缓存，Promies 和锁

package main
import (    "fmt"    "time"    "github.com/go-redis/redis"    "github.com/kristoff-it/redis-memolock/go/memolock")
func main () {    // First, we need a redis connection pool:    r := redis.NewClient(&redis.Options{        Addr:     "localhost:6379", // use default Addr        Password: "",               // no password set        DB:       0,                // use default DB    })
    // A memolock instance handles multiple resources of the same type,    // all united by the same tag name, which will be then used as a key    // prefix in Redis.    queryResourceTag := "likes"    queryMemoLock, _ := memolock.NewRedisMemoLock(r, queryResourceTag, 5 * time.Second)    // This instance has a 5 second default lock timeout:    // Later in the code you can use the memolock to cache the result of a function and    // make sure that multiple requests don't cause a stampede.
    // Here I'm requesting a queryset (saved in Redis as a String) and providing      // a function that can be used if the value needs to be generated:    resourceID := "kristoff"    requestTimeout := 10 * time.Second    cachedQueryset, _ := queryMemoLock.GetResource(resourceID, requestTimeout,         func () (string, time.Duration, error) {            fmt.Println("Cache miss!\n")                        // Sleeping to simulate work.             <- time.After(2 * time.Second)
            result := fmt.Sprintf(`{"user":"%s", "likes": ["redis"]}`, resourceID)                        // The function will return a value, a cache time-to-live, and an error.            // If the error is not nil, it will be returned to you by GetResource()            return result, 5 * time.Second, nil        },    )
    fmt.Println(cachedQueryset)    fmt.Println("Launch the script multiple times, see what changes. Use redis-cli to see what happens in Redis.")}