Chris@0: <?php
Chris@0: 
Chris@0: namespace Drupal\Core\Cache;
Chris@0: 
Chris@14: use Drupal\Component\Assertion\Inspector;
Chris@0: use Drupal\Core\Database\Query\SelectInterface;
Chris@0: 
Chris@0: /**
Chris@0:  * Helper methods for cache.
Chris@0:  *
Chris@0:  * @ingroup cache
Chris@0:  */
Chris@0: class Cache {
Chris@0: 
Chris@0:   /**
Chris@0:    * Indicates that the item should never be removed unless explicitly deleted.
Chris@0:    */
Chris@0:   const PERMANENT = CacheBackendInterface::CACHE_PERMANENT;
Chris@0: 
Chris@0:   /**
Chris@0:    * Merges arrays of cache contexts and removes duplicates.
Chris@0:    *
Chris@0:    * @param array $a
Chris@0:    *   Cache contexts array to merge.
Chris@0:    * @param array $b
Chris@0:    *   Cache contexts array to merge.
Chris@0:    *
Chris@0:    * @return string[]
Chris@0:    *   The merged array of cache contexts.
Chris@0:    */
Chris@0:   public static function mergeContexts(array $a = [], array $b = []) {
Chris@0:     $cache_contexts = array_unique(array_merge($a, $b));
Chris@14:     assert(\Drupal::service('cache_contexts_manager')->assertValidTokens($cache_contexts));
Chris@0:     sort($cache_contexts);
Chris@0:     return $cache_contexts;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Merges arrays of cache tags and removes duplicates.
Chris@0:    *
Chris@0:    * The cache tags array is returned in a format that is valid for
Chris@0:    * \Drupal\Core\Cache\CacheBackendInterface::set().
Chris@0:    *
Chris@0:    * When caching elements, it is necessary to collect all cache tags into a
Chris@0:    * single array, from both the element itself and all child elements. This
Chris@0:    * allows items to be invalidated based on all tags attached to the content
Chris@0:    * they're constituted from.
Chris@0:    *
Chris@0:    * @param array $a
Chris@0:    *   Cache tags array to merge.
Chris@0:    * @param array $b
Chris@0:    *   Cache tags array to merge.
Chris@0:    *
Chris@0:    * @return string[]
Chris@0:    *   The merged array of cache tags.
Chris@0:    */
Chris@0:   public static function mergeTags(array $a = [], array $b = []) {
Chris@14:     assert(Inspector::assertAllStrings($a) && Inspector::assertAllStrings($b), 'Cache tags must be valid strings');
Chris@0: 
Chris@0:     $cache_tags = array_unique(array_merge($a, $b));
Chris@0:     sort($cache_tags);
Chris@0:     return $cache_tags;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Merges max-age values (expressed in seconds), finds the lowest max-age.
Chris@0:    *
Chris@0:    * Ensures infinite max-age (Cache::PERMANENT) is taken into account.
Chris@0:    *
Chris@0:    * @param int $a
Chris@0:    *   Max age value to merge.
Chris@0:    * @param int $b
Chris@0:    *   Max age value to merge.
Chris@0:    *
Chris@0:    * @return int
Chris@0:    *   The minimum max-age value.
Chris@0:    */
Chris@0:   public static function mergeMaxAges($a = Cache::PERMANENT, $b = Cache::PERMANENT) {
Chris@0:     // If one of the values is Cache::PERMANENT, return the other value.
Chris@0:     if ($a === Cache::PERMANENT) {
Chris@0:       return $b;
Chris@0:     }
Chris@0:     if ($b === Cache::PERMANENT) {
Chris@0:       return $a;
Chris@0:     }
Chris@0: 
Chris@0:     // If none or the values are Cache::PERMANENT, return the minimum value.
Chris@0:     return min($a, $b);
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Validates an array of cache tags.
Chris@0:    *
Chris@0:    * Can be called before using cache tags in operations, to ensure validity.
Chris@0:    *
Chris@0:    * @param string[] $tags
Chris@0:    *   An array of cache tags.
Chris@0:    *
Chris@0:    * @deprecated
Chris@14:    *   Use assert(Inspector::assertAllStrings($tags));
Chris@0:    *
Chris@0:    * @throws \LogicException
Chris@0:    */
Chris@0:   public static function validateTags(array $tags) {
Chris@0:     if (empty($tags)) {
Chris@0:       return;
Chris@0:     }
Chris@0:     foreach ($tags as $value) {
Chris@0:       if (!is_string($value)) {
Chris@0:         throw new \LogicException('Cache tags must be strings, ' . gettype($value) . ' given.');
Chris@0:       }
Chris@0:     }
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Build an array of cache tags from a given prefix and an array of suffixes.
Chris@0:    *
Chris@0:    * Each suffix will be converted to a cache tag by appending it to the prefix,
Chris@0:    * with a colon between them.
Chris@0:    *
Chris@0:    * @param string $prefix
Chris@0:    *   A prefix string.
Chris@0:    * @param array $suffixes
Chris@0:    *   An array of suffixes. Will be cast to strings.
Chris@0:    * @param string $glue
Chris@0:    *   A string to be used as glue for concatenation. Defaults to a colon.
Chris@0:    *
Chris@0:    * @return string[]
Chris@0:    *   An array of cache tags.
Chris@0:    */
Chris@0:   public static function buildTags($prefix, array $suffixes, $glue = ':') {
Chris@0:     $tags = [];
Chris@0:     foreach ($suffixes as $suffix) {
Chris@0:       $tags[] = $prefix . $glue . $suffix;
Chris@0:     }
Chris@0:     return $tags;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Marks cache items from all bins with any of the specified tags as invalid.
Chris@0:    *
Chris@0:    * @param string[] $tags
Chris@0:    *   The list of tags to invalidate cache items for.
Chris@0:    */
Chris@0:   public static function invalidateTags(array $tags) {
Chris@0:     \Drupal::service('cache_tags.invalidator')->invalidateTags($tags);
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Gets all cache bin services.
Chris@0:    *
Chris@0:    * @return \Drupal\Core\Cache\CacheBackendInterface[]
Chris@0:    *   An array of cache backend objects keyed by cache bins.
Chris@0:    */
Chris@0:   public static function getBins() {
Chris@0:     $bins = [];
Chris@0:     $container = \Drupal::getContainer();
Chris@0:     foreach ($container->getParameter('cache_bins') as $service_id => $bin) {
Chris@0:       $bins[$bin] = $container->get($service_id);
Chris@0:     }
Chris@0:     return $bins;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Generates a hash from a query object, to be used as part of the cache key.
Chris@0:    *
Chris@0:    * This smart caching strategy saves Drupal from querying and rendering to
Chris@0:    * HTML when the underlying query is unchanged.
Chris@0:    *
Chris@0:    * Expensive queries should use the query builder to create the query and then
Chris@0:    * call this function. Executing the query and formatting results should
Chris@0:    * happen in a #pre_render callback.
Chris@0:    *
Chris@0:    * @param \Drupal\Core\Database\Query\SelectInterface $query
Chris@0:    *   A select query object.
Chris@0:    *
Chris@0:    * @return string
Chris@0:    *   A hash of the query arguments.
Chris@0:    */
Chris@0:   public static function keyFromQuery(SelectInterface $query) {
Chris@0:     $query->preExecute();
Chris@0:     $keys = [(string) $query, $query->getArguments()];
Chris@0:     return hash('sha256', serialize($keys));
Chris@0:   }
Chris@0: 
Chris@0: }