4 * This file is part of the Symfony package.
6 * (c) Fabien Potencier <fabien@symfony.com>
8 * For the full copyright and license information, please view the LICENSE
9 * file that was distributed with this source code.
12 namespace Symfony\Component\HttpFoundation\Session\Storage\Handler;
15 * Session handler using a PDO connection to read and write data.
17 * It works with MySQL, PostgreSQL, Oracle, SQL Server and SQLite and implements
18 * different locking strategies to handle concurrent access to the same session.
19 * Locking is necessary to prevent loss of data due to race conditions and to keep
20 * the session data consistent between read() and write(). With locking, requests
21 * for the same session will wait until the other one finished writing. For this
22 * reason it's best practice to close a session as early as possible to improve
23 * concurrency. PHPs internal files session handler also implements locking.
25 * Attention: Since SQLite does not support row level locks but locks the whole database,
26 * it means only one session can be accessed at a time. Even different sessions would wait
27 * for another to finish. So saving session in SQLite should only be considered for
28 * development or prototypes.
30 * Session data is a binary string that can contain non-printable characters like the null byte.
31 * For this reason it must be saved in a binary column in the database like BLOB in MySQL.
32 * Saving it in a character column could corrupt the data. You can use createTable()
33 * to initialize a correctly defined table.
35 * @see http://php.net/sessionhandlerinterface
37 * @author Fabien Potencier <fabien@symfony.com>
38 * @author Michael Williams <michael.williams@funsational.com>
39 * @author Tobias Schultze <http://tobion.de>
41 class PdoSessionHandler extends AbstractSessionHandler
44 * No locking is done. This means sessions are prone to loss of data due to
45 * race conditions of concurrent requests to the same session. The last session
46 * write will win in this case. It might be useful when you implement your own
47 * logic to deal with this like an optimistic approach.
52 * Creates an application-level lock on a session. The disadvantage is that the
53 * lock is not enforced by the database and thus other, unaware parts of the
54 * application could still concurrently modify the session. The advantage is it
55 * does not require a transaction.
56 * This mode is not available for SQLite and not yet implemented for oci and sqlsrv.
58 const LOCK_ADVISORY = 1;
61 * Issues a real row lock. Since it uses a transaction between opening and
62 * closing a session, you have to be careful when you use same database connection
63 * that you also use for your application logic. This mode is the default because
64 * it's the only reliable solution across DBMSs.
66 const LOCK_TRANSACTIONAL = 2;
69 * @var \PDO|null PDO instance or null when not connected yet
74 * @var string|null|false DSN string or null for session.save_path or false when lazy connection disabled
79 * @var string Database driver
84 * @var string Table name
86 private $table = 'sessions';
89 * @var string Column for session id
91 private $idCol = 'sess_id';
94 * @var string Column for session data
96 private $dataCol = 'sess_data';
99 * @var string Column for lifetime
101 private $lifetimeCol = 'sess_lifetime';
104 * @var string Column for timestamp
106 private $timeCol = 'sess_time';
109 * @var string Username when lazy-connect
111 private $username = '';
114 * @var string Password when lazy-connect
116 private $password = '';
119 * @var array Connection options when lazy-connect
121 private $connectionOptions = array();
124 * @var int The strategy for locking, see constants
126 private $lockMode = self::LOCK_TRANSACTIONAL;
129 * It's an array to support multiple reads before closing which is manual, non-standard usage.
131 * @var \PDOStatement[] An array of statements to release advisory locks
133 private $unlockStatements = array();
136 * @var bool True when the current session exists but expired according to session.gc_maxlifetime
138 private $sessionExpired = false;
141 * @var bool Whether a transaction is active
143 private $inTransaction = false;
146 * @var bool Whether gc() has been called
148 private $gcCalled = false;
151 * You can either pass an existing database connection as PDO instance or
152 * pass a DSN string that will be used to lazy-connect to the database
153 * when the session is actually used. Furthermore it's possible to pass null
154 * which will then use the session.save_path ini setting as PDO DSN parameter.
