Issue #1774332 by c960657: Better handling of invalid/expired cache entries.

core/includes/cache.inc

@@ -44,19 +44,38 @@ function cache($bin = 'cache') {
 }
 
 /**
- * Invalidates the items associated with given list of tags.
+ * Deletes items from all bins with any of the specified tags.
+ *
+ * Many sites have more than one active cache backend, and each backend may use
+ * a different strategy for storing tags against cache items, and deleting cache
+ * items associated with a given tag.
+ *
+ * When deleting a given list of tags, we iterate over each cache backend, and
+ * and call deleteTags() on each.
+ *
+ * @param array $tags
+ *   The list of tags to delete cache items for.
+ */
+function cache_delete_tags(array $tags) {
+  foreach (CacheFactory::getBackends() as $bin => $class) {
+    cache($bin)->deleteTags($tags);
+  }
+}
+
+/**
+ * Marks cache items from all bins with any of the specified tags as invalid.
  *
  * Many sites have more than one active cache backend, and each backend my use
  * a different strategy for storing tags against cache items, and invalidating
  * cache items associated with a given tag.
  *
  * When invalidating a given list of tags, we iterate over each cache backend,
- * and call invalidate on each.
+ * and call invalidateTags() on each.
  *
  * @param array $tags
  *   The list of tags to invalidate cache items for.
  */
-function cache_invalidate(array $tags) {
+function cache_invalidate_tags(array $tags) {
   foreach (CacheFactory::getBackends() as $bin => $class) {
     cache($bin)->invalidateTags($tags);
   }

core/includes/common.inc

@@ -6623,7 +6623,7 @@ function drupal_flush_all_caches() {
   // This is executed based on old/previously known information, which is
   // sufficient, since new extensions cannot have any primed caches yet.
   foreach (module_invoke_all('cache_flush') as $bin) {
-    cache($bin)->flush();
+    cache($bin)->deleteAll();
   }
 
   // Flush asset file caches.

core/includes/entity.inc

@@ -50,7 +50,7 @@ function entity_get_info($entity_type = NULL) {
 function entity_info_cache_clear() {
   drupal_static_reset('entity_get_info');
   // Clear all languages.
-  cache()->invalidateTags(array('entity_info' => TRUE));
+  cache()->deleteTags(array('entity_info' => TRUE));
 }
 
 /**

core/includes/menu.inc

@@ -2617,7 +2617,7 @@ function menu_link_load($mlid) {
  * Clears the cached cached data for a single named menu.
  */
 function menu_cache_clear($menu_name = 'tools') {
-  cache('menu')->invalidateTags(array('menu' => $menu_name));
+  cache('menu')->deleteTags(array('menu' => $menu_name));
   // Also clear the menu system static caches.
   menu_reset_static_cache();
 }
@@ -2629,7 +2629,7 @@ function menu_cache_clear($menu_name = 'tools') {
  * might have been made to the router items or menu links.
  */
 function menu_cache_clear_all() {
-  cache('menu')->flush();
+  cache('menu')->deleteAll();
   menu_reset_static_cache();
 }
 
@@ -3258,13 +3258,13 @@ function _menu_clear_page_cache() {
   // Clear the page and block caches, but at most twice, including at
   //  the end of the page load when there are multiple links saved or deleted.
   if ($cache_cleared == 0) {
-    cache_invalidate(array('content' => TRUE));
+    cache_invalidate_tags(array('content' => TRUE));
     // Keep track of which menus have expanded items.
     _menu_set_expanded_menus();
     $cache_cleared = 1;
   }
   elseif ($cache_cleared == 1) {
-    drupal_register_shutdown_function('cache_invalidate', array('content', TRUE));
+    drupal_register_shutdown_function('cache_invalidate_tags', array('content', TRUE));
     // Keep track of which menus have expanded items.
     drupal_register_shutdown_function('_menu_set_expanded_menus');
     $cache_cleared = 2;

core/includes/schema.inc

@@ -103,7 +103,7 @@ function drupal_get_complete_schema($rebuild = FALSE) {
       drupal_alter('schema', $schema);
 
       if ($rebuild) {
-        cache()->invalidateTags(array('schema' => TRUE));
+        cache()->deleteTags(array('schema' => TRUE));
       }
       // If the schema is empty, avoid saving it: some database engines require
       // the schema to perform queries, and this could lead to infinite loops.

