Category Archives: Elgg

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This week saw the election of a new president of America – triggering a massive spike in hope levels worldwide. At last the Bush years are drawing to a close.

On the Elgg front, I spent a good portion of the week optimising various parts of the system and drastically reducing the number of queries per page.

A lot of this was done by introducing a query cache into database.php which caches the results of individual queries. I also introduced some new delayed execution functionality on database queries – letting you delay some database operations until after the page has been sent to the browser.

All of these tweaks have slashed the number of queries being executed per page.

This week I also began to experiment with memcache – currently caching entities, datalists, metastrings and meta data. Reducing the number of queries per page to ~7 once the cache has been populated.

I also did a little bit of work on the activity stream, river and syndication… but more on this later…

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Sometimes things need to be done without user interaction – for example, database optimisation or log rotation.

For this, Elgg has a cron endpoint.

Cron is a unix tool which executes commands at a specific time of day (other operating systems have similar tools). This keys off a file called a crontab – an example is given file is included and called crontab.example.

The crontab calls simplified yet powerful cron endpoint – http://yoursite/pg/cron/PERIOD, where PERIOD is one of the following:

  • reboot – Execute on system reboot
  • minute – Execute every minute
  • fiveminute – Execute every five minutes
  • fifteenmin – Execute every fifteen minutes
  • halfhour – Execute every half hour
  • hourly – Execute once every hour
  • daily – Execute every day
  • weekly – Execute weekly
  • monthly – Execute once a month
  • yearly – Execute every year

When these endpoints are triggered by your crontab a plugin hook is triggered. To make use of this, register a plugin hook as follows:

register_plugin_hook('cron', PERIOD, 'my_cron_handler');

Where PERIOD is one of the key words listed above. Here is some sample code using Cron – in this case it is taken from the system log rotation module I added to SVN today.

<?php
/**
* Elgg log rotator.
*
* @package ElggLogRotate
* @license http://www.gnu.org/licenses/old-licenses/gpl-2.0.html GNU Public License version 2
* @author Curverider Ltd
* @copyright Curverider Ltd 2008
* @link http://elgg.com/
*/

/**
* Initialise the plugin.
*
*/
function logrotate_init()
{
$period = get_plugin_setting('period','logrotate');
switch ($period)
{
case 'weekly':
case 'monthly' :
case 'yearly' :
break;
default: $period = 'monthly';
}

// Register cron hook
register_plugin_hook('cron', $period, 'logrotate_cron');
}

/**
* Trigger the log rotation.
*
*/
function logrotate_cron($hook, $entity_type, $returnvalue, $params)
{
$resulttext = elgg_echo("logrotate:logrotated");
if (!archive_log())
$resulttext = elgg_echo("logrotate:lognotrotated");

return $returnvalue . $resulttext;
}

// Initialise plugin
register_elgg_event_handler('init','system','logrotate_init');
?>