Redis Cache

Redis Cache is a library for caching any data structure in Redis. Redis Cache is meant to be used with the official Redis Go client and works by unmarshalling and marshaling data structures from/to bytes automatically. By default, Redis Cache will use msgpack to marshal/unmarshal data, but you can customize the behavior by providing your own Marshaller and Unmarshaller using the Serialization option with the NewCache function.

Features

• Save/Load any data structure that can be represented as bytes/string
• Marshalling/Unmarshalling
• Compression
• Instrumentation/Metrics for Prometheus or OpenTelemetry

Requirements

• Go 1.19+
• Redis 6+

Getting Redis Cache

go get github.com/jkratz55/redis-cache

Usage

Under the hood Redis Cache was designed to be used with go-redis. However, it can work with any type that implements the RedisClient interface.

type RedisClient interface {
    Get(ctx context.Context, key string) *redis.StringCmd
    GetEx(ctx context.Context, key string, expiration time.Duration) *redis.StringCmd
    MGet(ctx context.Context, keys ...string) *redis.SliceCmd
    Set(ctx context.Context, key string, val any, ttl time.Duration) *redis.StatusCmd
    SetNX(ctx context.Context, key string, value any, expiration time.Duration) *redis.BoolCmd
    SetXX(ctx context.Context, key string, value any, expiration time.Duration) *redis.BoolCmd
    Del(ctx context.Context, keys ...string) *redis.IntCmd
    Watch(ctx context.Context, fn func(*redis.Tx) error, keys ...string) error
    Scan(ctx context.Context, cursor uint64, match string, count int64) *redis.ScanCmd
    FlushDB(ctx context.Context) *redis.StatusCmd
    FlushDBAsync(ctx context.Context) *redis.StatusCmd
    Ping(ctx context.Context) *redis.StatusCmd
    TTL(ctx context.Context, key string) *redis.DurationCmd
    Expire(ctx context.Context, key string, expiration time.Duration) *redis.BoolCmd
}

This means that the Cache type can work with the following types in the go-redis client library.

• redis.Client
• redis.ClusterClient
• redis.Ring

The following example shows the basic usage of the Redis Cache library.

package main

import (
	"context"
	"fmt"

	"github.com/redis/go-redis/v9"

	rcache "github.com/jkratz55/redis-cache"
)

type Person struct {
	FirstName string
	LastName  string
	Age       int
}

func main() {
	client := redis.NewClient(&redis.Options{
		Addr: "localhost:6379",
	})

	cache := rcache.NewCache(client)

	if err := cache.Set(context.Background(), "person", Person{
		FirstName: "Biily",
		LastName:  "Bob",
		Age:       45,
	}); err != nil {
		panic("ohhhhh snap!")
	}

	var p Person
	if err := cache.Get(context.Background(), "person", &p); err != nil {
		panic("ohhhhh snap")
	}
	fmt.Printf("%v\n", p)

	if err := cache.Delete(context.Background(), "person"); err != nil {
		panic("ohhh snap!")
	}

	if err := cache.Get(context.Background(), "person", &p); err != rcache.ErrKeyNotFound {
		panic("ohhhhh snap, this key should be gone!")
	}
}

If you wanted to use json instead of msgpack you could have customized the Cache like the example below.

marshaller := func(v any) ([]byte, error) {
    return json.Marshal(v)
}
unmarshaller := func(data []byte, v any) error {
    return json.Unmarshal(data, v)
}
rdb := rcache.NewCache(client, rcache.Serialization(marshaller, unmarshaller))

Because of limitations in GO's implementation of generics MGet is a function instead of a method on the Cache type. The MGet function accepts the Cache type as an argument to leverage the same marshaller and unmarshaller.

This library also supports atomic updates of existing keys by using the Upsert and UpsertTTL functions. If the key was modified while the upsert is in progress it will return RetryableError signaling the operation can be retried and the UpsertCallback can decide how to handle merging the changes.

Compression

In some cases compressing values stored in Redis can have tremendous benefits, particularly when storing large volumes of data, large values per key, or both. Compression reduces the size of the cache, significantly decreases bandwidth and latency but at the cost of additional CPU consumption.

This library can be configured to automatically compress and decompress values using the Compression option when calling NewCache. It accepts a Codec and out of the box gzip, flate, and lz4 are supported. However, you are free to compress data any way you please by implementing the Codec interface.

package main

import (
	"context"
	"fmt"

	"github.com/redis/go-redis/v9"

	rcache "github.com/jkratz55/redis-cache"
)

type Person struct {
	FirstName string
	LastName  string
	Age       int
}

func main() {
	client := redis.NewClient(&redis.Options{
		Addr: "localhost:6379",
	})

	c := rcache.NewCache(client, rcache.GZip())

	if err := c.Set(context.Background(), "person", Person{
		FirstName: "Biily",
		LastName:  "Bob",
		Age:       45,
	}); err != nil {
		panic("ohhhhh snap!")
	}

	var p Person
	if err := c.Get(context.Background(), "person", &p); err != nil {
		panic("ohhhhh snap")
	}
	fmt.Printf("%v\n", p)

	if err := c.Delete(context.Background(), "person"); err != nil {
		panic("ohhh snap!")
	}

	if err := c.Get(context.Background(), "person", &p); err != rcache.ErrKeyNotFound {
		panic("ohhhhh snap, this key should be gone!")
	}
}

Instrumentation

This library provides out of the box instrumentation for either Prometheus or OpenTelemetry. Instrumentation is provided for both the Redis Client and the Cache with minimal code.

Example for Prometheus:

func main() {

	redisClient := redis.NewClient(&redis.Options{
		Addr:         "localhost:6379",
		MinIdleConns: 10,
		MaxIdleConns: 100,
		PoolSize:     1000,
	})

	if err := redisClient.Ping(context.Background()).Err(); err != nil {
		fmt.Println("Opps ping to Redis failed!", err)
	}

	// Enable Redis client metrics
	if err := prometheus.InstrumentClientMetrics(redisClient); err != nil {
		panic(err)
	}

	rdb := cache.NewCache(redisClient)

	// Enable Cache metrics
	if err := prometheus.InstrumentMetrics(rdb); err != nil {
		panic(err)
	}

	// write some useful code here ...
}

The InstrumentClientMetrics and InstrumentMetrics functions accept Options to customize the metrics configuration if needed.