Chris@0: <?php
Chris@0: 
Chris@0: /*
Chris@0:  * This file is part of the Symfony package.
Chris@0:  *
Chris@0:  * (c) Fabien Potencier <fabien@symfony.com>
Chris@0:  *
Chris@0:  * For the full copyright and license information, please view the LICENSE
Chris@0:  * file that was distributed with this source code.
Chris@0:  */
Chris@0: 
Chris@0: namespace Symfony\Component\HttpFoundation\Session\Storage\Handler;
Chris@0: 
Chris@0: /**
Chris@0:  * Session handler using a PDO connection to read and write data.
Chris@0:  *
Chris@0:  * It works with MySQL, PostgreSQL, Oracle, SQL Server and SQLite and implements
Chris@0:  * different locking strategies to handle concurrent access to the same session.
Chris@0:  * Locking is necessary to prevent loss of data due to race conditions and to keep
Chris@0:  * the session data consistent between read() and write(). With locking, requests
Chris@0:  * for the same session will wait until the other one finished writing. For this
Chris@0:  * reason it's best practice to close a session as early as possible to improve
Chris@0:  * concurrency. PHPs internal files session handler also implements locking.
Chris@0:  *
Chris@0:  * Attention: Since SQLite does not support row level locks but locks the whole database,
Chris@0:  * it means only one session can be accessed at a time. Even different sessions would wait
Chris@0:  * for another to finish. So saving session in SQLite should only be considered for
Chris@0:  * development or prototypes.
Chris@0:  *
Chris@0:  * Session data is a binary string that can contain non-printable characters like the null byte.
Chris@0:  * For this reason it must be saved in a binary column in the database like BLOB in MySQL.
Chris@0:  * Saving it in a character column could corrupt the data. You can use createTable()
Chris@0:  * to initialize a correctly defined table.
Chris@0:  *
Chris@0:  * @see http://php.net/sessionhandlerinterface
Chris@0:  *
Chris@0:  * @author Fabien Potencier <fabien@symfony.com>
Chris@0:  * @author Michael Williams <michael.williams@funsational.com>
Chris@0:  * @author Tobias Schultze <http://tobion.de>
Chris@0:  */
Chris@0: class PdoSessionHandler implements \SessionHandlerInterface
Chris@0: {
Chris@0:     /**
Chris@0:      * No locking is done. This means sessions are prone to loss of data due to
Chris@0:      * race conditions of concurrent requests to the same session. The last session
Chris@0:      * write will win in this case. It might be useful when you implement your own
Chris@0:      * logic to deal with this like an optimistic approach.
Chris@0:      */
Chris@0:     const LOCK_NONE = 0;
Chris@0: 
Chris@0:     /**
Chris@0:      * Creates an application-level lock on a session. The disadvantage is that the
Chris@0:      * lock is not enforced by the database and thus other, unaware parts of the
Chris@0:      * application could still concurrently modify the session. The advantage is it
Chris@0:      * does not require a transaction.
Chris@0:      * This mode is not available for SQLite and not yet implemented for oci and sqlsrv.
Chris@0:      */
Chris@0:     const LOCK_ADVISORY = 1;
Chris@0: 
Chris@0:     /**
Chris@0:      * Issues a real row lock. Since it uses a transaction between opening and
Chris@0:      * closing a session, you have to be careful when you use same database connection
Chris@0:      * that you also use for your application logic. This mode is the default because
Chris@0:      * it's the only reliable solution across DBMSs.
