* should function correctly, but it can be harder to inspect/debug.
* - type: array|string, list of acceptable cache types, in order of preference.
* - prefetch: bool, whether to prefetch all data in cache (if possible).
+ * - withArray: bool|null|'fast', whether to setup a thread-local array-cache in front of the cache driver.
+ * Note that cache-values may be passed to the underlying driver with extra metadata,
+ * so this will slightly change/enlarge the on-disk format.
+ * Support varies by driver:
+ * - For most memory backed caches, this option is meaningful.
+ * - For SqlGroup, this option is ignored. SqlGroup has equivalent behavior built-in.
+ * - For Arraycache, this option is ignored. It's redundant.
+ * If this is a short-lived process in which TTL's don't matter, you might
+ * use 'fast' mode. It sacrifices some PSR-16 compliance and cache-coherency
+ * protections to improve performance.
* @return CRM_Utils_Cache_Interface
* @throws CRM_Core_Exception
* @see Civi::cache()
$dbCacheClass = 'CRM_Utils_Cache_' . CIVICRM_DB_CACHE_CLASS;
$settings = self::getCacheSettings(CIVICRM_DB_CACHE_CLASS);
$settings['prefix'] = CRM_Utils_Array::value('prefix', $settings, '') . self::DELIMITER . $params['name'] . self::DELIMITER;
- return new $dbCacheClass($settings);
+ $cache = new $dbCacheClass($settings);
+ if (!empty($params['withArray'])) {
+ $cache = $params['withArray'] === 'fast' ? new CRM_Utils_Cache_FastArrayDecorator($cache) : new CRM_Utils_Cache_ArrayDecorator($cache);
+ }
+ return $cache;
}
break;
return $className;
}
+ /**
+ * Generate a unique negative-acknowledgement token (NACK).
+ *
+ * When using PSR-16 to read a value, the `$cahce->get()` will a return a default
+ * value on cache-miss, so it's hard to know if you've gotten a geniune value
+ * from the cache or just a default. If you're in an edge-case where it matters
+ * (and you want to do has()+get() in a single roundtrip), use the nack() as
+ * the default:
+ *
+ * $nack = CRM_Utils_Cache::nack();
+ * $value = $cache->get('foo', $nack);
+ * echo ($value === $nack) ? "Cache has a value, and we got it" : "Cache has no value".
+ *
+ * The value should be unique to avoid accidental matches.
+ *
+ * @return string
+ * Unique nonce value indicating a "negative acknowledgement" (failed read).
+ * If we need to accurately perform has($key)+get($key), we can
+ * use `get($key,$nack)`.
+ */
+ public static function nack() {
+ $st =& Civi::$statics[__CLASS__];
+ if (!isset($st['nack-c'])) {
+ $st['nack-c'] = md5(CRM_Utils_Request::id() . CIVICRM_SITE_KEY . CIVICRM_DSN . mt_rand(0, 10000));
+ $st['nack-i'] = 0;
+ }
+ return 'NACK:' . $st['nack-c'] . $st['nack-i']++;
+ }
+
}