Verzeichnisstruktur phpBB-3.2.0
- Veröffentlicht
- 06.01.2017
So funktioniert es
|
|
Auf das letzte Element klicken. Dies geht jeweils ein Schritt zurück |
Auf das Icon klicken, dies öffnet das Verzeichnis. Nochmal klicken schließt das Verzeichnis. |
|
|
(Beispiel Datei-Icons)
|
Auf das Icon klicken um den Quellcode anzuzeigen |
PdoSessionHandler.php
001 <?php
002
003 /*
004 * This file is part of the Symfony package.
005 *
006 * (c) Fabien Potencier <fabien@symfony.com>
007 *
008 * For the full copyright and license information, please view the LICENSE
009 * file that was distributed with this source code.
010 */
011
012 namespace Symfony\Component\HttpFoundation\Session\Storage\Handler;
013
014 /**
015 * Session handler using a PDO connection to read and write data.
016 *
017 * It works with MySQL, PostgreSQL, Oracle, SQL Server and SQLite and implements
018 * different locking strategies to handle concurrent access to the same session.
019 * Locking is necessary to prevent loss of data due to race conditions and to keep
020 * the session data consistent between read() and write(). With locking, requests
021 * for the same session will wait until the other one finished writing. For this
022 * reason it's best practice to close a session as early as possible to improve
023 * concurrency. PHPs internal files session handler also implements locking.
024 *
025 * Attention: Since SQLite does not support row level locks but locks the whole database,
026 * it means only one session can be accessed at a time. Even different sessions would wait
027 * for another to finish. So saving session in SQLite should only be considered for
028 * development or prototypes.
029 *
030 * Session data is a binary string that can contain non-printable characters like the null byte.
031 * For this reason it must be saved in a binary column in the database like BLOB in MySQL.
032 * Saving it in a character column could corrupt the data. You can use createTable()
033 * to initialize a correctly defined table.
034 *
035 * @see http://php.net/sessionhandlerinterface
036 *
037 * @author Fabien Potencier <fabien@symfony.com>
038 * @author Michael Williams <michael.williams@funsational.com>
039 * @author Tobias Schultze <http://tobion.de>
040 */
041 class PdoSessionHandler implements \SessionHandlerInterface
042 {
043 /**
044 * No locking is done. This means sessions are prone to loss of data due to
045 * race conditions of concurrent requests to the same session. The last session
046 * write will win in this case. It might be useful when you implement your own
047 * logic to deal with this like an optimistic approach.
048 */
049 const LOCK_NONE = 0;
050
051 /**
052 * Creates an application-level lock on a session. The disadvantage is that the
053 * lock is not enforced by the database and thus other, unaware parts of the
054 * application could still concurrently modify the session. The advantage is it
055 * does not require a transaction.
056 * This mode is not available for SQLite and not yet implemented for oci and sqlsrv.
057 */
058 const LOCK_ADVISORY = 1;
059
060 /**
061 * Issues a real row lock. Since it uses a transaction between opening and
062 * closing a session, you have to be careful when you use same database connection
063 * that you also use for your application logic. This mode is the default because
064 * it's the only reliable solution across DBMSs.
065 */
066 const LOCK_TRANSACTIONAL = 2;
067
068 /**
069 * @var \PDO|null PDO instance or null when not connected yet
070 */
071 private $pdo;
072
073 /**
074 * @var string|null|false DSN string or null for session.save_path or false when lazy connection disabled
075 */
076 private $dsn = false;
077
078 /**
079 * @var string Database driver
080 */
081 private $driver;
082
083 /**
084 * @var string Table name
085 */
086 private $table = 'sessions';
087
088 /**
089 * @var string Column for session id
090 */
091 private $idCol = 'sess_id';
092
093 /**
094 * @var string Column for session data
095 */
096 private $dataCol = 'sess_data';
097
098 /**
099 * @var string Column for lifetime
100 */
101 private $lifetimeCol = 'sess_lifetime';
102
103 /**
104 * @var string Column for timestamp
105 */
106 private $timeCol = 'sess_time';
107
108 /**
109 * @var string Username when lazy-connect
110 */
111 private $username = '';
112
113 /**
114 * @var string Password when lazy-connect
115 */
116 private $password = '';
117
118 /**
119 * @var array Connection options when lazy-connect
120 */
121 private $connectionOptions = array();
122
123 /**
124 * @var int The strategy for locking, see constants
125 */
126 private $lockMode = self::LOCK_TRANSACTIONAL;
127
128 /**
129 * It's an array to support multiple reads before closing which is manual, non-standard usage.
