Developing (v7+)

Using php register_shutdown_function

Permalink October 13, 2012 at 12:15 PM

In response to a prb comment from mkly, I have been playing with php register_shutdown_function().

The attached class provides a pair of calls to be placed about a section of code (with microtime measurement as a side effect), with the intention that if the completion call does not happen (ie something between them fails), a message is added to the log. The aim was to try and catch failures that an exception handler would not catch, and be used on a bigger scale than the simple example below.

Loader::library('nice_ending_check','my_package_name');
NiceEndingCheck::register_start('my_package_name');
// Some critical code starts here
......
// Some critical code ends here
$ex_time = NiceEndingCheck::register_complete('my_package_name');

After various issues, I simply placed it about some code in a single page view to get some diagnostics. It runs OK when called correctly, but when I introduce a failure (by calling register_complete with a mismatched token), the final Log::addEvent is failing with an unknown mysql error.

My current conclusion is that something needed to run the sql within Log::addEvent is no longer in existence when called from register_shutdown_function().

If anyone feels like playing and offering some ideas on making this work, I am looking at it as 'an interesting digression' rather than something that I absolutely have to get working.

<?php
defined('C5_EXECUTE') or die("Access Denied.");
/*
Library to put round important bits of code
The idea is that code in question is wrapped in register_start
and register_complete. $token being used to match them together.
The check_complete should then be called automatically to confirm
that register_complete has been done for the $token, and log if
it has not.
BUGS - Log::addEvent fails
*/
if (! class_exists('NiceEndingCheck')){
class NiceEndingCheck {
  public static $client_track = array();
  public static function register_start($token, $failure_message=null){

Viewing 15 lines of 86 lines. View entire code block.

 
<?php
defined('C5_EXECUTE') or die("Access Denied.");
/*
Library to put round important bits of code
 
The idea is that code in question is wrapped in register_start
and register_complete. $token being used to match them together.
 
The check_complete should then be called automatically to confirm
that register_complete has been done for the $token, and log if
it has not.
 
BUGS - Log::addEvent fails
*/
 
if (! class_exists('NiceEndingCheck')){
class NiceEndingCheck {
 
  public static $client_track = array();
 
  public static function register_start($token, $failure_message=null){
    if (empty(self::$client_track)){
      self::$client_track = array();
    }
 
    self::$client_track[$token] = array ( 'start_time' => microtime(true),'failure_message'  => $failure_message,);
    /*
    Assume that register_shutdown_function is supported unless
    we are explicitly told that it is not by a definition of
    NICE_ENDING_CHECK_REGISTER_SHUTDOWN_FUNCTION_SUPPORTED as false (or 'false')
 
   http://php.net/manual/en/function.register-shutdown-function.php...
    */
    if (  ! defined(NICE_ENDING_CHECK_REGISTER_SHUTDOWN_FUNCTION_SUPPORTED)
        ||
        (  NICE_ENDING_CHECK_REGISTER_SHUTDOWN_FUNCTION_SUPPORTED &&
          NICE_ENDING_CHECK_REGISTER_SHUTDOWN_FUNCTION_SUPPORTED != 'false'
        )
      ){
      try {
        register_shutdown_function (array('NiceEndingCheck','check_complete'), $token);
      } catch(Exception $e) {
        // obviously not supported
        Log::addEntry (t('PHP register_shutdown_function failed for token %s with exception %s.',$token,$e->getMessage()), $token);
        return false;
      }
    }
    return self::$client_track[$token]['start_time'];
  }
 
  public static function register_complete($token){
    if (empty(self::$client_track)){
      return;
    }
    self::$client_track[$token]['complete_time'] = microtime(true);
    // by returning a time, this can also be used for execution timing in addition to checking sucessful completion.
    return round((self::$client_track[$token]['complete_time'] - self::$client_track[$token]['start_time']),3);
  }
 
 
  /*
  Designed to be called through register_shutdown_function.
  */
  public static function check_complete($token='unknown token'){
 
    try {
      // Have a complete time associated with teh token, so completed successfully.
      if (!empty(NiceEndingCheck::$client_track[$token]['complete_time'])){
        return true;
      }
 
      $exec_time = round(microtime(true) - NiceEndingCheck::$client_track[$token]['start_time'],3);
      // no completion mark, so report an error.
      $msg = NiceEndingCheck::$client_track[$token]['failure_message'];
      if (empty($msg)){
        $msg = t('Execution completion check on %s failed after a total execution time of %s seconds.',$token, $exec_time);
      }
 
      $t_params = substr_count($msg, '%s');
      if ($t_params == 1){
        $msg = sprintf($msg, $exec_time);
 
      } else if ($t_params == 2){
        $msg = sprintf($msg, $token, $exec_time);
      }
 
      Log::addEntry($msg,$token);
      return false;
    } catch (Exception $e) {
 
      // Some debug code
      echo "<pre>";
      echo "********************\n";
      echo $e->getMessage();
      echo "--------------------\n";
      echo htmlentities(print_r(debug_backtrace(),true));
      echo "\n====================";
      echo "</pre>";
 
      return false;
    }
  }
}
}

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