PHP使用Redis实现Session共享的实现示例


						前言



小型web服务, session数据基本是保存在本地(更多是本地磁盘文件), 但是当部署多台服务, 且需要共享session, 确保每个服务都能共享到同一份session数据.

redis 数据存储在内存中, 性能好, 配合持久化可确保数据完整.

设计方案



1. 通过php自身session配置实现







# 使用 redis 作为存储方案

session.save_handler = redis

session.save_path = "tcp://127.0.0.1:6379"

# 若设置了连接密码, 则使用如下

session.save_path = "tcp://127.0.0.1:6379?auth=密码"





测试代码





<?php

ini_set("session.save_handler", "redis");

ini_set("session.save_path", "tcp://127.0.0.1:6379");



session_start();

echo "<pre>";

$_SESSION['usertest'.rand(1,5)]=1;

var_dump($_SESSION);



echo "</pre>";







输出 ↓



array(2) {

  ["usertest1"]=>

  int(88)

  ["usertest3"]=>

  int(1)

}

usertest1|i:1;usertest3|i:1;





评价



  优点: 实现简单, 无需修改php代码

  缺点: 配置不支持多样化, 只能应用于简单场景



2. 设置用户自定义会话存储函数



通过 session_set_save_handler() 函数设置用户自定义会话函数.





session_set_save_handler ( callable $open , callable $close , callable $read , callable $write , callable $destroy , callable $gc [, callable $create_sid [, callable $validate_sid [, callable $update_timestamp ]]] ) : bool

  

# >= php5.4

session_set_save_handler ( object $sessionhandler [, bool $register_shutdown = TRUE ] ) : bool





在配置完会话存储函数后, 再执行 session_start() 即可.

具体代码略, 以下提供一份 Memcached 的(来自Symfony框架代码):





<?php



/*

 * This file is part of the Symfony package.

 *

 * (c) Fabien Potencier <fabien@symfony.com>

 *

 * For the full copyright and license information, please view the LICENSE

 * file that was distributed with this source code.

 */



namespace Symfony\Component\HttpFoundation\Session\Storage\Handler;



/**

 * MemcacheSessionHandler.

 *

 * @author Drak <drak@zikula.org>

 */

class MemcacheSessionHandler implements \SessionHandlerInterface

{

  /**

   * @var \Memcache Memcache driver.

   */

  private $memcache;



  /**

   * @var int Time to live in seconds

   */

  private $ttl;



  /**

   * @var string Key prefix for shared environments.

   */

  private $prefix;



  /**

   * Constructor.

   *

   * List of available options:

   * * prefix: The prefix to use for the memcache keys in order to avoid collision

   * * expiretime: The time to live in seconds

   *

   * @param \Memcache $memcache A \Memcache instance

   * @param array   $options An associative array of Memcache options

   *

   * @throws \InvalidArgumentException When unsupported options are passed

   */

  public function __construct(\Memcache $memcache, array $options = array())

  {

    if ($diff = array_diff(array_keys($options), array('prefix', 'expiretime'))) {

      throw new \InvalidArgumentException(sprintf(

        'The following options are not supported "%s"', implode(', ', $diff)

      ));

    }



    $this->memcache = $memcache;

    $this->ttl = isset($options['expiretime']) ? (int) $options['expiretime'] : 86400;

    $this->prefix = isset($options['prefix']) ? $options['prefix'] : 'sf2s';

  }



  /**

   * {@inheritdoc}

   */

  public function open($savePath, $sessionName)

  {

    return true;

  }



  /**

   * {@inheritdoc}

   */

  public function close()

  {

    return $this->memcache->close();

  }



  /**

   * {@inheritdoc}

   */

  public function read($sessionId)

  {

    return $this->memcache->get($this->prefix.$sessionId) ?: '';

  }



  /**

   * {@inheritdoc}

   */

  public function write($sessionId, $data)

  {

    return $this->memcache->set($this->prefix.$sessionId, $data, 0, time() + $this->ttl);

  }



  /**

   * {@inheritdoc}

   */

  public function destroy($sessionId)

  {

    return $this->memcache->delete($this->prefix.$sessionId);

  }



  /**

   * {@inheritdoc}

   */

  public function gc($maxlifetime)

  {

    // not required here because memcache will auto expire the records anyhow.

    return true;

  }



  /**

   * Return a Memcache instance

   *

   * @return \Memcache

   */

  protected function getMemcache()

  {

    return $this->memcache;

  }

}







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