130 *
131 * @var \PDOStatement[] An array of statements to release advisory locks
132 */
133 private $unlockStatements = array();
134
135 /**
136 * @var bool True when the current session exists but expired according to session.gc_maxlifetime
137 */
138 private $sessionExpired = false;
139
140 /**
141 * @var bool Whether a transaction is active
142 */
143 private $inTransaction = false;
144
145 /**
146 * @var bool Whether gc() has been called
147 */
148 private $gcCalled = false;
149
150 /**
151 * Constructor.
152 *
153 * You can either pass an existing database connection as PDO instance or
154 * pass a DSN string that will be used to lazy-connect to the database
155 * when the session is actually used. Furthermore it's possible to pass null
156 * which will then use the session.save_path ini setting as PDO DSN parameter.
157 *
158 * List of available options:
159 * * db_table: The name of the table [default: sessions]
160 * * db_id_col: The column where to store the session id [default: sess_id]
161 * * db_data_col: The column where to store the session data [default: sess_data]
162 * * db_lifetime_col: The column where to store the lifetime [default: sess_lifetime]
163 * * db_time_col: The column where to store the timestamp [default: sess_time]
164 * * db_username: The username when lazy-connect [default: '']
165 * * db_password: The password when lazy-connect [default: '']
166 * * db_connection_options: An array of driver-specific connection options [default: array()]
167 * * lock_mode: The strategy for locking, see constants [default: LOCK_TRANSACTIONAL]
168 *
169 * @param \PDO|string|null $pdoOrDsn A \PDO instance or DSN string or null
170 * @param array $options An associative array of options
171 *
172 * @throws \InvalidArgumentException When PDO error mode is not PDO::ERRMODE_EXCEPTION
173 */
174 public function __construct($pdoOrDsn = null, array $options = array())
175 {
176 if ($pdoOrDsn instanceof \PDO) {
177 if (\PDO::ERRMODE_EXCEPTION !== $pdoOrDsn->getAttribute(\PDO::ATTR_ERRMODE)) {
178 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 }
180
181 $this->pdo = $pdoOrDsn;
182 $this->driver = $this->pdo->getAttribute(\PDO::ATTR_DRIVER_NAME);
183 } else {
184 $this->dsn = $pdoOrDsn;
185 }
186
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;
196 }
197
198 /**
199 * Creates the table to store sessions which can be called once for setup.
200 *
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.
205 *
206 * @throws \PDOException When the table already exists
207 * @throws \DomainException When an unsupported PDO driver is used
208 */
209 public function createTable()
210 {
211 // connect if we are not yet
212 $this->getConnection();
213
214 switch ($this->driver) {
215 case 'mysql':
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";
222 break;
223 case 'sqlite':
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)";
225 break;
226 case 'pgsql':
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)";
228 break;
229 case 'oci':
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)";
231 break;
232 case 'sqlsrv':
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)";
234 break;
235 default:
236 throw new \DomainException(sprintf('Creating the session table is currently not implemented for PDO driver "%s".', $this->driver));
237 }
238
239 try {
240 $this->pdo->exec($sql);
241 } catch (\PDOException $e) {
242 $this->rollback();
243
244 throw $e;
245 }
246 }
247
248 /**
249 * Returns true when the current session exists but expired according to session.gc_maxlifetime.
250 *
251 * Can be used to distinguish between a new session and one that expired due to inactivity.
252 *
253 * @return bool Whether current session expired
254 */
255 public function isSessionExpired()
256 {
257 return $this->sessionExpired;
258 }
259
260 /**
261 * {@inheritdoc}
262 */
263 public function open($savePath, $sessionName)
264 {
265 if (null === $this->pdo) {
266 $this->connect($this->dsn ?: $savePath);
267 }
268
269 return true;
270 }
271
272 /**
273 * {@inheritdoc}
274 */
275 public function read($sessionId)
276 {
277 try {
278 return $this->doRead($sessionId);
279 } catch (\PDOException $e) {
280 $this->rollback();
281
282 throw $e;
283 }
284 }
285
286 /**
287 * {@inheritdoc}
288 */
289 public function gc($maxlifetime)
290 {
291 // We delay gc() to close() so that it is executed outside the transactional and blocking read-write process.
292 // This way, pruning expired sessions does not block them from being started while the current session is used.
