Chris@0: <?php
Chris@0: 
Chris@0: namespace Drupal\Core\Cache;
Chris@0: 
Chris@14: use Drupal\Component\Assertion\Inspector;
Chris@0: use Drupal\Component\Utility\Crypt;
Chris@0: use Drupal\Core\Database\Connection;
Chris@0: use Drupal\Core\Database\SchemaObjectExistsException;
Chris@0: 
Chris@0: /**
Chris@0:  * Defines a default cache implementation.
Chris@0:  *
Chris@0:  * This is Drupal's default cache implementation. It uses the database to store
Chris@0:  * cached data. Each cache bin corresponds to a database table by the same name.
Chris@0:  *
Chris@0:  * @ingroup cache
Chris@0:  */
Chris@0: class DatabaseBackend implements CacheBackendInterface {
Chris@0: 
Chris@0:   /**
Chris@0:    * The default maximum number of rows that this cache bin table can store.
Chris@0:    *
Chris@0:    * This maximum is introduced to ensure that the database is not filled with
Chris@0:    * hundred of thousand of cache entries with gigabytes in size.
Chris@0:    *
Chris@0:    * Read about how to change it in the @link cache Cache API topic. @endlink
Chris@0:    */
Chris@0:   const DEFAULT_MAX_ROWS = 5000;
Chris@0: 
Chris@0:   /**
Chris@0:    * -1 means infinite allows numbers of rows for the cache backend.
Chris@0:    */
Chris@0:   const MAXIMUM_NONE = -1;
Chris@0: 
Chris@0:   /**
Chris@0:    * The maximum number of rows that this cache bin table is allowed to store.
Chris@0:    *
Chris@0:    * @see ::MAXIMUM_NONE
Chris@0:    *
Chris@0:    * @var int
Chris@0:    */
Chris@0:   protected $maxRows;
Chris@0: 
Chris@0:   /**
Chris@0:    * @var string
Chris@0:    */
Chris@0:   protected $bin;
Chris@0: 
Chris@0: 
Chris@0:   /**
Chris@0:    * The database connection.
Chris@0:    *
Chris@0:    * @var \Drupal\Core\Database\Connection
Chris@0:    */
Chris@0:   protected $connection;
Chris@0: 
Chris@0:   /**
Chris@0:    * The cache tags checksum provider.
Chris@0:    *
Chris@0:    * @var \Drupal\Core\Cache\CacheTagsChecksumInterface
Chris@0:    */
Chris@0:   protected $checksumProvider;
Chris@0: 
Chris@0:   /**
Chris@0:    * Constructs a DatabaseBackend object.
Chris@0:    *
Chris@0:    * @param \Drupal\Core\Database\Connection $connection
Chris@0:    *   The database connection.
Chris@0:    * @param \Drupal\Core\Cache\CacheTagsChecksumInterface $checksum_provider
Chris@0:    *   The cache tags checksum provider.
Chris@0:    * @param string $bin
Chris@0:    *   The cache bin for which the object is created.
Chris@0:    * @param int $max_rows
Chris@0:    *   (optional) The maximum number of rows that are allowed in this cache bin
Chris@0:    *   table.
Chris@0:    */
Chris@0:   public function __construct(Connection $connection, CacheTagsChecksumInterface $checksum_provider, $bin, $max_rows = NULL) {
Chris@0:     // All cache tables should be prefixed with 'cache_'.
Chris@0:     $bin = 'cache_' . $bin;
Chris@0: 
Chris@0:     $this->bin = $bin;
Chris@0:     $this->connection = $connection;
Chris@0:     $this->checksumProvider = $checksum_provider;
Chris@0:     $this->maxRows = $max_rows === NULL ? static::DEFAULT_MAX_ROWS : $max_rows;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function get($cid, $allow_invalid = FALSE) {
Chris@0:     $cids = [$cid];
Chris@0:     $cache = $this->getMultiple($cids, $allow_invalid);
Chris@0:     return reset($cache);
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function getMultiple(&$cids, $allow_invalid = FALSE) {
Chris@0:     $cid_mapping = [];
Chris@0:     foreach ($cids as $cid) {
Chris@0:       $cid_mapping[$this->normalizeCid($cid)] = $cid;
Chris@0:     }
Chris@0:     // When serving cached pages, the overhead of using ::select() was found
Chris@0:     // to add around 30% overhead to the request. Since $this->bin is a
Chris@0:     // variable, this means the call to ::query() here uses a concatenated
Chris@0:     // string. This is highly discouraged under any other circumstances, and
Chris@0:     // is used here only due to the performance overhead we would incur
Chris@0:     // otherwise. When serving an uncached page, the overhead of using
Chris@0:     // ::select() is a much smaller proportion of the request.
