事务的原子性的解析
1.进队列之前redis已经识别错误了，会保持原子性
127.0.0.1:6379> get a
"100"
127.0.0.1:6379> multi
OK
127.0.0.1:6379> incrby a 10
QUEUED
127.0.0.1:6379> sda
(error) ERR unknown command 'sda'
127.0.0.1:6379> exec
(error) EXECABORT Transaction discarded because of previous errors.
127.0.0.1:6379> get a
"100"
2.进队列之前redis不能识别错误，会保持原子性（需要开发者规避）
127.0.0.1:6379> get a
"100"
127.0.0.1:6379> multi
OK
127.0.0.1:6379> incrby a 10
QUEUED
127.0.0.1:6379> sadd a "sss"
QUEUED
127.0.0.1:6379> exec
1) (integer) 110
2) (error) WRONGTYPE Operation against a key holding the wrong kind of value
127.0.0.1:6379> get a
"110"
3.watch加乐观锁(别的进程对key进行改变)
127.0.0.1:6379> get a
"100"
127.0.0.1:6379> watch a
OK
127.0.0.1:6379> multi
OK
127.0.0.1:6379> incrby a 10
QUEUED
127.0.0.1:6379> exec
(nil)
4.取消事务discard
直接取消队列
