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<?php |
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namespace Drupal\mongodb_cache; |
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/* |
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* This is the actual MongoDB cache backend. |
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* |
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* - It replaces the core cache backend file. See README.md for details. |
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* - It cannot abide by PSR-1 "side-effects or symbols" rule because of the low |
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* level at which it operates, where the autoloader is not available. |
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*/ |
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include_once __DIR__ . '/../mongodb.module'; |
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/** |
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* MongoDB cache implementation. |
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* |
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* This is Drupal's default cache implementation. It uses the MongoDB to store |
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* cached data. Each cache bin corresponds to a collection by the same name. |
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*/ |
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class Cache implements \DrupalCacheInterface { |
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/** |
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* The name of the collection holding the cache data. |
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* |
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* @var string |
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*/ |
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protected $bin; |
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/** |
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* A closure wrapping MongoBinData::__construct() with its default $type. |
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* |
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* @var \Closure |
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*/ |
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protected $binDataCreator; |
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/** |
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* The collection holding the cache data. |
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* |
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* @var \MongoCollection|\MongoDebugCollection|\MongodbDummy |
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*/ |
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protected $collection; |
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/** |
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* Has a connection exception already been notified ? |
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* |
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* @var bool |
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* |
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* @see \Drupal\mongodb_cache\Cache::notifyException() |
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* @see \Drupal\mongodb_cache\Cache::hasException() |
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* |
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* This is a static, because the plugin assumes that connection errors will be |
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* share between all bins, under the hypothesis that all bins will be using |
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* the same connection. |
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*/ |
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protected static $isExceptionNotified = FALSE; |
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/** |
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* The default write options for this collection: unsafe mode. |
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* |
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* @var array |
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* |
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* @see self::__construct() |
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*/ |
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protected $unsafe; |
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/** |
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* The name of the state variable holding the latest bin expire timestamp. |
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* |
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* @var string |
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*/ |
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protected $flushVarName; |
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/** |
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* The number of seconds during which a new flush will be ignored. |
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* |
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* @var int |
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* |
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* @see self::__construct() |
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*/ |
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protected $stampedeDelay; |
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/** |
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* Constructor. |
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* |
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* @param string $bin |
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* The name of the cache bin for which to build a backend. |
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* |
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* @throws \MongoConnectionException |
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*/ |
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public function __construct($bin) { |
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$this->bin = $bin; |
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try { |
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$this->collection = mongodb_collection($bin); |
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} |
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catch (\MongoConnectionException $e) { |
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static::notifyException($e); |
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$this->collection = new \MongodbDummy(); |
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} |
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// Default is FALSE: this is a cache, so a missed write is not an issue. |
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$this->unsafe = mongodb_default_write_options(FALSE); |
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$this->stampedeDelay = variable_get('mongodb_cache_stampede_delay', 5); |
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$this->flushVarName = "flush_cache_{$bin}"; |
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$this->binDataCreator = $this->getBinDataCreator(); |
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} |
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/** |
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* Display an exception error message only once. |
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* |
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* @param \MongoException $e |
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* The exception to notify to the user. |