core/includes/update.inc

@@ -228,7 +228,7 @@ function update_prepare_d8_bootstrap() {
 
       // Make sure that the bootstrap cache is cleared as that might contain
       // incompatible data structures.
-      cache('bootstrap')->flush();
+      cache('bootstrap')->deleteAll();
 
       // Retrieve all installed extensions from the {system} table.
       // Uninstalled extensions are ignored and not converted.

core/lib/Drupal/Core/Cache/BackendChain.php

@@ -30,6 +30,15 @@ class BackendChain implements CacheBackendInterface {
    */
   protected $backends = array();
 
+  /**
+   * Constructs a DatabaseBackend object.
+   *
+   * @param string $bin
+   *   The cache bin for which the object is created.
+   */
+  public function __construct($bin) {
+  }
+
   /**
    * Appends a cache backend to the cache chain.
    *
@@ -60,18 +69,12 @@ public function prependBackend(CacheBackendInterface $backend) {
     return $this;
   }
 
-  /**
-   * Implements Drupal\Core\Cache\CacheBackendInterface::__construct().
-   */
-  public function __construct($bin) {
-  }
-
   /**
    * Implements Drupal\Core\Cache\CacheBackendInterface::get().
    */
-  public function get($cid) {
+  public function get($cid, $allow_invalid = FALSE) {
     foreach ($this->backends as $index => $backend) {
-      if (($return = $backend->get($cid)) !== FALSE) {
+      if (($return = $backend->get($cid, $allow_invalid)) !== FALSE) {
         // We found a result, propagate it to all missed backends.
         if ($index > 0) {
           for ($i = ($index - 1); 0 <= $i; --$i) {
@@ -89,11 +92,11 @@ public function get($cid) {
   /**
    * Implements Drupal\Core\Cache\CacheBackendInterface::getMultiple().
    */
-  function getMultiple(&$cids) {
+  public function getMultiple(&$cids, $allow_invalid = FALSE) {
     $return = array();
 
     foreach ($this->backends as $index => $backend) {
-      $items = $backend->getMultiple($cids);
+      $items = $backend->getMultiple($cids, $allow_invalid);
 
       // Propagate the values that could be retrieved from the current cache
       // backend to all missed backends.
@@ -120,7 +123,7 @@ function getMultiple(&$cids) {
   /**
    * Implements Drupal\Core\Cache\CacheBackendInterface::set().
    */
-  function set($cid, $data, $expire = CacheBackendInterface::CACHE_PERMANENT, array $tags = array()) {
+  public function set($cid, $data, $expire = CacheBackendInterface::CACHE_PERMANENT, array $tags = array()) {
     foreach ($this->backends as $backend) {
       $backend->set($cid, $data, $expire, $tags);
     }
@@ -129,7 +132,7 @@ function set($cid, $data, $expire = CacheBackendInterface::CACHE_PERMANENT, arra
   /**
    * Implements Drupal\Core\Cache\CacheBackendInterface::delete().
    */
-  function delete($cid) {
+  public function delete($cid) {
     foreach ($this->backends as $backend) {
       $backend->delete($cid);
     }
@@ -138,27 +141,54 @@ function delete($cid) {
   /**
    * Implements Drupal\Core\Cache\CacheBackendInterface::deleteMultiple().
    */
-  function deleteMultiple(array $cids) {
+  public function deleteMultiple(array $cids) {
     foreach ($this->backends as $backend) {
       $backend->deleteMultiple($cids);
     }
   }
 
   /**
-   * Implements Drupal\Core\Cache\CacheBackendInterface::flush().
+   * Implements Drupal\Core\Cache\CacheBackendInterface::deleteTags().
    */
-  public function flush() {
+  public function deleteTags(array $tags) {
     foreach ($this->backends as $backend) {
-      $backend->flush();
+      $backend->deleteTags($tags);
+    }
+  }
+
+  /**
+   * Implements Drupal\Core\Cache\CacheBackendInterface::deleteAll().
+   */
+  public function deleteAll() {
+    foreach ($this->backends as $backend) {
+      $backend->deleteAll();
     }
   }
 