Chris@0:      */
Chris@0:     const LOCK_TRANSACTIONAL = 2;
Chris@0: 
Chris@0:     /**
Chris@0:      * @var \PDO|null PDO instance or null when not connected yet
Chris@0:      */
Chris@0:     private $pdo;
Chris@0: 
Chris@0:     /**
Chris@0:      * @var string|null|false DSN string or null for session.save_path or false when lazy connection disabled
Chris@0:      */
Chris@0:     private $dsn = false;
Chris@0: 
Chris@0:     /**
Chris@0:      * @var string Database driver
Chris@0:      */
Chris@0:     private $driver;
Chris@0: 
Chris@0:     /**
Chris@0:      * @var string Table name
Chris@0:      */
Chris@0:     private $table = 'sessions';
Chris@0: 
Chris@0:     /**
Chris@0:      * @var string Column for session id
Chris@0:      */
Chris@0:     private $idCol = 'sess_id';
Chris@0: 
Chris@0:     /**
Chris@0:      * @var string Column for session data
Chris@0:      */
Chris@0:     private $dataCol = 'sess_data';
Chris@0: 
Chris@0:     /**
Chris@0:      * @var string Column for lifetime
Chris@0:      */
Chris@0:     private $lifetimeCol = 'sess_lifetime';
Chris@0: 
Chris@0:     /**
Chris@0:      * @var string Column for timestamp
Chris@0:      */
Chris@0:     private $timeCol = 'sess_time';
Chris@0: 
Chris@0:     /**
Chris@0:      * @var string Username when lazy-connect
Chris@0:      */
Chris@0:     private $username = '';
Chris@0: 
Chris@0:     /**
Chris@0:      * @var string Password when lazy-connect
Chris@0:      */
Chris@0:     private $password = '';
Chris@0: 
Chris@0:     /**
Chris@0:      * @var array Connection options when lazy-connect
Chris@0:      */
Chris@0:     private $connectionOptions = array();
Chris@0: 
Chris@0:     /**
Chris@0:      * @var int The strategy for locking, see constants
Chris@0:      */
Chris@0:     private $lockMode = self::LOCK_TRANSACTIONAL;
Chris@0: 
Chris@0:     /**
Chris@0:      * It's an array to support multiple reads before closing which is manual, non-standard usage.
Chris@0:      *
Chris@0:      * @var \PDOStatement[] An array of statements to release advisory locks
Chris@0:      */
Chris@0:     private $unlockStatements = array();
Chris@0: 
Chris@0:     /**
Chris@0:      * @var bool True when the current session exists but expired according to session.gc_maxlifetime
Chris@0:      */
Chris@0:     private $sessionExpired = false;
Chris@0: 
Chris@0:     /**
Chris@0:      * @var bool Whether a transaction is active
Chris@0:      */
Chris@0:     private $inTransaction = false;
Chris@0: 
Chris@0:     /**
Chris@0:      * @var bool Whether gc() has been called
Chris@0:      */
Chris@0:     private $gcCalled = false;
Chris@0: 
Chris@0:     /**
Chris@0:      * Constructor.
Chris@0:      *
Chris@0:      * You can either pass an existing database connection as PDO instance or
Chris@0:      * pass a DSN string that will be used to lazy-connect to the database
Chris@0:      * when the session is actually used. Furthermore it's possible to pass null
Chris@0:      * which will then use the session.save_path ini setting as PDO DSN parameter.
Chris@0:      *
Chris@0:      * List of available options:
Chris@0:      *  * db_table: The name of the table [default: sessions]
Chris@0:      *  * db_id_col: The column where to store the session id [default: sess_id]
Chris@0:      *  * db_data_col: The column where to store the session data [default: sess_data]
Chris@0:      *  * db_lifetime_col: The column where to store the lifetime [default: sess_lifetime]
Chris@0:      *  * db_time_col: The column where to store the timestamp [default: sess_time]
Chris@0:      *  * db_username: The username when lazy-connect [default: '']
Chris@0:      *  * db_password: The password when lazy-connect [default: '']
Chris@0:      *  * db_connection_options: An array of driver-specific connection options [default: array()]
Chris@0:      *  * lock_mode: The strategy for locking, see constants [default: LOCK_TRANSACTIONAL]
Chris@0:      *
Chris@0:      * @param \PDO|string|null $pdoOrDsn A \PDO instance or DSN string or null
Chris@0:      * @param array            $options  An associative array of options
Chris@0:      *
Chris@0:      * @throws \InvalidArgumentException When PDO error mode is not PDO::ERRMODE_EXCEPTION
Chris@0:      */
Chris@0:     public function __construct($pdoOrDsn = null, array $options = array())
Chris@0:     {
Chris@0:         if ($pdoOrDsn instanceof \PDO) {
Chris@0:             if (\PDO::ERRMODE_EXCEPTION !== $pdoOrDsn->getAttribute(\PDO::ATTR_ERRMODE)) {
Chris@0:                 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__));
Chris@0:             }
Chris@0: 
Chris@0:             $this->pdo = $pdoOrDsn;
Chris@0:             $this->driver = $this->pdo->getAttribute(\PDO::ATTR_DRIVER_NAME);
Chris@0:         } else {
Chris@0:             $this->dsn = $pdoOrDsn;
Chris@0:         }
Chris@0: 
Chris@0:         $this->table = isset($options['db_table']) ? $options['db_table'] : $this->table;
Chris@0:         $this->idCol = isset($options['db_id_col']) ? $options['db_id_col'] : $this->idCol;
Chris@0:         $this->dataCol = isset($options['db_data_col']) ? $options['db_data_col'] : $this->dataCol;
Chris@0:         $this->lifetimeCol = isset($options['db_lifetime_col']) ? $options['db_lifetime_col'] : $this->lifetimeCol;
Chris@0:         $this->timeCol = isset($options['db_time_col']) ? $options['db_time_col'] : $this->timeCol;
Chris@0:         $this->username = isset($options['db_username']) ? $options['db_username'] : $this->username;
Chris@0:         $this->password = isset($options['db_password']) ? $options['db_password'] : $this->password;
Chris@0:         $this->connectionOptions = isset($options['db_connection_options']) ? $options['db_connection_options'] : $this->connectionOptions;
Chris@0:         $this->lockMode = isset($options['lock_mode']) ? $options['lock_mode'] : $this->lockMode;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Creates the table to store sessions which can be called once for setup.
