Database::getConnection

final public static Database::getConnection($target = 'default', $key = NULL)

final public static function getConnection($target = 'default', $key = NULL) {
  if (!isset($key)) {
    // By default, we want the active connection, set in setActiveConnection.
    $key = self::$activeKey;
  }
  // If the requested target does not exist, or if it is ignored, we fall back
  // to the default target. The target is typically either "default" or
  // "replica", indicating to use a replica SQL server if one is available. If
  // it's not available, then the default/primary server is the correct server
  // to use.
  if (!empty(self::$ignoreTargets[$key][$target]) || !isset(self::$databaseInfo[$key][$target])) {
    $target = 'default';
  }

  if (!isset(self::$connections[$key][$target])) {
    // If necessary, a new connection is opened.
    self::$connections[$key][$target] = self::openConnection($key, $target);
  }
  return self::$connections[$key][$target];
}