在Golang中的不同包中获取Redis变量

Question

I'm using go-redis/redis and go-redis/cache to cache Go objects.

import (
    "communication/MQ_pkg"

    "gopkg.in/go-redis/cache.v3"
    "gopkg.in/vmihailenco/msgpack.v2"
)

obj := &VAR_STRUCT{}        

Codec.Set(&cache.Item{
            Key:    key,
            Object: obj,
        })

where obj is an structure having go maps(key value pair) By Using above code i am setting a key and saving values into it. This is in package common. Now i want to access this in different package say GetRedis_pkg without importing pkg. Is there are any way i can do that. And can i access particular map inside that that structure by any means using redis key imorted gopkg.in/go-redis/cache.v3 to use redis in my code

Answer 1

Yes, you can access the same map by using a common Codec instance for both packages and both of set and get operations. For this purposes you need to implement a singleton instance producer. Desirably it should be a thread safe implementation. In this way you will save a lot of resource and guarantee connection correctness. This is significant to keep a client the only to prevent bugs and save resource.

Client is a Redis client representing a pool of zero or more underlying connections. It's safe for concurrent use by multiple goroutines.

Singleton codec

package singleton

import (                       
    "sync"                     
    "gopkg.in/go-redis/cache.v5"
    "gopkg.in/redis.v5"
)                                                            

var codec *cache.Codec        
var once sync.Once             

func GetInstance() *cache.Codec {
    once.Do(func() {           
        client := redis.NewClient(&redis.Options{
            Addr:     "localhost:6379",
            Password: "", // no password set
            DB:       0,  // use default DB
        })

        codec = &cache.Codec{
            Redis: client,

            Marshal: func(v interface{}) ([]byte, error) {
                return msgpack.Marshal(v)
            },
            Unmarshal: func(b []byte, v interface{}) error {
                return msgpack.Unmarshal(b, v)
            },
        }
    })                         
    return codec            
}        

Set key using codec instance

package setter                           

import (                                         
    "github.com/Me/myapp/singleton"  
    "sync"                              
)                                       

func Set(keys []string, vals []SomeObj, wg *sync.WaitGroup){
    for i, k := range keys {            
        wg.Add(1)
        // singleton is thread safe and could be used with goroutines                       
        go func() {                     
            codec := single.GetInstance()

            codec.Set(&cache.Item{
                Key:        k,
                Object:     vals[i],
                Expiration: time.Hour,
            })
            wg.Done()                   
        }()                             
    }                                   
}                                       

Get object using the same codec instance

package getter                           

import (                                         
    "github.com/Me/myapp/singleton"  
    "sync"                              
)                                       

func Set(keys []string, wg *sync.WaitGroup) chan SomeObj {
    wanted_objs := make(chan *SomeObj)
    for i, k := range keys {            
        wg.Add(1)
        // singleton is thread safe and could be used with goroutines                       
        go func() {                     
            codec := singleton.GetInstance()
            wanted := new(SomeObj)
            if err := codec.Get(key, wanted); err == nil {
                wanted_objs <- wanted
            }
        }()
    }
    return wanted_objs
}