293 $this->gcCalled = true;
294
295 return true;
296 }
297
298 /**
299 * {@inheritdoc}
300 */
301 public function destroy($sessionId)
302 {
303 // delete the record associated with this id
304 $sql = "DELETE FROM $this->table WHERE $this->idCol = :id";
305
306 try {
307 $stmt = $this->pdo->prepare($sql);
308 $stmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
309 $stmt->execute();
310 } catch (\PDOException $e) {
311 $this->rollback();
312
313 throw $e;
314 }
315
316 return true;
317 }
318
319 /**
320 * {@inheritdoc}
321 */
322 public function write($sessionId, $data)
323 {
324 $maxlifetime = (int) ini_get('session.gc_maxlifetime');
325
326 try {
327 // We use a single MERGE SQL query when supported by the database.
328 $mergeStmt = $this->getMergeStatement($sessionId, $data, $maxlifetime);
329 if (null !== $mergeStmt) {
330 $mergeStmt->execute();
331
332 return true;
333 }
334
335 $updateStmt = $this->pdo->prepare(
336 "UPDATE $this->table SET $this->dataCol = :data, $this->lifetimeCol = :lifetime, $this->timeCol = :time WHERE $this->idCol = :id"
337 );
338 $updateStmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
339 $updateStmt->bindParam(':data', $data, \PDO::PARAM_LOB);
340 $updateStmt->bindParam(':lifetime', $maxlifetime, \PDO::PARAM_INT);
341 $updateStmt->bindValue(':time', time(), \PDO::PARAM_INT);
342 $updateStmt->execute();
343
344 // When MERGE is not supported, like in Postgres < 9.5, we have to use this approach that can result in
345 // duplicate key errors when the same session is written simultaneously (given the LOCK_NONE behavior).
346 // We can just catch such an error and re-execute the update. This is similar to a serializable
347 // transaction with retry logic on serialization failures but without the overhead and without possible
348 // false positives due to longer gap locking.
349 if (!$updateStmt->rowCount()) {
350 try {
351 $insertStmt = $this->pdo->prepare(
352 "INSERT INTO $this->table ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (:id, :data, :lifetime, :time)"
353 );
354 $insertStmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
355 $insertStmt->bindParam(':data', $data, \PDO::PARAM_LOB);
356 $insertStmt->bindParam(':lifetime', $maxlifetime, \PDO::PARAM_INT);
357 $insertStmt->bindValue(':time', time(), \PDO::PARAM_INT);
358 $insertStmt->execute();
359 } catch (\PDOException $e) {
360 // Handle integrity violation SQLSTATE 23000 (or a subclass like 23505 in Postgres) for duplicate keys
361 if (0 === strpos($e->getCode(), '23')) {
362 $updateStmt->execute();
363 } else {
364 throw $e;
365 }
366 }
367 }
368 } catch (\PDOException $e) {
369 $this->rollback();
370
371 throw $e;
372 }
373
374 return true;
375 }
376
377 /**
378 * {@inheritdoc}
379 */
380 public function close()
381 {
382 $this->commit();
383
384 while ($unlockStmt = array_shift($this->unlockStatements)) {
385 $unlockStmt->execute();
386 }
387
388 if ($this->gcCalled) {
389 $this->gcCalled = false;
390
391 // delete the session records that have expired
392 $sql = "DELETE FROM $this->table WHERE $this->lifetimeCol + $this->timeCol < :time";
393
394 $stmt = $this->pdo->prepare($sql);
395 $stmt->bindValue(':time', time(), \PDO::PARAM_INT);
396 $stmt->execute();
397 }
398
399 if (false !== $this->dsn) {
400 $this->pdo = null; // only close lazy-connection
401 }
402
403 return true;
404 }
405
406 /**
407 * Lazy-connects to the database.
408 *
409 * @param string $dsn DSN string
410 */
411 private function connect($dsn)
412 {
413 $this->pdo = new \PDO($dsn, $this->username, $this->password, $this->connectionOptions);
414 $this->pdo->setAttribute(\PDO::ATTR_ERRMODE, \PDO::ERRMODE_EXCEPTION);
415 $this->driver = $this->pdo->getAttribute(\PDO::ATTR_DRIVER_NAME);
416 }
417
418 /**
419 * Helper method to begin a transaction.
420 *
421 * Since SQLite does not support row level locks, we have to acquire a reserved lock
422 * on the database immediately. Because of https://bugs.php.net/42766 we have to create
423 * such a transaction manually which also means we cannot use PDO::commit or
424 * PDO::rollback or PDO::inTransaction for SQLite.
