Revision as of 18:35, 19 May 2009

Cron Tasks

A placeholder for cron-like functioning in phpBB.

• The reason for this is that the common.php includes the following conditional which causes the cron.php task to fail in our shared code implementation, since this causes it to attempt to resolve the cache directory in /var/www/phpBB-common/cache which doesn't exist. What the logic for doing this, heaven knows, but my work-around is to reset $phpbb_root_path back after including this in the cron.php routine.

if (defined('IN_CRON'))
{
    $phpbb_root_path = dirname(__FILE__) . DIRECTORY_SEPARATOR;
}

The way the cron hook is executed is that the footer template includes the hook:

 <!-- IF not S_IS_BOT -->{RUN_CRON_TASK}<!-- ENDIF -->

The page_footer setup function has an optional parameter $run_cron which defaults to true, and in fact is always called page_footer(), so this cron path is executed on every page generation. The code is (I've compressed its layout to save space):

 $cron_type = ;
 if ( time() - $config['queue_interval'] > $config['last_queue_run'] && 
      !defined('IN_ADMIN') && 
      file_exists($phpbb_root_path . 'cache/queue.' . $phpEx))             { // Process email queue
     $cron_type = 'queue';
 } else if (method_exists($cache, 'tidy') && 
            time() - $config['cache_gc'] > $config['cache_last_gc'])       { // Tidy the cache
     $cron_type = 'tidy_cache';
 } else if (time() - $config['warnings_gc'] > $config['warnings_last_gc']) {
     $cron_type = 'tidy_warnings';
 } else if (time() - $config['database_gc'] > $config['database_last_gc']) { // Tidy the database
     $cron_type = 'tidy_database';
 } else if (time() - $config['search_gc'] > $config['search_last_gc'])     { // Tidy the search
     $cron_type = 'tidy_search';
 } else if (time() - $config['session_gc'] > $config['session_last_gc'])   {
     $cron_type = 'tidy_sessions';
 }
 if ($cron_type) {
     $template->assign_var('RUN_CRON_TASK',
                           '<img src="' . append_sid($phpbb_root_path . 'cron.' . 
                                                     $phpEx,'cron_type=' . $cron_type) . 
                           '" width="1" height="1" alt="cron" />');
 }

What this ladder does is that when one of these thresholds has passed the page includes a image link to a dummy image which is one blank pixel, but in reality this triggers the cleanup function. This trigger occurs at page load but most browsers implement a lazy image load so this doesn't impair the user experience.

I have put in this fix, but also set the email_package_size parameter to zero for now. I will review this for tuning and optimisation later, but for now this works.