Chris@0:     $result = [];
Chris@0:     try {
Chris@0:       $result = $this->connection->query('SELECT cid, data, created, expire, serialized, tags, checksum FROM {' . $this->connection->escapeTable($this->bin) . '} WHERE cid IN ( :cids[] ) ORDER BY cid', [':cids[]' => array_keys($cid_mapping)]);
Chris@0:     }
Chris@0:     catch (\Exception $e) {
Chris@0:       // Nothing to do.
Chris@0:     }
Chris@0:     $cache = [];
Chris@0:     foreach ($result as $item) {
Chris@0:       // Map the cache ID back to the original.
Chris@0:       $item->cid = $cid_mapping[$item->cid];
Chris@0:       $item = $this->prepareItem($item, $allow_invalid);
Chris@0:       if ($item) {
Chris@0:         $cache[$item->cid] = $item;
Chris@0:       }
Chris@0:     }
Chris@0:     $cids = array_diff($cids, array_keys($cache));
Chris@0:     return $cache;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Prepares a cached item.
Chris@0:    *
Chris@0:    * Checks that items are either permanent or did not expire, and unserializes
Chris@0:    * data as appropriate.
Chris@0:    *
Chris@0:    * @param object $cache
Chris@18:    *   An item loaded from self::get() or self::getMultiple().
Chris@0:    * @param bool $allow_invalid
Chris@0:    *   If FALSE, the method returns FALSE if the cache item is not valid.
Chris@0:    *
Chris@0:    * @return mixed|false
Chris@0:    *   The item with data unserialized as appropriate and a property indicating
Chris@0:    *   whether the item is valid, or FALSE if there is no valid item to load.
Chris@0:    */
Chris@0:   protected function prepareItem($cache, $allow_invalid) {
Chris@0:     if (!isset($cache->data)) {
Chris@0:       return FALSE;
Chris@0:     }
Chris@0: 
Chris@0:     $cache->tags = $cache->tags ? explode(' ', $cache->tags) : [];
Chris@0: 
Chris@0:     // Check expire time.
Chris@0:     $cache->valid = $cache->expire == Cache::PERMANENT || $cache->expire >= REQUEST_TIME;
Chris@0: 
Chris@0:     // Check if invalidateTags() has been called with any of the items's tags.
Chris@0:     if (!$this->checksumProvider->isValid($cache->checksum, $cache->tags)) {
Chris@0:       $cache->valid = FALSE;
Chris@0:     }
Chris@0: 
Chris@0:     if (!$allow_invalid && !$cache->valid) {
Chris@0:       return FALSE;
Chris@0:     }
Chris@0: 
Chris@0:     // Unserialize and return the cached data.
Chris@0:     if ($cache->serialized) {
Chris@0:       $cache->data = unserialize($cache->data);
Chris@0:     }
Chris@0: 
Chris@0:     return $cache;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function set($cid, $data, $expire = Cache::PERMANENT, array $tags = []) {
Chris@0:     $this->setMultiple([
Chris@0:       $cid => [
Chris@0:         'data' => $data,
Chris@0:         'expire' => $expire,
Chris@0:         'tags' => $tags,
Chris@0:       ],
Chris@0:     ]);
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function setMultiple(array $items) {
Chris@0:     $try_again = FALSE;
Chris@0:     try {
Chris@0:       // The bin might not yet exist.
Chris@0:       $this->doSetMultiple($items);
Chris@0:     }
Chris@0:     catch (\Exception $e) {
Chris@0:       // If there was an exception, try to create the bins.
Chris@0:       if (!$try_again = $this->ensureBinExists()) {
Chris@0:         // If the exception happened for other reason than the missing bin
Chris@0:         // table, propagate the exception.
Chris@0:         throw $e;
Chris@0:       }
Chris@0:     }
Chris@0:     // Now that the bin has been created, try again if necessary.
