session_write_close - PHP code example

Why Should You Use the PHP Function Session_WriteClose?

If you've been working with PHP for any length of time, then you have likely come across the php function session_write_close. But what is it exactly, and why should you use it?

Session handling is a way of making information available to different pages of your website or application. This allows you to track things like when a user starts browsing the site, what they're doing and how they close it. This is all done by storing all of this information in a temporary file on the webserver and allowing each page to access the data from that file.

PHP stores its sessions' data inside files. When a script uses a session, it acquires an exclusive lock on the file relative to the current Session, meaning that other scripts cannot read or write to the file until the current request finishes. This can cause issues if you're using AJAX to send data from one page to another. Because each AJAX call has to wait until the previous page's Session ends, it can take a long time for that to happen and slow down your webpage.

When you call session_write_close(), it closes the current session by writing the updated data to the file and releasing the lock on the file, enabling other scripts to continue reading the data from it. This can help you avoid the problem described above and also helps to clean up the $_SESSION array. You can also use it to regenerate the session ID and destroy all of the session data for that particular session, if you'd like.

session_write_close example

        $themeId = $this->Request()->getParam('themeId');
        $shopId = $this->Request()->getParam('shopId');

        $theme = $this->getRepository()->find($themeId);
        if (!$theme instanceof Template) {
            throw new ModelNotFoundException(Template::class, $themeId);
        }

        $shop = $this->getManager()->getRepository(Shop::class)->getActiveById($shopId);

        session_write_close();

        $this->get(ShopRegistrationServiceInterface::class)->registerShop($shop);

        $session = $this->get('session');

        $session->template = $theme->getTemplate();
        $session->Admin = true;

        if (!$this->Request()->isXmlHttpRequest()) {
            $this->get('events')->notify('Shopware_Theme_Preview_Starts', [
                'session' => Shopware()->Session(),

// Register error handler to add information about the current save handler         $previousHandler = set_error_handler(function D$type, $msg, $file, $line) use (&$previousHandler) {
            if (\E_WARNING === $type && str_starts_with($msg, 'session_write_close():')) {
                $handler = $this->saveHandler instanceof SessionHandlerProxy ? $this->saveHandler->getHandler() : $this->saveHandler;
                $msg = sprintf('session_write_close(): Failed to write session data with "%s" handler', $handler::class);
            }

            return $previousHandler ? $previousHandler($type, $msg, $file, $line) : false;
        });

        try {
            session_write_close();
        } finally {
            restore_error_handler();

            // Restore only if not empty             if ($_SESSION) {
                $_SESSION = $session;
            }
        }

        $this->closed = true;
        $this->started = false;
    }

protected function setUp(): void
    {
        $this->iniSet('session.save_handler', 'files');
        $this->iniSet('session.save_path', $this->savePath = sys_get_temp_dir().'/sftest');
        if (!is_dir($this->savePath)) {
            mkdir($this->savePath);
        }
    }

    protected function tearDown(): void
    {
        session_write_close();
        array_map('unlink', glob($this->savePath.'/*'));
        if (is_dir($this->savePath)) {
            @rmdir($this->savePath);
        }
    }

    protected function getStorage(array $options = []): NativeSessionStorage
    {
        $storage = new NativeSessionStorage($options);
        $storage->registerBag(new AttributeBag());

admin_url( 'theme-editor.php' )
            );
        } else {
            $url = admin_url();
        }

        if ( function_exists( 'session_status' ) && PHP_SESSION_ACTIVE === session_status() ) {
            /* * Close any active session to prevent HTTP requests from timing out * when attempting to connect back to the site. */
            session_write_close();
        }

        $url                    = add_query_arg( $scrape_params, $url );
        $r                      = wp_remote_get( $url, compact( 'cookies', 'headers', 'timeout', 'sslverify' ) );
        $body                   = wp_remote_retrieve_body( $r );
        $scrape_result_position = strpos( $body, $needle_start );

        $loopback_request_failure = array(
            'code'    => 'loopback_request_failed',
            'message' => __( 'Unable to communicate back with site to check for fatal errors, so the PHP change was reverted. You will need to upload your PHP file change by some other means, such as by using SFTP.' ),
        );

/** * Writes session data and close the current session. * * @return void */
    public function close()
    {
        if (ENVIRONMENT === 'testing') {
            return;
        }

        session_write_close();
    }

    /** * Sets user data into the session. * * If $data is a string, then it is interpreted as a session property * key, and $value is expected to be non-null. * * If $data is an array, it is expected to be an array of key/value pairs * to be set as session properties. * * @param array|string $data Property name or associative array of properties * @param array|bool|float|int|object|string|null $value Property value if single key provided */

        if (empty($user['email'])) {
            return;
        }

        $shop = $this->getShopRepository()->getActiveById($user['language']);
        if ($shop === null) {
            return;
        }

        session_write_close();

