Drupal 7 - example with static and regular cache

cache.php

<?php

function my_module_function() {
  $my_data = &drupal_static(__FUNCTION__);
  
  if (!empty($my_data)) {
    return $my_data;
  }
  
  if ($cache = cache_get('my_module_data')) {
    $my_data = $cache->data;
    return $my_data;
  }
  
  // Do your expensive calculations here and populate $my_data
  $my_data = expensive_calculations();
  
  // Store the result of calculation in cache.
  $cache_expiration = date('U', strtotime('1 hour'));
  cache_set('my_module_data', $my_data, 'cache', $cache_expiration);

  return $my_data;
}