Benchmarking Class
******************

CodeIgniter has a Benchmarking class that is always active, enabling
the time difference between any two marked points to be calculated.

Note:

  This class is initialized automatically by the system so there is no
  need to do it manually.

In addition, the benchmark is always started the moment the framework
is invoked, and ended by the output class right before sending the
final view to the browser, enabling a very accurate timing of the
entire system execution to be shown.

* Using the Benchmark Class

  * Profiling Your Benchmark Points

  * Displaying Total Execution Time

  * Displaying Memory Consumption

* Class Reference


Using the Benchmark Class
=========================

The Benchmark class can be used within your controllers, views, or
your models. The process for usage is this:

1. Mark a start point

2. Mark an end point

3. Run the “elapsed time” function to view the results

Here’s an example using real code:

   $this->benchmark->mark('code_start');

   // Some code happens here

   $this->benchmark->mark('code_end');

   echo $this->benchmark->elapsed_time('code_start', 'code_end');

Note:

  The words “code_start” and “code_end” are arbitrary. They are simply
  words used to set two markers. You can use any words you want, and
  you can set multiple sets of markers. Consider this example:

     $this->benchmark->mark('dog');

     // Some code happens here

     $this->benchmark->mark('cat');

     // More code happens here

     $this->benchmark->mark('bird');

     echo $this->benchmark->elapsed_time('dog', 'cat');
     echo $this->benchmark->elapsed_time('cat', 'bird');
     echo $this->benchmark->elapsed_time('dog', 'bird');


Profiling Your Benchmark Points
-------------------------------

If you want your benchmark data to be available to the Profiler all of
your marked points must be set up in pairs, and each mark point name
must end with _start and _end. Each pair of points must otherwise be
named identically. Example:

   $this->benchmark->mark('my_mark_start');

   // Some code happens here...

   $this->benchmark->mark('my_mark_end');

   $this->benchmark->mark('another_mark_start');

   // Some more code happens here...

   $this->benchmark->mark('another_mark_end');

Please read the Profiler page for more information.


Displaying Total Execution Time
-------------------------------

If you would like to display the total elapsed time from the moment
CodeIgniter starts to the moment the final output is sent to the
browser, simply place this in one of your view templates:

   <?php echo $this->benchmark->elapsed_time();?>

You’ll notice that it’s the same function used in the examples above
to calculate the time between two point, except you are **not** using
any parameters. When the parameters are absent, CodeIgniter does not
stop the benchmark until right before the final output is sent to the
browser. It doesn’t matter where you use the function call, the timer
will continue to run until the very end.

An alternate way to show your elapsed time in your view files is to
use this pseudo-variable, if you prefer not to use the pure PHP:

   {elapsed_time}

Note:

  If you want to benchmark anything within your controller functions
  you must set your own start/end points.


Displaying Memory Consumption
-----------------------------

If your PHP installation is configured with –enable-memory-limit, you
can display the amount of memory consumed by the entire system using
the following code in one of your view file:

   <?php echo $this->benchmark->memory_usage();?>

Note:

  This function can only be used in your view files. The consumption
  will reflect the total memory used by the entire app.

An alternate way to show your memory usage in your view files is to
use this pseudo-variable, if you prefer not to use the pure PHP:

   {memory_usage}


Class Reference
===============

class CI_Benchmark

   mark($name)

      Parameters:
         * **$name** ("string") – the name you wish to assign to your
           marker

      Return type:
         "void"

      Sets a benchmark marker.

   elapsed_time([$point1 = ''[, $point2 = ''[, $decimals = 4]]])

      Parameters:
         * **$point1** ("string") – a particular marked point

         * **$point2** ("string") – a particular marked point

         * **$decimals** ("int") – number of decimal places for
           precision

      Returns:
         Elapsed time

      Return type:
         "string"

      Calculates and returns the time difference between two marked
      points.

      If the first parameter is empty this function instead returns
      the "{elapsed_time}" pseudo-variable. This permits the full
      system execution time to be shown in a template. The output
      class will swap the real value for this variable.

   memory_usage()

      Returns:
         Memory usage info

      Return type:
         "string"

      Simply returns the "{memory_usage}" marker.

      This permits it to be put it anywhere in a template without the
      memory being calculated until the end. The Output Class will
      swap the real value for this variable.