156 * List of available options:
157 * * db_table: The name of the table [default: sessions]
158 * * db_id_col: The column where to store the session id [default: sess_id]
159 * * db_data_col: The column where to store the session data [default: sess_data]
160 * * db_lifetime_col: The column where to store the lifetime [default: sess_lifetime]
161 * * db_time_col: The column where to store the timestamp [default: sess_time]
162 * * db_username: The username when lazy-connect [default: '']
163 * * db_password: The password when lazy-connect [default: '']
164 * * db_connection_options: An array of driver-specific connection options [default: array()]
165 * * lock_mode: The strategy for locking, see constants [default: LOCK_TRANSACTIONAL]
167 * @param \PDO|string|null $pdoOrDsn A \PDO instance or DSN string or URL string or null
168 * @param array $options An associative array of options
170 * @throws \InvalidArgumentException When PDO error mode is not PDO::ERRMODE_EXCEPTION
172 public function __construct($pdoOrDsn = null, array $options = array())
174 if ($pdoOrDsn instanceof \PDO) {
175 if (\PDO::ERRMODE_EXCEPTION !== $pdoOrDsn->getAttribute(\PDO::ATTR_ERRMODE)) {
176 throw new \InvalidArgumentException(sprintf('"%s" requires PDO error mode attribute be set to throw Exceptions (i.e. $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION))', __CLASS__));
179 $this->pdo = $pdoOrDsn;
180 $this->driver = $this->pdo->getAttribute(\PDO::ATTR_DRIVER_NAME);
181 } elseif (is_string($pdoOrDsn) && false !== strpos($pdoOrDsn, '://')) {
182 $this->dsn = $this->buildDsnFromUrl($pdoOrDsn);
184 $this->dsn = $pdoOrDsn;
187 $this->table = isset($options['db_table']) ? $options['db_table'] : $this->table;
188 $this->idCol = isset($options['db_id_col']) ? $options['db_id_col'] : $this->idCol;
189 $this->dataCol = isset($options['db_data_col']) ? $options['db_data_col'] : $this->dataCol;
190 $this->lifetimeCol = isset($options['db_lifetime_col']) ? $options['db_lifetime_col'] : $this->lifetimeCol;
191 $this->timeCol = isset($options['db_time_col']) ? $options['db_time_col'] : $this->timeCol;
192 $this->username = isset($options['db_username']) ? $options['db_username'] : $this->username;
193 $this->password = isset($options['db_password']) ? $options['db_password'] : $this->password;
194 $this->connectionOptions = isset($options['db_connection_options']) ? $options['db_connection_options'] : $this->connectionOptions;
195 $this->lockMode = isset($options['lock_mode']) ? $options['lock_mode'] : $this->lockMode;
199 * Creates the table to store sessions which can be called once for setup.
201 * Session ID is saved in a column of maximum length 128 because that is enough even
202 * for a 512 bit configured session.hash_function like Whirlpool. Session data is
203 * saved in a BLOB. One could also use a shorter inlined varbinary column
204 * if one was sure the data fits into it.
206 * @throws \PDOException When the table already exists
207 * @throws \DomainException When an unsupported PDO driver is used
209 public function createTable()
211 // connect if we are not yet
212 $this->getConnection();
214 switch ($this->driver) {
216 // We use varbinary for the ID column because it prevents unwanted conversions:
217 // - character set conversions between server and client
218 // - trailing space removal
219 // - case-insensitivity
220 // - language processing like é == e
221 $sql = "CREATE TABLE $this->table ($this->idCol VARBINARY(128) NOT NULL PRIMARY KEY, $this->dataCol BLOB NOT NULL, $this->lifetimeCol MEDIUMINT NOT NULL, $this->timeCol INTEGER UNSIGNED NOT NULL) COLLATE utf8_bin, ENGINE = InnoDB";
224 $sql = "CREATE TABLE $this->table ($this->idCol TEXT NOT NULL PRIMARY KEY, $this->dataCol BLOB NOT NULL, $this->lifetimeCol INTEGER NOT NULL, $this->timeCol INTEGER NOT NULL)";
227 $sql = "CREATE TABLE $this->table ($this->idCol VARCHAR(128) NOT NULL PRIMARY KEY, $this->dataCol BYTEA NOT NULL, $this->lifetimeCol INTEGER NOT NULL, $this->timeCol INTEGER NOT NULL)";
230 $sql = "CREATE TABLE $this->table ($this->idCol VARCHAR2(128) NOT NULL PRIMARY KEY, $this->dataCol BLOB NOT NULL, $this->lifetimeCol INTEGER NOT NULL, $this->timeCol INTEGER NOT NULL)";
233 $sql = "CREATE TABLE $this->table ($this->idCol VARCHAR(128) NOT NULL PRIMARY KEY, $this->dataCol VARBINARY(MAX) NOT NULL, $this->lifetimeCol INTEGER NOT NULL, $this->timeCol INTEGER NOT NULL)";
236 throw new \DomainException(sprintf('Creating the session table is currently not implemented for PDO driver "%s".', $this->driver));
240 $this->pdo->exec($sql);
241 } catch (\PDOException $e) {
249 * Returns true when the current session exists but expired according to session.gc_maxlifetime.