Chris@0:      *
Chris@0:      * Session ID is saved in a column of maximum length 128 because that is enough even
Chris@0:      * for a 512 bit configured session.hash_function like Whirlpool. Session data is
Chris@0:      * saved in a BLOB. One could also use a shorter inlined varbinary column
Chris@0:      * if one was sure the data fits into it.
Chris@0:      *
Chris@0:      * @throws \PDOException    When the table already exists
Chris@0:      * @throws \DomainException When an unsupported PDO driver is used
Chris@0:      */
Chris@0:     public function createTable()
Chris@0:     {
Chris@0:         // connect if we are not yet
Chris@0:         $this->getConnection();
Chris@0: 
Chris@0:         switch ($this->driver) {
Chris@0:             case 'mysql':
Chris@0:                 // We use varbinary for the ID column because it prevents unwanted conversions:
Chris@0:                 // - character set conversions between server and client
Chris@0:                 // - trailing space removal
Chris@0:                 // - case-insensitivity
Chris@0:                 // - language processing like é == e
Chris@0:                 $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";
Chris@0:                 break;
Chris@0:             case 'sqlite':
Chris@0:                 $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)";
Chris@0:                 break;
Chris@0:             case 'pgsql':
Chris@0:                 $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)";
Chris@0:                 break;
Chris@0:             case 'oci':
Chris@0:                 $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)";
Chris@0:                 break;
Chris@0:             case 'sqlsrv':
Chris@0:                 $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)";
Chris@0:                 break;
Chris@0:             default:
Chris@0:                 throw new \DomainException(sprintf('Creating the session table is currently not implemented for PDO driver "%s".', $this->driver));
Chris@0:         }
Chris@0: 
Chris@0:         try {
Chris@0:             $this->pdo->exec($sql);
Chris@0:         } catch (\PDOException $e) {
Chris@0:             $this->rollback();
Chris@0: 
Chris@0:             throw $e;
Chris@0:         }
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Returns true when the current session exists but expired according to session.gc_maxlifetime.
Chris@0:      *
Chris@0:      * Can be used to distinguish between a new session and one that expired due to inactivity.
Chris@0:      *
Chris@0:      * @return bool Whether current session expired
Chris@0:      */
Chris@0:     public function isSessionExpired()
Chris@0:     {
Chris@0:         return $this->sessionExpired;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * {@inheritdoc}
Chris@0:      */
Chris@0:     public function open($savePath, $sessionName)
Chris@0:     {
Chris@0:         if (null === $this->pdo) {
Chris@0:             $this->connect($this->dsn ?: $savePath);
Chris@0:         }
Chris@0: 
Chris@0:         return true;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * {@inheritdoc}
Chris@0:      */
Chris@0:     public function read($sessionId)
Chris@0:     {
Chris@0:         try {
Chris@0:             return $this->doRead($sessionId);
Chris@0:         } catch (\PDOException $e) {
Chris@0:             $this->rollback();
Chris@0: 
Chris@0:             throw $e;
Chris@0:         }
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * {@inheritdoc}
Chris@0:      */
Chris@0:     public function gc($maxlifetime)
Chris@0:     {
Chris@0:         // We delay gc() to close() so that it is executed outside the transactional and blocking read-write process.
Chris@0:         // This way, pruning expired sessions does not block them from being started while the current session is used.
