class DatabaseLog

Database query logger.

We log queries in a separate object rather than in the connection object because we want to be able to see all queries sent to a given database, not database target. If we logged the queries in each connection object we would not be able to track what queries went to which target.

Every connection has one and only one logging object on it for all targets and logging keys.

Hierarchy

Expanded class hierarchy of DatabaseLog

Members

Contains filters are case sensitive
Namesort descending Modifiers Type Description
DatabaseLog::$connectionKey protected property The connection key for which this object is logging.
DatabaseLog::$queryLog protected property Cache of logged queries. This will only be used if the query logger is enabled.
DatabaseLog::clear public function Empty the query log for the specified logging key.
DatabaseLog::end public function Stop logging for the specified logging key.
DatabaseLog::findCaller public function Determine the routine that called this query.
DatabaseLog::get public function Retrieve the query log for the specified logging key so far.
DatabaseLog::log public function Log a query to all active logging keys.
DatabaseLog::start public function Begin logging queries to the specified connection and logging key.
DatabaseLog::__construct public function Constructor.

File

drupal/includes/database/log.inc, line 19
Logging classes for the database layer.

View source
class DatabaseLog {

  /**
   * Cache of logged queries. This will only be used if the query logger is enabled.
   *
   * The structure for the logging array is as follows:
   *
   * array(
   *   $logging_key = array(
   *     array(query => '', args => array(), caller => '', target => '', time => 0),
   *     array(query => '', args => array(), caller => '', target => '', time => 0),
   *   ),
   * );
   *
   * @var array
   */
  protected $queryLog = array();

  /**
   * The connection key for which this object is logging.
   *
   * @var string
   */
  protected $connectionKey = 'default';

  /**
   * Constructor.
   *
   * @param $key
   *   The database connection key for which to enable logging.
   */
  public function __construct($key = 'default') {
    $this->connectionKey = $key;
  }

  /**
   * Begin logging queries to the specified connection and logging key.
   *
   * If the specified logging key is already running this method does nothing.
   *
   * @param $logging_key
   *   The identification key for this log request. By specifying different
   *   logging keys we are able to start and stop multiple logging runs
   *   simultaneously without them colliding.
   */
  public function start($logging_key) {
    if (empty($this->queryLog[$logging_key])) {
      $this->clear($logging_key);
    }
  }

  /**
   * Retrieve the query log for the specified logging key so far.
   *
   * @param $logging_key
   *   The logging key to fetch.
   * @return
   *   An indexed array of all query records for this logging key.
   */
  public function get($logging_key) {
    return $this->queryLog[$logging_key];
  }

  /**
   * Empty the query log for the specified logging key.
   *
   * This method does not stop logging, it simply clears the log. To stop
   * logging, use the end() method.
   *
   * @param $logging_key
   *   The logging key to empty.
   */
  public function clear($logging_key) {
    $this->queryLog[$logging_key] = array();
  }

  /**
   * Stop logging for the specified logging key.
   *
   * @param $logging_key
   *   The logging key to stop.
   */
  public function end($logging_key) {
    unset($this->queryLog[$logging_key]);
  }

  /**
   * Log a query to all active logging keys.
   *
   * @param $statement
   *   The prepared statement object to log.
   * @param $args
   *   The arguments passed to the statement object.
   * @param $time
   *   The time in milliseconds the query took to execute.
   */
  public function log(DatabaseStatementInterface $statement, $args, $time) {
    foreach (array_keys($this->queryLog) as $key) {
      $this->queryLog[$key][] = array(
        'query' => $statement->getQueryString(),
        'args' => $args,
        'target' => $statement->dbh->getTarget(),
        'caller' => $this->findCaller(),
        'time' => $time,
      );
    }
  }

  /**
   * Determine the routine that called this query.
   *
   * We define "the routine that called this query" as the first entry in
   * the call stack that is not inside includes/database and does have a file
   * (which excludes call_user_func_array(), anonymous functions and similar).
   * That makes the climbing logic very simple, and handles the variable stack
   * depth caused by the query builders.
   *
   * @link http://www.php.net/debug_backtrace
   * @return
   *   This method returns a stack trace entry similar to that generated by
   *   debug_backtrace(). However, it flattens the trace entry and the trace
   *   entry before it so that we get the function and args of the function that
   *   called into the database system, not the function and args of the
   *   database call itself.
   */
  public function findCaller() {
    $stack = debug_backtrace();
    $stack_count = count($stack);
    for ($i = 0; $i < $stack_count; ++$i) {
      if (!empty($stack[$i]['file']) && strpos($stack[$i]['file'], 'includes' . DIRECTORY_SEPARATOR . 'database') === FALSE) {
        $stack[$i] += array('args' => array());
        return array(
          'file' => $stack[$i]['file'],
          'line' => $stack[$i]['line'],
          'function' => $stack[$i + 1]['function'],
          'class' => isset($stack[$i + 1]['class']) ? $stack[$i + 1]['class'] : NULL,
          'type' => isset($stack[$i + 1]['type']) ? $stack[$i + 1]['type'] : NULL,
          'args' => $stack[$i + 1]['args'],
        );
      }
    }
  }
}