使用Python操作Redis

深藏阁楼爱情的钟 2022-07-26 01:54 175阅读 0赞

转载地址：http://debugo.com/python-redis/

## 1. 安装pyredis ##

首先安装pip

<SHELL>\# apt-get install python-pip ...... <SHELL>\# pip install --proxy=http://172.1.2.6:8080 redis Downloading redis-2.9.1.tar.gz (62kB): 62kB downloaded Running setup.py (path:/tmp/pip\_build\_root/redis/setup.py) egg\_info for package redis ...... Successfully installed redis Cleaning up...

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      <span>&lt;</span> 
      <span>SHELL</span> 
      <span>&gt;</span> 
      <span># apt-get install python-pip</span> 
     </div> 
     <div> 
      <span>.</span> 
      <span>.</span> 
      <span>.</span> 
      <span>.</span> 
      <span>.</span> 
      <span>.</span> 
     </div> 
     <div> 
      <span>&lt;</span> 
      <span>SHELL</span> 
      <span>&gt;</span> 
      <span># pip install --proxy=http://172.1.2.6:8080 redis</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;</span> 
      <span>Downloading </span> 
      <span>redis</span> 
      <span>-</span> 
      <span>2.9.1.tar.gz</span> 
      <span> </span> 
      <span>(</span> 
      <span>62kB</span> 
      <span>)</span> 
      <span>:</span> 
      <span> </span> 
      <span>62kB</span> 
      <span> </span> 
      <span>downloaded</span> 
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      <span>&nbsp;&nbsp;</span> 
      <span>Running </span> 
      <span>setup</span> 
      <span>.py</span> 
      <span> </span> 
      <span>(</span> 
      <span>path</span> 
      <span>:</span> 
      <span>/</span> 
      <span>tmp</span> 
      <span>/</span> 
      <span>pip_build_root</span> 
      <span>/</span> 
      <span>redis</span> 
      <span>/</span> 
      <span>setup</span> 
      <span>.py</span> 
      <span>)</span> 
      <span> </span> 
      <span>egg_info </span> 
      <span>for</span> 
      <span> </span> 
      <span>package</span> 
      <span> </span> 
      <span>redis</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;</span> 
      <span>.</span> 
      <span>.</span> 
      <span>.</span> 
      <span>.</span> 
      <span>.</span> 
      <span>.</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;</span> 
      <span>Successfully </span> 
      <span>installed </span> 
      <span>redis</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;</span> 
      <span>Cleaning </span> 
      <span>up</span> 
      <span>.</span> 
      <span>.</span> 
      <span>.</span> 
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也可以使用easy\_install的方式来安装：

easy\_install redis

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      <span>easy_install </span> 
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或者直接编译安装：

wget https://pypi.python.org/packages/source/r/redis/redis-2.9.1.tar.gz tar xvzf redis-2.9.1.tar.gz cd redis-2.9.1 python setup.py install

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      <span>wget </span> 
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      <span>:</span> 
      <span>/</span> 
      <span>/</span> 
      <span>pypi</span> 
      <span>.python</span> 
      <span>.org</span> 
      <span>/</span> 
      <span>packages</span> 
      <span>/</span> 
      <span>source</span> 
      <span>/</span> 
      <span>r</span> 
      <span>/</span> 
      <span>redis</span> 
      <span>/</span> 
      <span>redis</span> 
      <span>-</span> 
      <span>2.9.1.tar.gz</span> 
     </div> 
     <div> 
      <span>tar </span> 
      <span>xvzf </span> 
      <span>redis</span> 
      <span>-</span> 
      <span>2.9.1.tar.gz</span> 
     </div> 
     <div> 
      <span>cd</span> 
      <span> </span> 
      <span>redis</span> 
      <span>-</span> 
      <span>2.9.1</span> 
     </div> 
     <div> 
      <span>python </span> 
      <span>setup</span> 
      <span>.py</span> 
      <span> </span> 
      <span>install</span> 
     </div> 
    </div> </td> 
  </tr> 
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</table>