Chris@0:         $this->gcCalled = true;
Chris@0: 
Chris@0:         return true;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * {@inheritdoc}
Chris@0:      */
Chris@0:     public function destroy($sessionId)
Chris@0:     {
Chris@0:         // delete the record associated with this id
Chris@0:         $sql = "DELETE FROM $this->table WHERE $this->idCol = :id";
Chris@0: 
Chris@0:         try {
Chris@0:             $stmt = $this->pdo->prepare($sql);
Chris@0:             $stmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
Chris@0:             $stmt->execute();
Chris@0:         } catch (\PDOException $e) {
Chris@0:             $this->rollback();
Chris@0: 
Chris@0:             throw $e;
Chris@0:         }
Chris@0: 
Chris@0:         return true;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * {@inheritdoc}
Chris@0:      */
Chris@0:     public function write($sessionId, $data)
Chris@0:     {
Chris@0:         $maxlifetime = (int) ini_get('session.gc_maxlifetime');
Chris@0: 
Chris@0:         try {
Chris@0:             // We use a single MERGE SQL query when supported by the database.
Chris@0:             $mergeStmt = $this->getMergeStatement($sessionId, $data, $maxlifetime);
Chris@0:             if (null !== $mergeStmt) {
Chris@0:                 $mergeStmt->execute();
Chris@0: 
Chris@0:                 return true;
Chris@0:             }
Chris@0: 
Chris@0:             $updateStmt = $this->pdo->prepare(
Chris@0:                 "UPDATE $this->table SET $this->dataCol = :data, $this->lifetimeCol = :lifetime, $this->timeCol = :time WHERE $this->idCol = :id"
Chris@0:             );
Chris@0:             $updateStmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
Chris@0:             $updateStmt->bindParam(':data', $data, \PDO::PARAM_LOB);
Chris@0:             $updateStmt->bindParam(':lifetime', $maxlifetime, \PDO::PARAM_INT);
Chris@0:             $updateStmt->bindValue(':time', time(), \PDO::PARAM_INT);
Chris@0:             $updateStmt->execute();
Chris@0: 
Chris@0:             // When MERGE is not supported, like in Postgres < 9.5, we have to use this approach that can result in
Chris@0:             // duplicate key errors when the same session is written simultaneously (given the LOCK_NONE behavior).
Chris@0:             // We can just catch such an error and re-execute the update. This is similar to a serializable
Chris@0:             // transaction with retry logic on serialization failures but without the overhead and without possible
Chris@0:             // false positives due to longer gap locking.
Chris@0:             if (!$updateStmt->rowCount()) {
Chris@0:                 try {
Chris@0:                     $insertStmt = $this->pdo->prepare(
Chris@0:                         "INSERT INTO $this->table ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (:id, :data, :lifetime, :time)"
Chris@0:                     );
Chris@0:                     $insertStmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
Chris@0:                     $insertStmt->bindParam(':data', $data, \PDO::PARAM_LOB);
Chris@0:                     $insertStmt->bindParam(':lifetime', $maxlifetime, \PDO::PARAM_INT);
Chris@0:                     $insertStmt->bindValue(':time', time(), \PDO::PARAM_INT);
Chris@0:                     $insertStmt->execute();
Chris@0:                 } catch (\PDOException $e) {
Chris@0:                     // Handle integrity violation SQLSTATE 23000 (or a subclass like 23505 in Postgres) for duplicate keys
Chris@0:                     if (0 === strpos($e->getCode(), '23')) {
Chris@0:                         $updateStmt->execute();
Chris@0:                     } else {
Chris@0:                         throw $e;
Chris@0:                     }
Chris@0:                 }
Chris@0:             }
Chris@0:         } catch (\PDOException $e) {
Chris@0:             $this->rollback();
Chris@0: 
Chris@0:             throw $e;
Chris@0:         }
Chris@0: 
Chris@0:         return true;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * {@inheritdoc}
Chris@0:      */
Chris@0:     public function close()
Chris@0:     {
Chris@0:         $this->commit();
Chris@0: 
Chris@0:         while ($unlockStmt = array_shift($this->unlockStatements)) {
Chris@0:             $unlockStmt->execute();
Chris@0:         }
Chris@0: 
Chris@0:         if ($this->gcCalled) {
Chris@0:             $this->gcCalled = false;
Chris@0: 
Chris@0:             // delete the session records that have expired
Chris@0:             $sql = "DELETE FROM $this->table WHERE $this->lifetimeCol + $this->timeCol < :time";
Chris@0: 
Chris@0:             $stmt = $this->pdo->prepare($sql);
Chris@0:             $stmt->bindValue(':time', time(), \PDO::PARAM_INT);
Chris@0:             $stmt->execute();
Chris@0:         }
Chris@0: 
Chris@0:         if (false !== $this->dsn) {
Chris@0:             $this->pdo = null; // only close lazy-connection
Chris@0:         }
Chris@0: 
Chris@0:         return true;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Lazy-connects to the database.
