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- <?php
- namespace Doctrine\DBAL\Id;
- use Doctrine\DBAL\Connection;
- use Doctrine\DBAL\Driver;
- use Doctrine\DBAL\DriverManager;
- use Doctrine\DBAL\Exception;
- use Doctrine\DBAL\LockMode;
- use Throwable;
- use function array_change_key_case;
- use function assert;
- use function is_int;
- use const CASE_LOWER;
- /**
- * 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 (sequence_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
- */
- class TableGenerator
- {
- /** @var Connection */
- private $conn;
- /** @var string */
- private $generatorTableName;
- /** @var mixed[][] */
- private $sequences = [];
- /**
- * @param string $generatorTableName
- *
- * @throws Exception
- */
- public function __construct(Connection $conn, $generatorTableName = 'sequences')
- {
- if ($conn->getDriver() instanceof Driver\PDOSqlite\Driver) {
- throw new Exception('Cannot use TableGenerator with SQLite.');
- }
- $this->conn = DriverManager::getConnection(
- $conn->getParams(),
- $conn->getConfiguration(),
- $conn->getEventManager()
- );
- $this->generatorTableName = $generatorTableName;
- }
- /**
- * Generates the next unused value for the given sequence name.
- *
- * @param string $sequence
- *
- * @return int
- *
- * @throws Exception
- */
- public function nextValue($sequence)
- {
- if (isset($this->sequences[$sequence])) {
- $value = $this->sequences[$sequence]['value'];
- $this->sequences[$sequence]['value']++;
- if ($this->sequences[$sequence]['value'] >= $this->sequences[$sequence]['max']) {
- unset($this->sequences[$sequence]);
- }
- return $value;
- }
- $this->conn->beginTransaction();
- try {
- $platform = $this->conn->getDatabasePlatform();
- $sql = 'SELECT sequence_value, sequence_increment_by'
- . ' FROM ' . $platform->appendLockHint($this->generatorTableName, LockMode::PESSIMISTIC_WRITE)
- . ' WHERE sequence_name = ? ' . $platform->getWriteLockSQL();
- $row = $this->conn->fetchAssociative($sql, [$sequence]);
- if ($row !== false) {
- $row = array_change_key_case($row, CASE_LOWER);
- $value = $row['sequence_value'];
- $value++;
- assert(is_int($value));
- if ($row['sequence_increment_by'] > 1) {
- $this->sequences[$sequence] = [
- '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 = $this->conn->executeStatement($sql, [$sequence, $row['sequence_value']]);
- if ($rows !== 1) {
- throw new Exception('Race-condition detected while updating sequence. Aborting generation');
- }
- } else {
- $this->conn->insert(
- $this->generatorTableName,
- ['sequence_name' => $sequence, 'sequence_value' => 1, 'sequence_increment_by' => 1]
- );
- $value = 1;
- }
- $this->conn->commit();
- } catch (Throwable $e) {
- $this->conn->rollBack();
- throw new Exception(
- 'Error occurred while generating ID with TableGenerator, aborted generation: ' . $e->getMessage(),
- 0,
- $e
- );
- }
- return $value;
- }
- }
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