## 2 . 简单的redis操作 ##

redis连接实例是线程安全的，可以直接将redis连接实例设置为一个全局变量，直接使用。如果需要另一个Redis实例（or Redis数据库）时，就需要重新创建redis连接实例来获取一个新的连接。同理，python的redis没有实现select命令。

>>> import redis >>> r = redis.Redis(host='localhost',port=6379,db=0) >>> r.set('guo','shuai') True >>> r.get('guo') 'shuai' >>> r\['guo'\] 'shuai' >>> r.keys() \['guo'\] >>> r.dbsize() \#当前数据库包含多少条数据 1L >>> r.delete('guo') 1 >>> r.save() \#执行“检查点”操作，将数据写回磁盘。保存时阻塞 True >>> r.get('guo'); >>> r.flushdb() \#清空r中的所有数据 True

## 3. pipeline操作 ##

管道（pipeline）是redis在提供单个请求中缓冲多条服务器命令的基类的子类。它通过减少服务器-客户端之间反复的TCP数据库包，从而大大提高了执行批量命令的功能。

>>> p = r.pipeline() --创建一个管道 >>> p.set('hello','redis') >>> p.sadd('faz','baz') >>> p.incr('num') >>> p.execute() \[True, 1, 1\] >>> r.get('hello') 'redis'

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      <span>&gt;&gt;&gt;</span> 
      <span> </span> 
      <span>p</span> 
      <span> </span> 
      <span>=</span> 
      <span> </span> 
      <span>r</span> 
      <span>.</span> 
      <span>pipeline</span> 
      <span>(</span> 
      <span>)</span> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>--</span>创建一个管道 
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      <span>&gt;&gt;&gt;</span> 
      <span> </span> 
      <span>p</span> 
      <span>.</span> 
      <span>set</span> 
      <span>(</span> 
      <span>'hello'</span> 
      <span>,</span> 
      <span>'redis'</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>&gt;&gt;&gt;</span> 
      <span> </span> 
      <span>p</span> 
      <span>.</span> 
      <span>sadd</span> 
      <span>(</span> 
      <span>'faz'</span> 
      <span>,</span> 
      <span>'baz'</span> 
      <span>)</span> 
     </div> 
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      <span>&gt;&gt;&gt;</span> 
      <span> </span> 
      <span>p</span> 
      <span>.</span> 
      <span>incr</span> 
      <span>(</span> 
      <span>'num'</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>&gt;&gt;&gt;</span> 
      <span> </span> 
      <span>p</span> 
      <span>.</span> 
      <span>execute</span> 
      <span>(</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>[</span> 
      <span>True</span> 
      <span>,</span> 
      <span> </span> 
      <span>1</span> 
      <span>,</span> 
      <span> </span> 
      <span>1</span> 
      <span>]</span> 
     </div> 
     <div> 
      <span>&gt;&gt;&gt;</span> 
      <span> </span> 
      <span>r</span> 
      <span>.</span> 
      <span>get</span> 
      <span>(</span> 
      <span>'hello'</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>'redis'</span> 
     </div> 
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管道的命令可以写在一起，如：

>>> p.set('hello','redis').sadd('faz','baz').incr('num').execute()

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    <div style=""> 
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      <span>&gt;&gt;&gt;</span> 
      <span> </span> 
      <span>p</span> 
      <span>.</span> 
      <span>set</span> 
      <span>(</span> 
      <span>'hello'</span> 
      <span>,</span> 
      <span>'redis'</span> 
      <span>)</span> 
      <span>.</span> 
      <span>sadd</span> 
      <span>(</span> 
      <span>'faz'</span> 
      <span>,</span> 
      <span>'baz'</span> 
      <span>)</span> 
      <span>.</span> 
      <span>incr</span> 
      <span>(</span> 
      <span>'num'</span> 
      <span>)</span> 
      <span>.</span> 
      <span>execute</span> 
      <span>(</span> 
      <span>)</span> 
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默认的情况下，管道里执行的命令可以保证执行的原子性，执行pipe = r.pipeline(transaction=False)可以禁用这一特性。