425 *
426 * Also MySQLs default isolation, REPEATABLE READ, causes deadlock for different sessions
427 * due to http://www.mysqlperformanceblog.com/2013/12/12/one-more-innodb-gap-lock-to-avoid/ .
428 * So we change it to READ COMMITTED.
429 */
430 private function beginTransaction()
431 {
432 if (!$this->inTransaction) {
433 if ('sqlite' === $this->driver) {
434 $this->pdo->exec('BEGIN IMMEDIATE TRANSACTION');
435 } else {
436 if ('mysql' === $this->driver) {
437 $this->pdo->exec('SET TRANSACTION ISOLATION LEVEL READ COMMITTED');
438 }
439 $this->pdo->beginTransaction();
440 }
441 $this->inTransaction = true;
442 }
443 }
444
445 /**
446 * Helper method to commit a transaction.
447 */
448 private function commit()
449 {
450 if ($this->inTransaction) {
451 try {
452 // commit read-write transaction which also releases the lock
453 if ('sqlite' === $this->driver) {
454 $this->pdo->exec('COMMIT');
455 } else {
456 $this->pdo->commit();
457 }
458 $this->inTransaction = false;
459 } catch (\PDOException $e) {
460 $this->rollback();
461
462 throw $e;
463 }
464 }
465 }
466
467 /**
468 * Helper method to rollback a transaction.
469 */
470 private function rollback()
471 {
472 // We only need to rollback if we are in a transaction. Otherwise the resulting
473 // error would hide the real problem why rollback was called. We might not be
474 // in a transaction when not using the transactional locking behavior or when
475 // two callbacks (e.g. destroy and write) are invoked that both fail.
476 if ($this->inTransaction) {
477 if ('sqlite' === $this->driver) {
478 $this->pdo->exec('ROLLBACK');
479 } else {
480 $this->pdo->rollBack();
481 }
482 $this->inTransaction = false;
483 }
484 }
485
486 /**
487 * Reads the session data in respect to the different locking strategies.
488 *
489 * We need to make sure we do not return session data that is already considered garbage according
490 * to the session.gc_maxlifetime setting because gc() is called after read() and only sometimes.
491 *
492 * @param string $sessionId Session ID
493 *
494 * @return string The session data
495 */
496 private function doRead($sessionId)
497 {
498 $this->sessionExpired = false;
499
500 if (self::LOCK_ADVISORY === $this->lockMode) {
501 $this->unlockStatements[] = $this->doAdvisoryLock($sessionId);
502 }
503
504 $selectSql = $this->getSelectSql();
505 $selectStmt = $this->pdo->prepare($selectSql);
506 $selectStmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
507
508 do {
509 $selectStmt->execute();
510 $sessionRows = $selectStmt->fetchAll(\PDO::FETCH_NUM);
511
512 if ($sessionRows) {
513 if ($sessionRows[0][1] + $sessionRows[0][2] < time()) {
514 $this->sessionExpired = true;
515
516 return '';
517 }
518
519 return is_resource($sessionRows[0][0]) ? stream_get_contents($sessionRows[0][0]) : $sessionRows[0][0];
520 }
521
522 if (self::LOCK_TRANSACTIONAL === $this->lockMode && 'sqlite' !== $this->driver) {
523 // Exclusive-reading of non-existent rows does not block, so we need to do an insert to block
524 // until other connections to the session are committed.
525 try {
526 $insertStmt = $this->pdo->prepare(
527 "INSERT INTO $this->table ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (:id, :data, :lifetime, :time)"
528 );
529 $insertStmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
530 $insertStmt->bindValue(':data', '', \PDO::PARAM_LOB);
531 $insertStmt->bindValue(':lifetime', 0, \PDO::PARAM_INT);
532 $insertStmt->bindValue(':time', time(), \PDO::PARAM_INT);
533 $insertStmt->execute();
534 } catch (\PDOException $e) {
535 // Catch duplicate key error because other connection created the session already.
536 // It would only not be the case when the other connection destroyed the session.
537 if (0 === strpos($e->getCode(), '23')) {
538 // Retrieve finished session data written by concurrent connection by restarting the loop.
539 // We have to start a new transaction as a failed query will mark the current transaction as
540 // aborted in PostgreSQL and disallow further queries within it.
541 $this->rollback();
542 $this->beginTransaction();
543 continue;
544 }
545
546 throw $e;
547 }
548 }
549
550 return '';
551 } while (true);
552 }
553
554 /**
555 * Executes an application-level lock on the database.
