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class DatabaseConnection_sqlite in Drupal 7

Specific SQLite implementation of DatabaseConnection.

Hierarchy

Expanded class hierarchy of DatabaseConnection_sqlite

File

includes/database/sqlite/database.inc, line 18
Database interface code for SQLite embedded database engine.

View source 
class DatabaseConnection_sqlite extends DatabaseConnection {

  /**
   * Whether this database connection supports savepoints.
   *
   * Version of sqlite lower then 3.6.8 can't use savepoints.
   * See http://www.sqlite.org/releaselog/3_6_8.html
   *
   * @var boolean
   */
  protected $savepointSupport = FALSE;

  /**
   * Whether or not the active transaction (if any) will be rolled back.
   *
   * @var boolean
   */
  protected $willRollback;

  /**
   * All databases attached to the current database. This is used to allow
   * prefixes to be safely handled without locking the table
   *
   * @var array
   */
  protected $attachedDatabases = array();

  /**
   * Whether or not a table has been dropped this request: the destructor will
   * only try to get rid of unnecessary databases if there is potential of them
   * being empty.
   *
   * This variable is set to public because DatabaseSchema_sqlite needs to
   * access it. However, it should not be manually set.
   *
   * @var boolean
   */
  var $tableDropped = FALSE;
  public function __construct(array $connection_options = array()) {

    // We don't need a specific PDOStatement class here, we simulate it below.
    $this->statementClass = NULL;

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

    // Allow PDO options to be overridden.
    $connection_options += array(
      'pdo' => array(),
    );
    $connection_options['pdo'] += array(
      // Convert numeric values to strings when fetching.
      PDO::ATTR_STRINGIFY_FETCHES => TRUE,
    );
    parent::__construct('sqlite:' . $connection_options['database'], '', '', $connection_options['pdo']);

    // Attach one database for each registered prefix.
    $prefixes = $this->prefixes;
    foreach ($prefixes as $table => &$prefix) {

      // Empty prefix means query the main database -- no need to attach anything.
      if (!empty($prefix)) {

        // Only attach the database once.
        if (!isset($this->attachedDatabases[$prefix])) {
          $this->attachedDatabases[$prefix] = $prefix;
          $this
            ->query('ATTACH DATABASE :database AS :prefix', array(
            ':database' => $connection_options['database'] . '-' . $prefix,
            ':prefix' => $prefix,
          ));
        }

        // Add a ., so queries become prefix.table, which is proper syntax for
        // querying an attached database.
        $prefix .= '.';
      }
    }

    // Regenerate the prefixes replacement table.
    $this
      ->setPrefix($prefixes);

    // Detect support for SAVEPOINT.
    $version = $this
      ->query('SELECT sqlite_version()')
      ->fetchField();
    $this->savepointSupport = version_compare($version, '3.6.8') >= 0;

    // Create functions needed by SQLite.
    $this
      ->sqliteCreateFunction('if', array(
      $this,
      'sqlFunctionIf',
    ));
    $this
      ->sqliteCreateFunction('greatest', array(
      $this,
      'sqlFunctionGreatest',
    ));
    $this
      ->sqliteCreateFunction('pow', 'pow', 2);
    $this
      ->sqliteCreateFunction('length', 'strlen', 1);
    $this
      ->sqliteCreateFunction('md5', 'md5', 1);
    $this
      ->sqliteCreateFunction('concat', array(
      $this,
      'sqlFunctionConcat',
    ));
    $this
      ->sqliteCreateFunction('substring', array(
      $this,
      'sqlFunctionSubstring',
    ), 3);
    $this
      ->sqliteCreateFunction('substring_index', array(
      $this,
      'sqlFunctionSubstringIndex',
    ), 3);
    $this
      ->sqliteCreateFunction('rand', array(
      $this,
      'sqlFunctionRand',
    ));

    // Enable the Write-Ahead Logging (WAL) option for SQLite if supported.
    // @see https://www.drupal.org/node/2348137
    // @see https://sqlite.org/wal.html
    if (version_compare($version, '3.7') >= 0) {
      $connection_options += array(
        'init_commands' => array(),
      );
      $connection_options['init_commands'] += array(
        'wal' => "PRAGMA journal_mode=WAL",
      );
    }

    // Execute sqlite init_commands.
    if (isset($connection_options['init_commands'])) {
      $this->connection
        ->exec(implode('; ', $connection_options['init_commands']));
    }
  }

