system/handlers/cronhandler.php

<?php
namespace Habari;

class CronHandler extends ActionHandler
{
  static function run_cron( $async = false )
  {
    // check if it's time to run crons, and if crons are already running.
    $next_cron = DateTime::create( Options::get( 'next_cron' ) );
    $time = DateTime::create();
    if ( ( $next_cron->int > $time->int )
      || ( Options::get( 'cron_running' ) && Options::get( 'cron_running' ) > microtime( true ) )
    ) {
      return;
    }

    // cron_running will timeout in 10 minutes
    // round cron_running to 4 decimals
    $run_time = microtime( true ) + 600;
    $run_time = sprintf( "%.4f", $run_time );
    Options::set( 'cron_running', $run_time );

    if ( $async ) {
      // Timeout is really low so that it doesn't wait for the request to finish
      $cronurl = URL::get( 'cron',
        array(
          'time' => $run_time,
          'asyncronous' => Utils::crypt( Options::get( 'public-GUID' ) )
        )
      );
      $request = new RemoteRequest( $cronurl, 'GET', 1 );

      try {
        $request->execute();
      }
      catch ( RemoteRequest_Timeout $e ) {
        // the request timed out - we knew that would happen
      }
      catch ( \Exception $e ) {
        // some other error occurred. we still don't care
      }
    }
    else {
      // @todo why do we usleep() and why don't we just call act_poll_cron()?
      usleep( 5000 );
      if ( Options::get( 'cron_running' ) != $run_time ) {
        return;
      }

      $time = DateTime::create();
      $crons = DB::get_results(
        'SELECT * FROM {crontab} WHERE start_time <= ? AND next_run <= ? AND active != ?',
        array( $time->sql, $time->sql, 0 ),
        'CronJob'
      );
      if ( $crons ) {
        foreach ( $crons as $cron ) {
          $cron->execute();
        }
      }

      EventLog::log( _t( 'CronTab run completed.' ), 'debug', 'crontab', 'habari', $crons );

      // set the next run time to the lowest next_run OR a max of one day.
      $next_cron = DB::get_value( 'SELECT next_run FROM {crontab} WHERE active != ? ORDER BY next_run ASC LIMIT 1', array( 0 ) );
      Options::set( 'next_cron', min( intval( $next_cron ), $time->modify( '+1 day' )->int ) );
      Options::set( 'cron_running', false );
    }
  }

  function act_poll_cron()
  {
    Utils::check_request_method( array( 'GET', 'HEAD', 'POST' ) );

    $time = doubleval( $this->handler_vars['time'] );
    if ( $time != Options::get( 'cron_running' ) ) {
      return;
    }

    // allow script to run for 10 minutes. This only works on host with safe mode DISABLED
    if ( !ini_get( 'safe_mode' ) ) {
      set_time_limit( 600 );
    }
    $time = DateTime::create();
    $crons = DB::get_results(
      'SELECT * FROM {crontab} WHERE start_time <= ? AND next_run <= ? AND active != ?',
      array( $time->sql, $time->sql, 0 ),
      'CronJob'
    );

    if ( $crons ) {
      foreach ( $crons as $cron ) {
        $cron->execute();
      }
    }

    // set the next run time to the lowest next_run OR a max of one day.
    $next_cron = DB::get_value( 'SELECT next_run FROM {crontab} WHERE active != ? ORDER BY next_run ASC LIMIT 1', array( 0 ) );
    Options::set( 'next_cron', min( intval( $next_cron ), $time->modify( '+1 day' )->int ) );
    Options::set( 'cron_running', false );
  }

}

?>