class Connection in Zircon Profile 8

MySQL implementation of \Drupal\Core\Database\Connection.

Hierarchy

• class \Drupal\Core\Database\Connection
  • class \Drupal\Core\Database\Driver\mysql\Connection

Related topics

Database abstraction layer

Allow the use of different database servers using the same code base.

1 file declares its use of Connection

Tasks.php in core/lib/Drupal/Core/Database/Driver/mysql/Install/Tasks.php

Contains \Drupal\Core\Database\Driver\mysql\Install\Tasks.

1 string reference to 'Connection'

StreamHandler::createStream in vendor/guzzlehttp/guzzle/src/Handler/StreamHandler.php

File

core/lib/Drupal/Core/Database/Driver/mysql/Connection.php, line 27

Contains \Drupal\Core\Database\Driver\mysql\Connection.

Namespace

Drupal\Core\Database\Driver\mysql

class Connection extends DatabaseConnection {

  /**
   * Error code for "Unknown database" error.
   */
  const DATABASE_NOT_FOUND = 1049;

  /**
   * Error code for "Can't initialize character set" error.
   */
  const UNSUPPORTED_CHARSET = 2019;

  /**
   * Driver-specific error code for "Unknown character set" error.
   */
  const UNKNOWN_CHARSET = 1115;

  /**
   * SQLSTATE error code for "Syntax error or access rule violation".
   */
  const SQLSTATE_SYNTAX_ERROR = 42000;

  /**
   * Flag to indicate if the cleanup function in __destruct() should run.
   *
   * @var bool
   */
  protected $needsCleanup = FALSE;

  /**
   * The minimal possible value for the max_allowed_packet setting of MySQL.
   *
   * @link https://mariadb.com/kb/en/mariadb/server-system-variables/#max_allowed_packet
   * @link https://dev.mysql.com/doc/refman/5.7/en/server-system-variables.html#sysvar_max_allowed_packet
   *
   * @var int
   */
  const MIN_MAX_ALLOWED_PACKET = 1024;

  /**
   * Constructs a Connection object.
   */
  public function __construct(\PDO $connection, array $connection_options = array()) {
    parent::__construct($connection, $connection_options);

    // This driver defaults to transaction support, except if explicitly passed FALSE.
    $this->transactionSupport = !isset($connection_options['transactions']) || $connection_options['transactions'] !== FALSE;

    // MySQL never supports transactional DDL.
    $this->transactionalDDLSupport = FALSE;
    $this->connectionOptions = $connection_options;
  }

  /**
   * {@inheritdoc}
   */
  public function query($query, array $args = array(), $options = array()) {
    try {
      return parent::query($query, $args, $options);
    } catch (DatabaseException $e) {
      if ($e
        ->getPrevious()->errorInfo[1] == 1153) {

        // If a max_allowed_packet error occurs the message length is truncated.
        // This should prevent the error from recurring if the exception is
        // logged to the database using dblog or the like.
        $message = Unicode::truncateBytes($e
          ->getMessage(), self::MIN_MAX_ALLOWED_PACKET);
        $e = new DatabaseExceptionWrapper($message, $e
          ->getCode(), $e
          ->getPrevious());
      }
      throw $e;
    }
  }

  /**
   * {@inheritdoc}
   */
  public static function open(array &$connection_options = array()) {
    if (isset($connection_options['_dsn_utf8_fallback']) && $connection_options['_dsn_utf8_fallback'] === TRUE) {

      // Only used during the installer version check, as a fallback from utf8mb4.
      $charset = 'utf8';
    }
    else {
      $charset = 'utf8mb4';
    }

    // The DSN should use either a socket or a host/port.
    if (isset($connection_options['unix_socket'])) {
      $dsn = 'mysql:unix_socket=' . $connection_options['unix_socket'];
    }
    else {

      // Default to TCP connection on port 3306.
      $dsn = 'mysql:host=' . $connection_options['host'] . ';port=' . (empty($connection_options['port']) ? 3306 : $connection_options['port']);
    }

    // Character set is added to dsn to ensure PDO uses the proper character
    // set when escaping. This has security implications. See
    // https://www.drupal.org/node/1201452 for further discussion.
    $dsn .= ';charset=' . $charset;
    if (!empty($connection_options['database'])) {
      $dsn .= ';dbname=' . $connection_options['database'];
    }

    // Allow PDO options to be overridden.
    $connection_options += array(
      'pdo' => array(),
    );
    $connection_options['pdo'] += array(
      \PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION,
      // So we don't have to mess around with cursors and unbuffered queries by default.
      \PDO::MYSQL_ATTR_USE_BUFFERED_QUERY => TRUE,
      // Make sure MySQL returns all matched rows on update queries including
      // rows that actually didn't have to be updated because the values didn't
      // change. This matches common behavior among other database systems.
      \PDO::MYSQL_ATTR_FOUND_ROWS => TRUE,
      // Because MySQL's prepared statements skip the query cache, because it's dumb.
      \PDO::ATTR_EMULATE_PREPARES => TRUE,
    );
    if (defined('\\PDO::MYSQL_ATTR_MULTI_STATEMENTS')) {