Chris@0:      *
Chris@0:      * @param string $dsn DSN string
Chris@0:      */
Chris@0:     private function connect($dsn)
Chris@0:     {
Chris@0:         $this->pdo = new \PDO($dsn, $this->username, $this->password, $this->connectionOptions);
Chris@0:         $this->pdo->setAttribute(\PDO::ATTR_ERRMODE, \PDO::ERRMODE_EXCEPTION);
Chris@0:         $this->driver = $this->pdo->getAttribute(\PDO::ATTR_DRIVER_NAME);
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Helper method to begin a transaction.
Chris@0:      *
Chris@0:      * Since SQLite does not support row level locks, we have to acquire a reserved lock
Chris@0:      * on the database immediately. Because of https://bugs.php.net/42766 we have to create
Chris@0:      * such a transaction manually which also means we cannot use PDO::commit or
Chris@0:      * PDO::rollback or PDO::inTransaction for SQLite.
Chris@0:      *
Chris@0:      * Also MySQLs default isolation, REPEATABLE READ, causes deadlock for different sessions
Chris@0:      * due to http://www.mysqlperformanceblog.com/2013/12/12/one-more-innodb-gap-lock-to-avoid/ .
Chris@0:      * So we change it to READ COMMITTED.
Chris@0:      */
Chris@0:     private function beginTransaction()
Chris@0:     {
Chris@0:         if (!$this->inTransaction) {
Chris@0:             if ('sqlite' === $this->driver) {
Chris@0:                 $this->pdo->exec('BEGIN IMMEDIATE TRANSACTION');
Chris@0:             } else {
Chris@0:                 if ('mysql' === $this->driver) {
Chris@0:                     $this->pdo->exec('SET TRANSACTION ISOLATION LEVEL READ COMMITTED');
Chris@0:                 }
Chris@0:                 $this->pdo->beginTransaction();
Chris@0:             }
Chris@0:             $this->inTransaction = true;
Chris@0:         }
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Helper method to commit a transaction.
Chris@0:      */
Chris@0:     private function commit()
Chris@0:     {
Chris@0:         if ($this->inTransaction) {
Chris@0:             try {
Chris@0:                 // commit read-write transaction which also releases the lock
Chris@0:                 if ('sqlite' === $this->driver) {
Chris@0:                     $this->pdo->exec('COMMIT');
Chris@0:                 } else {
Chris@0:                     $this->pdo->commit();
Chris@0:                 }
Chris@0:                 $this->inTransaction = false;
Chris@0:             } catch (\PDOException $e) {
Chris@0:                 $this->rollback();
Chris@0: 
Chris@0:                 throw $e;
Chris@0:             }
Chris@0:         }
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Helper method to rollback a transaction.
Chris@0:      */
Chris@0:     private function rollback()
Chris@0:     {
Chris@0:         // We only need to rollback if we are in a transaction. Otherwise the resulting
Chris@0:         // error would hide the real problem why rollback was called. We might not be
Chris@0:         // in a transaction when not using the transactional locking behavior or when
Chris@0:         // two callbacks (e.g. destroy and write) are invoked that both fail.
Chris@0:         if ($this->inTransaction) {
Chris@0:             if ('sqlite' === $this->driver) {
Chris@0:                 $this->pdo->exec('ROLLBACK');
Chris@0:             } else {
Chris@0:                 $this->pdo->rollBack();
Chris@0:             }
Chris@0:             $this->inTransaction = false;
Chris@0:         }
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Reads the session data in respect to the different locking strategies.
Chris@0:      *
Chris@0:      * We need to make sure we do not return session data that is already considered garbage according
Chris@0:      * to the session.gc_maxlifetime setting because gc() is called after read() and only sometimes.