## 4. 应用场景 – 页面点击数 ##

《Redis Cookbook》对这个经典场景进行详细描述。假定我们对一系列页面需要记录点击次数。例如论坛的每个帖子都要记录点击次数，而点击次数比回帖的次数的多得多。如果使用关系数据库来存储点击，可能存在大量的行级锁争用。所以，点击数的增加使用redis的INCR命令最好不过了。  
当redis服务器启动时，可以从关系数据库读入点击数的初始值（1237这个页面被访问了34634次）

>>> r.set("visit:1237:totals",34634) True

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    <div style=""> 
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      <span>&gt;&gt;&gt;</span> 
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      <span>(</span> 
      <span>"visit:1237:totals"</span> 
      <span>,</span> 
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每当有一个页面点击，则使用INCR增加点击数即可。

>>> r.incr("visit:1237:totals") 34635 >>> r.incr("visit:1237:totals") 34636

页面载入的时候则可直接获取这个值

>>> r.get ("visit:1237:totals") '34636'

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      <span>get</span> 
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      <span>(</span> 
      <span>"visit:1237:totals"</span> 
      <span>)</span> 
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      <span>'34636'</span> 
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## 5. 使用hash类型保存多样化对象 ##

当有大量类型文档的对象，文档的内容都不一样时，（即“表”没有固定的列），可以使用hash来表达。

>>> r.hset('users:jdoe', 'name', "John Doe") 1L >>> r.hset('users:jdoe', 'email', 'John@test.com') 1L >>> r.hset('users:jdoe', 'phone', '1555313940') 1L >>> r.hincrby('users:jdoe', 'visits', 1) 1L >>> r.hgetall('users:jdoe') \{'phone': '1555313940', 'name': 'John Doe', 'visits': '1', 'email': 'John@test.com'\} >>> r.hkeys('users:jdoe') \['name', 'email', 'phone', 'visits'\]

## 6. 应用场景 – 社交圈子数据 ##

在社交网站中，每一个圈子(circle)都有自己的用户群。通过圈子可以找到有共同特征（比如某一体育活动、游戏、电影等爱好者）的人。当一个用户加入一个或几个圈子后，系统可以向这个用户推荐圈子中的人。  
我们定义这样两个圈子,并加入一些圈子成员。

>>> r.sadd('circle:game:lol','user:debugo') 1 >>> r.sadd('circle:game:lol','user:leo') 1 >>> r.sadd('circle:game:lol','user:Guo') 1 >>> r.sadd('circle:soccer:InterMilan','user:Guo') 1 >>> r.sadd('circle:soccer:InterMilan','user:Levis') 1 >>> r.sadd('circle:soccer:InterMilan','user:leo') 1

\#获得某一圈子的成员

>>> r.smembers('circle:game:lol') set(\['user:Guo', 'user:debugo', 'user:leo'\]) redis> smembers circle:jdoe:family

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      <span>(</span> 
      <span>'circle:game:lol'</span> 
      <span>)</span> 
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     <div> 
      <span>set</span> 
      <span>(</span> 
      <span>[</span> 
      <span>'user:Guo'</span> 
      <span>,</span> 
      <span> </span> 
      <span>'user:debugo'</span> 
      <span>,</span> 
      <span> </span> 
      <span>'user:leo'</span> 
      <span>]</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>redis</span> 
      <span>&gt;</span> 
      <span> </span> 
      <span>smembers </span> 
      <span>circle</span> 
      <span>:</span> 
      <span>jdoe</span> 
      <span>:</span> 
      <span>family</span> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
     </div> 
    </div> </td> 
  </tr> 
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可以使用集合运算来得到几个圈子的共同成员：

