db-slaves-05.php

<?php

// Ignore slave database briefly.
variable_set('maximum_replication_lag', 300);
db_ignore_slave();

// Remove all links from the links array already in the database and only
// add missing links to database.
$missing_links = _linkchecker_bean_links_missing($bean->bid, $links);

// Only add unique links to database that do not exist.
$i = 0;
foreach ($missing_links as $url) {
  $urlhash = drupal_hash_base64($url);
  $link = db_query('SELECT lid FROM {linkchecker_link} WHERE urlhash = :urlhash', 
    array(':urlhash' => $urlhash))->fetchObject();
  if (!$link) {
    $link = new stdClass();
    $link->urlhash = $urlhash;
    $link->url = $url;
    $link->status = _linkchecker_link_check_status_filter($url);
    drupal_write_record('linkchecker_link', $link);
  }

  $txn = db_transaction();
  try {
    db_insert('linkchecker_bean')
      ->fields(array(
        'bid' => $bean->bid,
        'lid' => $link->lid,
      ))
      ->execute();
  }
  catch (Exception $e) {
    $txn->rollback();
    watchdog_exception('linkchecker_bean', $e);
  }

  // Go back to using the slave database.
  // db_ignore_slave() sets this session variable that another function uses to see if the slave should be ignored.
  unset($_SESSION['ignore_slave_server']);
  
  // ...