'Cache example',
'description' => 'Example of Drupal Cache API',
'page callback' => 'drupal_get_form',
'page arguments' => array('cache_example_page_form'),
'access callback' => TRUE,
);
return $items;
}
/**
* Main page for cache_example.
*
* Displays a page/form which outlines how Drupal's cache works.
*/
function cache_example_page_form($form, &$form_state) {
// Log execution time.
$start_time = microtime(TRUE);
// Try to load the files count from cache. This function will accept two
// arguments:
// - cache object name (cid)
// - cache bin, the (optional) cache bin (most often a database table) where
// the object is to be saved.
//
// cache_get() returns the cached object or FALSE if object does not exist.
if ($cache = cache_get('cache_example_files_count')) {
/*
* Get cached data. Complex data types will be unserialized automatically.
*/
$files_count = $cache->data;
}
else {
// If there was no cached data available we have to search filesystem.
// Recursively get all files from Drupal's folder.
$files_count = count(file_scan_directory('.', '/.*/'));
// Since we have recalculated, we now need to store the new data into cache.
// Complex data types will be automatically serialized before being saved
// into cache.
// Here we use the default setting and create an unexpiring cache item.
// See below for an example that creates an expiring cache item.
cache_set('cache_example_files_count', $files_count);
}
$end_time = microtime(TRUE);
$duration = $end_time - $start_time;
// Format intro message.
$intro_message = '' . t('This example will search the entire drupal folder and display a count of the files in it.') . ' ';
$intro_message .= t('This can take a while, since there are a lot of files to be searched.') . ' ';
$intro_message .= t('We will search filesystem just once and save output to the cache. We will use cached data for later requests.') . '
';
$intro_message .= '' . t('Reload this page to see cache in action.', array('@url' => request_uri())) . ' ';
$intro_message .= t('You can use the button below to remove cached data.') . '
';
$form['file_search'] = array(
'#type' => 'fieldset',
'#title' => t('File search caching'),
);
$form['file_search']['introduction'] = array(
'#markup' => $intro_message,
);
$color = empty($cache) ? 'red' : 'green';
$retrieval = empty($cache) ? t('calculated by traversing the filesystem') : t('retrieved from cache');
$form['file_search']['statistics'] = array(
'#type' => 'item',
'#markup' => t('%count files exist in this Drupal installation; @retrieval in @time ms.
(Source: @source)',
array(
'%count' => $files_count,
'@retrieval' => $retrieval,
'@time' => number_format($duration * 1000, 2),
'@color' => $color,
'@source' => empty($cache) ? t('actual file search') : t('cached'),
)
),
);
$form['file_search']['remove_file_count'] = array(
'#type' => 'submit',
'#submit' => array('cache_example_form_expire_files'),
'#value' => t('Explicitly remove cached file count'),
);
$form['expiration_demo'] = array(
'#type' => 'fieldset',
'#title' => t('Cache expiration settings'),
);
$form['expiration_demo']['explanation'] = array(
'#markup' => t('A cache item can be set as CACHE_PERMANENT, meaning that it will only be removed when explicitly cleared, or it can have an expiration time (a Unix timestamp).'),
);
$expiring_item = cache_get('cache_example_expiring_item');
$item_status = $expiring_item ?