251 * Can be used to distinguish between a new session and one that expired due to inactivity.
253 * @return bool Whether current session expired
255 public function isSessionExpired()
257 return $this->sessionExpired;
263 public function open($savePath, $sessionName)
265 $this->sessionExpired = false;
267 if (null === $this->pdo) {
268 $this->connect($this->dsn ?: $savePath);
271 return parent::open($savePath, $sessionName);
277 public function read($sessionId)
280 return parent::read($sessionId);
281 } catch (\PDOException $e) {
291 public function gc($maxlifetime)
293 // We delay gc() to close() so that it is executed outside the transactional and blocking read-write process.
294 // This way, pruning expired sessions does not block them from being started while the current session is used.
295 $this->gcCalled = true;
303 protected function doDestroy($sessionId)
305 // delete the record associated with this id
306 $sql = "DELETE FROM $this->table WHERE $this->idCol = :id";
309 $stmt = $this->pdo->prepare($sql);
310 $stmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
312 } catch (\PDOException $e) {
324 protected function doWrite($sessionId, $data)
326 $maxlifetime = (int) ini_get('session.gc_maxlifetime');
329 // We use a single MERGE SQL query when supported by the database.
330 $mergeStmt = $this->getMergeStatement($sessionId, $data, $maxlifetime);
331 if (null !== $mergeStmt) {
332 $mergeStmt->execute();
337 $updateStmt = $this->getUpdateStatement($sessionId, $data, $maxlifetime);
338 $updateStmt->execute();
340 // When MERGE is not supported, like in Postgres < 9.5, we have to use this approach that can result in
341 // duplicate key errors when the same session is written simultaneously (given the LOCK_NONE behavior).
342 // We can just catch such an error and re-execute the update. This is similar to a serializable
343 // transaction with retry logic on serialization failures but without the overhead and without possible
344 // false positives due to longer gap locking.
345 if (!$updateStmt->rowCount()) {
347 $insertStmt = $this->getInsertStatement($sessionId, $data, $maxlifetime);
348 $insertStmt->execute();
349 } catch (\PDOException $e) {
350 // Handle integrity violation SQLSTATE 23000 (or a subclass like 23505 in Postgres) for duplicate keys
351 if (0 === strpos($e->getCode(), '23')) {
352 $updateStmt->execute();
358 } catch (\PDOException $e) {
370 public function updateTimestamp($sessionId, $data)
372 $maxlifetime = (int) ini_get('session.gc_maxlifetime');
375 $updateStmt = $this->pdo->prepare(
376 "UPDATE $this->table SET $this->lifetimeCol = :lifetime, $this->timeCol = :time WHERE $this->idCol = :id"
378 $updateStmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
379 $updateStmt->bindParam(':lifetime', $maxlifetime, \PDO::PARAM_INT);
380 $updateStmt->bindValue(':time', time(), \PDO::PARAM_INT);
381 $updateStmt->execute();
382 } catch (\PDOException $e) {
394 public function close()
398 while ($unlockStmt = array_shift($this->unlockStatements)) {
399 $unlockStmt->execute();
402 if ($this->gcCalled) {
403 $this->gcCalled = false;
405 // delete the session records that have expired
406 if ('mysql' === $this->driver) {
407 $sql = "DELETE FROM $this->table WHERE $this->lifetimeCol + $this->timeCol < :time";
409 $sql = "DELETE FROM $this->table WHERE $this->lifetimeCol < :time - $this->timeCol";
412 $stmt = $this->pdo->prepare($sql);
413 $stmt->bindValue(':time', time(), \PDO::PARAM_INT);
417 if (false !== $this->dsn) {
418 $this->pdo = null; // only close lazy-connection
425 * Lazy-connects to the database.