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*/ |
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protected static function notifyException(\MongoException $e) { |
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if (!self::$isExceptionNotified) { |
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drupal_set_message(t('MongoDB cache problem %exception.', [ |
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'%exception' => $e->getMessage(), |
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]), 'error'); |
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self::$isExceptionNotified = TRUE; |
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} |
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} |
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/** |
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* An alternate \MongoBinData constructor using default $type. |
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* |
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* @param mixed $data |
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* The data to convert to \MongoBinData. |
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* |
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* @return \Closure |
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* The alternate constructor with $type following the extension version. |
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*/ |
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protected function createBinData($data) { |
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$creator = $this->binDataCreator; |
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$result = $creator($data); |
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return $result; |
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} |
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/** |
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* Return the proper MongoBinData constructor with its type argument. |
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* |
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* The signature of \MongoBinData::__construct() changed in 1.2.11 to require |
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* $type and default to BYTE_ARRAY, then again in 1.5.0 to default to GENERIC. |
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* |
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* @return \Closure |
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* A closure wrapping the constructor with its expected $type. |
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*/ |
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protected function getBinDataCreator() { |
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$mongoVersion = phpversion('mongo'); |
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if (version_compare($mongoVersion, '1.2.11') < 0) { |
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$result = function ($data) { |
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return new \MongoBinData($data); |
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}; |
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} |
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else { |
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$type = version_compare($mongoVersion, '1.5.0') < 0 |
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? \MongoBinData::BYTE_ARRAY |
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: \MongoBinData::GENERIC; |
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$result = function ($data) use ($type) { |
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return new \MongoBinData($data, $type); |
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}; |
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} |
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return $result; |
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} |
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/** |
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* Return the timestamp of the latest flush. |
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* |
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* @return int |
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* A UNIX timestamp. |
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*/ |
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protected function getFlushTimestamp() { |
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$result = intval(variable_get($this->flushVarName, 0)); |
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return $result; |
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} |
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/** |
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* Record a timestamp as marking the latest flush for the current bin. |
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* |
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* As this performs a variable_set(), it is a costly operation. |
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* |
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* @param int $timestamp |
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* A UNIX timestamp. May be 0. |
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*/ |
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protected function setFlushTimestamp($timestamp) { |
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variable_set($this->flushVarName, $timestamp); |
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} |
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/** |
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* {@inheritdoc} |
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*/ |
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public function get($cid) { |
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try { |
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// Garbage collection necessary when enforcing a minimum cache lifetime. |
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$this->garbageCollection(); |
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$cache = $this->collection->findOne(['_id' => (string) $cid]); |
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$result = $this->prepareItem($cache); |
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} |
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catch (\MongoConnectionException $e) { |
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self::notifyException($e); |
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$result = FALSE; |
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} |
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return $result; |
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} |
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/** |
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* {@inheritdoc} |
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*/ |
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public function getMultiple(&$cids) { |
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$cache = []; |
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try { |
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// Garbage collection necessary when enforcing a minimum cache lifetime. |
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$this->garbageCollection(); |
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$criteria = [ |
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'_id' => [ |
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'$in' => array_map('strval', $cids), |
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], |
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]; |