      // An added connection option in PHP 5.5.21 to optionally limit SQL to a
      // single statement like mysqli.
      $connection_options['pdo'] += [
        \PDO::MYSQL_ATTR_MULTI_STATEMENTS => FALSE,
      ];
    }
    $pdo = new \PDO($dsn, $connection_options['username'], $connection_options['password'], $connection_options['pdo']);

    // Force MySQL to use the UTF-8 character set. Also set the collation, if a
    // certain one has been set; otherwise, MySQL defaults to
    // 'utf8mb4_general_ci' for utf8mb4.
    if (!empty($connection_options['collation'])) {
      $pdo
        ->exec('SET NAMES ' . $charset . ' COLLATE ' . $connection_options['collation']);
    }
    else {
      $pdo
        ->exec('SET NAMES ' . $charset);
    }

    // Set MySQL init_commands if not already defined.  Default Drupal's MySQL
    // behavior to conform more closely to SQL standards.  This allows Drupal
    // to run almost seamlessly on many different kinds of database systems.
    // These settings force MySQL to behave the same as postgresql, or sqlite
    // in regards to syntax interpretation and invalid data handling.  See
    // https://www.drupal.org/node/344575 for further discussion. Also, as MySQL
    // 5.5 changed the meaning of TRADITIONAL we need to spell out the modes one
    // by one.
    $connection_options += array(
      'init_commands' => array(),
    );
    $connection_options['init_commands'] += array(
      'sql_mode' => "SET sql_mode = 'ANSI,STRICT_TRANS_TABLES,STRICT_ALL_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,ONLY_FULL_GROUP_BY'",
    );

    // Execute initial commands.
    foreach ($connection_options['init_commands'] as $sql) {
      $pdo
        ->exec($sql);
    }
    return $pdo;
  }

  /**
   * {@inheritdoc}
   */
  public function serialize() {

    // Cleanup the connection, much like __destruct() does it as well.
    if ($this->needsCleanup) {
      $this
        ->nextIdDelete();
    }
    $this->needsCleanup = FALSE;
    return parent::serialize();
  }

  /**
   * {@inheritdoc}
   */
  public function __destruct() {
    if ($this->needsCleanup) {
      $this
        ->nextIdDelete();
    }
  }
  public function queryRange($query, $from, $count, array $args = array(), array $options = array()) {
    return $this
      ->query($query . ' LIMIT ' . (int) $from . ', ' . (int) $count, $args, $options);
  }
  public function queryTemporary($query, array $args = array(), array $options = array()) {
    $tablename = $this
      ->generateTemporaryTableName();
    $this
      ->query('CREATE TEMPORARY TABLE {' . $tablename . '} Engine=MEMORY ' . $query, $args, $options);
    return $tablename;
  }
  public function driver() {
    return 'mysql';
  }
  public function databaseType() {
    return 'mysql';
  }

  /**
   * Overrides \Drupal\Core\Database\Connection::createDatabase().
   *
   * @param string $database
   *   The name of the database to create.
   *
   * @throws \Drupal\Core\Database\DatabaseNotFoundException
   */
  public function createDatabase($database) {

    // Escape the database name.
    $database = Database::getConnection()
      ->escapeDatabase($database);
    try {

      // Create the database and set it as active.
      $this->connection
        ->exec("CREATE DATABASE {$database}");
      $this->connection
        ->exec("USE {$database}");
    } catch (\Exception $e) {
      throw new DatabaseNotFoundException($e
        ->getMessage());
    }
  }
  public function mapConditionOperator($operator) {

    // We don't want to override any of the defaults.
    return NULL;
  }
  public function nextId($existing_id = 0) {
    $new_id = $this
      ->query('INSERT INTO {sequences} () VALUES ()', array(), array(
      'return' => Database::RETURN_INSERT_ID,
    ));

    // This should only happen after an import or similar event.
    if ($existing_id >= $new_id) {

      // If we INSERT a value manually into the sequences table, on the next
      // INSERT, MySQL will generate a larger value. However, there is no way
      // of knowing whether this value already exists in the table. MySQL
      // provides an INSERT IGNORE which would work, but that can mask problems
      // other than duplicate keys. Instead, we use INSERT ... ON DUPLICATE KEY
      // UPDATE in such a way that the UPDATE does not do anything. This way,
      // duplicate keys do not generate errors but everything else does.
      $this
        ->query('INSERT INTO {sequences} (value) VALUES (:value) ON DUPLICATE KEY UPDATE value = value', array(
        ':value' => $existing_id,
      ));
      $new_id = $this
        ->query('INSERT INTO {sequences} () VALUES ()', array(), array(
        'return' => Database::RETURN_INSERT_ID,
      ));
    }
    $this->needsCleanup = TRUE;
    return $new_id;
  }
  public function nextIdDelete() {