427 * @param string $dsn DSN string
429 private function connect($dsn)
431 $this->pdo = new \PDO($dsn, $this->username, $this->password, $this->connectionOptions);
432 $this->pdo->setAttribute(\PDO::ATTR_ERRMODE, \PDO::ERRMODE_EXCEPTION);
433 $this->driver = $this->pdo->getAttribute(\PDO::ATTR_DRIVER_NAME);
437 * Builds a PDO DSN from a URL-like connection string.
439 * @param string $dsnOrUrl
443 * @todo implement missing support for oci DSN (which look totally different from other PDO ones)
445 private function buildDsnFromUrl($dsnOrUrl)
447 // (pdo_)?sqlite3?:///... => (pdo_)?sqlite3?://localhost/... or else the URL will be invalid
448 $url = preg_replace('#^((?:pdo_)?sqlite3?):///#', '$1://localhost/', $dsnOrUrl);
450 $params = parse_url($url);
452 if (false === $params) {
453 return $dsnOrUrl; // If the URL is not valid, let's assume it might be a DSN already.
456 $params = array_map('rawurldecode', $params);
458 // Override the default username and password. Values passed through options will still win over these in the constructor.
459 if (isset($params['user'])) {
460 $this->username = $params['user'];
463 if (isset($params['pass'])) {
464 $this->password = $params['pass'];
467 if (!isset($params['scheme'])) {
468 throw new \InvalidArgumentException('URLs without scheme are not supported to configure the PdoSessionHandler');
471 $driverAliasMap = array(
473 'mysql2' => 'mysql', // Amazon RDS, for some weird reason
474 'postgres' => 'pgsql',
475 'postgresql' => 'pgsql',
476 'sqlite3' => 'sqlite',
479 $driver = isset($driverAliasMap[$params['scheme']]) ? $driverAliasMap[$params['scheme']] : $params['scheme'];
481 // Doctrine DBAL supports passing its internal pdo_* driver names directly too (allowing both dashes and underscores). This allows supporting the same here.
482 if (0 === strpos($driver, 'pdo_') || 0 === strpos($driver, 'pdo-')) {
483 $driver = substr($driver, 4);
491 if (isset($params['host']) && '' !== $params['host']) {
492 $dsn .= 'host='.$params['host'].';';
495 if (isset($params['port']) && '' !== $params['port']) {
496 $dsn .= 'port='.$params['port'].';';
499 if (isset($params['path'])) {
500 $dbName = substr($params['path'], 1); // Remove the leading slash
501 $dsn .= 'dbname='.$dbName.';';
507 return 'sqlite:'.substr($params['path'], 1);
510 $dsn = 'sqlsrv:server=';
512 if (isset($params['host'])) {
513 $dsn .= $params['host'];
516 if (isset($params['port']) && '' !== $params['port']) {
517 $dsn .= ','.$params['port'];
520 if (isset($params['path'])) {
521 $dbName = substr($params['path'], 1); // Remove the leading slash
522 $dsn .= ';Database='.$dbName;
528 throw new \InvalidArgumentException(sprintf('The scheme "%s" is not supported by the PdoSessionHandler URL configuration. Pass a PDO DSN directly.', $params['scheme']));
533 * Helper method to begin a transaction.
535 * Since SQLite does not support row level locks, we have to acquire a reserved lock
536 * on the database immediately. Because of https://bugs.php.net/42766 we have to create
537 * such a transaction manually which also means we cannot use PDO::commit or
538 * PDO::rollback or PDO::inTransaction for SQLite.
540 * Also MySQLs default isolation, REPEATABLE READ, causes deadlock for different sessions
541 * due to http://www.mysqlperformanceblog.com/2013/12/12/one-more-innodb-gap-lock-to-avoid/ .
542 * So we change it to READ COMMITTED.
544 private function beginTransaction()
546 if (!$this->inTransaction) {
547 if ('sqlite' === $this->driver) {
548 $this->pdo->exec('BEGIN IMMEDIATE TRANSACTION');
550 if ('mysql' === $this->driver) {
551 $this->pdo->exec('SET TRANSACTION ISOLATION LEVEL READ COMMITTED');
553 $this->pdo->beginTransaction();
555 $this->inTransaction = true;
560 * Helper method to commit a transaction.
562 private function commit()
564 if ($this->inTransaction) {
566 // commit read-write transaction which also releases the lock
567 if ('sqlite' === $this->driver) {
568 $this->pdo->exec('COMMIT');
570 $this->pdo->commit();
572 $this->inTransaction = false;
573 } catch (\PDOException $e) {
582 * Helper method to rollback a transaction.
