setRate function refresh the key expire time when the key exist?

[jinhao]

hi,
i have a question, this function below in store_redis.go

  func (s RedisStore) setRate(c redis.Conn, key string, rate Rate) ([]int, error) {
        c.Send("MULTI")
        c.Send("SETNX", key, 1)
        c.Send("EXPIRE", key, rate.Period.Seconds())
        return redis.Ints(c.Do("EXEC"))
 }

if the key exist in redis, the function will refresh the expire time of the key, it's design so or bug?

[gillesfabio]

Hi @jinhao,

Thanks for your interest.

This function uses SETNX. When key already holds a value, no operation is performed.

So, this function should not refresh the expire time of the key.

[jinhao]

@gillesfabio

redis 127.0.0.1:6379> get a
"18"
redis 127.0.0.1:6379> ttl a
(integer) 907
redis 127.0.0.1:6379> watch a
OK
redis 127.0.0.1:6379> MULTI
OK
redis 127.0.0.1:6379> setnx a 1000
QUEUED
redis 127.0.0.1:6379> expire a 1000
QUEUED
redis 127.0.0.1:6379> EXEC

1. (integer) 0
2. (integer) 1
   redis 127.0.0.1:6379> ttl a
   (integer) 995

this is my test result, .is it any problem? my redis version is 2.6.14

[jinhao]

@gillesfabio
I test it, and add print ttl every request

131     if count < rate.Limit {
132         remaining = rate.Limit - count
133     }
134
135     log.Printf("count:%d ttl:%d remaining:%d\n", count, ttl, remaining)

the result:

➜ http git:(master) ✗ go run main.go
Server is running on port 6379...
2015/10/27 19:03:28 count:2 ttl:60 remaining:2
2015/10/27 19:03:28 count:3 ttl:60 remaining:1
2015/10/27 19:03:30 count:4 ttl:60 remaining:0
2015/10/27 19:03:31 count:5 ttl:60 remaining:0
2015/10/27 19:03:31 count:6 ttl:60 remaining:0
2015/10/27 19:03:33 count:7 ttl:60 remaining:0
2015/10/27 19:03:34 count:8 ttl:60 remaining:0
2015/10/27 19:03:34 count:9 ttl:60 remaining:0
2015/10/27 19:03:36 count:10 ttl:60 remaining:0
2015/10/27 19:03:36 count:11 ttl:60 remaining:0
2015/10/27 19:03:36 count:12 ttl:60 remaining:0
2015/10/27 19:03:38 count:13 ttl:60 remaining:0
2015/10/27 19:03:38 count:14 ttl:60 remaining:0
2015/10/27 19:03:38 count:15 ttl:60 remaining:0
2015/10/27 19:03:49 count:16 ttl:60 remaining:0
2015/10/27 19:03:49 count:17 ttl:60 remaining:0
2015/10/27 19:03:49 count:18 ttl:60 remaining:0

[gillesfabio]

👍 Argh. Yes. SETNX only works with value.

Fixed here: 8ba0f24

Tell me if it works for you. I tried with a time.Sleep() and it properly sets TTL.

Thanks @jinhao.

[jinhao]

ok, it works! Thanks.