Chris@0:      *
Chris@0:      * @param string $sessionId Session ID
Chris@0:      *
Chris@0:      * @return string The session data
Chris@0:      */
Chris@0:     private function doRead($sessionId)
Chris@0:     {
Chris@0:         $this->sessionExpired = false;
Chris@0: 
Chris@0:         if (self::LOCK_ADVISORY === $this->lockMode) {
Chris@0:             $this->unlockStatements[] = $this->doAdvisoryLock($sessionId);
Chris@0:         }
Chris@0: 
Chris@0:         $selectSql = $this->getSelectSql();
Chris@0:         $selectStmt = $this->pdo->prepare($selectSql);
Chris@0:         $selectStmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
Chris@0: 
Chris@0:         do {
Chris@0:             $selectStmt->execute();
Chris@0:             $sessionRows = $selectStmt->fetchAll(\PDO::FETCH_NUM);
Chris@0: 
Chris@0:             if ($sessionRows) {
Chris@0:                 if ($sessionRows[0][1] + $sessionRows[0][2] < time()) {
Chris@0:                     $this->sessionExpired = true;
Chris@0: 
Chris@0:                     return '';
Chris@0:                 }
Chris@0: 
Chris@0:                 return is_resource($sessionRows[0][0]) ? stream_get_contents($sessionRows[0][0]) : $sessionRows[0][0];
Chris@0:             }
Chris@0: 
Chris@0:             if (self::LOCK_TRANSACTIONAL === $this->lockMode && 'sqlite' !== $this->driver) {
Chris@0:                 // Exclusive-reading of non-existent rows does not block, so we need to do an insert to block
Chris@0:                 // until other connections to the session are committed.
Chris@0:                 try {
Chris@0:                     $insertStmt = $this->pdo->prepare(
Chris@0:                         "INSERT INTO $this->table ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (:id, :data, :lifetime, :time)"
Chris@0:                     );
Chris@0:                     $insertStmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
Chris@0:                     $insertStmt->bindValue(':data', '', \PDO::PARAM_LOB);
Chris@0:                     $insertStmt->bindValue(':lifetime', 0, \PDO::PARAM_INT);
Chris@0:                     $insertStmt->bindValue(':time', time(), \PDO::PARAM_INT);
Chris@0:                     $insertStmt->execute();
Chris@0:                 } catch (\PDOException $e) {
Chris@0:                     // Catch duplicate key error because other connection created the session already.
Chris@0:                     // It would only not be the case when the other connection destroyed the session.
Chris@0:                     if (0 === strpos($e->getCode(), '23')) {
Chris@0:                         // Retrieve finished session data written by concurrent connection by restarting the loop.
Chris@0:                         // We have to start a new transaction as a failed query will mark the current transaction as
Chris@0:                         // aborted in PostgreSQL and disallow further queries within it.
Chris@0:                         $this->rollback();
Chris@0:                         $this->beginTransaction();
Chris@0:                         continue;
Chris@0:                     }
Chris@0: 
Chris@0:                     throw $e;
Chris@0:                 }
Chris@0:             }
Chris@0: 
Chris@0:             return '';
Chris@0:         } while (true);
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Executes an application-level lock on the database.
Chris@0:      *
Chris@0:      * @param string $sessionId Session ID
Chris@0:      *
Chris@0:      * @return \PDOStatement The statement that needs to be executed later to release the lock
Chris@0:      *
Chris@0:      * @throws \DomainException When an unsupported PDO driver is used
Chris@0:      *
Chris@0:      * @todo implement missing advisory locks
Chris@0:      *       - for oci using DBMS_LOCK.REQUEST
Chris@0:      *       - for sqlsrv using sp_getapplock with LockOwner = Session
Chris@0:      */
Chris@0:     private function doAdvisoryLock($sessionId)
Chris@0:     {
Chris@0:         switch ($this->driver) {
Chris@0:             case 'mysql':
Chris@0:                 // should we handle the return value? 0 on timeout, null on error
Chris@0:                 // we use a timeout of 50 seconds which is also the default for innodb_lock_wait_timeout
Chris@0:                 $stmt = $this->pdo->prepare('SELECT GET_LOCK(:key, 50)');
Chris@0:                 $stmt->bindValue(':key', $sessionId, \PDO::PARAM_STR);
Chris@0:                 $stmt->execute();
Chris@0: 
Chris@0:                 $releaseStmt = $this->pdo->prepare('DO RELEASE_LOCK(:key)');
Chris@0:                 $releaseStmt->bindValue(':key', $sessionId, \PDO::PARAM_STR);
Chris@0: 
Chris@0:                 return $releaseStmt;
Chris@0:             case 'pgsql':
Chris@0:                 // Obtaining an exclusive session level advisory lock requires an integer key.
Chris@0:                 // So we convert the HEX representation of the session id to an integer.
Chris@0:                 // Since integers are signed, we have to skip one hex char to fit in the range.
