用Redis来存储关注关系

Redis提供了丰富的数据类型，比起关系型数据库或者简单的Key-Value存储（比如Memcached）来，Redis的数据模型与实际应用的数据模型更相近。比如下面说到的好友关系的存储，原作者使用了Redis的 Sets（集合）数据结构。具体存储方式如下：对于每一个用户，其关注关系存储两份列表，一份为此用户关注的人的UID列表，另一份为此用户粉丝的UID列表，这两个列表都使用Sets（集合）。比如对于用户ID为123的用户，graph:user:123:following 保存的是其关注人的列表，graph:user:1:followed_by 保存的是关注他的人的列表。下面是一个PHP代码的关注关系类，包括了常规的关注关系操作查询等方法，具体可看注释：<？/** This example would probably work best if you"re using* an MVC framework, but it can be used standalone as well.** This example also assumes you are using Predis, the excellent* PHP Redis library available here:* https://github.com/nrk/predis*/class UserNode { // The user"s ID, probably loaded from MySQL private $id; // The redis server configuration private $redis_config = array（ array（"host" => "localhost", "port" => 6379 ））; // Stores the redis connection resource so that // we only need to connect to Redis once private $redis; public function __construct（$userID） { $this->id = $userID; } private function redis（） { if （！$this->redis） { $this->redis = new PredisClient（$redis_config）; } return $this->redis; } /* * Makes this user follow the user with the given ID. * In order to stay efficient, we need to make a two-way * directed graph. This means when we follow a user, we also * say that that user is followed by this user, making a forward * and backword directed graph. */ public function follow（$user） { $this->redis（）->sadd（"graph:user:{$this->id}:following", $user）; $this->redis（）->sadd（"graph:user:$user:followed_by", $this->id）; } /* * Makes this user unfollow the user with the given ID. * First we check to make sure that we are actually following * the user we want to unfollow, then we remove both the forward * and backward references. */ public function unfollow（$user） { if （$this->is_following（）） { $this->redis（）->srem（"graph:user:{$this->id}:following", $user）; $this->redis（）->srem（"graph:user:$user:followed_by", $this->id）; } } /* * Returns an array of user ID"s that this user follows. */ public function following（） { return $this->redis（）->smembers（"graph:user:{$this->id}:following"）; } /* * Returns an array of user ID"s that this user is followed by. */ public function followed_by（） { return $this->redis（）->smembers（"graph:user:{$this->id}:followed_by"）; } /* * Test to see if this user is following the given user or not. * Returns a boolean. */ public function is_following（$user） { return $this->redis（）->sismember（"graph:user:{$this->id}:following", $user）; } /* * Test to see if this user is followed by the given user. * Returns a boolean. */ public function is_followed_by（$user） { return $this->redis（）->sismember（"graph:user:{$this->id}:followed_by", $user）; } /* * Tests to see if the relationship between this user and the given user is mutual. */ public function is_mutual（$user） { return （$this->is_following（$user） && $this->is_followed_by（$user））; } /* * Returns the number of users that this user is following. */ public function follow_count（） { return $this->redis（）->scard（"graph:user:{$this->id}:following"）; } /* * Retuns the number of users that follow this user. */ public function follower_count（） { return $this->redis（）->scard（"graph:user:{$this->id}:followed_by"）; } /* * Finds all users that the given users follow in common. * Returns an array of user IDs */ public function common_following（$users） { $redis = $this->redis（）; $users[] = $this->id; $keys = array（）; foreach （$users as $user） { $keys[] = "graph:user:{$user}:following"; } return call_user_func_array（array（$redis, "sinter"）, $keys）; } /* * Finds all users that all of the given users are followed by in common. * Returns an array of user IDs */ public function common_followed_by（$users） { $redis = $this->redis（）; $users[] = $this->id; $keys = array（）; foreach （$users as $user） { $keys[] = "graph:user:{$user}:followed_by"; } return call_user_func_array（array（$redis, "sinter"）, $keys）; }}下面是使用这个类来操作关注关系的例子：<？// create two user nodes, assume for this example// they"re users with no social graph entries.$user1 = UserNode（1）;$user2 = UserNode（2）;$user1->follows（）; // array（）// add some followers$user1->follow（2）;$user1->follow（3）;// now check the follow list$user1->follows（）; // array（2, 3）// now we can also do:$user2->followed_by（）; // array（1）// if we do this...$user2->follow（3）;// then we can do this to see which people users #1 and #2 follow in common$user1->common_following（2）; // array（3）下面关于Redis的文章您也可能喜欢，不妨参考下：Ubuntu 14.04下Redis安装及简单测试 http://www.linuxidc.com/Linux/2014-05/101544.htmRedis主从复制基本配置 http://www.linuxidc.com/Linux/2015-03/115610.htmRedis集群明细文档 http://www.linuxidc.com/Linux/2013-09/90118.htmUbuntu 12.10下安装Redis（图文详解）+ Jedis连接Redis http://www.linuxidc.com/Linux/2013-06/85816.htmRedis系列-安装部署维护篇 http://www.linuxidc.com/Linux/2012-12/75627.htmCentOS 6.3安装Redis http://www.linuxidc.com/Linux/2012-12/75314.htmRedis安装部署学习笔记 http://www.linuxidc.com/Linux/2014-07/104306.htmRedis配置文件redis.conf 详解 http://www.linuxidc.com/Linux/2013-11/92524.htmRedis 的详细介绍：请点这里
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