/**
* Interface for caching
*
- * An abstract interface for caching.
+ * An abstract interface for caching. Because we originally used the
+ * Memcache plugin directly, the interface uses a small subset of the
+ * Memcache interface.
*
+ * @category Cache
+ * @package StatusNet
+ * @author Evan Prodromou <evan@status.net>
+ * @copyright 2009 StatusNet, Inc.
+ * @license http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPL 3.0
+ * @link http://status.net/
*/
-
class Cache
{
- var $_items = array();
+ var $_items = array();
static $_inst = null;
+ const COMPRESSED = 1;
+
+ /**
+ * Singleton constructor
+ *
+ * Use this to get the singleton instance of Cache.
+ *
+ * @return Cache cache object
+ */
static function instance()
{
if (is_null(self::$_inst)) {
return self::$_inst;
}
+ /**
+ * Create a cache key from input text
+ *
+ * Builds a cache key from input text. Helps to namespace
+ * the cache area (if shared with other applications or sites)
+ * and prevent conflicts.
+ *
+ * @param string $extra the real part of the key
+ *
+ * @return string full key
+ */
static function key($extra)
{
- $base_key = common_config('memcached', 'base');
+ $base_key = common_config('cache', 'base');
if (empty($base_key)) {
$base_key = common_keyize(common_config('site', 'name'));
return 'statusnet:' . $base_key . ':' . $extra;
}
+ /**
+ * Create a cache key for data dependent on code
+ *
+ * For cache elements that are dependent on changes in code, this creates
+ * a more-or-less fingerprint of the current running code and adds it to
+ * the cache key. In the case of an upgrade of core, or addition or
+ * removal of plugins, a new unique fingerprint is generated and used.
+ *
+ * There can still be problems with a) differences in versions of the
+ * plugins and b) people running code between official versions. This is
+ * usually a problem only for experienced users like developers, who know
+ * how to clear their cache.
+ *
+ * For sites that run code between versions (like the status.net cloud),
+ * there's an additional build number configuration setting.
+ *
+ * @param string $extra the real part of the key
+ *
+ * @return string full key
+ */
+
+ static function codeKey($extra)
+ {
+ static $prefix = null;
+
+ if (empty($prefix)) {
+
+ $plugins = StatusNet::getActivePlugins();
+ $names = array();
+
+ foreach ($plugins as $plugin) {
+ $names[] = $plugin[0];
+ }
+
+ $names = array_unique($names);
+ asort($names);
+
+ // Unique enough.
+
+ $uniq = crc32(implode(',', $names));
+
+ $build = common_config('site', 'build');
+
+ $prefix = STATUSNET_VERSION.':'.$build.':'.$uniq;
+ }
+
+ return Cache::key($prefix.':'.$extra);
+ }
+
+ /**
+ * Make a string suitable for use as a key
+ *
+ * Useful for turning primary keys of tables into cache keys.
+ *
+ * @param string $str string to turn into a key
+ *
+ * @return string keyized string
+ */
static function keyize($str)
{
$str = strtolower($str);
return $str;
}
+ /**
+ * Get a value associated with a key
+ *
+ * The value should have been set previously.
+ *
+ * @param string $key Lookup key
+ *
+ * @return string retrieved value or null if unfound
+ */
function get($key)
{
- $value = null;
-
- if (!Event::handle('StartCacheGet', array(&$key, &$value))) {
- if (array_key_exists($_items, $key)) {
- common_log(LOG_INFO, 'Cache HIT for key ' . $key);
- $value = $_items[$key];
- } else {
- common_log(LOG_INFO, 'Cache MISS for key ' . $key);
+ $value = false;
+
+ common_perf_counter('Cache::get', $key);
+ if (Event::handle('StartCacheGet', array(&$key, &$value))) {
+ if (array_key_exists($key, $this->_items)) {
+ $value = unserialize($this->_items[$key]);
}
Event::handle('EndCacheGet', array($key, &$value));
}
return $value;
}
+ /**
+ * Set the value associated with a key
+ *
+ * @param string $key The key to use for lookups
+ * @param string $value The value to store
+ * @param integer $flag Flags to use, may include Cache::COMPRESSED
+ * @param integer $expiry Expiry value, mostly ignored
+ *
+ * @return boolean success flag
+ */
function set($key, $value, $flag=null, $expiry=null)
{
$success = false;
- if (!Event::handle('StartCacheSet', array(&$key, &$value, &$flag, &$expiry, &$success))) {
- common_log(LOG_INFO, 'Setting cache value for key ' . $key);
- $_items[$key] = $value;
+ common_perf_counter('Cache::set', $key);
+ if (Event::handle('StartCacheSet', array(&$key, &$value, &$flag,
+ &$expiry, &$success))) {
+
+ $this->_items[$key] = serialize($value);
+
$success = true;
- Event::handle('EndCacheSet', array($key, $value, $flag, $expiry));
+
+ Event::handle('EndCacheSet', array($key, $value, $flag,
+ $expiry));
}
return $success;
}
+ /**
+ * Atomically increment an existing numeric value.
+ * Existing expiration time should remain unchanged, if any.
+ *
+ * @param string $key The key to use for lookups
+ * @param int $step Amount to increment (default 1)
+ *
+ * @return mixed incremented value, or false if not set.
+ */
+ function increment($key, $step=1)
+ {
+ $value = false;
+ common_perf_counter('Cache::increment', $key);
+ if (Event::handle('StartCacheIncrement', array(&$key, &$step, &$value))) {
+ // Fallback is not guaranteed to be atomic,
+ // and may original expiry value.
+ $value = $this->get($key);
+ if ($value !== false) {
+ $value += $step;
+ $ok = $this->set($key, $value);
+ $got = $this->get($key);
+ }
+ Event::handle('EndCacheIncrement', array($key, $step, $value));
+ }
+ return $value;
+ }
+
+ /**
+ * Delete the value associated with a key
+ *
+ * @param string $key Key to delete
+ *
+ * @return boolean success flag
+ */
function delete($key)
{
$success = false;
- if (!Event::handle('StartCacheDelete', array(&$key, &$success))) {
- common_log(LOG_INFO, 'Deleting cache value for key ' . $key);
- unset($_items[$key]);
+ common_perf_counter('Cache::delete', $key);
+ if (Event::handle('StartCacheDelete', array(&$key, &$success))) {
+ if (array_key_exists($key, $this->_items)) {
+ unset($this->_items[$key]);
+ }
$success = true;
Event::handle('EndCacheDelete', array($key));
}
return $success;
}
+
+ /**
+ * Close or reconnect any remote connections, such as to give
+ * daemon processes a chance to reconnect on a fresh socket.
+ *
+ * @return boolean success flag
+ */
+ function reconnect()
+ {
+ $success = false;
+
+ if (Event::handle('StartCacheReconnect', array(&$success))) {
+ $success = true;
+ Event::handle('EndCacheReconnect', array());
+ }
+
+ return $success;
+ }
}
projects / quix0rs-gnu-social.git / blobdiff