redis的搭建及应用(五)-布隆过滤器插件

redis布隆过滤器

可以把布隆过滤器理解为bitmap结构，判断某个对象是否存在时，它可能会误判。但是布隆过滤器也不是特别不精确，只要参数设置得合理，它的精确度也可以控制得相对足够精确，只会有小小的误判概率。
总得来说，当布隆过滤器说某个值存在时，这个值可能不存在；当它说某个值不存在时，那就肯定不存在。

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布隆过滤器在项目开发中非常有用，主要应用在如下方面:

黑白名单
内容推广过滤器
爬虫地址url去重
邮件垃圾过滤
防止redis的缓存穿透

下载布隆过滤器插件

使用redis的布隆过滤器插件，实现布隆过滤器的功能。

wget https://github.com/RedisBloom/RedisBloom/archive/v2.2.4.tar.gz

编译

安装gcc

yum -y install gcc

makefile

make

拷贝redisbloom.so到容器

[root@localhost RedisBloom-2.2.4]# docker cp redisbloom.so redis_6379:/usr/local/etc/redis
                                             Successfully copied 334kB to redis_6379:/usr/local/etc/redis

修改配置文件

添加redisbloom.so到MODULES模块

# Load modules at startup. If the server is not able to load modules
# it will abort. It is possible to use multiple loadmodule directives.
#
# loadmodule /path/to/my_module.so
# loadmodule /path/to/other_module.so
loadmodule /usr/local/etc/redis/redisbloom.so

重启容器

docker restart redis_6379

              _._                                                  
           _.-``__ ''-._                                             
      _.-``    `.  `_.  ''-._           Redis 6.2.6 (00000000/0) 64 bit
  .-`` .-```.  ```\/    _.,_ ''-._                                  
 (    '      ,       .-`  | `,    )     Running in standalone mode
 |`-._`-...-` __...-.``-._|'` _.-'|     Port: 6379
 |    `-._   `._    /     _.-'    |     PID: 1
  `-._    `-._  `-./  _.-'    _.-'                                   
 |`-._`-._    `-.__.-'    _.-'_.-'|                                  
 |    `-._`-._        _.-'_.-'    |           https://redis.io       
  `-._    `-._`-.__.-'_.-'    _.-'                                   
 |`-._`-._    `-.__.-'    _.-'_.-'|                                  
 |    `-._`-._        _.-'_.-'    |                                  
  `-._    `-._`-.__.-'_.-'    _.-'                                   
      `-._    `-.__.-'    _.-'                                       
          `-._        _.-'                                           
              `-.__.-'                                               

1:M 20 Jul 2023 14:12:33.987 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
1:M 20 Jul 2023 14:12:33.987 # Server initialized
1:M 20 Jul 2023 14:12:33.987 # WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.
1:M 20 Jul 2023 14:12:33.988 * Module 'bf' loaded from /usr/local/etc/redis/redisbloom.so
1:M 20 Jul 2023 14:12:33.989 * Loading RDB produced by version 6.2.6
1:M 20 Jul 2023 14:12:33.989 * RDB age 0 seconds
1:M 20 Jul 2023 14:12:33.989 * RDB memory usage when created 0.77 Mb
1:M 20 Jul 2023 14:12:33.989 # Done loading RDB, keys loaded: 0, keys expired: 0.
1:M 20 Jul 2023 14:12:33.989 * DB loaded from disk: 0.001 seconds
1:M 20 Jul 2023 14:12:33.989 * Ready to accept connections

布隆过滤器命令

BF.ADD

BF.ADD key item

127.0.0.1:6379> bf.add usernames tom
(integer) 1
127.0.0.1:6379> bf.add usernames jack
(integer) 1

BF.EXISTS

BF.EXISTS key item

127.0.0.1:6379> bf.exists usernames tom
(integer) 1
127.0.0.1:6379> bf.exists usernames jack
(integer) 1
127.0.0.1:6379> bf.exists usernames jackx
(integer) 0