    // While we want to clean up the table to keep it up from occupying too
    // much storage and memory, we must keep the highest value in the table
    // because InnoDB uses an in-memory auto-increment counter as long as the
    // server runs. When the server is stopped and restarted, InnoDB
    // reinitializes the counter for each table for the first INSERT to the
    // table based solely on values from the table so deleting all values would
    // be a problem in this case. Also, TRUNCATE resets the auto increment
    // counter.
    try {
      $max_id = $this
        ->query('SELECT MAX(value) FROM {sequences}')
        ->fetchField();

      // We know we are using MySQL here, no need for the slower db_delete().
      $this
        ->query('DELETE FROM {sequences} WHERE value < :value', array(
        ':value' => $max_id,
      ));
    } catch (DatabaseException $e) {
    }
  }

  /**
   * Overridden to work around issues to MySQL not supporting transactional DDL.
   */
  protected function popCommittableTransactions() {

    // Commit all the committable layers.
    foreach (array_reverse($this->transactionLayers) as $name => $active) {

      // Stop once we found an active transaction.
      if ($active) {
        break;
      }

      // If there are no more layers left then we should commit.
      unset($this->transactionLayers[$name]);
      if (empty($this->transactionLayers)) {
        if (!$this->connection
          ->commit()) {
          throw new TransactionCommitFailedException();
        }
      }
      else {

        // Attempt to release this savepoint in the standard way.
        try {
          $this
            ->query('RELEASE SAVEPOINT ' . $name);
        } catch (DatabaseExceptionWrapper $e) {

          // However, in MySQL (InnoDB), savepoints are automatically committed
          // when tables are altered or created (DDL transactions are not
          // supported). This can cause exceptions due to trying to release
          // savepoints which no longer exist.
          //
          // To avoid exceptions when no actual error has occurred, we silently
          // succeed for MySQL error code 1305 ("SAVEPOINT does not exist").
          if ($e
            ->getPrevious()->errorInfo[1] == '1305') {

            // If one SAVEPOINT was released automatically, then all were.
            // Therefore, clean the transaction stack.
            $this->transactionLayers = array();

            // We also have to explain to PDO that the transaction stack has
            // been cleaned-up.
            $this->connection
              ->commit();
          }
          else {
            throw $e;
          }
        }
      }
    }
  }

