class MemcacheSessionHandler

MemcacheSessionHandlerTest.php in drupal/core/vendor/symfony/http-foundation/Symfony/Component/HttpFoundation/Tests/Session/Storage/Handler/MemcacheSessionHandlerTest.php

class MemcacheSessionHandler implements \SessionHandlerInterface {

  /**
   * @var \Memcache Memcache driver.
   */
  private $memcache;

  /**
   * @var integer 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($lifetime) {

    // not required here because memcache will auto expire the records anyhow.
    return true;
  }

}