class ThemeRegistry in Zircon Profile 8

Builds the run-time theme registry.

A cache collector to allow the theme registry to be accessed as a complete registry, while internally caching only the parts of the registry that are actually in use on the site. On cache misses the complete theme registry is loaded and used to update the run-time cache.

Hierarchy

• class \Drupal\Core\Cache\CacheCollector implements CacheCollectorInterface, DestructableInterface
  • class \Drupal\Core\Utility\ThemeRegistry implements DestructableInterface

2 files declare their use of ThemeRegistry

Registry.php in core/lib/Drupal/Core/Theme/Registry.php

Contains \Drupal\Core\Theme\Registry.

RegistryTest.php in core/modules/system/src/Tests/Theme/RegistryTest.php

Contains \Drupal\system\Tests\Theme\RegistryTest.

File

core/lib/Drupal/Core/Utility/ThemeRegistry.php, line 24

Contains \Drupal\Core\Utility\ThemeRegistry.

Namespace

Drupal\Core\Utility

class ThemeRegistry extends CacheCollector implements DestructableInterface {

  /**
   * Whether the partial registry can be persisted to the cache.
   *
   * This is only allowed if all modules and the request method is GET. _theme()
   * should be very rarely called on POST requests and this avoids polluting
   * the runtime cache.
   */
  protected $persistable;

  /**
   * The complete theme registry array.
   */
  protected $completeRegistry;

  /**
   * Constructs a ThemeRegistry object.
   *
   * @param string $cid
   *   The cid for the array being cached.
   * @param \Drupal\Core\Cache\CacheBackendInterface $cache
   *   The cache backend.
   * @param \Drupal\Core\Lock\LockBackendInterface $lock
   *   The lock backend.
   * @param array $tags
   *   (optional) The tags to specify for the cache item.
   * @param bool $modules_loaded
   *   Whether all modules have already been loaded.
   */
  function __construct($cid, CacheBackendInterface $cache, LockBackendInterface $lock, $tags = array(), $modules_loaded = FALSE) {
    $this->cid = $cid;
    $this->cache = $cache;
    $this->lock = $lock;
    $this->tags = $tags;
    $this->persistable = $modules_loaded && \Drupal::hasRequest() && \Drupal::request()
      ->isMethod('GET');

    // @todo: Implement lazyload.
    $this->cacheLoaded = TRUE;
    if ($this->persistable && ($cached = $this->cache
      ->get($this->cid))) {
      $this->storage = $cached->data;
    }
    else {

      // If there is no runtime cache stored, fetch the full theme registry,
      // but then initialize each value to NULL. This allows offsetExists()
      // to function correctly on non-registered theme hooks without triggering
      // a call to resolveCacheMiss().
      $this->storage = $this
        ->initializeRegistry();
      foreach (array_keys($this->storage) as $key) {
        $this
          ->persist($key);
      }

      // RegistryTest::testRaceCondition() ensures that the cache entry is
      // written on the initial construction of the theme registry.
      $this
        ->updateCache();
    }
  }

  /**
   * Initializes the full theme registry.
   *
   * @return
   *   An array with the keys of the full theme registry, but the values
   *   initialized to NULL.
   */
  function initializeRegistry() {

    // @todo DIC this.
    $this->completeRegistry = \Drupal::service('theme.registry')
      ->get();
    return array_fill_keys(array_keys($this->completeRegistry), NULL);
  }

  /**
   * {@inheritdoc}
   */
  public function has($key) {

    // Since the theme registry allows for theme hooks to be requested that
    // are not registered, just check the existence of the key in the registry.
    // Use array_key_exists() here since a NULL value indicates that the theme
    // hook exists but has not yet been requested.
    return array_key_exists($key, $this->storage);
  }

  /**
   * {@inheritdoc}
   */
  public function get($key) {

    // If the offset is set but empty, it is a registered theme hook that has
    // not yet been requested. Offsets that do not exist at all were not
    // registered in hook_theme().
    if (isset($this->storage[$key])) {
      return $this->storage[$key];
    }
    elseif (array_key_exists($key, $this->storage)) {
      return $this
        ->resolveCacheMiss($key);
    }
  }