Chris@0:     if ($try_again) {
Chris@0:       $this->doSetMultiple($items);
Chris@0:     }
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Stores multiple items in the persistent cache.
Chris@0:    *
Chris@0:    * @param array $items
Chris@0:    *   An array of cache items, keyed by cid.
Chris@0:    *
Chris@0:    * @see \Drupal\Core\Cache\CacheBackendInterface::setMultiple()
Chris@0:    */
Chris@0:   protected function doSetMultiple(array $items) {
Chris@0:     $values = [];
Chris@0: 
Chris@0:     foreach ($items as $cid => $item) {
Chris@0:       $item += [
Chris@0:         'expire' => CacheBackendInterface::CACHE_PERMANENT,
Chris@0:         'tags' => [],
Chris@0:       ];
Chris@0: 
Chris@14:       assert(Inspector::assertAllStrings($item['tags']), 'Cache Tags must be strings.');
Chris@0:       $item['tags'] = array_unique($item['tags']);
Chris@0:       // Sort the cache tags so that they are stored consistently in the DB.
Chris@0:       sort($item['tags']);
Chris@0: 
Chris@0:       $fields = [
Chris@0:         'cid' => $this->normalizeCid($cid),
Chris@0:         'expire' => $item['expire'],
Chris@0:         'created' => round(microtime(TRUE), 3),
Chris@0:         'tags' => implode(' ', $item['tags']),
Chris@0:         'checksum' => $this->checksumProvider->getCurrentChecksum($item['tags']),
Chris@0:       ];
Chris@0: 
Chris@0:       if (!is_string($item['data'])) {
Chris@0:         $fields['data'] = serialize($item['data']);
Chris@0:         $fields['serialized'] = 1;
Chris@0:       }
Chris@0:       else {
Chris@0:         $fields['data'] = $item['data'];
Chris@0:         $fields['serialized'] = 0;
Chris@0:       }
Chris@0:       $values[] = $fields;
Chris@0:     }
Chris@0: 
Chris@0:     // Use an upsert query which is atomic and optimized for multiple-row
Chris@0:     // merges.
Chris@0:     $query = $this->connection
Chris@0:       ->upsert($this->bin)
Chris@0:       ->key('cid')
Chris@0:       ->fields(['cid', 'expire', 'created', 'tags', 'checksum', 'data', 'serialized']);
Chris@0:     foreach ($values as $fields) {
Chris@0:       // Only pass the values since the order of $fields matches the order of
Chris@0:       // the insert fields. This is a performance optimization to avoid
Chris@0:       // unnecessary loops within the method.
Chris@0:       $query->values(array_values($fields));
Chris@0:     }
Chris@0: 
Chris@0:     $query->execute();
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function delete($cid) {
Chris@0:     $this->deleteMultiple([$cid]);
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function deleteMultiple(array $cids) {
Chris@0:     $cids = array_values(array_map([$this, 'normalizeCid'], $cids));
Chris@0:     try {
Chris@0:       // Delete in chunks when a large array is passed.
Chris@0:       foreach (array_chunk($cids, 1000) as $cids_chunk) {
Chris@0:         $this->connection->delete($this->bin)
Chris@0:           ->condition('cid', $cids_chunk, 'IN')
Chris@0:           ->execute();
Chris@0:       }
Chris@0:     }
Chris@0:     catch (\Exception $e) {
Chris@0:       // Create the cache table, which will be empty. This fixes cases during
Chris@0:       // core install where a cache table is cleared before it is set
Chris@0:       // with {cache_render} and {cache_data}.
Chris@0:       if (!$this->ensureBinExists()) {
Chris@0:         $this->catchException($e);
Chris@0:       }
Chris@0:     }
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function deleteAll() {
Chris@0:     try {
Chris@0:       $this->connection->truncate($this->bin)->execute();
Chris@0:     }
Chris@0:     catch (\Exception $e) {
Chris@0:       // Create the cache table, which will be empty. This fixes cases during
Chris@0:       // core install where a cache table is cleared before it is set
Chris@0:       // with {cache_render} and {cache_data}.
