Loads the persistent variable table.
The variable table is composed of values that have been saved in the table with variable_set() as well as those explicitly specified in the configuration file.
function variable_initialize($conf = array()) {
// NOTE: caching the variables improves performance by 20% when serving
// cached pages.
if ($cached = cache('bootstrap')
->get('variables')) {
$variables = $cached->data;
}
else {
// Cache miss. Avoid a stampede.
$name = 'variable_init';
$lock = Drupal::lock();
if (!$lock
->acquire($name, 1)) {
// Another request is building the variable cache.
// Wait, then re-run this function.
$lock
->wait($name);
return variable_initialize($conf);
}
else {
// Proceed with variable rebuild.
$variables = array_map('unserialize', db_query('SELECT name, value FROM {variable}')
->fetchAllKeyed());
cache('bootstrap')
->set('variables', $variables);
$lock
->release($name);
}
}
foreach ($conf as $name => $value) {
$variables[$name] = $value;
}
return $variables;
}