   /**
    * Implements Drupal\Core\Cache\CacheBackendInterface::expire().
    */
-  public function expire() {
+  public function deleteExpired() {
     foreach ($this->backends as $backend) {
-      $backend->expire();
+      $backend->deleteExpired();
+    }
+  }
+
+  /**
+   * Implements Drupal\Core\Cache\CacheBackendInterface::invalidate().
+   */
+  public function invalidate($cid) {
+    foreach ($this->backends as $backend) {
+      $backend->invalidate($cid);
+    }
+  }
+
+  /**
+   * Implements Drupal\Core\Cache\CacheBackendInterface::invalidateMultiple().
+   */
+  public function invalidateMultiple(array $cids) {
+    foreach ($this->backends as $backend) {
+      $backend->invalidateMultiple($cids);
     }
   }
 
@@ -171,6 +201,15 @@ public function invalidateTags(array $tags) {
     }
   }
 
+  /**
+   * Implements Drupal\Core\Cache\CacheBackendInterface::invalidateAll().
+   */
+  public function invalidateAll() {
+    foreach ($this->backends as $backend) {
+      $backend->invalidateAll();
+    }
+  }
+
   /**
    * Implements Drupal\Core\Cache\CacheBackendInterface::garbageCollection().
    */

core/lib/Drupal/Core/Cache/InstallBackend.php

@@ -36,14 +36,14 @@ class InstallBackend extends DatabaseBackend {
   /**
    * Overrides Drupal\Core\Cache\DatabaseBackend::get().
    */
-  public function get($cid) {
+  public function get($cid, $allow_invalid = FALSE) {
     return FALSE;
   }
 
   /**
    * Overrides Drupal\Core\Cache\DatabaseBackend::getMultiple().
    */
-  public function getMultiple(&$cids) {
+  public function getMultiple(&$cids, $allow_invalid = FALSE) {
     return array();
   }
 
@@ -77,36 +77,84 @@ public function deleteMultiple(array $cids) {
   }
 
   /**
-   * Overrides Drupal\Core\Cache\DatabaseBackend::invalidateTags().
+   * Overrides Drupal\Core\Cache\DatabaseBackend::deleteAll().
    */
-  public function invalidateTags(array $tags) {
+  public function deleteAll() {
     try {
       if (class_exists('Drupal\Core\Database\Database')) {
-        parent::invalidateTags($tags);
+        parent::deleteAll();
+      }
+    }
+    catch (Exception $e) {}
+  }
+
+  /**
+   * Overrides Drupal\Core\Cache\DatabaseBackend::deleteExpired().
+   */
+  public function deleteExpired() {
+    try {
+      if (class_exists('Drupal\Core\Database\Database')) {
+        parent::deleteExpired();
+      }
+    }
+    catch (Exception $e) {}
+  }
+
+  /**
+   * Overrides Drupal\Core\Cache\DatabaseBackend::deleteTags().
+   */
+  public function deleteTags(array $tags) {
+    try {
+      if (class_exists('Drupal\Core\Database\Database')) {
+        parent::deleteTags($tags);
       }
     }
     catch (Exception $e) {}
   }
 
   /**
-   * Overrides Drupal\Core\Cache\DatabaseBackend::flush().
+   * Overrides Drupal\Core\Cache\DatabaseBackend::invalidate().
    */
-  public function flush() {
+  public function invalidate($cid) {
     try {
       if (class_exists('Drupal\Core\Database\Database')) {
-        parent::flush();
+        parent::invalidate($cid);
+      }
+    }
+    catch (Exception $e) {}
+  }
+
+  /**
+   * Overrides Drupal\Core\Cache\DatabaseBackend::invalidateMultiple().
+   */
+  public function invalidateMultiple(array $cids) {
+    try {
+      if (class_exists('Drupal\Core\Database\Database')) {
+        parent::invalidateMultiple($cids);
+      }
+    }
+    catch (Exception $e) {}
+  }
+
+  /**
+   * Overrides Drupal\Core\Cache\DatabaseBackend::invalidateTags().
+   */
+  public function invalidateTags(array $tags) {
+    try {
+      if (class_exists('Drupal\Core\Database\Database')) {
+        parent::invalidateTags($tags);
       }
     }
     catch (Exception $e) {}
   }
 
