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