Chris@0:                 if (4 === PHP_INT_SIZE) {
Chris@0:                     $sessionInt1 = hexdec(substr($sessionId, 0, 7));
Chris@0:                     $sessionInt2 = hexdec(substr($sessionId, 7, 7));
Chris@0: 
Chris@0:                     $stmt = $this->pdo->prepare('SELECT pg_advisory_lock(:key1, :key2)');
Chris@0:                     $stmt->bindValue(':key1', $sessionInt1, \PDO::PARAM_INT);
Chris@0:                     $stmt->bindValue(':key2', $sessionInt2, \PDO::PARAM_INT);
Chris@0:                     $stmt->execute();
Chris@0: 
Chris@0:                     $releaseStmt = $this->pdo->prepare('SELECT pg_advisory_unlock(:key1, :key2)');
Chris@0:                     $releaseStmt->bindValue(':key1', $sessionInt1, \PDO::PARAM_INT);
Chris@0:                     $releaseStmt->bindValue(':key2', $sessionInt2, \PDO::PARAM_INT);
Chris@0:                 } else {
Chris@0:                     $sessionBigInt = hexdec(substr($sessionId, 0, 15));
Chris@0: 
Chris@0:                     $stmt = $this->pdo->prepare('SELECT pg_advisory_lock(:key)');
Chris@0:                     $stmt->bindValue(':key', $sessionBigInt, \PDO::PARAM_INT);
Chris@0:                     $stmt->execute();
Chris@0: 
Chris@0:                     $releaseStmt = $this->pdo->prepare('SELECT pg_advisory_unlock(:key)');
Chris@0:                     $releaseStmt->bindValue(':key', $sessionBigInt, \PDO::PARAM_INT);
Chris@0:                 }
Chris@0: 
Chris@0:                 return $releaseStmt;
Chris@0:             case 'sqlite':
Chris@0:                 throw new \DomainException('SQLite does not support advisory locks.');
Chris@0:             default:
Chris@0:                 throw new \DomainException(sprintf('Advisory locks are currently not implemented for PDO driver "%s".', $this->driver));
Chris@0:         }
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Return a locking or nonlocking SQL query to read session information.
Chris@0:      *
Chris@0:      * @return string The SQL string
Chris@0:      *
Chris@0:      * @throws \DomainException When an unsupported PDO driver is used
Chris@0:      */
Chris@0:     private function getSelectSql()
Chris@0:     {
Chris@0:         if (self::LOCK_TRANSACTIONAL === $this->lockMode) {
Chris@0:             $this->beginTransaction();
Chris@0: 
Chris@0:             switch ($this->driver) {
Chris@0:                 case 'mysql':
Chris@0:                 case 'oci':
Chris@0:                 case 'pgsql':
Chris@0:                     return "SELECT $this->dataCol, $this->lifetimeCol, $this->timeCol FROM $this->table WHERE $this->idCol = :id FOR UPDATE";
Chris@0:                 case 'sqlsrv':
Chris@0:                     return "SELECT $this->dataCol, $this->lifetimeCol, $this->timeCol FROM $this->table WITH (UPDLOCK, ROWLOCK) WHERE $this->idCol = :id";
Chris@0:                 case 'sqlite':
Chris@0:                     // we already locked when starting transaction
Chris@0:                     break;
Chris@0:                 default:
Chris@0:                     throw new \DomainException(sprintf('Transactional locks are currently not implemented for PDO driver "%s".', $this->driver));
Chris@0:             }
Chris@0:         }
Chris@0: 
Chris@0:         return "SELECT $this->dataCol, $this->lifetimeCol, $this->timeCol FROM $this->table WHERE $this->idCol = :id";
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Returns a merge/upsert (i.e. insert or update) statement when supported by the database for writing session data.
Chris@0:      *
Chris@0:      * @param string $sessionId   Session ID
Chris@0:      * @param string $data        Encoded session data
Chris@0:      * @param int    $maxlifetime session.gc_maxlifetime
Chris@0:      *
Chris@0:      * @return \PDOStatement|null The merge statement or null when not supported
Chris@0:      */
Chris@0:     private function getMergeStatement($sessionId, $data, $maxlifetime)
Chris@0:     {
Chris@0:         $mergeSql = null;
Chris@0:         switch (true) {
Chris@0:             case 'mysql' === $this->driver:
Chris@0:                 $mergeSql = "INSERT INTO $this->table ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (:id, :data, :lifetime, :time) ".
