go-cache

在具体的获取数据操作(fetcher)前加一层缓存操作

go-cache

• 1、先根据key从cache中获取数据，如果不存在则从fetcher中获取数据（并发调用时只会有一个请求会调用fetcher,其他请求会复用这个请求返回的数据）

• 2、从fetcher获取到数据之后然后存储到cache中,然后返回从fetcher获取到的对象

• 3、如果cache中存在数据，则decode进model对象中返回（注意这时候返回的是model的指针）

tips

注意：如果对象在缓存中存在则一定返回的是对象指针，如果不存在返回的是fetcher返回的数据(为了统一fetcher最好也返回对象的指针)

安装

go get github.com/liyanbing/go-cache

使用

package main

import (
	"context"
	"fmt"
	"log"
	"time"

	"github.com/golang/protobuf/proto"

	redis "github.com/go-redis/redis/v8"
	go_cache "github.com/liyanbing/go-cache"
	redis_cacher "github.com/liyanbing/go-cache/cacher/redis"
)

type User struct {
	Name string `json:"name"`
	Age  int    `json:"age"`
	Id   uint64 `json:"id"`
}

func main() {
	cache := redis_cacher.NewRedisCache(redis.NewClient(&redis.Options{
		Addr: "127.0.0.1:6379",
		DB:   0,
	}))

	// 1、 json
	temp, err := go_cache.FetchWithJson(context.Background(), cache, "json1", func() (interface{}, time.Duration, error) {
		return &User{
			Name: "peter",
			Age:  23,
			Id:   123123,
		}, time.Hour, nil
	}, User{})
	if err != nil {
		log.Fatal(err)
	}
	ret := temp.(*User)
	fmt.Println("json:", *ret)

	// 2、json2
	temp, err = go_cache.FetchWithJson(context.Background(), cache, "json2", func() (interface{}, time.Duration, error) {
		// 这里返回的不是指针
		return User{
			Name: "peter",
			Age:  23,
			Id:   123123,
		}, time.Hour, nil
	}, User{})
	if err != nil {
		log.Fatal(err)
	}

	// 这里因为fetcher中返回的是非对象指针，但是从缓存中获取到数据之后返回的是对象指针所以需要判断
	switch temp.(type) {
	case *User:
		ret = temp.(*User)
	case User:
		ret1 := temp.(User)
		ret = &ret1
	}
	fmt.Println("json:", *ret)

	// 3、string
	str, err := go_cache.FetchWithString(context.Background(), cache, "string", func() (interface{}, time.Duration, error) {
		return "golang", time.Hour, nil
	})
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(str)

	// 4、protobuf
	pro, err := go_cache.FetchWithProtobuf(context.Background(), cache, "protobuf", func() (interface{}, time.Duration, error) {
		return &TempModelPb{
			IsMember: true,
			ExpireAt: 19999,
		}, time.Hour, nil
	}, new(TempModelPb))
	if err != nil {
		log.Fatal(err)
	}
	proRet := pro.(*TempModelPb)
	fmt.Println(*proRet)

	// 5、number
	num, err := go_cache.FetchWithNumber(context.Background(), cache, "number", func() (interface{}, time.Duration, error) {
		return int64(100), time.Hour, nil
	})
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(num)

	// 6、number
	// 也可以通过go_cache.WithNoUseCache来表示不使用缓存直接从fetcher中获取数据，这时候会顺便更新缓存数据
	ctx := go_cache.WithNoUseCache(context.Background())
	num, err = go_cache.FetchWithNumber(ctx, cache, "number", func() (interface{}, time.Duration, error) {
		return 300.02, time.Hour, nil
	})
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(num)

	// 7、array1
	arr, err := go_cache.FetchWithArray(context.Background(), cache, "array", func() (interface{}, time.Duration, error) {
		return []*User{
			{
				Name: "golang",
				Age:  5,
			},
			{
				Name: "java",
				Age:  10,
			},
		}, time.Hour, nil
	}, []*User{})
	if err != nil {
		log.Fatal(err)
	}
	arrRet := arr.([]*User)
	fmt.Println(arrRet)

	// 7、array2
	arr1, err := go_cache.FetchWithArray(context.Background(), cache, "array2", func() (interface{}, time.Duration, error) {
		return []*User{
			{
				Name: "golang",
				Age:  5,
			},
			{
				Name: "java",
				Age:  10,
			},
		}, time.Hour, nil
	}, []User{})
	if err != nil {
		log.Fatal(err)
	}
	arr1Ret := arr1.([]User)
	fmt.Println(arr1Ret)

	// 8、array3
	type Temp struct {
		Users []*User
	}

	arr3, err := go_cache.FetchWithJson(context.Background(), cache, "array3", func() (interface{}, time.Duration, error) {
		return &Temp{
			Users: []*User{
				{
					Name: "golang",
					Age:  5,
				},
				{
					Name: "java",
					Age:  10,
				},
			},
		}, time.Hour, nil
	}, new(Temp))
	if err != nil {
		log.Fatal(err)
	}
	arr3Ret := arr3.(*Temp)
	fmt.Println(*arr3Ret)
}

type TempModelPb struct {
	IsMember bool  `protobuf:"varint,1,opt,name=is_member,json=isMember" json:"is_member,omitempty"`
	ExpireAt int64 `protobuf:"varint,2,opt,name=expire_at,json=expireAt" json:"expire_at,omitempty"`
}

func (m *TempModelPb) Reset()                    { *m = TempModelPb{} }
func (m *TempModelPb) String() string            { return proto.CompactTextString(m) }
func (*TempModelPb) ProtoMessage()               {}
func (*TempModelPb) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{7} }

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	// 582 bytes of a gzipped FileDescriptorProto
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