}

Members

Name	Modifiers	Type	Description	Overrides
Connection::$connection	protected	property	The actual PDO connection.
Connection::$connectionOptions	protected	property	The connection information for this connection object.
Connection::$driverClasses	protected	property	Index of what driver-specific class to use for various operations.
Connection::$key	protected	property	The key representing this connection.
Connection::$logger	protected	property	The current database logging object for this connection.
Connection::$needsCleanup	protected	property	Flag to indicate if the cleanup function in __destruct() should run.
Connection::$prefixes	protected	property	The prefixes used by this database connection.
Connection::$prefixReplace	protected	property	List of replacement values for use in prefixTables().
Connection::$prefixSearch	protected	property	List of search values for use in prefixTables().
Connection::$schema	protected	property	The schema object for this connection.
Connection::$statementClass	protected	property	The name of the Statement class for this connection.
Connection::$target	protected	property	The database target this connection is for.
Connection::$temporaryNameIndex	protected	property	An index used to generate unique temporary table names.
Connection::$transactionalDDLSupport	protected	property	Whether this database connection supports transactional DDL.
Connection::$transactionLayers	protected	property	Tracks the number of "layers" of transactions currently active.
Connection::$transactionSupport	protected	property	Whether this database connection supports transactions.
Connection::$unprefixedTablesMap	protected	property	List of un-prefixed table names, keyed by prefixed table names.
Connection::clientVersion	public	function	Returns the version of the database client.
Connection::commit	public	function	Throws an exception to deny direct access to transaction commits.
Connection::createDatabase	public	function	Overrides \Drupal\Core\Database\Connection::createDatabase(). Overrides Connection::createDatabase
Connection::databaseType	public	function	Returns the name of the PDO driver for this connection. Overrides Connection::databaseType
Connection::DATABASE_NOT_FOUND		constant	Error code for "Unknown database" error.
Connection::defaultOptions	protected	function	Returns the default query options for any given query.
Connection::delete	public	function	Prepares and returns a DELETE query object.
Connection::destroy	public	function	Destroys this Connection object.
Connection::driver	public	function	Returns the type of database driver. Overrides Connection::driver
Connection::escapeAlias	public	function	Escapes an alias name string.	1
Connection::escapeDatabase	public	function	Escapes a database name string.
Connection::escapeField	public	function	Escapes a field name string.	1
Connection::escapeLike	public	function	Escapes characters that work as wildcard characters in a LIKE pattern.
Connection::escapeTable	public	function	Escapes a table name string.	1
Connection::expandArguments	protected	function	Expands out shorthand placeholders.
Connection::filterComment	protected	function	Sanitize a query comment string.
Connection::generateTemporaryTableName	protected	function	Generates a temporary table name.
Connection::getConnectionOptions	public	function	Returns the connection information for this connection object.
Connection::getDriverClass	public	function	Gets the driver-specific override class if any for the specified class.
Connection::getFullQualifiedTableName	public	function	Get a fully qualified table name.	2
Connection::getKey	public	function	Returns the key this connection is associated with.
Connection::getLogger	public	function	Gets the current logging object for this connection.
Connection::getTarget	public	function	Returns the target this connection is associated with.
Connection::getUnprefixedTablesMap	public	function	Gets a list of individually prefixed table names.
Connection::handleQueryException	protected	function	Wraps and re-throws any PDO exception thrown by static::query().	1
Connection::insert	public	function	Prepares and returns an INSERT query object.
Connection::inTransaction	public	function	Determines if there is an active transaction open.
Connection::makeComment	public	function	Flatten an array of query comments into a single comment string.
Connection::makeSequenceName	public	function	Creates the appropriate sequence name for a given table and serial field.
Connection::mapConditionOperator	public	function	Gets any special processing requirements for the condition operator. Overrides Connection::mapConditionOperator
Connection::merge	public	function	Prepares and returns a MERGE query object.
Connection::MIN_MAX_ALLOWED_PACKET		constant	The minimal possible value for the max_allowed_packet setting of MySQL.
Connection::nextId	public	function	Retrieves an unique ID from a given sequence. Overrides Connection::nextId
Connection::nextIdDelete	public	function
Connection::open	public static	function	Opens a PDO connection. Overrides Connection::open
Connection::popCommittableTransactions	protected	function	Overridden to work around issues to MySQL not supporting transactional DDL. Overrides Connection::popCommittableTransactions
Connection::popTransaction	public	function	Decreases the depth of transaction nesting.
Connection::prefixTables	public	function	Appends a database prefix to all tables in a query.
Connection::prepare	public	function	Prepares a statement for execution and returns a statement object	1
Connection::prepareQuery	public	function	Prepares a query string and returns the prepared statement.	2
Connection::pushTransaction	public	function	Increases the depth of transaction nesting.
Connection::query	public	function	Executes a query string against the database. Overrides Connection::query
Connection::queryRange	public	function	Runs a limited-range query on this database object. Overrides Connection::queryRange
Connection::queryTemporary	public	function	Runs a SELECT query and stores its results in a temporary table. Overrides Connection::queryTemporary
Connection::quote	public	function	Quotes a string for use in a query.
Connection::rollback	public	function	Rolls back the transaction entirely or to a named savepoint.
Connection::schema	public	function	Returns a DatabaseSchema object for manipulating the schema.
Connection::select	public	function	Prepares and returns a SELECT query object.
Connection::serialize	public	function
Connection::setKey	public	function	Tells this connection object what its key is.
Connection::setLogger	public	function	Associates a logging object with this connection.
Connection::setPrefix	protected	function	Set the list of prefixes used by this database connection.
Connection::setTarget	public	function	Tells this connection object what its target value is.
Connection::SQLSTATE_SYNTAX_ERROR		constant	SQLSTATE error code for "Syntax error or access rule violation".
Connection::startTransaction	public	function	Returns a new DatabaseTransaction object on this connection.
Connection::supportsTransactionalDDL	public	function	Determines if this driver supports transactional DDL.
Connection::supportsTransactions	public	function	Determines if this driver supports transactions.
Connection::tablePrefix	public	function	Find the prefix for a table.
Connection::transactionDepth	public	function	Determines the current transaction depth.
Connection::truncate	public	function	Prepares and returns a TRUNCATE query object.
Connection::UNKNOWN_CHARSET		constant	Driver-specific error code for "Unknown character set" error.
Connection::UNSUPPORTED_CHARSET		constant	Error code for "Can't initialize character set" error.
Connection::update	public	function	Prepares and returns an UPDATE query object.
Connection::upsert	public	function	Prepares and returns an UPSERT query object.	1
Connection::version	public	function	Returns the version of the database server.
Connection::__construct	public	function	Constructs a Connection object. Overrides Connection::__construct
Connection::__destruct	public	function
Connection::__sleep	public	function	Prevents the database connection from being serialized.