Chris@0:       if (!$this->ensureBinExists()) {
Chris@0:         $this->catchException($e);
Chris@0:       }
Chris@0:     }
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function invalidate($cid) {
Chris@0:     $this->invalidateMultiple([$cid]);
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function invalidateMultiple(array $cids) {
Chris@0:     $cids = array_values(array_map([$this, 'normalizeCid'], $cids));
Chris@0:     try {
Chris@0:       // Update in chunks when a large array is passed.
Chris@0:       foreach (array_chunk($cids, 1000) as $cids_chunk) {
Chris@0:         $this->connection->update($this->bin)
Chris@0:           ->fields(['expire' => REQUEST_TIME - 1])
Chris@0:           ->condition('cid', $cids_chunk, 'IN')
Chris@0:           ->execute();
Chris@0:       }
Chris@0:     }
Chris@0:     catch (\Exception $e) {
Chris@0:       $this->catchException($e);
Chris@0:     }
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function invalidateAll() {
Chris@0:     try {
Chris@0:       $this->connection->update($this->bin)
Chris@0:         ->fields(['expire' => REQUEST_TIME - 1])
Chris@0:         ->execute();
Chris@0:     }
Chris@0:     catch (\Exception $e) {
Chris@0:       $this->catchException($e);
Chris@0:     }
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function garbageCollection() {
Chris@0:     try {
Chris@0:       // Bounded size cache bin, using FIFO.
Chris@0:       if ($this->maxRows !== static::MAXIMUM_NONE) {
Chris@0:         $first_invalid_create_time = $this->connection->select($this->bin)
Chris@0:           ->fields($this->bin, ['created'])
Chris@0:           ->orderBy("{$this->bin}.created", 'DESC')
Chris@0:           ->range($this->maxRows, $this->maxRows + 1)
Chris@0:           ->execute()
Chris@0:           ->fetchField();
Chris@0: 
Chris@0:         if ($first_invalid_create_time) {
Chris@0:           $this->connection->delete($this->bin)
Chris@0:             ->condition('created', $first_invalid_create_time, '<=')
Chris@0:             ->execute();
Chris@0:         }
Chris@0:       }
Chris@0: 
Chris@0:       $this->connection->delete($this->bin)
Chris@0:         ->condition('expire', Cache::PERMANENT, '<>')
Chris@0:         ->condition('expire', REQUEST_TIME, '<')
Chris@0:         ->execute();
Chris@0:     }
Chris@0:     catch (\Exception $e) {
Chris@0:       // If the table does not exist, it surely does not have garbage in it.
Chris@0:       // If the table exists, the next garbage collection will clean up.
Chris@0:       // There is nothing to do.
Chris@0:     }
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function removeBin() {
Chris@0:     try {
Chris@0:       $this->connection->schema()->dropTable($this->bin);
Chris@0:     }
Chris@0:     catch (\Exception $e) {
Chris@0:       $this->catchException($e);
Chris@0:     }
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Check if the cache bin exists and create it if not.
Chris@0:    */
Chris@0:   protected function ensureBinExists() {
Chris@0:     try {
Chris@0:       $database_schema = $this->connection->schema();
Chris@0:       if (!$database_schema->tableExists($this->bin)) {
Chris@0:         $schema_definition = $this->schemaDefinition();
Chris@0:         $database_schema->createTable($this->bin, $schema_definition);
Chris@0:         return TRUE;
Chris@0:       }
Chris@0:     }
Chris@0:     // If another process has already created the cache table, attempting to
Chris@0:     // recreate it will throw an exception. In this case just catch the
Chris@0:     // exception and do nothing.
Chris@0:     catch (SchemaObjectExistsException $e) {
Chris@0:       return TRUE;
Chris@0:     }
Chris@0:     return FALSE;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Act on an exception when cache might be stale.
Chris@0:    *
Chris@0:    * If the table does not yet exist, that's fine, but if the table exists and
Chris@0:    * yet the query failed, then the cache is stale and the exception needs to
Chris@0:    * propagate.
Chris@0:    *
Chris@0:    * @param $e
Chris@0:    *   The exception.
Chris@0:    * @param string|null $table_name
Chris@0:    *   The table name. Defaults to $this->bin.
