function radioactivity_cron in Radioactivity 5

Same name and namespace in other branches

1. 8.3 radioactivity.module \radioactivity_cron()
2. 8.2 radioactivity.module \radioactivity_cron()
3. 6 radioactivity.module \radioactivity_cron()
4. 7.2 radioactivity.module \radioactivity_cron()
5. 7 radioactivity.module \radioactivity_cron()
6. 4.0.x radioactivity.module \radioactivity_cron()

File

./radioactivity.module, line 455

Code

function radioactivity_cron() {
  if (radioactivity_get_memcached_enable()) {
    radioactivity_process_memcached_entries();
  }
  $timestamp = time();

  // last cron
  $last_cron_timestamp = (int) variable_get('radioactivity_last_cron_timestamp', 0);
  $granularity = (int) _radioactivity_get_decay_granularity();
  $threshold_timestamp = $last_cron_timestamp - $last_cron_timestamp % $granularity + $granularity;
  if ($timestamp < $threshold_timestamp) {
    return;
  }

  // don't update yet
  foreach (_radioactivity_get_decay_profiles() as $dpid => $decay_profile) {
    $half_life = (double) $decay_profile["half_life"];
    $cut_off_energy = (double) $decay_profile["cut_off_energy"];

    // the formula is:
    // E=E_0 * 2^(- delta_time / half_life)
    db_query("UPDATE {radioactivity} SET energy=energy * pow(2, (last_emission_timestamp-%d)*1.0/%f), last_emission_timestamp=%d " . "WHERE decay_profile=%d AND last_emission_timestamp<%d", $timestamp, $half_life, $timestamp, $dpid, $timestamp);

    // delete clean (l. non-radioactive) nodes
    db_query("DELETE FROM {radioactivity} WHERE decay_profile=%d AND energy < %f", $dpid, $cut_off_energy);
  }
  variable_set('radioactivity_last_cron_timestamp', $timestamp);
}