Put session into cache (redis), DB

Why should SESSION be saved in cache

　As far as PHP is concerned, the session supported by the language itself is saved to a disk file in the form of a file and saved in a specified folder. The saved path can be set in the configuration file or using the function session_save_path() in the program. , but there are disadvantages to doing so,

The first is to save it to the file system, which is inefficient. As long as the session is used, the specified sessionid will be searched from multiple files, which is very inefficient.

The second is that when using multiple servers, the problem of session loss may occur (actually it is saved on other servers).

　Of course, saving in the cache can solve the above problem. If you use PHP's own session function, you can use the session_set_save_handler() function to easily re-control the session processing process. If you don't use PHP's session series functions, you can write a similar session function yourself. It's also possible. This is the project I'm working on now. It will calculate the hash as the sessionId based on the user's mid and login time. Each time it is requested, The sessionId must be added to be legal (it is not needed when logging in for the first time, the sessionId will be created at this time and returned to the client). This is also very convenient, concise and efficient. Of course, what I am mainly talking about in this article is "manipulating things" in PHP's own SESSION.

SESSION saved in cache

　 PHP saves the cache to redis. You can use the configuration file to modify the processing and saving of the session. Of course, you can also use the ini_set() function in the program to modify it. This is very convenient for testing. I will use this here. Method, of course, it is recommended to use configuration files in a production environment.

<span>php
</span><span>ini_set</span>("session.save_handler", "redis"<span>);
</span><span>ini_set</span>("session.save_path", "tcp://localhost:6379"<span>);
</span><span>session_start</span><span>();
</span><span>header</span>("Content-type:text/html;charset=utf-8"<span>);
</span><span>if</span>(<span>isset</span>(<span>$_SESSION</span>['view'<span>])){
    </span><span>$_SESSION</span>['view'] = <span>$_SESSION</span>['view'] + 1<span>;
}</span><span>else</span><span>{
    </span><span>$_SESSION</span>['view'] = 1<span>;
}
</span><span>echo</span> "【view】{<span>$_SESSION</span>['view']}";

Here, set the session.save_handler method to redis, and session.save_path to the address and port of redis. After setting, refresh, and then look back at redis. You will find that the sessionId is generated in redis, and the sessionId is the same as the one requested by the browser.

Isn’t it very convenient? You only need to change the configuration file to save the session in redis. But what I want to talk about here is to use the program to save the session to redis or db. Let’s take a look.

Rewrite the session processing function by yourself through the interface provided by php

Here you can first take a look at the function session_set_save_handler in PHP. PHP5.4 and later can directly implement the SessionHandlerInterface interface, and the code will be more concise. When rewriting, there are mainly the following methods

open(string $savePath, string $sessionName); //open is similar to a constructor and will be called when starting a session, such as after using the session_start() function

close(); //Similar to the destructor of a class, it is called after the write function is called, and will also be executed after session_write_close()

read(string $sessionId); //Called when reading session

write(string $sessionId, string $data); //Called when saving data

destory($sessionId); //When destroying the session (session_destory() or session_regenerate_id()) it will be called

gc($lifeTime); //Garbage cleaning function to clean up expired data

　The main thing is to implement these methods. You can set different specific methods according to different storage drivers. I have implemented mysql database and redis, two drivers for saving sessions. If necessary, you can expand it yourself. Expansion is very convenient and very convenient. easy.

The following is my redis implementation (db is similar to redis, redis code is less, posted here):

I used the interface method, which makes it easier to expand. I wanted to use memcached that day, so just add it directly

<span>php
</span><span>include_once</span> __DIR__."/interfaceSession.php"<span>;
</span><span>/*</span><span>*
 * 以db的方式存储session
 </span><span>*/</span>
<span>class</span> redisSession <span>implements</span><span> interfaceSession{
    </span><span>/*</span><span>*
     * 保存session的数据库表的信息
     </span><span>*/</span>
    <span>private</span> <span>$_options</span> = <span>array</span><span>(
        </span>'handler' => <span>null</span>, <span>//</span><span>数据库连接句柄</span>
        'host' => <span>null</span>,
        'port' => <span>null</span>,
        'lifeTime' => <span>null</span>,<span>
    );

    </span><span>/*</span><span>*
     * 构造函数
     * @param $options 设置信息数组
     </span><span>*/</span>
    <span>public</span> <span>function</span> __construct(<span>$options</span>=<span>array</span><span>()){
        </span><span>if</span>(!<span>class_exists</span>("redis", <span>false</span><span>)){
            </span><span>die</span>("必须安装redis扩展"<span>);
        }
        </span><span>if</span>(!<span>isset</span>(<span>$options</span>['lifeTime']) || <span>$options</span>['lifeTime'] ){
            <span>$options</span>['lifeTime'] = <span>ini_get</span>('session.gc_maxlifetime'<span>);
        }
        </span><span>$this</span>->_options = <span>array_merge</span>(<span>$this</span>->_options, <span>$options</span><span>);
    }

