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- <?php
- namespace Drupal\Core\Cache;
- use Drupal\Core\Database\Connection;
- use Drupal\Core\Database\DatabaseException;
- /**
- * Cache tags invalidations checksum implementation that uses the database.
- */
- class DatabaseCacheTagsChecksum implements CacheTagsChecksumInterface, CacheTagsInvalidatorInterface {
- use CacheTagsChecksumTrait;
- /**
- * The database connection.
- *
- * @var \Drupal\Core\Database\Connection
- */
- protected $connection;
- /**
- * Constructs a DatabaseCacheTagsChecksum object.
- *
- * @param \Drupal\Core\Database\Connection $connection
- * The database connection.
- */
- public function __construct(Connection $connection) {
- $this->connection = $connection;
- }
- /**
- * {@inheritdoc}
- */
- protected function doInvalidateTags(array $tags) {
- try {
- foreach ($tags as $tag) {
- $this->connection->merge('cachetags')
- ->insertFields(['invalidations' => 1])
- ->expression('invalidations', 'invalidations + 1')
- ->key('tag', $tag)
- ->execute();
- }
- }
- catch (\Exception $e) {
- // Create the cache table, which will be empty. This fixes cases during
- // core install where cache tags are invalidated before the table is
- // created.
- if (!$this->ensureTableExists()) {
- $this->catchException($e);
- }
- }
- }
- /**
- * {@inheritdoc}
- */
- protected function getTagInvalidationCounts(array $tags) {
- try {
- return $this->connection->query('SELECT tag, invalidations FROM {cachetags} WHERE tag IN ( :tags[] )', [':tags[]' => $tags])
- ->fetchAllKeyed();
- }
- catch (\Exception $e) {
- // If the table does not exist yet, create.
- if (!$this->ensureTableExists()) {
- $this->catchException($e);
- }
- }
- return [];
- }
- /**
- * Check if the cache tags table exists and create it if not.
- */
- protected function ensureTableExists() {
- try {
- $database_schema = $this->connection->schema();
- // Create the cache tags table if it does not exist.
- if (!$database_schema->tableExists('cachetags')) {
- $schema_definition = $this->schemaDefinition();
- $database_schema->createTable('cachetags', $schema_definition);
- return TRUE;
- }
- }
- // If another process has already created the cachetags table, attempting to
- // recreate it will throw an exception. In this case just catch the
- // exception and do nothing.
- catch (DatabaseException $e) {
- return TRUE;
- }
- return FALSE;
- }
- /**
- * Defines the schema for the {cachetags} table.
- *
- * @internal
- */
- public function schemaDefinition() {
- $schema = [
- 'description' => 'Cache table for tracking cache tag invalidations.',
- 'fields' => [
- 'tag' => [
- 'description' => 'Namespace-prefixed tag string.',
- 'type' => 'varchar_ascii',
- 'length' => 255,
- 'not null' => TRUE,
- 'default' => '',
- ],
- 'invalidations' => [
- 'description' => 'Number incremented when the tag is invalidated.',
- 'type' => 'int',
- 'not null' => TRUE,
- 'default' => 0,
- ],
- ],
- 'primary key' => ['tag'],
- ];
- return $schema;
- }
- /**
- * Act on an exception when cache might be stale.
- *
- * If the {cachetags} table does not yet exist, that's fine but if the table
- * exists and yet the query failed, then the cache is stale and the
- * exception needs to propagate.
- *
- * @param \Exception $e
- * The exception.
- *
- * @throws \Exception
- */
- protected function catchException(\Exception $e) {
- if ($this->connection->schema()->tableExists('cachetags')) {
- throw $e;
- }
- }
- /**
- * {@inheritdoc}
- */
- public function getDatabaseConnection() {
- return $this->connection;
- }
- }
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