t('Cache item exists and is set to expire at %time', array('%time' => $expiring_item->data)) :
t('Cache item does not exist');
$form['expiration_demo']['current_status'] = array(
'#type' => 'item',
'#title' => t('Current status of cache item "cache_example_expiring_item"'),
'#markup' => $item_status,
);
$form['expiration_demo']['expiration'] = array(
'#type' => 'select',
'#title' => t('Time before cache expiration'),
'#options' => array(
'never_remove' => t('CACHE_PERMANENT'),
-10 => t('Immediate expiration'),
10 => t('10 seconds from form submission'),
60 => t('1 minute from form submission'),
300 => t('5 minutes from form submission'),
),
'#default_value' => -10,
'#description' => t('Any cache item can be set to only expire when explicitly cleared, or to expire at a given time.'),
);
$form['expiration_demo']['create_cache_item'] = array(
'#type' => 'submit',
'#value' => t('Create a cache item with this expiration'),
'#submit' => array('cache_example_form_create_expiring_item'),
);
$form['cache_clearing'] = array(
'#type' => 'fieldset',
'#title' => t('Expire and remove options'),
'#description' => t("We have APIs to expire cached items and also to just remove them. Unfortunately, they're all the same API, cache_clear_all"),
);
$form['cache_clearing']['cache_clear_type'] = array(
'#type' => 'radios',
'#title' => t('Type of cache clearing to do'),
'#options' => array(
'expire' => t('Remove items from the "cache" bin that have expired'),
'remove_all' => t('Remove all items from the "cache" bin regardless of expiration (super-wildcard)'),
'remove_wildcard' => t('Remove all items from the "cache" bin that match the pattern "cache_example"'),
),
'#default_value' => 'expire',
);
// Submit button to clear cached data.
$form['cache_clearing']['clear_expired'] = array(
'#type' => 'submit',
'#value' => t('Clear or expire cache'),
'#submit' => array('cache_example_form_cache_clearing'),
'#access' => user_access('administer site configuration'),
);
return $form;
}
/**
* Submit handler that explicitly clears cache_example_files_count from cache.
*/
function cache_example_form_expire_files($form, &$form_state) {
// Clear cached data. This function will delete cached object from cache bin.
//
// The first argument is cache id to be deleted. Since we've provided it
// explicitly, it will be removed whether or not it has an associated
// expiration time. The second argument (required here) is the cache bin.
// Using cache_clear_all() explicitly in this way
// forces removal of the cached item.
cache_clear_all('cache_example_files_count', 'cache');
// Display message to the user.
drupal_set_message(t('Cached data key "cache_example_files_count" was cleared.'), 'status');
}
/**
* Submit handler to create a new cache item with specified expiration.
*/
function cache_example_form_create_expiring_item($form, &$form_state) {
$interval = $form_state['values']['expiration'];
if ($interval == 'never_remove') {
$expiration = CACHE_PERMANENT;
$expiration_friendly = t('Never expires');
}
else {
$expiration = time() + $interval;
$expiration_friendly = format_date($expiration);
}
// Set the expiration to the actual Unix timestamp of the end of the required
// interval.
cache_set('cache_example_expiring_item', $expiration_friendly, 'cache', $expiration);
drupal_set_message(t('cache_example_expiring_item was set to expire at %time', array('%time' => $expiration_friendly)));
}
/**
* Submit handler to demonstrate the various uses of cache_clear_all().
*/
function cache_example_form_cache_clearing($form, &$form_state) {
switch ($form_state['values']['cache_clear_type']) {
case 'expire':
// Here we'll remove all cache keys in the 'cache' bin that have expired.
cache_clear_all(NULL, 'cache');
drupal_set_message(t('cache_clear_all(NULL, "cache") was called, removing any expired cache items.'));
break;
case 'remove_all':
// This removes all keys in a bin using a super-wildcard. This
// has nothing to do with expiration. It's just brute-force removal.
cache_clear_all('*', 'cache', TRUE);
drupal_set_message(t('ALL entries in the "cache" bin were removed with cache_clear_all("*", "cache", TRUE).'));
break;
case 'remove_wildcard':
// We can also explicitly remove all cache items whose cid begins with
// 'cache_example' by using a wildcard. This again is brute-force
// removal, not expiration.
cache_clear_all('cache_example', 'cache', TRUE);
drupal_set_message(t('Cache entries whose cid began with "cache_example" in the "cache" bin were removed with cache_clear_all("cache_example", "cache", TRUE).'));
break;
}
}
/**
* @} End of "defgroup cache_example".
*/