584 private function rollback()
586 // We only need to rollback if we are in a transaction. Otherwise the resulting
587 // error would hide the real problem why rollback was called. We might not be
588 // in a transaction when not using the transactional locking behavior or when
589 // two callbacks (e.g. destroy and write) are invoked that both fail.
590 if ($this->inTransaction) {
591 if ('sqlite' === $this->driver) {
592 $this->pdo->exec('ROLLBACK');
594 $this->pdo->rollBack();
596 $this->inTransaction = false;
601 * Reads the session data in respect to the different locking strategies.
603 * We need to make sure we do not return session data that is already considered garbage according
604 * to the session.gc_maxlifetime setting because gc() is called after read() and only sometimes.
606 * @param string $sessionId Session ID
608 * @return string The session data
610 protected function doRead($sessionId)
612 if (self::LOCK_ADVISORY === $this->lockMode) {
613 $this->unlockStatements[] = $this->doAdvisoryLock($sessionId);
616 $selectSql = $this->getSelectSql();
617 $selectStmt = $this->pdo->prepare($selectSql);
618 $selectStmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
621 $selectStmt->execute();
622 $sessionRows = $selectStmt->fetchAll(\PDO::FETCH_NUM);
625 if ($sessionRows[0][1] + $sessionRows[0][2] < time()) {
626 $this->sessionExpired = true;
631 return is_resource($sessionRows[0][0]) ? stream_get_contents($sessionRows[0][0]) : $sessionRows[0][0];
634 if (!ini_get('session.use_strict_mode') && self::LOCK_TRANSACTIONAL === $this->lockMode && 'sqlite' !== $this->driver) {
635 // In strict mode, session fixation is not possible: new sessions always start with a unique
636 // random id, so that concurrency is not possible and this code path can be skipped.
637 // Exclusive-reading of non-existent rows does not block, so we need to do an insert to block
638 // until other connections to the session are committed.
640 $insertStmt = $this->getInsertStatement($sessionId, '', 0);
641 $insertStmt->execute();
642 } catch (\PDOException $e) {
643 // Catch duplicate key error because other connection created the session already.
644 // It would only not be the case when the other connection destroyed the session.
645 if (0 === strpos($e->getCode(), '23')) {
646 // Retrieve finished session data written by concurrent connection by restarting the loop.
647 // We have to start a new transaction as a failed query will mark the current transaction as
648 // aborted in PostgreSQL and disallow further queries within it.
650 $this->beginTransaction();
663 * Executes an application-level lock on the database.
665 * @param string $sessionId Session ID
667 * @return \PDOStatement The statement that needs to be executed later to release the lock
669 * @throws \DomainException When an unsupported PDO driver is used
671 * @todo implement missing advisory locks
672 * - for oci using DBMS_LOCK.REQUEST
673 * - for sqlsrv using sp_getapplock with LockOwner = Session
675 private function doAdvisoryLock($sessionId)
677 switch ($this->driver) {
679 // MySQL 5.7.5 and later enforces a maximum length on lock names of 64 characters. Previously, no limit was enforced.
680 $lockId = \substr($sessionId, 0, 64);
681 // should we handle the return value? 0 on timeout, null on error
682 // we use a timeout of 50 seconds which is also the default for innodb_lock_wait_timeout
683 $stmt = $this->pdo->prepare('SELECT GET_LOCK(:key, 50)');
684 $stmt->bindValue(':key', $lockId, \PDO::PARAM_STR);
687 $releaseStmt = $this->pdo->prepare('DO RELEASE_LOCK(:key)');
688 $releaseStmt->bindValue(':key', $lockId, \PDO::PARAM_STR);
692 // Obtaining an exclusive session level advisory lock requires an integer key.
693 // When session.sid_bits_per_character > 4, the session id can contain non-hex-characters.
694 // So we cannot just use hexdec().
