// zpop pops a value from the ZSET key using WATCH/MULTI/EXEC commands.
func zpop(c redis.Conn, key string) (result string, err error) {
defer func() {
// Return connection to normal state on error.
if err != nil {
c.Do("DISCARD")
}
}()
// Loop until transaction is successful.
for {
if _, err := c.Do("WATCH", key); err != nil {
return "", err
}
members, err := redis.Strings(c.Do("ZRANGE", key, 0, 0))
if err != nil {
return "", err
}
if len(members) != 1 {
return "", redis.ErrNil
}
c.Send("MULTI")
c.Send("ZREM", key, members[0])
queued, err := c.Do("EXEC")
if err != nil {
return "", err
}
if queued != nil {
result = members[0]
break
}
}
return result, nil
}
v interface{}
err error
}
func ve(v interface{}, err error) valueError {
return valueError{v, err}
}
var replyTests = []struct {
name interface{}
actual valueError
expected valueError
}{
{
"strings([v1, v2])",
ve(redis.Strings([]interface{}{[]byte("v1"), []byte("v2")}, nil)),
ve([]string{"v1", "v2"}, nil),
},
{
"strings(nil)",
ve(redis.Strings(nil, nil)),
ve([]string(nil), redis.ErrNil),
},
{
"values([v1, v2])",
ve(redis.Values([]interface{}{[]byte("v1"), []byte("v2")}, nil)),
ve([]interface{}{[]byte("v1"), []byte("v2")}, nil),
},
{
"values(nil)",
ve(redis.Values(nil, nil)),