jetcache-go是基于go-redis/cache拓展的通用缓存访问框架。 实现了类似Java版JetCache的核心功能，包括：
- ✅ 二级缓存自由组合：本地缓存、分布式缓存、本地缓存+分布式缓存
- ✅
Once接口采用单飞(singleflight)模式，高并发且线程安全 - ✅ 默认采用MsgPack来编解码Value。可选sonic、原生
json - ✅ 本地缓存默认实现了TinyLFU和FreeCache
- ✅ 分布式缓存默认实现了go-redis/v8的适配器，你也可以自定义实现
- ✅ 可以自定义
errNotFound，通过占位符替换，缓存空结果防止缓存穿透 - ✅ 支持开启分布式缓存异步刷新
- ✅ 指标采集，默认实现了通过日志打印各级缓存的统计指标（QPM、Hit、Miss、Query、QueryFail）
- ✅ 分布式缓存查询故障自动降级
- ✅
MGet接口支持Load函数。带分布缓存场景，采用Pipeline模式实现
使用最新版本的jetcache-go，您可以在项目中导入该库：
go get github.com/mgtv-tech/jetcache-gopackage cache_test
import (
"bytes"
"context"
"errors"
"fmt"
"time"
"github.com/go-redis/redis/v8"
"github.com/mgtv-tech/jetcache-go"
"github.com/mgtv-tech/jetcache-go/local"
"github.com/mgtv-tech/jetcache-go/remote"
"github.com/mgtv-tech/jetcache-go/util"
)
var errRecordNotFound = errors.New("mock gorm.errRecordNotFound")
type object struct {
Str string
Num int
}
func mockDBGetObject(id int) (*object, error) {
if id > 100 {
return nil, errRecordNotFound
}
return &object{Str: "mystring", Num: 42}, nil
}
func mockDBMGetObject(ids []int) (map[int]*object, error) {
ret := make(map[int]*object)
for _, id := range ids {
if id == 3 {
continue
}
ret[id] = &object{Str: "mystring", Num: id}
}
return ret, nil
}
func Example_basicUsage() {
ring := redis.NewRing(&redis.RingOptions{
Addrs: map[string]string{
"localhost": ":6379",
},
})
mycache := cache.New(cache.WithName("any"),
cache.WithRemote(remote.NewGoRedisV8Adaptor(ring)),
cache.WithLocal(local.NewFreeCache(256*local.MB, time.Minute)),
cache.WithErrNotFound(errRecordNotFound))
ctx := context.TODO()
key := util.JoinAny(":", "mykey", 1)
obj, _ := mockDBGetObject(1)
if err := mycache.Set(ctx, key, cache.Value(obj), cache.TTL(time.Hour)); err != nil {
panic(err)
}
var wanted object
if err := mycache.Get(ctx, key, &wanted); err == nil {
fmt.Println(wanted)
}
// Output: {mystring 42}
mycache.Close()
}
func Example_advancedUsage() {
ring := redis.NewRing(&redis.RingOptions{
Addrs: map[string]string{
"localhost": ":6379",
},
})
mycache := cache.New(cache.WithName("any"),
cache.WithRemote(remote.NewGoRedisV8Adaptor(ring)),
cache.WithLocal(local.NewFreeCache(256*local.MB, time.Minute)),
cache.WithErrNotFound(errRecordNotFound),
cache.WithRefreshDuration(time.Minute))
ctx := context.TODO()
key := util.JoinAny(":", "mykey", 1)
obj := new(object)
if err := mycache.Once(ctx, key, cache.Value(obj), cache.TTL(time.Hour), cache.Refresh(true),
cache.Do(func(ctx context.Context) (any, error) {
return mockDBGetObject(1)
})); err != nil {
panic(err)
}
fmt.Println(obj)
//Output: &{mystring 42}
mycache.Close()
}
func Example_mGetUsage() {
ring := redis.NewRing(&redis.RingOptions{
Addrs: map[string]string{
"localhost": ":6379",
},
})
mycache := cache.New(cache.WithName("any"),
cache.WithRemote(remote.NewGoRedisV8Adaptor(ring)),
cache.WithLocal(local.NewFreeCache(256*local.MB, time.Minute)),
cache.WithErrNotFound(errRecordNotFound),
cache.WithRemoteExpiry(time.Minute),
)
cacheT := cache.NewT[int, *object](mycache)
ctx := context.TODO()
key := "mget"
ids := []int{1, 2, 3}
ret := cacheT.MGet(ctx, key, ids, func(ctx context.Context, ids []int) (map[int]*object, error) {
return mockDBMGetObject(ids)
})
var b bytes.Buffer
for _, id := range ids {
b.WriteString(fmt.Sprintf("%v", ret[id]))
}
fmt.Println(b.String())
//Output: &{mystring 1}&{mystring 2}<nil>
cacheT.Close()
}// Options are used to store cache options.