  /**
   * {@inheritdoc}
   */
  public function resolveCacheMiss($key) {
    if (!isset($this->completeRegistry)) {
      $this->completeRegistry = \Drupal::service('theme.registry')
        ->get();
    }
    $this->storage[$key] = $this->completeRegistry[$key];
    if ($this->persistable) {
      $this
        ->persist($key);
    }
    return $this->storage[$key];
  }

  /**
   * {@inheritdoc}
   */
  protected function updateCache($lock = TRUE) {
    if (!$this->persistable) {
      return;
    }

    // @todo: Is the custom implementation necessary?
    $data = array();
    foreach ($this->keysToPersist as $offset => $persist) {
      if ($persist) {
        $data[$offset] = $this->storage[$offset];
      }
    }
    if (empty($data)) {
      return;
    }
    $lock_name = $this->cid . ':' . __CLASS__;
    if (!$lock || $this->lock
      ->acquire($lock_name)) {
      if ($cached = $this->cache
        ->get($this->cid)) {

        // Use array merge instead of union so that filled in values in $data
        // overwrite empty values in the current cache.
        $data = array_merge($cached->data, $data);
      }
      else {
        $registry = $this
          ->initializeRegistry();
        $data = array_merge($registry, $data);
      }
      $this->cache
        ->set($this->cid, $data, Cache::PERMANENT, $this->tags);
      if ($lock) {
        $this->lock
          ->release($lock_name);
      }
    }
  }

}

Members

Name	Modifiers	Type	Description	Overrides
CacheCollector::$cache	protected	property	The cache backend that should be used.	2
CacheCollector::$cacheCreated	protected	property	Stores the cache creation time.
CacheCollector::$cacheInvalidated	protected	property	Flag that indicates of the cache has been invalidated.
CacheCollector::$cacheLoaded	protected	property	Indicates if the collected cache was already loaded.
CacheCollector::$cid	protected	property	The cache id that is used for the cache entry.
CacheCollector::$keysToPersist	protected	property	An array of keys to add to the cache on service termination.
CacheCollector::$keysToRemove	protected	property	An array of keys to remove from the cache on service termination.
CacheCollector::$lock	protected	property	The lock backend that should be used.	2
CacheCollector::$storage	protected	property	Storage for the data itself.
CacheCollector::$tags	protected	property	A list of tags that are used for the cache entry.
CacheCollector::clear	public	function	Clears the collected cache entry. Overrides CacheCollectorInterface::clear	1
CacheCollector::delete	public	function	Deletes the element. Overrides CacheCollectorInterface::delete
CacheCollector::destruct	public	function	Performs destruct operations. Overrides DestructableInterface::destruct
CacheCollector::getCid	protected	function	Gets the cache ID.	3
CacheCollector::invalidateCache	protected	function	Invalidate the cache.
CacheCollector::lazyLoadCache	protected	function	Loads the cache if not already done.	1
CacheCollector::normalizeLockName	protected	function	Normalizes a cache ID in order to comply with database limitations.
CacheCollector::persist	protected	function	Flags an offset value to be written to the persistent cache.
CacheCollector::reset	public	function	Resets the local cache. Overrides CacheCollectorInterface::reset	1
CacheCollector::set	public	function	Implements \Drupal\Core\Cache\CacheCollectorInterface::set(). Overrides CacheCollectorInterface::set	1
ThemeRegistry::$completeRegistry	protected	property	The complete theme registry array.
ThemeRegistry::$persistable	protected	property	Whether the partial registry can be persisted to the cache.
ThemeRegistry::get	public	function	Gets value from the cache. Overrides CacheCollector::get
ThemeRegistry::has	public	function	Returns whether data exists for this key. Overrides CacheCollector::has
ThemeRegistry::initializeRegistry		function	Initializes the full theme registry.
ThemeRegistry::resolveCacheMiss	public	function	Resolves a cache miss. Overrides CacheCollector::resolveCacheMiss
ThemeRegistry::updateCache	protected	function	Writes a value to the persistent cache immediately. Overrides CacheCollector::updateCache
ThemeRegistry::__construct		function	Constructs a ThemeRegistry object. Overrides CacheCollector::__construct