    </span><span>/*</span><span>*
     * 开始使用该驱动的session
     </span><span>*/</span>
    <span>public</span> <span>function</span><span> begin(){
        </span><span>if</span>(<span>$this</span>->_options['host'] === <span>null</span> ||
           <span>$this</span>->_options['port'] === <span>null</span> ||
           <span>$this</span>->_options['lifeTime'] === <span>null</span><span>
        ){
            </span><span>return</span> <span>false</span><span>;
        }
        </span><span>//</span><span>设置session处理函数</span>
        <span>session_set_save_handler</span><span>(
            </span><span>array</span>(<span>$this</span>, 'open'),
            <span>array</span>(<span>$this</span>, 'close'),
            <span>array</span>(<span>$this</span>, 'read'),
            <span>array</span>(<span>$this</span>, 'write'),
            <span>array</span>(<span>$this</span>, 'destory'),
            <span>array</span>(<span>$this</span>, 'gc'<span>)
        );
    }
    </span><span>/*</span><span>*
     * 自动开始回话或者session_start()开始回话后第一个调用的函数
     * 类似于构造函数的作用
     * @param $savePath 默认的保存路径
     * @param $sessionName 默认的参数名，PHPSESSID
     </span><span>*/</span>
    <span>public</span> <span>function</span> open(<span>$savePath</span>, <span>$sessionName</span><span>){
        </span><span>if</span>(<span>is_resource</span>(<span>$this</span>->_options['handler'])) <span>return</span> <span>true</span><span>;
        </span><span>//</span><span>连接redis</span>
        <span>$redisHandle</span> = <span>new</span><span> Redis();
        </span><span>$redisHandle</span>->connect(<span>$this</span>->_options['host'], <span>$this</span>->_options['port'<span>]);
        </span><span>if</span>(!<span>$redisHandle</span><span>){
            </span><span>return</span> <span>false</span><span>;
        }

        </span><span>$this</span>->_options['handler'] = <span>$redisHandle</span><span>;
        </span><span>$this</span>->gc(<span>null</span><span>);
        </span><span>return</span> <span>true</span><span>;

    }

    </span><span>/*</span><span>*
     * 类似于析构函数，在write之后调用或者session_write_close()函数之后调用
     </span><span>*/</span>
    <span>public</span> <span>function</span><span> close(){
        </span><span>return</span> <span>$this</span>->_options['handler']-><span>close();
    }

    </span><span>/*</span><span>*
     * 读取session信息
     * @param $sessionId 通过该Id唯一确定对应的session数据
     * @return session信息/空串
     </span><span>*/</span>
    <span>public</span> <span>function</span> read(<span>$sessionId</span><span>){
        </span><span>return</span> <span>$this</span>->_options['handler']->get(<span>$sessionId</span><span>);
    }

    </span><span>/*</span><span>*
     * 写入或者修改session数据
     * @param $sessionId 要写入数据的session对应的id
     * @param $sessionData 要写入的数据，已经序列化过了
     </span><span>*/</span>
    <span>public</span> <span>function</span> write(<span>$sessionId</span>, <span>$sessionData</span><span>){
        </span><span>return</span> <span>$this</span>->_options['handler']->setex(<span>$sessionId</span>, <span>$this</span>->_options['lifeTime'], <span>$sessionData</span><span>);
    }

    </span><span>/*</span><span>*
     * 主动销毁session会话
     * @param $sessionId 要销毁的会话的唯一id
     </span><span>*/</span>
    <span>public</span> <span>function</span> destory(<span>$sessionId</span><span>){
        </span><span>return</span> <span>$this</span>->_options['handler']->delete(<span>$sessionId</span>) >= 1 ? <span>true</span> : <span>false</span><span>;
    }

    </span><span>/*</span><span>*
     * 清理绘画中的过期数据
     * @param 有效期
     </span><span>*/</span>
    <span>public</span> <span>function</span> gc(<span>$lifeTime</span><span>){
        </span><span>//</span><span>获取所有sessionid，让过期的释放掉</span>
        <span>$this</span>->_options['handler']->keys("*"<span>);
        </span><span>return</span> <span>true</span><span>;
    }

}</span>

Look at the simple factory pattern

<span>class</span><span> session {
    </span><span>/*</span><span>*
     * 驱动程序句柄保存
     </span><span>*/</span>
    <span>private</span> <span>static</span> <span>$_handler</span> = <span>null</span><span>;

    </span><span>/*</span><span>*
     * 创建session驱动程序
     </span><span>*/</span>
    <span>public</span> <span>static</span> <span>function</span> getSession(<span>$type</span>, <span>$options</span><span>){
        </span><span>//</span><span>单例</span>
        <span>if</span>(<span>isset</span>(<span>$handler</span><span>)){
            </span><span>return</span> self::<span>$_handler</span><span>;
        }

        </span><span>switch</span> (<span>$type</span><span>) {
            </span><span>case</span> 'db': <span>//</span><span>数据库驱动session类型</span>
                    <span>include_once</span> __DIR__."/driver/dbSession.php"<span>;
                    </span><span>$handler</span> = <span>new</span> dbSession(<span>$options</span><span>);
                </span><span>break</span><span>;
            
            </span><span>case</span> 'redis': <span>//</span><span>redis驱动session类型</span>
                    <span>include_once</span> __DIR__."/driver/redisSession.php"<span>;
                    </span><span>$handler</span> = <span>new</span> redisSession(<span>$options</span><span>);
                </span><span>break</span><span>;
            </span><span>default</span>:
                    <span>return</span> <span>false</span><span>;
                </span><span>break</span><span>;
        }

        </span><span>return</span> self::<span>$_handler</span> = <span>$handler</span><span>;
    }
}</span>

　Calling is also very simple,

session::getSession('redis',<span>array</span><span>(
        </span>'host' => "localhost",
        'port' => "6379",<span>
    ))</span>-><span>begin();

</span><span>session_start</span>();

　The database version is also very simple to configure. If necessary, you can download the full version and demo here

　The copyright of this article belongs to the author iforever (luluyrt@163.com). Any form of reprinting is prohibited without the author's consent. After reprinting the article, the author and the original text link must be provided in an obvious position on the article page, otherwise the right to pursue legal liability is reserved. .

The above introduces the session into cache (redis) and DB, including the content. I hope it will be helpful to friends who are interested in PHP tutorials.