556 *
557 * @param string $sessionId Session ID
558 *
559 * @return \PDOStatement The statement that needs to be executed later to release the lock
560 *
561 * @throws \DomainException When an unsupported PDO driver is used
562 *
563 * @todo implement missing advisory locks
564 * - for oci using DBMS_LOCK.REQUEST
565 * - for sqlsrv using sp_getapplock with LockOwner = Session
566 */
567 private function doAdvisoryLock($sessionId)
568 {
569 switch ($this->driver) {
570 case 'mysql':
571 // should we handle the return value? 0 on timeout, null on error
572 // we use a timeout of 50 seconds which is also the default for innodb_lock_wait_timeout
573 $stmt = $this->pdo->prepare('SELECT GET_LOCK(:key, 50)');
574 $stmt->bindValue(':key', $sessionId, \PDO::PARAM_STR);
575 $stmt->execute();
576
577 $releaseStmt = $this->pdo->prepare('DO RELEASE_LOCK(:key)');
578 $releaseStmt->bindValue(':key', $sessionId, \PDO::PARAM_STR);
579
580 return $releaseStmt;
581 case 'pgsql':
582 // Obtaining an exclusive session level advisory lock requires an integer key.
583 // So we convert the HEX representation of the session id to an integer.
584 // Since integers are signed, we have to skip one hex char to fit in the range.
585 if (4 === PHP_INT_SIZE) {
586 $sessionInt1 = hexdec(substr($sessionId, 0, 7));
587 $sessionInt2 = hexdec(substr($sessionId, 7, 7));
588
589 $stmt = $this->pdo->prepare('SELECT pg_advisory_lock(:key1, :key2)');
590 $stmt->bindValue(':key1', $sessionInt1, \PDO::PARAM_INT);
591 $stmt->bindValue(':key2', $sessionInt2, \PDO::PARAM_INT);
592 $stmt->execute();
593
594 $releaseStmt = $this->pdo->prepare('SELECT pg_advisory_unlock(:key1, :key2)');
595 $releaseStmt->bindValue(':key1', $sessionInt1, \PDO::PARAM_INT);
596 $releaseStmt->bindValue(':key2', $sessionInt2, \PDO::PARAM_INT);
597 } else {
598 $sessionBigInt = hexdec(substr($sessionId, 0, 15));
599
600 $stmt = $this->pdo->prepare('SELECT pg_advisory_lock(:key)');
601 $stmt->bindValue(':key', $sessionBigInt, \PDO::PARAM_INT);
602 $stmt->execute();
603
604 $releaseStmt = $this->pdo->prepare('SELECT pg_advisory_unlock(:key)');
605 $releaseStmt->bindValue(':key', $sessionBigInt, \PDO::PARAM_INT);
606 }
607
608 return $releaseStmt;
609 case 'sqlite':
610 throw new \DomainException('SQLite does not support advisory locks.');
611 default:
612 throw new \DomainException(sprintf('Advisory locks are currently not implemented for PDO driver "%s".', $this->driver));
613 }
614 }
615
616 /**
617 * Return a locking or nonlocking SQL query to read session information.
618 *
619 * @return string The SQL string
620 *
621 * @throws \DomainException When an unsupported PDO driver is used
622 */
623 private function getSelectSql()
624 {
625 if (self::LOCK_TRANSACTIONAL === $this->lockMode) {
626 $this->beginTransaction();
627
628 switch ($this->driver) {
629 case 'mysql':
630 case 'oci':
631 case 'pgsql':
632 return "SELECT $this->dataCol, $this->lifetimeCol, $this->timeCol FROM $this->table WHERE $this->idCol = :id FOR UPDATE";
633 case 'sqlsrv':
634 return "SELECT $this->dataCol, $this->lifetimeCol, $this->timeCol FROM $this->table WITH (UPDLOCK, ROWLOCK) WHERE $this->idCol = :id";
635 case 'sqlite':
636 // we already locked when starting transaction
637 break;
638 default:
639 throw new \DomainException(sprintf('Transactional locks are currently not implemented for PDO driver "%s".', $this->driver));
640 }
641 }
642
643 return "SELECT $this->dataCol, $this->lifetimeCol, $this->timeCol FROM $this->table WHERE $this->idCol = :id";
644 }
645
646 /**
647 * Returns a merge/upsert (i.e. insert or update) statement when supported by the database for writing session data.
