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[HttpFoundation] use different approach for duplicate keys in postgres, fix merge for sqlsrv and oracle

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This commit is contained in:
Tobias Schultze 2014-05-28 13:11:33 +02:00
parent cff410507f
commit 00d707f76c
2 changed files with 42 additions and 34 deletions
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68
src/Symfony/Component/HttpFoundation/Session/Storage/Handler/PdoSessionHandler.php
View File

@ -12,7 +12,13 @@
namespace Symfony\Component\HttpFoundation\Session\Storage\Handler;
/**
* PdoSessionHandler.
* Session handler using a PDO connection to read and write data.
*
* Session data is a binary string that can contain non-printable characters like the null byte.
* For this reason this handler base64 encodes the data to be able to save it in a character column.
*
* This version of the PdoSessionHandler does NOT implement locking. So concurrent requests to the
* same session can result in data loss due to race conditions.
*
* @author Fabien Potencier <fabien@symfony.com>
* @author Michael Williams <michael.williams@funsational.com>
@ -164,13 +170,10 @@ class PdoSessionHandler implements \SessionHandlerInterface
*/
public function write($sessionId, $data)
{
// Session data can contain non binary safe characters so we need to encode it.
$encoded = base64_encode($data);
// We use a MERGE SQL query when supported by the database.
// Otherwise we have to use a transactional DELETE followed by INSERT to prevent duplicate entries under high concurrency.
try {
// We use a MERGE SQL query when supported by the database.
$mergeSql = $this->getMergeSql();
if (null !== $mergeSql) {
@ -183,28 +186,33 @@ class PdoSessionHandler implements \SessionHandlerInterface
return true;
}
$this->pdo->beginTransaction();
$updateStmt = $this->pdo->prepare(
"UPDATE $this->table SET $this->dataCol = :data, $this->timeCol = :time WHERE $this->idCol = :id"
);
$updateStmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
$updateStmt->bindParam(':data', $encoded, \PDO::PARAM_STR);
$updateStmt->bindValue(':time', time(), \PDO::PARAM_INT);
$updateStmt->execute();
try {
$deleteStmt = $this->pdo->prepare(
"DELETE FROM $this->table WHERE $this->idCol = :id"
);
$deleteStmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
$deleteStmt->execute();
$insertStmt = $this->pdo->prepare(
"INSERT INTO $this->table ($this->idCol, $this->dataCol, $this->timeCol) VALUES (:id, :data, :time)"
);
$insertStmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
$insertStmt->bindParam(':data', $encoded, \PDO::PARAM_STR);
$insertStmt->bindValue(':time', time(), \PDO::PARAM_INT);
$insertStmt->execute();
$this->pdo->commit();
} catch (\PDOException $e) {
$this->pdo->rollback();
throw $e;
// Since Postgres does not support MERGE (without custom stored procedure), we have to use this approach
// that can result in duplicate key errors when the same session is written simultaneously. We can just
// ignore such an error because either the data did not change anyway or which data is written does not
// matter as proper locking to serialize access to a session is not implemented.
if (!$updateStmt->rowCount()) {
try {
$insertStmt = $this->pdo->prepare(
"INSERT INTO $this->table ($this->idCol, $this->dataCol, $this->timeCol) VALUES (:id, :data, :time)"
);
$insertStmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
$insertStmt->bindParam(':data', $encoded, \PDO::PARAM_STR);
$insertStmt->bindValue(':time', time(), \PDO::PARAM_INT);
$insertStmt->execute();
} catch (\PDOException $e) {
// ignore unique violation SQLSTATE
if ('23505' !== $e->getCode()) {
throw $e;
}
}
}
} catch (\PDOException $e) {
throw new \RuntimeException(sprintf('PDOException was thrown when trying to write the session data: %s', $e->getMessage()), 0, $e);
@ -230,12 +238,12 @@ class PdoSessionHandler implements \SessionHandlerInterface
// DUAL is Oracle specific dummy table
return "MERGE INTO $this->table USING DUAL ON ($this->idCol = :id) " .
"WHEN NOT MATCHED THEN INSERT ($this->idCol, $this->dataCol, $this->timeCol) VALUES (:id, :data, :time) " .
"WHEN MATCHED THEN UPDATE SET $this->dataCol = :data";
case 'sqlsrv':
// MS SQL Server requires MERGE be terminated by semicolon
"WHEN MATCHED THEN UPDATE SET $this->dataCol = :data, $this->timeCol = :time";
case 'sqlsrv' && version_compare($this->pdo->getAttribute(\PDO::ATTR_SERVER_VERSION), '10', '>='):
// MERGE is only available since SQL Server 2008 and must be terminated by semicolon
return "MERGE INTO $this->table USING (SELECT 'x' AS dummy) AS src ON ($this->idCol = :id) " .
"WHEN NOT MATCHED THEN INSERT ($this->idCol, $this->dataCol, $this->timeCol) VALUES (:id, :data, :time) " .
"WHEN MATCHED THEN UPDATE SET $this->dataCol = :data;";
"WHEN MATCHED THEN UPDATE SET $this->dataCol = :data, $this->timeCol = :time;";
case 'sqlite':
return "INSERT OR REPLACE INTO $this->table ($this->idCol, $this->dataCol, $this->timeCol) VALUES (:id, :data, :time)";
}

8
src/Symfony/Component/HttpFoundation/Tests/Session/Storage/Handler/PdoSessionHandlerTest.php
View File

@ -23,9 +23,9 @@ class PdoSessionHandlerTest extends \PHPUnit_Framework_TestCase
$this->markTestSkipped('This test requires SQLite support in your environment');
}
$this->pdo = new \PDO("sqlite::memory:");
$this->pdo = new \PDO('sqlite::memory:');
$this->pdo->setAttribute(\PDO::ATTR_ERRMODE, \PDO::ERRMODE_EXCEPTION);
$sql = "CREATE TABLE sessions (sess_id VARCHAR(255) PRIMARY KEY, sess_data TEXT, sess_time INTEGER)";
$sql = 'CREATE TABLE sessions (sess_id VARCHAR(128) PRIMARY KEY, sess_data TEXT, sess_time INTEGER)';
$this->pdo->exec($sql);
}
@ -37,9 +37,9 @@ class PdoSessionHandlerTest extends \PHPUnit_Framework_TestCase
public function testWrongPdoErrMode()
{
$pdo = new \PDO("sqlite::memory:");
$pdo = new \PDO('sqlite::memory:');
$pdo->setAttribute(\PDO::ATTR_ERRMODE, \PDO::ERRMODE_SILENT);
$pdo->exec("CREATE TABLE sessions (sess_id VARCHAR(255) PRIMARY KEY, sess_data TEXT, sess_time INTEGER)");
$pdo->exec('CREATE TABLE sessions (sess_id VARCHAR(128) PRIMARY KEY, sess_data TEXT, sess_time INTEGER)');
$this->setExpectedException('InvalidArgumentException');
$storage = new PdoSessionHandler($pdo, array('db_table' => 'sessions'));