跨路线共享Redis设置

Question

I have a number of routes in my routes.go file and they all call my redis database. I'm wondering how I can avoid calling the dial and AUTH calls in every route.

I've tried setting variables outside the functions like this:

var (
  c, err = redis.Dial("tcp", ADDRESS)
  _, err = c.Do("AUTH", "testing")
)

but then the compiler doesn't like err being used twice.

Answer 1

First, only use var for declaring variables. You can't run code outside of functions, so there's no use in trying to create connections inside a var statement. Use init() if you need something run at startup.

The redis connections can't be used with concurrent requests. If you want to share a redis connection across multiple routes, you need to have a safe method for concurrent use. In the case of github.com/garyburd/redigo/redis you want to use a Pool. You can do the AUTH call inside the Dial function, returning a ready connection each time.

var redisPool *redis.Pool

func init() {
    redisPool = &redis.Pool{
        MaxIdle:     3,
        IdleTimeout: 240 * time.Second,
        Dial: func() (redis.Conn, error) {
            c, err := redis.Dial("tcp", server)
            if err != nil {
                return nil, err
            }
            if _, err := c.Do("AUTH", password); err != nil {
                c.Close()
                return nil, err
            }
            return c, err
        },
    }
}

Then each time you need a connection, you get one from the pool, and return it when you're done.

conn := redisPool.Get()
// conn.Close() just returns the connection to the pool
defer conn.Close()

if err := conn.Err(); err != nil {
    // conn.Err() will have connection or Dial related errors
    return nil, err
}