695 if (4 === \PHP_INT_SIZE) {
696 $sessionInt1 = $this->convertStringToInt($sessionId);
697 $sessionInt2 = $this->convertStringToInt(substr($sessionId, 4, 4));
699 $stmt = $this->pdo->prepare('SELECT pg_advisory_lock(:key1, :key2)');
700 $stmt->bindValue(':key1', $sessionInt1, \PDO::PARAM_INT);
701 $stmt->bindValue(':key2', $sessionInt2, \PDO::PARAM_INT);
704 $releaseStmt = $this->pdo->prepare('SELECT pg_advisory_unlock(:key1, :key2)');
705 $releaseStmt->bindValue(':key1', $sessionInt1, \PDO::PARAM_INT);
706 $releaseStmt->bindValue(':key2', $sessionInt2, \PDO::PARAM_INT);
708 $sessionBigInt = $this->convertStringToInt($sessionId);
710 $stmt = $this->pdo->prepare('SELECT pg_advisory_lock(:key)');
711 $stmt->bindValue(':key', $sessionBigInt, \PDO::PARAM_INT);
714 $releaseStmt = $this->pdo->prepare('SELECT pg_advisory_unlock(:key)');
715 $releaseStmt->bindValue(':key', $sessionBigInt, \PDO::PARAM_INT);
720 throw new \DomainException('SQLite does not support advisory locks.');
722 throw new \DomainException(sprintf('Advisory locks are currently not implemented for PDO driver "%s".', $this->driver));
727 * Encodes the first 4 (when PHP_INT_SIZE == 4) or 8 characters of the string as an integer.
729 * Keep in mind, PHP integers are signed.
731 * @param string $string
735 private function convertStringToInt($string)
737 if (4 === \PHP_INT_SIZE) {
738 return (ord($string[3]) << 24) + (ord($string[2]) << 16) + (ord($string[1]) << 8) + ord($string[0]);
741 $int1 = (ord($string[7]) << 24) + (ord($string[6]) << 16) + (ord($string[5]) << 8) + ord($string[4]);
742 $int2 = (ord($string[3]) << 24) + (ord($string[2]) << 16) + (ord($string[1]) << 8) + ord($string[0]);
744 return $int2 + ($int1 << 32);
748 * Return a locking or nonlocking SQL query to read session information.
750 * @return string The SQL string
752 * @throws \DomainException When an unsupported PDO driver is used
754 private function getSelectSql()
756 if (self::LOCK_TRANSACTIONAL === $this->lockMode) {
757 $this->beginTransaction();
759 switch ($this->driver) {
763 return "SELECT $this->dataCol, $this->lifetimeCol, $this->timeCol FROM $this->table WHERE $this->idCol = :id FOR UPDATE";
765 return "SELECT $this->dataCol, $this->lifetimeCol, $this->timeCol FROM $this->table WITH (UPDLOCK, ROWLOCK) WHERE $this->idCol = :id";
767 // we already locked when starting transaction
770 throw new \DomainException(sprintf('Transactional locks are currently not implemented for PDO driver "%s".', $this->driver));
774 return "SELECT $this->dataCol, $this->lifetimeCol, $this->timeCol FROM $this->table WHERE $this->idCol = :id";
778 * Returns an insert statement supported by the database for writing session data.
780 * @param string $sessionId Session ID
781 * @param string $sessionData Encoded session data
782 * @param int $maxlifetime session.gc_maxlifetime
784 * @return \PDOStatement The insert statement
786 private function getInsertStatement($sessionId, $sessionData, $maxlifetime)
788 switch ($this->driver) {
790 $data = fopen('php://memory', 'r+');
791 fwrite($data, $sessionData);
793 $sql = "INSERT INTO $this->table ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (:id, EMPTY_BLOB(), :lifetime, :time) RETURNING $this->dataCol into :data";
796 $data = $sessionData;
797 $sql = "INSERT INTO $this->table ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (:id, :data, :lifetime, :time)";
801 $stmt = $this->pdo->prepare($sql);
802 $stmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
803 $stmt->bindParam(':data', $data, \PDO::PARAM_LOB);
804 $stmt->bindParam(':lifetime', $maxlifetime, \PDO::PARAM_INT);
805 $stmt->bindValue(':time', time(), \PDO::PARAM_INT);
811 * Returns an update statement supported by the database for writing session data.
