Redis 事务及发布订阅命令实现

事务本质：一组命令的集合！一个事务中的所有命名都会被序列化，在事务执行过程中，会按照顺序执行！
一次性、顺序性、排他性！执行一系列命令！Copy

127.0.0.1:6379[1]> MULTI    # 开启事务
OK
127.0.0.1:6379[1]> set k1 v1    # 命令入队
QUEUED
127.0.0.1:6379[1]> set k2 v2
QUEUED
127.0.0.1:6379[1]> get k2
QUEUED
127.0.0.1:6379[1]> set k3 v3
QUEUED
127.0.0.1:6379[1]> EXEC    # 执行事务
1) OK
2) OK
3) "v2"
4) OKCopy

127.0.0.1:6379[1]> multi    # 开启事务
OK
127.0.0.1:6379[1]> set k1 v1
QUEUED
127.0.0.1:6379[1]> set k2 v2
QUEUED
127.0.0.1:6379[1]> set k4 v2
QUEUED
127.0.0.1:6379[1]> DISCARD    # 取消事务
OK
127.0.0.1:6379[1]> get k4    # 事务队列中命令都不会被执行
(nil)Copy

127.0.0.1:6379[1]> MULTI
OK
127.0.0.1:6379[1]> set k1 v1
QUEUED
127.0.0.1:6379[1]> set k2 v2
QUEUED
127.0.0.1:6379[1]> set k3 v3
QUEUED
127.0.0.1:6379[1]> getset k3    # 错误的命名
(error) ERR wrong number of arguments for 'getset' command
127.0.0.1:6379[1]> set k4 v4
QUEUED
127.0.0.1:6379[1]> set k5 v5
QUEUED
127.0.0.1:6379[1]> EXEC    # 执行事务报错！
(error) EXECABORT Transaction discarded because of previous errors.
127.0.0.1:6379[1]> get k5    # 所有的命令都不会被执行！
(nil)Copy

127.0.0.1:6379[1]> set k1 v1
OK
127.0.0.1:6379[1]> multi
OK
127.0.0.1:6379[1]> incr k1
QUEUED
127.0.0.1:6379[1]> set k2 v2
QUEUED
127.0.0.1:6379[1]> set k3 v3
QUEUED
127.0.0.1:6379[1]> get k3
QUEUED
127.0.0.1:6379[1]> exec
1) (error) ERR value is not an integer or out of range    # 虽然一条命令报错了，但是依旧正常执行成功了
2) OK
3) OK
4) "v3"
127.0.0.1:6379[1]> get k2
"v2"
127.0.0.1:6379[1]> get k3
"v3"Copy

127.0.0.1:6379[1]> set money 100
OK
127.0.0.1:6379[1]> set out 0
OK
127.0.0.1:6379[1]> watch money    # 监视 mony
OK
127.0.0.1:6379[1]> multi    # 事务正常结束，数据期间没有发生变动，这个时候就正常执行成功
OK
127.0.0.1:6379[1]> decrby money 20
QUEUED
127.0.0.1:6379[1]> incrby out 20
QUEUED
127.0.0.1:6379[1]> exec
1) (integer) 80
2) (integer) 20Copy

127.0.0.1:6379[1]> watch money    # 监视money
OK
127.0.0.1:6379[1]> multi
OK
127.0.0.1:6379[1]> decrby money 10
QUEUED
127.0.0.1:6379[1]> incrby money 10
QUEUED
127.0.0.1:6379[1]> get money
QUEUED
127.0.0.1:6379[1]> exec    # 执行之前，另一个线程修改了值，就会导致事务执行失败
(nil)Copy

127.0.0.1:6379> SUBSCRIBE channel1
Reading messages... (press Ctrl-C to quit)
1) "subscribe"
2) "channel1"
3) (integer) 1Copy

127.0.0.1:6379> PUBLISH channel1 hello
(integer) 1Copy

127.0.0.1:6379> SUBSCRIBE channel1
Reading messages... (press Ctrl-C to quit)
1) "subscribe"
2) "channel1"
3) (integer) 1
1) "message"
2) "channel1"
3) "hello"Copy