Chris@0:                     "ON DUPLICATE KEY UPDATE $this->dataCol = VALUES($this->dataCol), $this->lifetimeCol = VALUES($this->lifetimeCol), $this->timeCol = VALUES($this->timeCol)";
Chris@0:                 break;
Chris@0:             case 'oci' === $this->driver:
Chris@0:                 // DUAL is Oracle specific dummy table
Chris@0:                 $mergeSql = "MERGE INTO $this->table USING DUAL ON ($this->idCol = ?) ".
Chris@0:                     "WHEN NOT MATCHED THEN INSERT ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (?, ?, ?, ?) ".
Chris@0:                     "WHEN MATCHED THEN UPDATE SET $this->dataCol = ?, $this->lifetimeCol = ?, $this->timeCol = ?";
Chris@0:                 break;
Chris@0:             case 'sqlsrv' === $this->driver && version_compare($this->pdo->getAttribute(\PDO::ATTR_SERVER_VERSION), '10', '>='):
Chris@0:                 // MERGE is only available since SQL Server 2008 and must be terminated by semicolon
Chris@0:                 // It also requires HOLDLOCK according to http://weblogs.sqlteam.com/dang/archive/2009/01/31/UPSERT-Race-Condition-With-MERGE.aspx
Chris@0:                 $mergeSql = "MERGE INTO $this->table WITH (HOLDLOCK) USING (SELECT 1 AS dummy) AS src ON ($this->idCol = ?) ".
Chris@0:                     "WHEN NOT MATCHED THEN INSERT ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (?, ?, ?, ?) ".
Chris@0:                     "WHEN MATCHED THEN UPDATE SET $this->dataCol = ?, $this->lifetimeCol = ?, $this->timeCol = ?;";
Chris@0:                 break;
Chris@0:             case 'sqlite' === $this->driver:
Chris@0:                 $mergeSql = "INSERT OR REPLACE INTO $this->table ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (:id, :data, :lifetime, :time)";
Chris@0:                 break;
Chris@0:             case 'pgsql' === $this->driver && version_compare($this->pdo->getAttribute(\PDO::ATTR_SERVER_VERSION), '9.5', '>='):
Chris@0:                 $mergeSql = "INSERT INTO $this->table ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (:id, :data, :lifetime, :time) ".
Chris@0:                     "ON CONFLICT ($this->idCol) DO UPDATE SET ($this->dataCol, $this->lifetimeCol, $this->timeCol) = (EXCLUDED.$this->dataCol, EXCLUDED.$this->lifetimeCol, EXCLUDED.$this->timeCol)";
Chris@0:                 break;
Chris@0:         }
Chris@0: 
Chris@0:         if (null !== $mergeSql) {
Chris@0:             $mergeStmt = $this->pdo->prepare($mergeSql);
Chris@0: 
Chris@0:             if ('sqlsrv' === $this->driver || 'oci' === $this->driver) {
Chris@0:                 $mergeStmt->bindParam(1, $sessionId, \PDO::PARAM_STR);
Chris@0:                 $mergeStmt->bindParam(2, $sessionId, \PDO::PARAM_STR);
Chris@0:                 $mergeStmt->bindParam(3, $data, \PDO::PARAM_LOB);
Chris@0:                 $mergeStmt->bindParam(4, $maxlifetime, \PDO::PARAM_INT);
Chris@0:                 $mergeStmt->bindValue(5, time(), \PDO::PARAM_INT);
Chris@0:                 $mergeStmt->bindParam(6, $data, \PDO::PARAM_LOB);
Chris@0:                 $mergeStmt->bindParam(7, $maxlifetime, \PDO::PARAM_INT);
Chris@0:                 $mergeStmt->bindValue(8, time(), \PDO::PARAM_INT);
Chris@0:             } else {
Chris@0:                 $mergeStmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
Chris@0:                 $mergeStmt->bindParam(':data', $data, \PDO::PARAM_LOB);
Chris@0:                 $mergeStmt->bindParam(':lifetime', $maxlifetime, \PDO::PARAM_INT);
Chris@0:                 $mergeStmt->bindValue(':time', time(), \PDO::PARAM_INT);
Chris@0:             }
Chris@0: 
Chris@0:             return $mergeStmt;
Chris@0:         }
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Return a PDO instance.
Chris@0:      *
Chris@0:      * @return \PDO
Chris@0:      */
Chris@0:     protected function getConnection()
Chris@0:     {
Chris@0:         if (null === $this->pdo) {
Chris@0:             $this->connect($this->dsn ?: ini_get('session.save_path'));
Chris@0:         }
Chris@0: 
Chris@0:         return $this->pdo;
Chris@0:     }
Chris@0: }