813 * @param string $sessionId Session ID
814 * @param string $sessionData Encoded session data
815 * @param int $maxlifetime session.gc_maxlifetime
817 * @return \PDOStatement The update statement
819 private function getUpdateStatement($sessionId, $sessionData, $maxlifetime)
821 switch ($this->driver) {
823 $data = fopen('php://memory', 'r+');
824 fwrite($data, $sessionData);
826 $sql = "UPDATE $this->table SET $this->dataCol = EMPTY_BLOB(), $this->lifetimeCol = :lifetime, $this->timeCol = :time WHERE $this->idCol = :id RETURNING $this->dataCol into :data";
829 $data = $sessionData;
830 $sql = "UPDATE $this->table SET $this->dataCol = :data, $this->lifetimeCol = :lifetime, $this->timeCol = :time WHERE $this->idCol = :id";
834 $stmt = $this->pdo->prepare($sql);
835 $stmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
836 $stmt->bindParam(':data', $data, \PDO::PARAM_LOB);
837 $stmt->bindParam(':lifetime', $maxlifetime, \PDO::PARAM_INT);
838 $stmt->bindValue(':time', time(), \PDO::PARAM_INT);
844 * Returns a merge/upsert (i.e. insert or update) statement when supported by the database for writing session data.
846 * @param string $sessionId Session ID
847 * @param string $data Encoded session data
848 * @param int $maxlifetime session.gc_maxlifetime
850 * @return \PDOStatement|null The merge statement or null when not supported
852 private function getMergeStatement($sessionId, $data, $maxlifetime)
855 case 'mysql' === $this->driver:
856 $mergeSql = "INSERT INTO $this->table ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (:id, :data, :lifetime, :time) ".
857 "ON DUPLICATE KEY UPDATE $this->dataCol = VALUES($this->dataCol), $this->lifetimeCol = VALUES($this->lifetimeCol), $this->timeCol = VALUES($this->timeCol)";
859 case 'sqlsrv' === $this->driver && version_compare($this->pdo->getAttribute(\PDO::ATTR_SERVER_VERSION), '10', '>='):
860 // MERGE is only available since SQL Server 2008 and must be terminated by semicolon
861 // It also requires HOLDLOCK according to http://weblogs.sqlteam.com/dang/archive/2009/01/31/UPSERT-Race-Condition-With-MERGE.aspx
862 $mergeSql = "MERGE INTO $this->table WITH (HOLDLOCK) USING (SELECT 1 AS dummy) AS src ON ($this->idCol = ?) ".
863 "WHEN NOT MATCHED THEN INSERT ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (?, ?, ?, ?) ".
864 "WHEN MATCHED THEN UPDATE SET $this->dataCol = ?, $this->lifetimeCol = ?, $this->timeCol = ?;";
866 case 'sqlite' === $this->driver:
867 $mergeSql = "INSERT OR REPLACE INTO $this->table ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (:id, :data, :lifetime, :time)";
869 case 'pgsql' === $this->driver && version_compare($this->pdo->getAttribute(\PDO::ATTR_SERVER_VERSION), '9.5', '>='):
870 $mergeSql = "INSERT INTO $this->table ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (:id, :data, :lifetime, :time) ".
871 "ON CONFLICT ($this->idCol) DO UPDATE SET ($this->dataCol, $this->lifetimeCol, $this->timeCol) = (EXCLUDED.$this->dataCol, EXCLUDED.$this->lifetimeCol, EXCLUDED.$this->timeCol)";
874 // MERGE is not supported with LOBs: http://www.oracle.com/technetwork/articles/fuecks-lobs-095315.html
878 $mergeStmt = $this->pdo->prepare($mergeSql);
880 if ('sqlsrv' === $this->driver) {
881 $mergeStmt->bindParam(1, $sessionId, \PDO::PARAM_STR);
882 $mergeStmt->bindParam(2, $sessionId, \PDO::PARAM_STR);
883 $mergeStmt->bindParam(3, $data, \PDO::PARAM_LOB);
884 $mergeStmt->bindParam(4, $maxlifetime, \PDO::PARAM_INT);
885 $mergeStmt->bindValue(5, time(), \PDO::PARAM_INT);
886 $mergeStmt->bindParam(6, $data, \PDO::PARAM_LOB);
887 $mergeStmt->bindParam(7, $maxlifetime, \PDO::PARAM_INT);
888 $mergeStmt->bindValue(8, time(), \PDO::PARAM_INT);
890 $mergeStmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
891 $mergeStmt->bindParam(':data', $data, \PDO::PARAM_LOB);
892 $mergeStmt->bindParam(':lifetime', $maxlifetime, \PDO::PARAM_INT);
893 $mergeStmt->bindValue(':time', time(), \PDO::PARAM_INT);
900 * Return a PDO instance.
904 protected function getConnection()
906 if (null === $this->pdo) {
907 $this->connect($this->dsn ?: ini_get('session.save_path'));