>>> r.sinter('circle:game:lol', 'circle:soccer:InterMilan') set(\['user:Guo', 'user:leo'\]) >>> r.sunion('circle:game:lol', 'circle:soccer:InterMilan') set(\['user:Levis', 'user:Guo', 'user:debugo', 'user:leo'\])

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    <div style=""> 
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      <span>&gt;&gt;&gt;</span> 
      <span> </span> 
      <span>r</span> 
      <span>.</span> 
      <span>sinter</span> 
      <span>(</span> 
      <span>'circle:game:lol'</span> 
      <span>,</span> 
      <span> </span> 
      <span>'circle:soccer:InterMilan'</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>set</span> 
      <span>(</span> 
      <span>[</span> 
      <span>'user:Guo'</span> 
      <span>,</span> 
      <span> </span> 
      <span>'user:leo'</span> 
      <span>]</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>&gt;&gt;&gt;</span> 
      <span> </span> 
      <span>r</span> 
      <span>.</span> 
      <span>sunion</span> 
      <span>(</span> 
      <span>'circle:game:lol'</span> 
      <span>,</span> 
      <span> </span> 
      <span>'circle:soccer:InterMilan'</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>set</span> 
      <span>(</span> 
      <span>[</span> 
      <span>'user:Levis'</span> 
      <span>,</span> 
      <span> </span> 
      <span>'user:Guo'</span> 
      <span>,</span> 
      <span> </span> 
      <span>'user:debugo'</span> 
      <span>,</span> 
      <span> </span> 
      <span>'user:leo'</span> 
      <span>]</span> 
      <span>)</span> 
     </div> 
    </div> </td> 
  </tr> 
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</table>

## 7. 应用场景 – 实时用户统计 ##

[Counting Online Users with Redis][]介绍了这个方法。当我们需要在页面上显示当前的在线用户时，就可以使用Redis来完成了。首先获得当前时间（以Unix timestamps方式）除以60，可以基于这个值创建一个key。然后添加用户到这个集合中。当超过你设定的最大的超时时间，则将这个集合设为过期；而当需要查询当前在线用户的时候，则将最后N分钟的集合交集在一起即可。由于redis连接对象是线程安全的，所以可以直接使用一个全局变量来表示。

import time from redis import Redis from datetime import datetime ONLINE\_LAST\_MINUTES = 5 redis = Redis() def mark\_online(user\_id): \#将一个用户标记为online now = int(time.time()) \#当前的UNIX时间戳 expires = now + (app.config\['ONLINE\_LAST\_MINUTES'\] \* 60) + 10 \#过期的UNIX时间戳 all\_users\_key = 'online-users/%d' % (now // 60) \#集合名，包含分钟信息 user\_key = 'user-activity/%s' % user\_id p = redis.pipeline() p.sadd(all\_users\_key, user\_id) \#将用户id插入到包含分钟信息的集合中 p.set(user\_key, now) \#记录用户的标记时间 p.expireat(all\_users\_key, expires) \#设定集合的过期时间为UNIX的时间戳 p.expireat(user\_key, expires) p.execute() def get\_user\_last\_activity(user\_id): \#获得用户的最后活跃时间 last\_active = redis.get('user-activity/%s' % user\_id) \#如果获取不到，则返回None if last\_active is None: return None return datetime.utcfromtimestamp(int(last\_active)) def get\_online\_users(): \#获得当前online用户的列表 current = int(time.time()) // 60 minutes = xrange(app.config\['ONLINE\_LAST\_MINUTES'\]) return redis.sunion(\['online-users/%d' % (current - x) \#取ONLINE\_LAST\_MINUTES分钟对应集合的交集 for x in minutes\])

