PHP使用Redis实现Session共享

摘要：年月日前言小型服务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确保每个服务都能共享到同一份数据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通过自身配置实现使用作为存储方案若设置了连接密码则使用如下密码测试代

Last-Modified: 2019年5月10日16:06:36

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.

# 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

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

echo "

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

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):

 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace SymfonyComponentHttpFoundationSessionStorageHandler;

/**
 * MemcacheSessionHandler.
 *
 * @author Drak 
 */
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;
    }
}