type Options struct {
name string // Cache name, used for log identification and metric reporting
remote remote.Remote // Remote is distributed cache, such as Redis.
local local.Local // Local is memory cache, such as FreeCache.
codec string // Value encoding and decoding method. Default is "msgpack.Name". You can also customize it.
errNotFound error // Error to return for cache miss. Used to prevent cache penetration.
remoteExpiry time.Duration // Remote cache ttl, Default is 1 hour.
notFoundExpiry time.Duration // Duration for placeholder cache when there is a cache miss. Default is 1 minute.
offset time.Duration // Expiration time jitter factor for cache misses.
refreshDuration time.Duration // Interval for asynchronous cache refresh. Default is 0 (refresh is disabled).
stopRefreshAfterLastAccess time.Duration // Duration for cache to stop refreshing after no access. Default is refreshDuration + 1 second.
refreshConcurrency int // Maximum number of concurrent cache refreshes. Default is 4.
statsDisabled bool // Flag to disable cache statistics.
statsHandler stats.Handler // Metrics statsHandler collector.
}您可以实现stats.Handler接口并注册到Cache组件来自定义收集指标，例如使用Prometheus
采集指标。我们默认实现了通过日志打印统计指标，如下所示：
2023/09/11 16:42:30.695294 statslogger.go:178: [INFO] jetcache-go stats last 1m0s.
cache | qpm| hit_ratio| hit| miss| query| query_fail
------------+------------+------------+------------+------------+------------+------------
bench | 216440123| 100.00%| 216439867| 256| 256| 0|
bench_local | 216440123| 100.00%| 216434970| 5153| -| -|
bench_remote| 5153| 95.03%| 4897| 256| -| -|
------------+------------+------------+------------+------------+------------+------------import "github.com/mgtv-tech/jetcache-go/logger"
// Set your Logger
logger.SetDefaultLogger(l logger.Logger)import (
"github.com/mgtv-tech/jetcache-go"
"github.com/mgtv-tech/jetcache-go/encoding"
)
// Register your codec
encoding.RegisterCodec(codec Codec)
// Set your codec name
mycache := cache.New[string, any]("any",
cache.WithRemote(...),
cache.WithCodec(yourCodecName string))jetcache-go提供了自动刷新缓存的能力，目的是为了防止缓存失效时造成的雪崩效应打爆数据库。对一些key比较少，实时性要求不高，加载开销非常大的缓存场景，适合使用自动刷新。下面的代码指定每分钟刷新一次，1小时如果没有访问就停止刷新。如果缓存是redis或者多级缓存最后一级是redis，缓存加载行为是全局唯一的，也就是说不管有多少台服务器，同时只有一个服务器在刷新，目的是为了降低后端的加载负担。
mycache := cache.New(cache.WithName("any"),
// ...
// cache.WithRefreshDuration 设置异步刷新时间间隔
cache.WithRefreshDuration(time.Minute),
// cache.WithStopRefreshAfterLastAccess 设置缓存 key 没有访问后的刷新任务取消时间
cache.WithStopRefreshAfterLastAccess(time.Hour))
// `Once` 接口通过 `cache.Refresh(true)` 开启自动刷新
err := mycache.Once(ctx, key, cache.Value(obj), cache.Refresh(true), cache.Do(func(ctx context.Context) (any, error) {
return mockDBGetObject(1)
}))MGet 通过 golang的泛型机制 + Load 函数，非常友好的多级缓存批量查询ID对应的实体。如果缓存是redis或者多级缓存最后一级是redis，查询时采用Pipeline实现读写操作，提升性能。需要说明是，针对异常场景（IO异常、序列化异常等），我们设计思路是尽可能提供有损服务，防止穿透。
mycache := cache.New(cache.WithName("any"),
// ...
cache.WithRemoteExpiry(time.Minute),
)
cacheT := cache.NewT[int, *object](mycache)
ctx := context.TODO()
key := "mykey"
ids := []int{1, 2, 3}
ret := cacheT.MGet(ctx, key, ids, func(ctx context.Context, ids []int) (map[int]*object, error) {
return mockDBMGetObject(ids)
})jetcache-go默认实现了三种编解码方式，sonic、MsgPack和原生json。
选择指导：
- 追求编解码性能： 例如本地缓存命中率极高，但本地缓存byte数组转对象的反序列化操作非常耗CPU，那么选择
sonic。 - 兼顾性能和极致的存储空间： 选择
MsgPack，MsgPack采用MsgPack编解码，内容>64个字节，会采用snappy压缩。
Tip：使用的时候记得按需导包来完成对应的编解码器注册
_ "github.com/mgtv-tech/jetcache-go/encoding/sonic"
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