Merge pull request #14876 from eileenmcnaughton/is_front

[civicrm-core.git] / CRM / Utils / Cache.php

diff --git a/CRM/Utils/Cache.php b/CRM/Utils/Cache.php
index 3306f821a73508dfc85f6ed88d3826f75402785f..26bdc6c3b7dd76e68fea0cf846868309ea66f36a 100644 (file)
--- a/CRM/Utils/Cache.php
+++ b/CRM/Utils/Cache.php
@@ -89,18 +89,18 @@ class CRM_Utils_Cache {
     switch ($cachePlugin) {
       case 'ArrayCache':
       case 'NoCache':
-        $defaults = array();
+        $defaults = [];
         break;
 
       case 'Redis':
       case 'Memcache':
       case 'Memcached':
-        $defaults = array(
+        $defaults = [
           'host' => 'localhost',
           'port' => 11211,
           'timeout' => 3600,
           'prefix' => '',
-        );
+        ];
 
         // Use old constants if needed to ensure backward compatibility
         if (defined('CIVICRM_MEMCACHE_HOST')) {
@@ -139,7 +139,7 @@ class CRM_Utils_Cache {
         break;
 
       case 'APCcache':
-        $defaults = array();
+        $defaults = [];
         if (defined('CIVICRM_DB_CACHE_TIMEOUT')) {
           $defaults['timeout'] = CIVICRM_DB_CACHE_TIMEOUT;
         }
@@ -165,11 +165,21 @@ class CRM_Utils_Cache {
    *     should function correctly, but it can be harder to inspect/debug.
    *   - type: array|string, list of acceptable cache types, in order of preference.
    *   - prefetch: bool, whether to prefetch all data in cache (if possible).
+   *   - withArray: bool|null|'fast', whether to setup a thread-local array-cache in front of the cache driver.
+   *     Note that cache-values may be passed to the underlying driver with extra metadata,
+   *     so this will slightly change/enlarge the on-disk format.
+   *     Support varies by driver:
+   *       - For most memory backed caches, this option is meaningful.
+   *       - For SqlGroup, this option is ignored. SqlGroup has equivalent behavior built-in.
+   *       - For ArrayCache, this option is ignored. It's redundant.
+   *      If this is a short-lived process in which TTL's don't matter, you might
+   *      use 'fast' mode. It sacrifices some PSR-16 compliance and cache-coherency
+   *      protections to improve performance.
    * @return CRM_Utils_Cache_Interface
    * @throws CRM_Core_Exception
    * @see Civi::cache()
    */
-  public static function create($params = array()) {
+  public static function create($params = []) {
     $types = (array) $params['type'];
 
     if (!empty($params['name'])) {
@@ -179,26 +189,30 @@ class CRM_Utils_Cache {
     foreach ($types as $type) {
       switch ($type) {
         case '*memory*':
-          if (defined('CIVICRM_DB_CACHE_CLASS') && in_array(CIVICRM_DB_CACHE_CLASS, array('Memcache', 'Memcached', 'Redis'))) {
+          if (defined('CIVICRM_DB_CACHE_CLASS') && in_array(CIVICRM_DB_CACHE_CLASS, ['Memcache', 'Memcached', 'Redis'])) {
             $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;
 
         case 'SqlGroup':
           if (defined('CIVICRM_DSN') && CIVICRM_DSN) {
-            return new CRM_Utils_Cache_SqlGroup(array(
+            return new CRM_Utils_Cache_SqlGroup([
               'group' => $params['name'],
               'prefetch' => CRM_Utils_Array::value('prefetch', $params, FALSE),
-            ));
+            ]);
           }
           break;
 
         case 'Arraycache':
         case 'ArrayCache':
-          return new CRM_Utils_Cache_ArrayCache(array());
+          return new CRM_Utils_Cache_ArrayCache([]);
 
       }
     }
@@ -237,7 +251,8 @@ class CRM_Utils_Cache {
    *   Ex: 'ArrayCache', 'Memcache', 'Redis'.
    */
   public static function getCacheDriver() {
-    $className = 'ArrayCache';   // default to ArrayCache for now
+    // default to ArrayCache for now
+    $className = 'ArrayCache';
 
     // Maintain backward compatibility for now.
     // Setting CIVICRM_USE_MEMCACHE or CIVICRM_USE_ARRAYCACHE will
@@ -258,4 +273,33 @@ class CRM_Utils_Cache {
     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']++;
+  }
+
 }