
		books: make(map[string]Book),
		indexers: Indexers{
			"author": authorIndexFunc,
			"genre":  genreIndexFunc,
		},
		indices: make(Indices),
	}
}
func (l *Library) AddBook(book Book) {
	l.books[book.ID] = book
	for indexName, indexFunc := range l.indexers {
		indexvalues := indexFunc(book)
		for _, value := range indexvalues {
			if l.indices[indexName] == nil {
				l.indices[indexName] = make(Index)
			}
			l.indices[indexName][value] = append(l.indices[indexName][value], book.ID)
		}
	}
}
func (l *Library) FindBooksByAuthor(author string) []Book {
	bookIDs := l.indices["author"][author]
	var books []Book
	for _, id := range bookIDs {
		books = append(books, l.books[id])
	}
	return books
}
// AddIndexer 方法用于添加新的索引器
func (l *Library) AddIndexer(name string, indexFunc IndexFunc) {
	l.indexers[name] = indexFunc
	l.indices[name] = make(Index)

	// 为现有的书籍创建新的索引
	for _, book := range l.books {
		l.indexBook(name, book)
	}
}
func (l *Library) indexBook(indexName string, book Book) {
	indexFunc := l.indexers[indexName]
	indexValues := indexFunc(book)
	for _, value := range indexValues {
		l.indices[indexName][value] = append(l.indices[indexName][value], book.ID)
	}
}
func main() {
	// 创建一个新的 Library
	library := NewLibrary()

	// 添加一些书籍
	library.AddBook(Book{ID: "1", Title: "Harry Potter and the Philosopher's Stone", Author: "J.K. Rowling", Genre: "Fantasy"})
	library.AddBook(Book{ID: "2", Title: "Harry Potter and the Chamber of Secrets", Author: "J.K. Rowling", Genre: "Fantasy"})
	library.AddBook(Book{ID: "3", Title: "1984", Author: "George Orwell", Genre: "Dystopian"})

	// 测试 FindBooksByAuthor 方法
	rowlingBooks := library.FindBooksByAuthor("J.K. Rowling")
	fmt.Println("Books by J.K. Rowling:")
	for _, book := range rowlingBooks {
		fmt.Printf("- %s\n", book.Title)
	}

	orwellBooks := library.FindBooksByAuthor("George Orwell")
	fmt.Println("\nBooks by George Orwell:")
	for _, book := range orwellBooks {
		fmt.Printf("- %s\n", book.Title)
	}
}

通过这个例子，我们可以更好的理解indexer的代码。比如，下面代码是创建一个名叫library的结构体的代码，可以看到这里indexer也是type Indexers map[string]IndexFunc，然后这里也定义了type IndexFunc func(Book) []string，那么就可以将indexer定义为"author"：authorIndexFunc，查看index.go的源码，可以看到类似的type定义。

func NewLibrary() *Library {

return &Library{

books: make(map[string]Book),

indexers: Indexers{

"author": authorIndexFunc,

"genre": genreIndexFunc,

},

indices: make(Indices),

}

Go 复制代码

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)
	// GetIndexers return the indexers
	GetIndexers() Indexers

	// AddIndexers adds more indexers to this store. This supports adding indexes after the store already has items.
	AddIndexers(newIndexers Indexers) error
}

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

// IndexFuncToKeyFuncAdapter adapts an indexFunc to a keyFunc.  This is only useful if your index function returns
// unique values for every object.  This conversion can create errors when more than one key is found.  You
// should prefer to make proper key and index functions.
func IndexFuncToKeyFuncAdapter(indexFunc IndexFunc) KeyFunc {
	return func(obj interface{}) (string, error) {
		indexKeys, err := indexFunc(obj)
		if err != nil {
			return "", err
		}
		if len(indexKeys) > 1 {
			return "", fmt.Errorf("too many keys: %v", indexKeys)
		}
		if len(indexKeys) == 0 {
			return "", fmt.Errorf("unexpected empty indexKeys")
		}
		return indexKeys[0], nil
	}
}

const (
	// NamespaceIndex is the lookup name for the most common index function, which is to index by the namespace field.
	NamespaceIndex string = "namespace"
)

// MetaNamespaceIndexFunc is a default index function that indexes based on an object's namespace
func MetaNamespaceIndexFunc(obj interface{}) ([]string, error) {
	meta, err := meta.Accessor(obj)
	if err != nil {
		return []string{""}, fmt.Errorf("object has no meta: %v", err)
	}
	return []string{meta.GetNamespace()}, nil
}

// Index maps the indexed value to a set of keys in the store that match on that value
type Index map[string]sets.String

// Indexers maps a name to an IndexFunc
type Indexers map[string]IndexFunc

// Indices maps a name to an Index
type Indices map[string]Index

同理，indexer demo中，"nodeName"：func（）和上面的"author"：authorIndexFunc是一个道理。

func main() {

// 创建 Indexer

indexer := cache.NewIndexer(

cache.MetaNamespaceKeyFunc,

cache.Indexers{

"namespace": func(obj interface{}) ([]string, error) {

pod, ok := obj.(*v1.Pod)

if !ok {

return []string{}, nil

}

return []string{pod.Namespace}, nil

},

},

)

// 添加 nodeName 索引

err := indexer.AddIndexers(cache.Indexers{

"nodeName": func(obj interface{}) ([]string, error) {

pod, ok := obj.(*v1.Pod)

if !ok {

return []string{}, nil

}

return []string{pod.Spec.NodeName}, nil

},

})

if err != nil {

panic(err)

}