  /**
   * Destructor for the SQLite connection.
   *
   * We prune empty databases on destruct, but only if tables have been
   * dropped. This is especially needed when running the test suite, which
   * creates and destroy databases several times in a row.
   */
  public function __destruct() {
    if ($this->tableDropped && !empty($this->attachedDatabases)) {
      foreach ($this->attachedDatabases as $prefix) {

        // Check if the database is now empty, ignore the internal SQLite tables.
        try {
          $count = $this
            ->query('SELECT COUNT(*) FROM ' . $prefix . '.sqlite_master WHERE type = :type AND name NOT LIKE :pattern', array(
            ':type' => 'table',
            ':pattern' => 'sqlite_%',
          ))
            ->fetchField();

          // We can prune the database file if it doesn't have any tables.
          if ($count == 0 && $this->connectionOptions['database'] != ':memory:') {

            // Detaching the database fails at this point, but no other queries
            // are executed after the connection is destructed so we can simply
            // remove the database file.
            unlink($this->connectionOptions['database'] . '-' . $prefix);
          }
        } catch (Exception $e) {

          // Ignore the exception and continue. There is nothing we can do here
          // to report the error or fail safe.
        }
      }
    }
  }

  /**
   * Gets all the attached databases.
   *
   * @return array
   *   An array of attached database names.
   *
   * @see DatabaseConnection_sqlite::__construct().
   */
  public function getAttachedDatabases() {
    return $this->attachedDatabases;
  }

  /**
   * SQLite compatibility implementation for the IF() SQL function.
   */
  public function sqlFunctionIf($condition, $expr1, $expr2 = NULL) {
    return $condition ? $expr1 : $expr2;
  }

  /**
   * SQLite compatibility implementation for the GREATEST() SQL function.
   */
  public function sqlFunctionGreatest() {
    $args = func_get_args();
    foreach ($args as $k => $v) {
      if (!isset($v)) {
        unset($args);
      }
    }
    if (count($args)) {
      return max($args);
    }
    else {
      return NULL;
    }
  }

  /**
   * SQLite compatibility implementation for the CONCAT() SQL function.
   */
  public function sqlFunctionConcat() {
    $args = func_get_args();
    return implode('', $args);
  }

  /**
   * SQLite compatibility implementation for the SUBSTRING() SQL function.
   */
  public function sqlFunctionSubstring($string, $from, $length) {
    return substr($string, $from - 1, $length);
  }

  /**
   * SQLite compatibility implementation for the SUBSTRING_INDEX() SQL function.
   */
  public function sqlFunctionSubstringIndex($string, $delimiter, $count) {

    // If string is empty, simply return an empty string.
    if (empty($string)) {
      return '';
    }
    $end = 0;
    for ($i = 0; $i < $count; $i++) {
      $end = strpos($string, $delimiter, $end + 1);
      if ($end === FALSE) {
        $end = strlen($string);
      }
    }
    return substr($string, 0, $end);
  }

  /**
   * SQLite compatibility implementation for the RAND() SQL function.
   */
  public function sqlFunctionRand($seed = NULL) {
    if (isset($seed)) {
      mt_srand($seed);
    }
    return mt_rand() / mt_getrandmax();
  }

  /**
   * SQLite-specific implementation of DatabaseConnection::prepare().
   *
   * We don't use prepared statements at all at this stage. We just create
   * a DatabaseStatement_sqlite object, that will create a PDOStatement
   * using the semi-private PDOPrepare() method below.
   */
  public function prepare($query, $options = array()) {
    return new DatabaseStatement_sqlite($this, $query, $options);
  }

  /**
   * NEVER CALL THIS FUNCTION: YOU MIGHT DEADLOCK YOUR PHP PROCESS.
   *
   * This is a wrapper around the parent PDO::prepare method. However, as
   * the PDO SQLite driver only closes SELECT statements when the PDOStatement
   * destructor is called and SQLite does not allow data change (INSERT,
   * UPDATE etc) on a table which has open SELECT statements, you should never
   * call this function and keep a PDOStatement object alive as that can lead
   * to a deadlock. This really, really should be private, but as
   * DatabaseStatement_sqlite needs to call it, we have no other choice but to
   * expose this function to the world.
   */
  public function PDOPrepare($query, array $options = array()) {
    return $this->connection
      ->prepare($query, $options);
  }
  public function queryRange($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()) {

