How is the session initialized?

dmitry_fedyuk · May 8, 2017, 1:19pm

app/etc/di.xml

magento/magento2/blob/2.1.6/app/etc/di.xml#L111-L111


<preference for="Magento\Framework\Session\SessionManagerInterface" type="Magento\Framework\Session\Generic" />

Magento\Framework\Session\Generic

github.com

magento/magento2/blob/2.1.6/lib/internal/Magento/Framework/Session/Generic.php#L6-L10


namespace Magento\Framework\Session;


class Generic extends SessionManager
{
}

Details: The virtualType variants of Magento\Framework\Session\Generic

Step 1. Magento\Framework\Session\SessionManager::__construct()

github.com

magento/magento2/blob/2.1.6/lib/internal/Magento/Framework/Session/SessionManager.php#L95-L131


/**
 * @param \Magento\Framework\App\Request\Http $request
 * @param SidResolverInterface $sidResolver
 * @param ConfigInterface $sessionConfig
 * @param SaveHandlerInterface $saveHandler
 * @param ValidatorInterface $validator
 * @param StorageInterface $storage
 * @param \Magento\Framework\Stdlib\CookieManagerInterface $cookieManager
 * @param \Magento\Framework\Stdlib\Cookie\CookieMetadataFactory $cookieMetadataFactory
 * @param \Magento\Framework\App\State $appState
 * @throws \Magento\Framework\Exception\SessionException
 */
public function __construct(
    \Magento\Framework\App\Request\Http $request,
    SidResolverInterface $sidResolver,
    ConfigInterface $sessionConfig,
    SaveHandlerInterface $saveHandler,
    ValidatorInterface $validator,
    StorageInterface $storage,
    \Magento\Framework\Stdlib\CookieManagerInterface $cookieManager,
    \Magento\Framework\Stdlib\Cookie\CookieMetadataFactory $cookieMetadataFactory,
    \Magento\Framework\App\State $appState
) {
    $this->request = $request;
    $this->sidResolver = $sidResolver;
    $this->sessionConfig = $sessionConfig;
    $this->saveHandler = $saveHandler;
    $this->validator = $validator;
    $this->storage = $storage;
    $this->cookieManager = $cookieManager;
    $this->cookieMetadataFactory = $cookieMetadataFactory;
    $this->appState = $appState;


    // Enable session.use_only_cookies
    ini_set('session.use_only_cookies', '1');
    $this->start();
}

Details: How does Magento 2 detect whether it should use the database or filesystem to store the visitors sessions?

Step 2. Magento\Customer\CustomerData\Plugin\SessionChecker::beforeStart()

github.com

magento/magento2/blob/2.1.6/app/code/Magento/Customer/etc/frontend/di.xml#L60-L62


<type name="Magento\Framework\Session\SessionManager">
    <plugin name="session_checker" type="Magento\Customer\CustomerData\Plugin\SessionChecker" />
</type>

github.com

magento/magento2/blob/2.1.6/app/code/Magento/Customer/CustomerData/Plugin/SessionChecker.php#L36-L50


/**
 * Delete frontend session cookie if customer session is expired
 *
 * @param SessionManager $sessionManager
 */
public function beforeStart(SessionManager $sessionManager)
{
    if (!$this->cookieManager->getCookie($sessionManager->getName())
        && $this->cookieManager->getCookie('mage-cache-sessid')
    ) {
        $metadata = $this->cookieMetadataFactory->createCookieMetadata();
        $metadata->setPath('/');
        $this->cookieManager->deleteCookie('mage-cache-sessid', $metadata);
    }
}

Step 3. Magento\Framework\Session\SessionManager::start()

github.com

magento/magento2/blob/2.1.6/lib/internal/Magento/Framework/Session/SessionManager.php#L161-L199


/**
 * Configure session handler and start session
 *
 * @throws \Magento\Framework\Exception\SessionException
 * @return $this
 */
public function start()
{
    if (!$this->isSessionExists()) {
        \Magento\Framework\Profiler::start('session_start');


        try {
            $this->appState->getAreaCode();
        } catch (\Magento\Framework\Exception\LocalizedException $e) {
            throw new \Magento\Framework\Exception\SessionException(
                new \Magento\Framework\Phrase(
                    'Area code not set: Area code must be set before starting a session.'
                ),
                $e
            );
        }


        // Need to apply the config options so they can be ready by session_start
        $this->initIniOptions();
        $this->registerSaveHandler();


        // potential custom logic for session id (ex. switching between hosts)
        $this->setSessionId($this->sidResolver->getSid($this));
        session_start();
        $this->validator->validate($this);


        register_shutdown_function([$this, 'writeClose']);


        $this->_addHost();
        \Magento\Framework\Profiler::stop('session_start');
    }
    $this->storage->init(isset($_SESSION) ? $_SESSION : []);
    return $this;
}

Step 4. Magento\Framework\Session\SaveHandler::open()

github.com

magento/magento2/blob/2.1.6/lib/internal/Magento/Framework/Session/SaveHandler.php#L63-L73


/**
 * Open Session - retrieve resources
 *
 * @param string $savePath
 * @param string $name
 * @return bool
 */
public function open($savePath, $name)
{
    return $this->saveHandlerAdapter->open($savePath, $name);
}

dmitry_fedyuk · May 8, 2017, 2:19pm