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    <div style=""> 
     <div> 
      <span>import</span> 
      <span> </span> 
      <span>time</span> 
     </div> 
     <div> 
      <span>from</span> 
      <span> </span> 
      <span>redis </span> 
      <span>import</span> 
      <span> </span> 
      <span>Redis</span> 
     </div> 
     <div> 
      <span>from</span> 
      <span> </span> 
      <span>datetime</span> 
      <span> </span> 
      <span>import</span> 
      <span> </span> 
      <span>datetime</span> 
     </div> 
     <div> 
      <span>ONLINE_LAST_MINUTES</span> 
      <span> </span> 
      <span>=</span> 
      <span> </span> 
      <span>5</span> 
     </div> 
     <div> 
      <span>redis</span> 
      <span> </span> 
      <span>=</span> 
      <span> </span> 
      <span>Redis</span> 
      <span>(</span> 
      <span>)</span> 
     </div> 
     <div>
       &nbsp; 
     </div> 
     <div> 
      <span>def</span> 
      <span> </span> 
      <span>mark_online</span> 
      <span>(</span> 
      <span>user_id</span> 
      <span>)</span> 
      <span>:</span> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span> 
      <span>#将一个用户标记为online</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>now</span> 
      <span> </span> 
      <span>=</span> 
      <span> </span> 
      <span>int</span> 
      <span>(</span> 
      <span>time</span> 
      <span>.</span> 
      <span>time</span> 
      <span>(</span> 
      <span>)</span> 
      <span>)</span> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>#当前的UNIX时间戳</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>expires</span> 
      <span> </span> 
      <span>=</span> 
      <span> </span> 
      <span>now</span> 
      <span> </span> 
      <span>+</span> 
      <span> </span> 
      <span>(</span> 
      <span>app</span> 
      <span>.</span> 
      <span>config</span> 
      <span>[</span> 
      <span>'ONLINE_LAST_MINUTES'</span> 
      <span>]</span> 
      <span> </span> 
      <span>*</span> 
      <span> </span> 
      <span>60</span> 
      <span>)</span> 
      <span> </span> 
      <span>+</span> 
      <span> </span> 
      <span>10</span> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>#过期的UNIX时间戳</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>all_users_key</span> 
      <span> </span> 
      <span>=</span> 
      <span> </span> 
      <span>'online-users/%d'</span> 
      <span> </span> 
      <span>%</span> 
      <span> </span> 
      <span>(</span> 
      <span>now</span> 
      <span> </span> 
      <span>/</span> 
      <span>/</span> 
      <span> </span> 
      <span>60</span> 
      <span>)</span> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>#集合名，包含分钟信息</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>user_key</span> 
      <span> </span> 
      <span>=</span> 
      <span> </span> 
      <span>'user-activity/%s'</span> 
      <span> </span> 
      <span>%</span> 
      <span> </span> 
      <span>user</span> 
      <span>_</span>id 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>p</span> 
      <span> </span> 
      <span>=</span> 
      <span> </span> 
      <span>redis</span> 
      <span>.</span> 
      <span>pipeline</span> 
      <span>(</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>p</span> 
      <span>.</span> 
      <span>sadd</span> 
      <span>(</span> 
      <span>all_users_key</span> 
      <span>,</span> 
      <span> </span> 
      <span>user_id</span> 
      <span>)</span> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span> 
      <span>#将用户id插入到包含分钟信息的集合中</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>p</span> 
      <span>.</span> 
      <span>set</span> 
      <span>(</span> 
      <span>user_key</span> 
      <span>,</span> 
      <span> </span> 
      <span>now</span> 
      <span>)</span> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span> 
      <span>#记录用户的标记时间</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>p</span> 
      <span>.</span> 
      <span>expireat</span> 
      <span>(</span> 
      <span>all_users_key</span> 
      <span>,</span> 
      <span> </span> 
      <span>expires</span> 
      <span>)</span> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span> 