    // Generate a new temporary table name and protect it from prefixing.
    // SQLite requires that temporary tables to be non-qualified.
    $tablename = $this
      ->generateTemporaryTableName();
    $prefixes = $this->prefixes;
    $prefixes[$tablename] = '';
    $this
      ->setPrefix($prefixes);
    $this
      ->query('CREATE TEMPORARY TABLE ' . $tablename . ' AS ' . $query, $args, $options);
    return $tablename;
  }
  public function driver() {
    return 'sqlite';
  }
  public function databaseType() {
    return 'sqlite';
  }
  public function mapConditionOperator($operator) {

    // We don't want to override any of the defaults.
    static $specials = array(
      'LIKE' => array(
        'postfix' => " ESCAPE '\\'",
      ),
      'NOT LIKE' => array(
        'postfix' => " ESCAPE '\\'",
      ),
    );
    return isset($specials[$operator]) ? $specials[$operator] : NULL;
  }
  public function prepareQuery($query) {
    return $this
      ->prepare($this
      ->prefixTables($query));
  }
  public function nextId($existing_id = 0) {
    $transaction = $this
      ->startTransaction();

    // We can safely use literal queries here instead of the slower query
    // builder because if a given database breaks here then it can simply
    // override nextId. However, this is unlikely as we deal with short strings
    // and integers and no known databases require special handling for those
    // simple cases. If another transaction wants to write the same row, it will
    // wait until this transaction commits.
    $stmt = $this
      ->query('UPDATE {sequences} SET value = GREATEST(value, :existing_id) + 1', array(
      ':existing_id' => $existing_id,
    ));
    if (!$stmt
      ->rowCount()) {
      $this
        ->query('INSERT INTO {sequences} (value) VALUES (:existing_id + 1)', array(
        ':existing_id' => $existing_id,
      ));
    }

    // The transaction gets committed when the transaction object gets destroyed
    // because it gets out of scope.
    return $this
      ->query('SELECT value FROM {sequences}')
      ->fetchField();
  }
  public function rollback($savepoint_name = 'drupal_transaction') {
    if ($this->savepointSupport) {
      return parent::rollBack($savepoint_name);
    }
    if (!$this
      ->inTransaction()) {
      throw new DatabaseTransactionNoActiveException();
    }

    // A previous rollback to an earlier savepoint may mean that the savepoint
    // in question has already been rolled back.
    if (!in_array($savepoint_name, $this->transactionLayers)) {
      return;
    }

    // We need to find the point we're rolling back to, all other savepoints
    // before are no longer needed.
    while ($savepoint = array_pop($this->transactionLayers)) {
      if ($savepoint == $savepoint_name) {

        // Mark whole stack of transactions as needed roll back.
        $this->willRollback = TRUE;

        // If it is the last the transaction in the stack, then it is not a
        // savepoint, it is the transaction itself so we will need to roll back
        // the transaction rather than a savepoint.
        if (empty($this->transactionLayers)) {
          break;
        }
        return;
      }
    }
    if ($this
      ->supportsTransactions()) {
      $this->connection
        ->rollBack();
    }
  }
  public function pushTransaction($name) {
    if ($this->savepointSupport) {
      return parent::pushTransaction($name);
    }
    if (!$this
      ->supportsTransactions()) {
      return;
    }
    if (isset($this->transactionLayers[$name])) {
      throw new DatabaseTransactionNameNonUniqueException($name . " is already in use.");
    }
    if (!$this
      ->inTransaction()) {
      $this->connection
        ->beginTransaction();
    }
    $this->transactionLayers[$name] = $name;
  }
  public function popTransaction($name) {
    if ($this->savepointSupport) {
      return parent::popTransaction($name);
    }
    if (!$this
      ->supportsTransactions()) {
      return;
    }
    if (!$this
      ->inTransaction()) {
      throw new DatabaseTransactionNoActiveException();
    }

    // Commit everything since SAVEPOINT $name.
    while ($savepoint = array_pop($this->transactionLayers)) {
      if ($savepoint != $name) {
        continue;
      }

      // If there are no more layers left then we should commit or rollback.
      if (empty($this->transactionLayers)) {

