Detailed explanation of using Redis to save user sessions

Preface

PHP’s built-in painting storage mechanism is Save all session data in text files on the server. These files are usually stored in a temporary directory on the server. If the amount of concurrency is large, the reading and writing efficiency is very low. Redis has very good support for high concurrency, so you can use redis to replace file storage sessions.

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session_set_save_handler function

PHP's session_set_save_handler function is used to define user-level session saving functions (such as opening, closing, writing, etc.). The prototype is as follows:

bool session_set_save_hanler(callback open,callback close,callback read,callback write,callback destory,callback gc)

Session management class

Find the PHP configuration file php.ini and modify it to Below, save and restart the php-fpm service.

session.save_handler = redis

We write a class to manage sessions:

<?php 
class SessionManager{

 private $redis;
 private $sessionSavePath;
 private $sessionName;
 private $sessionExpireTime = 60;//redis，session的过期时间为30s

 public function __construct(){
 $this->redis = new Redis();//创建phpredis实例
 $this->redis->connect(&#39;127.0.0.1&#39;, 6379);//连接redis
 //$this->redis->auth("123456x");//授权
 $retval = session_set_save_handler(
 array($this,"open"),
 array($this,"close"),
 array($this,"read"),
 array($this,"write"),
 array($this,"destroy"),
 array($this,"gc")
 );
 session_start();
 }

 public function open($path,$name){
 return true;
 }

 public function close(){
 return true;
 }

 public function read($id){
 $value = $this->redis->get($id);//获取redis中的指定记录
 if($value){
 return $value;
 }else{
 return &#39;&#39;;
 }
 }

 public function write($id,$data){
 if($this->redis->set($id,$data)){//以session ID为键，存储
 $this->redis->expire($id,$this->sessionExpireTime);//设置redis中数据的过期时间，即session的过期时间
 return true;
 }

 return false;
 }

 public function destroy($id){
 if($this->redis->delete($id)){//删除redis中的指定记录
 return true;
 }
 return false;
 }

 public function gc($maxlifetime){
 return true;
 }

 public function __destruct(){
 session_write_close();
 }
}

The SessionManager constructor is mainly used to connect to the Redis server, use the session_set_save_handler function to set the session callback function, and call session_startThe function starts the session function. Because the open, close and gc callback functions in this example are not very useful, they return true directly.

In the write callback function, use the session ID as the key, store the session data as the value in the redis server, and set the session expiration time to 30 seconds. In the read callback function, use the session ID as the key to read data from the redis server and return this data. In the destroy callback function, the session ID is used as the key to delete the corresponding session data from the redis server.

Using Session

First create a set.php file to set the Session:

<?php 
require_once &#39;SessionManager.php&#39;;
new SessionManager();
$_SESSION[&#39;username&#39;] = &#39;helloweba&#39;;

Then Create the get.php file to obtain the Session:

<?php 
require_once &#39;SessionManager.php&#39;;
new SessionManager();
echo $_SESSION[&#39;username&#39;];

Obviously, we first include the session management class, and then after instantiation, we can use the normal PHP session function.

When testing, first access set.php, and then access get.php. The output result is as follows:

Finally, we check it in redis Result:

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