      <span>#设定集合的过期时间为UNIX的时间戳</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>p</span> 
      <span>.</span> 
      <span>expireat</span> 
      <span>(</span> 
      <span>user_key</span> 
      <span>,</span> 
      <span> </span> 
      <span>expires</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>p</span> 
      <span>.</span> 
      <span>execute</span> 
      <span>(</span> 
      <span>)</span> 
     </div> 
     <div>
       &nbsp; 
     </div> 
     <div> 
      <span>def</span> 
      <span> </span> 
      <span>get_user_last_activity</span> 
      <span>(</span> 
      <span>user_id</span> 
      <span>)</span> 
      <span>:</span> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>#获得用户的最后活跃时间</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>last_active</span> 
      <span> </span> 
      <span>=</span> 
      <span> </span> 
      <span>redis</span> 
      <span>.</span> 
      <span>get</span> 
      <span>(</span> 
      <span>'user-activity/%s'</span> 
      <span> </span> 
      <span>%</span> 
      <span> </span> 
      <span>user_id</span> 
      <span>)</span> 
      <span>&nbsp;&nbsp;</span> 
      <span>#如果获取不到，则返回None</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>if</span> 
      <span> </span> 
      <span>last_active </span> 
      <span>is</span> 
      <span> </span> 
      <span>None</span> 
      <span>:</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>return</span> 
      <span> </span> 
      <span>None</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>return</span> 
      <span> </span> 
      <span>datetime</span> 
      <span>.</span> 
      <span>utcfromtimestamp</span> 
      <span>(</span> 
      <span>int</span> 
      <span>(</span> 
      <span>last_active</span> 
      <span>)</span> 
      <span>)</span> 
     </div> 
     <div>
       &nbsp; 
     </div> 
     <div> 
      <span>def</span> 
      <span> </span> 
      <span>get_online_users</span> 
      <span>(</span> 
      <span>)</span> 
      <span>:</span> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span> 
      <span>#获得当前online用户的列表</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>current</span> 
      <span> </span> 
      <span>=</span> 
      <span> </span> 
      <span>int</span> 
      <span>(</span> 
      <span>time</span> 
      <span>.</span> 
      <span>time</span> 
      <span>(</span> 
      <span>)</span> 
      <span>)</span> 
      <span> </span> 
      <span>/</span> 
      <span>/</span> 
      <span> </span> 
      <span>60</span> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>minutes</span> 
      <span> </span> 
      <span>=</span> 
      <span> </span> 
      <span>xrange</span> 
      <span>(</span> 
      <span>app</span> 
      <span>.</span> 
      <span>config</span> 
      <span>[</span> 
      <span>'ONLINE_LAST_MINUTES'</span> 
      <span>]</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>return</span> 
      <span> </span> 
      <span>redis</span> 
      <span>.</span> 
      <span>sunion</span> 
      <span>(</span> 
      <span>[</span> 
      <span>'online-users/%d'</span> 
      <span> </span> 
      <span>%</span> 
      <span> </span> 
      <span>(</span> 
      <span>current</span> 
      <span> </span> 
      <span>-</span> 
      <span> </span> 
      <span>x</span> 
      <span>)</span> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>#取ONLINE_LAST_MINUTES分钟对应集合的交集</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span> 
      <span>for</span> 
      <span> </span> 
      <span>x</span> 
      <span> </span> 
      <span>in</span> 
      <span> </span> 
      <span>minutes</span> 
      <span>]</span> 
      <span>)</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

## References: ##

[http://blog.csdn.net/vv\_demon/article/details/7676384  
][http_blog.csdn.net_vv_demon_article_details_7676384]  
tigerfish NoSQL和NewSQL数据库引航  
《Redis Cookbook》  
Redis-Python https://pypi.python.org/pypi/redis/2.9.1

[Counting Online Users with Redis]: http://flask.pocoo.org/snippets/71/
[http_blog.csdn.net_vv_demon_article_details_7676384]: http://blog.csdn.net/vv_demon/article/details/7676384