        // If there was any rollback() we should roll back whole transaction.
        if ($this->willRollback) {
          $this->willRollback = FALSE;
          $this->connection
            ->rollBack();
        }
        elseif (!$this->connection
          ->commit()) {
          throw new DatabaseTransactionCommitFailedException();
        }
      }
      else {
        break;
      }
    }
  }
  public function utf8mb4IsActive() {
    return TRUE;
  }
  public function utf8mb4IsSupported() {
    return TRUE;
  }

}

Members

Namesort descending Modifiers Type Description Overrides
DatabaseConnection::$connection protected property The actual PDO connection.
DatabaseConnection::$connectionOptions protected property The connection information for this connection object.
DatabaseConnection::$driverClasses protected property Index of what driver-specific class to use for various operations.
DatabaseConnection::$escapedAliases protected property List of escaped aliases names, keyed by unescaped aliases.
DatabaseConnection::$escapedNames protected property List of escaped database, table, and field names, keyed by unescaped names.
DatabaseConnection::$key protected property The key representing this connection.
DatabaseConnection::$logger protected property The current database logging object for this connection.
DatabaseConnection::$prefixes protected property The prefixes used by this database connection.
DatabaseConnection::$prefixReplace protected property List of replacement values for use in prefixTables().
DatabaseConnection::$prefixSearch protected property List of search values for use in prefixTables().
DatabaseConnection::$schema protected property The schema object for this connection.
DatabaseConnection::$statementClass protected property The name of the Statement class for this connection.
DatabaseConnection::$target protected property The database target this connection is for.
DatabaseConnection::$temporaryNameIndex protected property An index used to generate unique temporary table names.
DatabaseConnection::$transactionalDDLSupport protected property Whether this database connection supports transactional DDL.
DatabaseConnection::$transactionLayers protected property Tracks the number of "layers" of transactions currently active.
DatabaseConnection::$transactionSupport protected property Whether this database connection supports transactions.
DatabaseConnection::$unprefixedTablesMap protected property List of un-prefixed table names, keyed by prefixed table names.
DatabaseConnection::commit public function Throws an exception to deny direct access to transaction commits.
DatabaseConnection::defaultOptions protected function Returns the default query options for any given query.
DatabaseConnection::delete public function Prepares and returns a DELETE query object.
DatabaseConnection::destroy public function Destroys this Connection object.
DatabaseConnection::escapeAlias public function Escapes an alias name string. 1
DatabaseConnection::escapeField public function Escapes a field name string. 1
DatabaseConnection::escapeLike public function Escapes characters that work as wildcard characters in a LIKE pattern.
DatabaseConnection::escapeTable public function Escapes a table name string.
DatabaseConnection::expandArguments protected function Expands out shorthand placeholders.
DatabaseConnection::filterComment protected function Sanitize a query comment string.
DatabaseConnection::generateTemporaryTableName protected function Generates a temporary table name.
DatabaseConnection::getConnectionOptions public function Returns the connection information for this connection object.
DatabaseConnection::getDriverClass public function Gets the driver-specific override class if any for the specified class.
DatabaseConnection::getKey public function Returns the key this connection is associated with.
DatabaseConnection::getLogger public function Gets the current logging object for this connection.
DatabaseConnection::getTarget public function Returns the target this connection is associated with.
DatabaseConnection::getUnprefixedTablesMap public function Gets a list of individually prefixed table names.
DatabaseConnection::insert public function Prepares and returns an INSERT query object.
DatabaseConnection::inTransaction public function Determines if there is an active transaction open.
DatabaseConnection::makeComment public function Flatten an array of query comments into a single comment string.
DatabaseConnection::makeSequenceName public function Creates the appropriate sequence name for a given table and serial field.
DatabaseConnection::merge public function Prepares and returns a MERGE query object.
DatabaseConnection::popCommittableTransactions protected function Internal function: commit all the transaction layers that can commit. 1
DatabaseConnection::prefixTables public function Appends a database prefix to all tables in a query.
DatabaseConnection::query public function Executes a query string against the database. 1
DatabaseConnection::schema public function Returns a DatabaseSchema object for manipulating the schema.
DatabaseConnection::select public function Prepares and returns a SELECT query object.