648 *
649 * @param string $sessionId Session ID
650 * @param string $data Encoded session data
651 * @param int $maxlifetime session.gc_maxlifetime
652 *
653 * @return \PDOStatement|null The merge statement or null when not supported
654 */
655 private function getMergeStatement($sessionId, $data, $maxlifetime)
656 {
657 $mergeSql = null;
658 switch (true) {
659 case 'mysql' === $this->driver:
660 $mergeSql = "INSERT INTO $this->table ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (:id, :data, :lifetime, :time) ".
661 "ON DUPLICATE KEY UPDATE $this->dataCol = VALUES($this->dataCol), $this->lifetimeCol = VALUES($this->lifetimeCol), $this->timeCol = VALUES($this->timeCol)";
662 break;
663 case 'oci' === $this->driver:
664 // DUAL is Oracle specific dummy table
665 $mergeSql = "MERGE INTO $this->table USING DUAL ON ($this->idCol = ?) ".
666 "WHEN NOT MATCHED THEN INSERT ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (?, ?, ?, ?) ".
667 "WHEN MATCHED THEN UPDATE SET $this->dataCol = ?, $this->lifetimeCol = ?, $this->timeCol = ?";
668 break;
669 case 'sqlsrv' === $this->driver && version_compare($this->pdo->getAttribute(\PDO::ATTR_SERVER_VERSION), '10', '>='):
670 // MERGE is only available since SQL Server 2008 and must be terminated by semicolon
671 // It also requires HOLDLOCK according to http://weblogs.sqlteam.com/dang/archive/2009/01/31/UPSERT-Race-Condition-With-MERGE.aspx
672 $mergeSql = "MERGE INTO $this->table WITH (HOLDLOCK) USING (SELECT 1 AS dummy) AS src ON ($this->idCol = ?) ".
673 "WHEN NOT MATCHED THEN INSERT ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (?, ?, ?, ?) ".
674 "WHEN MATCHED THEN UPDATE SET $this->dataCol = ?, $this->lifetimeCol = ?, $this->timeCol = ?;";
675 break;
676 case 'sqlite' === $this->driver:
677 $mergeSql = "INSERT OR REPLACE INTO $this->table ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (:id, :data, :lifetime, :time)";
678 break;
679 case 'pgsql' === $this->driver && version_compare($this->pdo->getAttribute(\PDO::ATTR_SERVER_VERSION), '9.5', '>='):
680 $mergeSql = "INSERT INTO $this->table ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (:id, :data, :lifetime, :time) ".
681 "ON CONFLICT ($this->idCol) DO UPDATE SET ($this->dataCol, $this->lifetimeCol, $this->timeCol) = (EXCLUDED.$this->dataCol, EXCLUDED.$this->lifetimeCol, EXCLUDED.$this->timeCol)";
682 break;
683 }
684
685 if (null !== $mergeSql) {
686 $mergeStmt = $this->pdo->prepare($mergeSql);
687
688 if ('sqlsrv' === $this->driver || 'oci' === $this->driver) {
689 $mergeStmt->bindParam(1, $sessionId, \PDO::PARAM_STR);
690 $mergeStmt->bindParam(2, $sessionId, \PDO::PARAM_STR);
691 $mergeStmt->bindParam(3, $data, \PDO::PARAM_LOB);
692 $mergeStmt->bindParam(4, $maxlifetime, \PDO::PARAM_INT);
693 $mergeStmt->bindValue(5, time(), \PDO::PARAM_INT);
694 $mergeStmt->bindParam(6, $data, \PDO::PARAM_LOB);
695 $mergeStmt->bindParam(7, $maxlifetime, \PDO::PARAM_INT);
696 $mergeStmt->bindValue(8, time(), \PDO::PARAM_INT);
697 } else {
698 $mergeStmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
699 $mergeStmt->bindParam(':data', $data, \PDO::PARAM_LOB);
700 $mergeStmt->bindParam(':lifetime', $maxlifetime, \PDO::PARAM_INT);
701 $mergeStmt->bindValue(':time', time(), \PDO::PARAM_INT);
702 }
703
704 return $mergeStmt;
705 }
706 }
707
708 /**
709 * Return a PDO instance.
710 *
711 * @return \PDO
712 */
713 protected function getConnection()
714 {
715 if (null === $this->pdo) {
716 $this->connect($this->dsn ?: ini_get('session.save_path'));
717 }
718
719 return $this->pdo;
720 }
721 }
722