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$result = $this->collection->find($criteria); |
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foreach ($result as $item) { |
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$item = $this->prepareItem($item); |
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if ($item) { |
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$cache[$item->cid] = $item; |
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} |
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} |
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$cids = array_diff($cids, array_keys($cache)); |
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} |
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catch (\MongoConnectionException $e) { |
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self::notifyException($e); |
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} |
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return $cache; |
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} |
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/** |
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* Garbage collection for get() and getMultiple(). |
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* |
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* @throws \MongoCursorException |
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* @throws \MongoCursorTimeoutException |
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*/ |
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protected function garbageCollection() { |
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// Garbage collection only required when enforcing a minimum cache lifetime. |
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$flush_timestamp = $this->getFlushTimestamp(); |
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if ($flush_timestamp && ($flush_timestamp + variable_get('cache_lifetime', 0) <= REQUEST_TIME)) { |
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// Reset the variable immediately to prevent a meltdown under heavy load. |
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$this->setFlushTimestamp(0); |
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// Remove non-permanently cached items from the collection. |
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$criteria = [ |
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'expire' => [ |
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'$lte' => $flush_timestamp, |
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'$ne' => CACHE_PERMANENT, |
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], |
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]; |
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try { |
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$this->collection->remove($criteria, $this->unsafe); |
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} |
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catch (\MongoConnectionException $e) { |
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self::notifyException($e); |
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} |
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// Re-enable the expiration mechanism. |
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$this->setFlushTimestamp(REQUEST_TIME + $this->stampedeDelay); |
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} |
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} |
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/** |
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* Prepare a cached item. |
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* |
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* Checks that items are either permanent not yet expired, and unserializes |
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* data as appropriate. |
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* |
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* @param array|null $cache |
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* An item loaded from cache_get() or cache_get_multiple(). |
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* |
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* @return false|object |
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* The item with data unserialized as appropriate or FALSE if there is no |
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* valid item to load. |
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*/ |
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protected function prepareItem($cache) { |
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if (!$cache || !isset($cache['data'])) { |
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return FALSE; |
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} |
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unset($cache['_id']); |
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$cache = (object) $cache; |
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293
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// If enforcing a minimum cache lifetime, validate that the data is |
294
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// currently valid for this user before we return it by making sure the |
295
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// cache entry was created before the timestamp in the current session's |
296
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// cache timer. The cache variable is loaded into the $user object by |
297
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// _drupal_session_read() in session.inc. If the data is permanent or we're |
298
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// not enforcing a minimum cache lifetime always return the cached data. |
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if ($cache->expire != CACHE_PERMANENT && variable_get('cache_lifetime', 0) |
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&& isset($_SESSION['cache_expiration'][$this->bin]) |
301
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&& $_SESSION['cache_expiration'][$this->bin] > $cache->created) { |
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// These cached data are too old and thus not valid for us, ignore it. |
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return FALSE; |
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} |
305
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if ($cache->data instanceof \MongoBinData) { |
306
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$cache->data = $cache->data->bin; |
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} |
308
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if ($cache->serialized) { |
309
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$cache->data = unserialize($cache->data); |
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} |
311
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312
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return $cache; |
313
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} |
314
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315
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/** |
316
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* {@inheritdoc} |
317
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*/ |
318
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public function set($cid, $data, $expire = CACHE_PERMANENT) { |
319
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$scalar = is_scalar($data); |
320
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$entry = array( |
321
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'_id' => (string) $cid, |
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'cid' => (string) $cid, |