DatabaseConnection::setKey public function Tells this connection object what its key is.
DatabaseConnection::setLogger public function Associates a logging object with this connection.
DatabaseConnection::setPrefix protected function Set the list of prefixes used by this database connection. 1
DatabaseConnection::setTarget public function Tells this connection object what its target value is.
DatabaseConnection::startTransaction public function Returns a new DatabaseTransaction object on this connection.
DatabaseConnection::supportsTransactionalDDL public function Determines if this driver supports transactional DDL.
DatabaseConnection::supportsTransactions public function Determines if this driver supports transactions.
DatabaseConnection::tablePrefix public function Find the prefix for a table.
DatabaseConnection::transactionDepth public function Determines current transaction depth.
DatabaseConnection::truncate public function Prepares and returns a TRUNCATE query object.
DatabaseConnection::update public function Prepares and returns an UPDATE query object.
DatabaseConnection::utf8mb4IsConfigurable public function Checks whether utf8mb4 support is configurable in settings.php. 1
DatabaseConnection::version public function Returns the version of the database server.
DatabaseConnection::__call public function Proxy possible direct calls to the \PDO methods.
DatabaseConnection_sqlite::$attachedDatabases protected property All databases attached to the current database. This is used to allow prefixes to be safely handled without locking the table
DatabaseConnection_sqlite::$savepointSupport protected property Whether this database connection supports savepoints.
DatabaseConnection_sqlite::$tableDropped property Whether or not a table has been dropped this request: the destructor will only try to get rid of unnecessary databases if there is potential of them being empty.
DatabaseConnection_sqlite::$willRollback protected property Whether or not the active transaction (if any) will be rolled back.
DatabaseConnection_sqlite::databaseType public function Returns the name of the PDO driver for this connection. Overrides DatabaseConnection::databaseType
DatabaseConnection_sqlite::driver public function Returns the type of database driver. Overrides DatabaseConnection::driver
DatabaseConnection_sqlite::getAttachedDatabases public function Gets all the attached databases.
DatabaseConnection_sqlite::mapConditionOperator public function Gets any special processing requirements for the condition operator. Overrides DatabaseConnection::mapConditionOperator
DatabaseConnection_sqlite::nextId public function Retrieves an unique id from a given sequence. Overrides DatabaseConnection::nextId
DatabaseConnection_sqlite::PDOPrepare public function NEVER CALL THIS FUNCTION: YOU MIGHT DEADLOCK YOUR PHP PROCESS.
DatabaseConnection_sqlite::popTransaction public function Decreases the depth of transaction nesting. Overrides DatabaseConnection::popTransaction
DatabaseConnection_sqlite::prepare public function SQLite-specific implementation of DatabaseConnection::prepare().
DatabaseConnection_sqlite::prepareQuery public function Prepares a query string and returns the prepared statement. Overrides DatabaseConnection::prepareQuery
DatabaseConnection_sqlite::pushTransaction public function Increases the depth of transaction nesting. Overrides DatabaseConnection::pushTransaction
DatabaseConnection_sqlite::queryRange public function Runs a limited-range query on this database object. Overrides DatabaseConnection::queryRange
DatabaseConnection_sqlite::queryTemporary public function Runs a SELECT query and stores its results in a temporary table. Overrides DatabaseConnection::queryTemporary
DatabaseConnection_sqlite::rollback public function Rolls back the transaction entirely or to a named savepoint. Overrides DatabaseConnection::rollback
DatabaseConnection_sqlite::sqlFunctionConcat public function SQLite compatibility implementation for the CONCAT() SQL function.
DatabaseConnection_sqlite::sqlFunctionGreatest public function SQLite compatibility implementation for the GREATEST() SQL function.
DatabaseConnection_sqlite::sqlFunctionIf public function SQLite compatibility implementation for the IF() SQL function.
DatabaseConnection_sqlite::sqlFunctionRand public function SQLite compatibility implementation for the RAND() SQL function.
DatabaseConnection_sqlite::sqlFunctionSubstring public function SQLite compatibility implementation for the SUBSTRING() SQL function.
DatabaseConnection_sqlite::sqlFunctionSubstringIndex public function SQLite compatibility implementation for the SUBSTRING_INDEX() SQL function.
DatabaseConnection_sqlite::utf8mb4IsActive public function Checks whether utf8mb4 support is currently active. Overrides DatabaseConnection::utf8mb4IsActive
DatabaseConnection_sqlite::utf8mb4IsSupported public function Checks whether utf8mb4 support is available on the current database system. Overrides DatabaseConnection::utf8mb4IsSupported
DatabaseConnection_sqlite::__construct public function Overrides DatabaseConnection::__construct
DatabaseConnection_sqlite::__destruct public function Destructor for the SQLite connection.