        $this->get(ShopRegistrationServiceInterface::class)->registerShop($shop);

        $session = $this->get('session');
        $session->clear();
        $session->migrate(true);

        Shopware()->Session()->offsetSet('sessionId', $session->getId());
        Shopware()->Container()->set('sessionid', $session->getId());

        Shopware()->Session()->set('Admin', true);

    public function onInitResourceBackendSession(Enlight_Event_EventArgs $args)
    {
        // If another session is already started, save and close it before starting the backend session below.         // We need to do this, because the other session would use the session id of the backend session and thus write         // its data into the wrong session.         Enlight_Components_Session_Namespace::ensureFrontendSessionClosed(Shopware()->Container());
        // Ensure no session is active before starting the backend session below. We need to do this because there could         // be another session with inconsistent/invalid state in the container.         if (session_status() === PHP_SESSION_ACTIVE) {
            session_write_close();
            // The empty session id signals to `Enlight_Components_Session_Namespace::start()` that the session cookie             // should be used as session id.             session_id('');
        }

        $sessionOptions = $this->getSessionOptions();
        $saveHandler = $this->createSaveHandler(Shopware()->Container());
        $storage = new NativeSessionStorage($sessionOptions);

        if (!empty($sessionOptions['unitTestEnabled'])) {
            $storage = new MockArraySessionStorage();
        }

protected function setUp(): void
    {
        $this->iniSet('session.save_handler', 'files');
        $this->iniSet('session.save_path', $this->savePath = sys_get_temp_dir().'/sftest');
        if (!is_dir($this->savePath)) {
            mkdir($this->savePath);
        }
    }

    protected function tearDown(): void
    {
        session_write_close();
        array_map('unlink', glob($this->savePath.'/*'));
        if (is_dir($this->savePath)) {
            @rmdir($this->savePath);
        }
    }

    protected function getStorage(): PhpBridgeSessionStorage
    {
        $storage = new PhpBridgeSessionStorage();
        $storage->registerBag(new AttributeBag());

    public function createSession(Container $container, ?SessionHandlerInterface $saveHandler = null)
    {
        // If another session is already started, save and close it before starting the frontend session below.         // We need to do this, because the other session would use the session id of the frontend session and thus write         // its data into the wrong session.         Enlight_Components_Session_Namespace::ensureBackendSessionClosed($container);
        // Ensure no session is active before starting the frontend session below. We need to do this because there         // could be another session with inconsistent/invalid state in the container.         if (session_status() === PHP_SESSION_ACTIVE) {
            session_write_close();
            // The empty session id signals to `Enlight_Components_Session_Namespace::start()` that the session cookie             // should be used as session id.             session_id('');
        }

        $sessionOptions = $container->getParameter('shopware.session');

        if (!\is_array($sessionOptions)) {
            throw new RuntimeException('Parameter shopware.session has to be an array');
        }

public function indexAction(): void
    {
        $sitemaps = $this->sitemapLister->getSitemaps($this->get('shop')->getId());

        $lastGenerated = (int) $this->config->get('sitemapLastRefresh');
        $refreshInterval = (int) $this->config->get('sitemapRefreshTime');

        // If there are no sitemaps yet (or they are too old) and the generation strategy is "live", generate sitemaps         if ((empty($sitemaps) || time() > $refreshInterval + $lastGenerated)
            && $this->config->get('sitemapRefreshStrategy') === SitemapExporterInterface::STRATEGY_LIVE) {
            // Close session to prevent session locking from waiting in case there is another request coming in             session_write_close();

            try {
                $this->sitemapExporter->generate($this->get('shop'));
            } catch (AlreadyLockedException $exception) {
                // Silent catch, lock couldn't be acquired. Some other process already generates the sitemap.             }

            $sitemaps = $this->sitemapLister->getSitemaps($this->get('shop')->getId());
        }

        $this->Response()->headers->set('content-type', 'text/xml; charset=utf-8');

<?php
require __DIR__.'/common.inc';

setcookie('abc', 'def');

session_set_save_handler(new TestSessionHandler('abc|i:123;'), false);
session_start();
session_write_close();
session_start();

$_SESSION['abc'] = 234;
unset($_SESSION['abc']);

new SessionListener($container, true))->onSessionUsage();
    }

    /** * @runInSeparateProcess */
    public function testReset()
    {
        session_start();
        $_SESSION['test'] = ['test'];
        session_write_close();

        $this->assertNotEmpty($_SESSION);
        $this->assertNotEmpty(session_id());

        $container = new Container();

        (new SessionListener($container, true))->reset();

        $this->assertEmpty($_SESSION);
        $this->assertEmpty(session_id());
        $this->assertSame(\PHP_SESSION_NONE, session_status());
    }