323
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'created' => REQUEST_TIME, |
324
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'expire' => $expire, |
325
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'serialized' => !$scalar, |
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'data' => $scalar ? $data : serialize($data), |
327
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); |
328
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329
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// Use MongoBinData for non-UTF8 strings. |
330
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if (is_string($entry['data']) && !drupal_validate_utf8($entry['data'])) { |
331
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$entry['data'] = $this->createBinData($entry['data']); |
332
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} |
333
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334
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try { |
335
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$this->collection->save($entry, $this->unsafe); |
336
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} |
337
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// Multiple possible exceptions on save(), not just connection-related. |
338
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catch (\MongoException $e) { |
339
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self::notifyException($e); |
340
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// The database may not be available, so we'll ignore cache_set requests. |
341
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} |
342
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} |
343
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|
344
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/** |
345
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* Attempt removing data from the collection, notifying on exceptions. |
346
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* |
347
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* @param array|null $criteria |
348
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* NULL means to remove all documents from the collection. |
349
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* |
350
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* @throws \MongoCursorException |
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351
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* @throws \MongoCursorTimeoutException |
352
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*/ |
353
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protected function attemptRemove($criteria = NULL) { |
354
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try { |
355
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if ($criteria === []) { |
356
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$this->collection->drop(); |
357
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} |
358
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else { |
359
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$this->collection->remove($criteria, $this->unsafe); |
360
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} |
361
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} |
362
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catch (\MongoConnectionException $e) { |
363
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self::notifyException($e); |
364
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} |
365
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} |
366
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367
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/** |
368
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* {@inheritdoc} |
369
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*/ |
370
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public function clear($cid = NULL, $wildcard = FALSE) { |
|
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|
371
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$minimum_lifetime = variable_get('cache_lifetime', 0); |
372
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|
373
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if (empty($cid)) { |
374
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if ($minimum_lifetime) { |
375
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// We store the time in the current user's $user->cache variable which |
376
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// will be saved into the sessions bin by _drupal_session_write(). We |
377
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// then simulate that the cache was flushed for this user by not |
378
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// returning cached data that was cached before the timestamp. |
379
|
|
|
$_SESSION['cache_expiration'][$this->bin] = REQUEST_TIME; |
380
|
|
|
|
381
|
|
|
$flush_timestamp = $this->getFlushTimestamp(); |
382
|
|
|
if (empty($flush_timestamp)) { |
383
|
|
|
// This is the first request to clear the cache, start a timer. |
384
|
|
|
$this->setFlushTimestamp(REQUEST_TIME); |
385
|
|
|
} |
386
|
|
|
elseif (REQUEST_TIME > ($flush_timestamp + $minimum_lifetime)) { |
387
|
|
|
// Clear the cache for everyone, cache_lifetime seconds have passed |
388
|
|
|
// since the first request to clear the cache. |
389
|
|
|
$criteria = [ |
390
|
|
|
'expire' => [ |
391
|
|
|
'$ne' => CACHE_PERMANENT, |
392
|
|
|
'$lte' => REQUEST_TIME, |
393
|
|
|
], |
394
|
|
|
]; |
395
|
|
|
$this->attemptRemove($criteria); |
396
|
|
|
$this->setFlushTimestamp(REQUEST_TIME + $this->stampedeDelay); |
397
|
|
|
} |
398
|
|
|
} |
399
|
|
|
else { |
400
|
|
|
// No minimum cache lifetime, flush all temporary cache entries now. |
401
|
|
|
$criteria = [ |
402
|
|
|
'expire' => [ |
403
|
|
|
'$ne' => CACHE_PERMANENT, |
404
|
|
|
'$lte' => REQUEST_TIME, |
405
|
|
|
], |
406
|
|
|
]; |
407
|
|
|
$this->attemptRemove($criteria); |
408
|
|
|
} |
409
|
|
|
} |
410
|
|
|
else { |
411
|
|
|
if ($wildcard) { |
412
|
|
|
if ($cid == '*') { |
413
|
|
|
$criteria = []; |
414
|
|
|
$this->attemptRemove($criteria); |
415
|
|
|
} |
416
|
|
|
else { |
417
|
|
|
$criteria = [ |
418
|
|
|
'cid' => new \MongoRegex('/' . preg_quote($cid) . '.*/'), |
419
|
|
|
]; |
420
|
|
|
$this->attemptRemove($criteria); |
421
|
|
|
} |
422
|
|
|
} |
423
|
|
|
elseif (is_array($cid)) { |
424
|
|
|
// Delete in chunks in case a large array is passed. |
425
|
|
|
do { |
426
|
|
|
$criteria = [ |
427
|
|
|
'cid' => [ |
428
|
|
|
'$in' => array_map('strval', array_splice($cid, 0, 1000)), |
429
|
|
|
], |
430
|
|
|
]; |
431
|
|
|
$this->attemptRemove($criteria); |
432
|
|
|
} while (count($cid)); |
433
|
|
|
} |
434
|
|
|
else { |
435
|
|
|
$criteria = [ |
436
|
|
|
'_id' => (string) $cid, |
437
|
|
|
]; |
438
|
|
|
$this->attemptRemove($criteria); |
439
|
|
|
} |
440
|
|
|
} |
441
|
|
|
} |
442
|
|
|
|
443
|
|
|
/** |
444
|
|
|
* Has the plugin thrown an exception at any point ? |
445
|
|
|
* |
446
|
|
|
* @retun bool |
447
|
|
|
* Has it ? |
448
|
|
|
* |
449
|
|
|
* @see mongodb_cache_exit() |
450
|
|
|
*/ |
451
|
|
|
public static function hasException() { |
452
|
|
|
return static::$isExceptionNotified; |
453
|
|
|
} |
454
|
|
|
|
455
|
|
|
/** |
456
|
|
|
* {@inheritdoc} |
457
|
|
|
*/ |
458
|
|
|
public function isEmpty() { |
459
|
|
|
try { |
460
|
|
|
// Faster than findOne(). |
461
|
|
|
$result = !$this->collection->find([], ['_id' => 1])->limit(1)->next(); |
462
|
|
|
} |
463
|
|
|
catch (\MongoConnectionException $e) { |
464
|
|
|
// An unreachable cache is as good as empty. |
465
|
|
|
$result = TRUE; |
466
|
|
|
self::notifyException($e); |
467
|
|
|
} |
468
|
|
|
|
469
|
|
|
return $result; |
470
|
|
|
} |
471
|
|
|
|
472
|
|
|
} |
473
|
|
|
|