Calling query() function fails

[bp_travis]

Hello. I am working with an example in a MySQL performance book, but it involves PHP. I cannot get the code example to work.

It always reports:
Fatal error: Call to a member function query() on a non-object in C:\wamp\www\page1.php on line 15

Here is the code:

<?php
class mysqlx extends mysqli {
  function query($query, $resultmode) {
    $timer =  Timer::getInstance();
    $timer->startTime('MySQL');
    $res = parent::query($query, $resultmode);
    $timer->stopTime('MySQL', "Query: $query\n");
    return $res;
  }
}
  /*
 * Class DBQueryLog logs profiling data into the database
 */
    
    class DBQueryLog{
     
      function logProfilingData($data) {
        $table_name = "logs.performance_log_" . @date("ymd");
        $query = "INSERT DELAYED INTO $table_name (ip, page, utime,
               wtime, stime, mysql_time, sphinx_time, mysql_count_queries,
               mysql_queries, user_agent, referer) VALUES  (.. data ..)";
        $res = $this->mysqlx->query($query);
        // Handle "table not found" error - create new table for each new day
        if ((!$res) &&  ($this->mysqlx->errno == 1146)) { // 1146 is table not found
          $res = $this->mysqlx->query(
            "CREATE TABLE $table_name LIKE logs.performance_log_template");
          $res = $this->mysqlx->query($query);
        }
      }
      
        // This helper function implements the Singleton pattern
  function getInstance() {
    static $instance;
    if(!isset($instance)) {
      $instance = new Timer();
    }
    return($instance);
  }
    }
    
class Timer extends DBQueryLog {
  private $aTIMES = array();
  function startTime($point)
    {
        $dat = microtime()/time();
        $this->aTIMES[$point]['start'] = microtime(TRUE);
        $this->aTIMES[$point]['start_utime'] =
           $dat["ru_utime.tv_sec"]*1e6+$dat["ru_utime.tv_usec"];
        $this->aTIMES[$point]['start_stime'] =
           $dat["ru_stime.tv_sec"]*1e6+$dat["ru_stime.tv_usec"];
    }
  function stopTime($point, $comment='')
  {
    $dat = microtime()/time();
    $this->aTIMES[$point]['end'] = microtime(TRUE);
    $this->aTIMES[$point]['end_utime'] =
       $dat["ru_utime.tv_sec"] * 1e6 + $dat["ru_utime.tv_usec"];
    $this->aTIMES[$point]['end_stime'] =
       $dat["ru_stime.tv_sec"] * 1e6 + $dat["ru_stime.tv_usec"];
    $this->aTIMES[$point]['comment'] .= $comment;
    $this->aTIMES[$point]['sum'] +=
       $this->aTIMES[$point]['end'] - $this->aTIMES[$point]['start'];
    $this->aTIMES[$point]['sum_utime'] +=
       ($this->aTIMES[$point]['end_utime'] -
          $this->aTIMES[$point]['start_utime']) / 1e6;
    $this->aTIMES[$point]['sum_stime'] +=
       ($this->aTIMES[$point]['end_stime'] -
          $this->aTIMES[$point]['start_stime']) / 1e6;
  }
  function logdata() {
    $query_logger = DBQueryLog::getInstance('DBQueryLog');
    $data['utime'] = $this->aTIMES['Page']['sum_utime'];
    $data['wtime'] = $this->aTIMES['Page']['sum'];
    $data['stime'] = $this->aTIMES['Page']['sum_stime'];
    $data['mysql_time'] = $this->aTIMES['MySQL']['sum'];
    $data['mysql_count_queries'] = $this->aTIMES['MySQL']['cnt'];
    $data['mysql_queries'] = $this->aTIMES['MySQL']['comment'];
    $data['sphinx_time'] = $this->aTIMES['Sphinx']['sum'];
    $query_logger->logProfilingData($data);
  }
  

}

// Start of the page execution
mysql_connect("localhost","root","");
$timer =  Timer::getInstance();
$timer->startTime('Page');
    
    // $query = "SELECT * FROM sakila";
    // mysql_query($query,$db);
// End of the page execution
$timer->stopTime('Page');
$timer->logdata();
?>

[NogDog]

As currently coded, there is no instance of your mysqlx class in the DBQueryLog class.

[bp_travis]

When I try to create the a class instance in the DBQueryLog() class like so: mysqlx = new mysqlx();

I receive this error:
Parse error: parse error, expecting `T_FUNCTION' in C:\wamp\www\page1.php on line 16

[NogDog]

How/where are you instantiating it?

You may want a __construct() method in the class to instantiate it:

class ClassName
{
   protected $mysqlx;
   public function __construct()
   {
      $this->mysqlx = new mysqlx();
   }
   // rest of class...
} 

However, since mysqlx extends MySQLi, which normally gets the DB connection credentials passed to its constructor, you might be better off instantiating it in your main script, then passing that instance as a parameter to the constructor:

class ClassName
{
   protected $mysqlx;
   public function __construct(mysqlx $mysqlx)
   {
      $this->mysqlx = $mysqlx;
   }
   // rest of class...
}
$mysqlx = new mysqlx($dbhost, $dbuser, $dbpass, $dbname);
$foo = new ClassName($mysqlx);