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<?php
/*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* This software consists of voluntary contributions made by many individuals
* and is licensed under the MIT license. For more information, see
* <http://www.doctrine-project.org>.
*/
namespace Doctrine\DBAL\Id;
use Doctrine\DBAL\DriverManager;
use Doctrine\DBAL\Connection;
/**
* Table ID Generator for those poor languages that are missing sequences.
*
* WARNING: The Table Id Generator clones a second independent database
* connection to work correctly. This means using the generator requests that
* generate IDs will have two open database connections. This is necessary to
* be safe from transaction failures in the main connection. Make sure to only
* ever use one TableGenerator otherwise you end up with many connections.
*
* TableID Generator does not work with SQLite.
*
* The TableGenerator does not take care of creating the SQL Table itself. You
* should look at the `TableGeneratorSchemaVisitor` to do this for you.
* Otherwise the schema for a table looks like:
*
* CREATE sequences (
* sequence_name VARCHAR(255) NOT NULL,
* sequence_value INT NOT NULL DEFAULT '1',
* sequence_increment_by INT NOT NULL DEFAULT '1',
* PRIMARY KEY (table_name)
* );
*
* Technically this generator works as follows:
*
* 1. Use a robust transaction serialization level.
* 2. Open transaction
* 3. Acquire a read lock on the table row (SELECT .. FOR UPDATE)
* 4. Increment current value by one and write back to database
* 5. Commit transaction
*
* If you are using a sequence_increment_by value that is larger than one the
* ID Generator will keep incrementing values until it hits the incrementation
* gap before issuing another query.
*
* If no row is present for a given sequence a new one will be created with the
* default values 'value' = 1 and 'increment_by' = 1
*
* @author Benjamin Eberlei <kontakt@beberlei.de>
*/
class TableGenerator
{
/**
* @var \Doctrine\DBAL\Connection
*/
private $conn;
/**
* @var string
*/
private $generatorTableName;
/**
* @var array
*/
private $sequences = array();
/**
* @param \Doctrine\DBAL\Connection $conn
* @param string $generatorTableName
*
* @throws \Doctrine\DBAL\DBALException
*/
public function __construct(Connection $conn, $generatorTableName = 'sequences')
{
$params = $conn->getParams();
if ($params['driver'] == 'pdo_sqlite') {
throw new \Doctrine\DBAL\DBALException("Cannot use TableGenerator with SQLite.");
}
$this->conn = DriverManager::getConnection($params, $conn->getConfiguration(), $conn->getEventManager());
$this->generatorTableName = $generatorTableName;
}
/**
* Generates the next unused value for the given sequence name.
*
* @param string $sequenceName
*
* @return integer
*
* @throws \Doctrine\DBAL\DBALException
*/
public function nextValue($sequenceName)
{
if (isset($this->sequences[$sequenceName])) {
$value = $this->sequences[$sequenceName]['value'];
$this->sequences[$sequenceName]['value']++;
if ($this->sequences[$sequenceName]['value'] >= $this->sequences[$sequenceName]['max']) {
unset ($this->sequences[$sequenceName]);
}
return $value;
}
$this->conn->beginTransaction();
try {
$platform = $this->conn->getDatabasePlatform();
$sql = "SELECT sequence_value, sequence_increment_by " .
"FROM " . $platform->appendLockHint($this->generatorTableName, \Doctrine\DBAL\LockMode::PESSIMISTIC_WRITE) . " " .
"WHERE sequence_name = ? " . $platform->getWriteLockSQL();
$stmt = $this->conn->executeQuery($sql, array($sequenceName));
if ($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
$row = array_change_key_case($row, CASE_LOWER);
$value = $row['sequence_value'];
$value++;
if ($row['sequence_increment_by'] > 1) {
$this->sequences[$sequenceName] = array(
'value' => $value,
'max' => $row['sequence_value'] + $row['sequence_increment_by']
);
}
$sql = "UPDATE " . $this->generatorTableName . " ".
"SET sequence_value = sequence_value + sequence_increment_by " .
"WHERE sequence_name = ? AND sequence_value = ?";
$rows = $this->conn->executeUpdate($sql, array($sequenceName, $row['sequence_value']));
if ($rows != 1) {
throw new \Doctrine\DBAL\DBALException("Race-condition detected while updating sequence. Aborting generation");
}
} else {
$this->conn->insert(
$this->generatorTableName,
array('sequence_name' => $sequenceName, 'sequence_value' => 1, 'sequence_increment_by' => 1)
);
$value = 1;
}
$this->conn->commit();
} catch(\Exception $e) {
$this->conn->rollback();
throw new \Doctrine\DBAL\DBALException("Error occurred while generating ID with TableGenerator, aborted generation: " . $e->getMessage(), 0, $e);
}
return $value;
}
}
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