Chris@0:    *
Chris@0:    * @throws \Exception
Chris@0:    */
Chris@0:   protected function catchException(\Exception $e, $table_name = NULL) {
Chris@0:     if ($this->connection->schema()->tableExists($table_name ?: $this->bin)) {
Chris@0:       throw $e;
Chris@0:     }
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Normalizes a cache ID in order to comply with database limitations.
Chris@0:    *
Chris@0:    * @param string $cid
Chris@0:    *   The passed in cache ID.
Chris@0:    *
Chris@0:    * @return string
Chris@0:    *   An ASCII-encoded cache ID that is at most 255 characters long.
Chris@0:    */
Chris@0:   protected function normalizeCid($cid) {
Chris@0:     // Nothing to do if the ID is a US ASCII string of 255 characters or less.
Chris@0:     $cid_is_ascii = mb_check_encoding($cid, 'ASCII');
Chris@0:     if (strlen($cid) <= 255 && $cid_is_ascii) {
Chris@0:       return $cid;
Chris@0:     }
Chris@0:     // Return a string that uses as much as possible of the original cache ID
Chris@0:     // with the hash appended.
Chris@0:     $hash = Crypt::hashBase64($cid);
Chris@0:     if (!$cid_is_ascii) {
Chris@0:       return $hash;
Chris@0:     }
Chris@0:     return substr($cid, 0, 255 - strlen($hash)) . $hash;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Defines the schema for the {cache_*} bin tables.
Chris@0:    *
Chris@0:    * @internal
Chris@0:    */
Chris@0:   public function schemaDefinition() {
Chris@0:     $schema = [
Chris@0:       'description' => 'Storage for the cache API.',
Chris@0:       'fields' => [
Chris@0:         'cid' => [
Chris@0:           'description' => 'Primary Key: Unique cache ID.',
Chris@0:           'type' => 'varchar_ascii',
Chris@0:           'length' => 255,
Chris@0:           'not null' => TRUE,
Chris@0:           'default' => '',
Chris@0:           'binary' => TRUE,
Chris@0:         ],
Chris@0:         'data' => [
Chris@0:           'description' => 'A collection of data to cache.',
Chris@0:           'type' => 'blob',
Chris@0:           'not null' => FALSE,
Chris@0:           'size' => 'big',
Chris@0:         ],
Chris@0:         'expire' => [
Chris@0:           'description' => 'A Unix timestamp indicating when the cache entry should expire, or ' . Cache::PERMANENT . ' for never.',
Chris@0:           'type' => 'int',
Chris@0:           'not null' => TRUE,
Chris@0:           'default' => 0,
Chris@0:         ],
Chris@0:         'created' => [
Chris@0:           'description' => 'A timestamp with millisecond precision indicating when the cache entry was created.',
Chris@0:           'type' => 'numeric',
Chris@0:           'precision' => 14,
Chris@0:           'scale' => 3,
Chris@0:           'not null' => TRUE,
Chris@0:           'default' => 0,
Chris@0:         ],
Chris@0:         'serialized' => [
Chris@0:           'description' => 'A flag to indicate whether content is serialized (1) or not (0).',
Chris@0:           'type' => 'int',
Chris@0:           'size' => 'small',
Chris@0:           'not null' => TRUE,
Chris@0:           'default' => 0,
Chris@0:         ],
Chris@0:         'tags' => [
Chris@0:           'description' => 'Space-separated list of cache tags for this entry.',
Chris@0:           'type' => 'text',
Chris@0:           'size' => 'big',
Chris@0:           'not null' => FALSE,
Chris@0:         ],
Chris@0:         'checksum' => [
Chris@0:           'description' => 'The tag invalidation checksum when this entry was saved.',
Chris@0:           'type' => 'varchar_ascii',
Chris@0:           'length' => 255,
Chris@0:           'not null' => TRUE,
Chris@0:         ],
Chris@0:       ],
Chris@0:       'indexes' => [
Chris@0:         'expire' => ['expire'],
Chris@0:         'created' => ['created'],
Chris@0:       ],
Chris@0:       'primary key' => ['cid'],
Chris@0:     ];
Chris@0:     return $schema;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * The maximum number of rows that this cache bin table is allowed to store.
Chris@0:    *
Chris@0:    * @return int
Chris@0:    */
Chris@0:   public function getMaxRows() {
Chris@0:     return $this->maxRows;
Chris@0:   }
Chris@0: 
Chris@0: }