   /**
-   * Overrides Drupal\Core\Cache\DatabaseBackend::expire().
+   * Implements Drupal\Core\Cache\CacheBackendInterface::invalidateAll().
    */
-  public function expire() {
+  public function invalidateAll() {
     try {
       if (class_exists('Drupal\Core\Database\Database')) {
-        parent::expire();
+        parent::invalidateAll($tags);
       }
     }
     catch (Exception $e) {}

core/lib/Drupal/Core/Cache/MemoryBackend.php

@@ -23,11 +23,6 @@ class MemoryBackend implements CacheBackendInterface {
    */
   protected $cache = array();
 
-  /**
-   * All tags invalidated during the request.
-   */
-  protected $invalidatedTags = array();
-
   /**
    * Constructs a MemoryBackend object.
    *
@@ -40,9 +35,9 @@ public function __construct($bin) {
   /**
    * Implements Drupal\Core\Cache\CacheBackendInterface::get().
    */
-  public function get($cid) {
+  public function get($cid, $allow_invalid = FALSE) {
     if (isset($this->cache[$cid])) {
-      return $this->prepareItem($this->cache[$cid]);
+      return $this->prepareItem($this->cache[$cid], $allow_invalid);
     }
     else {
       return FALSE;
@@ -52,13 +47,13 @@ public function get($cid) {
   /**
    * Implements Drupal\Core\Cache\CacheBackendInterface::getMultiple().
    */
-  public function getMultiple(&$cids) {
+  public function getMultiple(&$cids, $allow_invalid = FALSE) {
     $ret = array();
 
     $items = array_intersect_key($this->cache, array_flip($cids));
 
     foreach ($items as $item) {
-      $item = $this->prepareItem($item);
+      $item = $this->prepareItem($item, $allow_invalid);
       if ($item) {
         $ret[$item->cid] = $item;
       }
@@ -82,13 +77,15 @@ public function getMultiple(&$cids) {
    *   The item with data as appropriate or FALSE if there is no
    *   valid item to load.
    */
-  protected function prepareItem($cache) {
+  protected function prepareItem($cache, $allow_invalid) {
     if (!isset($cache->data)) {
       return FALSE;
     }
 
-    // The cache data is invalid if any of its tags have been cleared since.
-    if (count($cache->tags) && $this->hasInvalidatedTags($cache)) {
+    // Check expire time.
+    $cache->valid = $cache->expire == CacheBackendInterface::CACHE_PERMANENT || $cache->expire >= REQUEST_TIME;
+
+    if (!$allow_invalid && !$cache->valid) {
       return FALSE;
     }
 
@@ -102,28 +99,12 @@ public function set($cid, $data, $expire = CacheBackendInterface::CACHE_PERMANEN
     $this->cache[$cid] = (object) array(
       'cid' => $cid,
       'data' => $data,
+      'created' => REQUEST_TIME,
       'expire' => $expire,
-      'tags' => $tags,
-      'checksum' => $this->checksum($this->flattenTags($tags)),
+      'tags' => $this->flattenTags($tags),
     );
   }
 
-  /**
-   * Calculates a checksum so data can be invalidated using tags.
-   */
-  public function checksum($tags) {
-    $checksum = '';
-
-    foreach ($tags as $tag) {
-      // Has the tag already been invalidated.
-      if (isset($this->invalidatedTags[$tag])) {
-        $checksum = $checksum . $tag . ':' . $this->invalidatedTags[$tag];
-      }
-    }
-
-    return $checksum;
-  }
-
   /**
    * Implements Drupal\Core\Cache\CacheBackendInterface::delete().
    */
@@ -139,47 +120,79 @@ public function deleteMultiple(array $cids) {
   }
 
   /**
-   * Implements Drupal\Core\Cache\CacheBackendInterface::flush().
+   * Implements Drupal\Core\Cache\CacheBackendInterface::deleteTags().
    */
-  public function flush() {
+  public function deleteTags(array $tags) {
+    $flat_tags = $this->flattenTags($tags);
+    foreach ($this->cache as $cid => $item) {
+      if (array_intersect($flat_tags, $item->tags)) {
+        unset($this->cache[$cid]);
+      }
+    }
+  }
+
+  /**
+   * Implements Drupal\Core\Cache\CacheBackendInterface::deleteAll().
+   */
+  public function deleteAll() {
     $this->cache = array();
   }
 
   /**
-   * Implements Drupal\Core\Cache\CacheBackendInterface::expire().
+   * Implements Drupal\Core\Cache\CacheBackendInterface::deleteExpired().
    *
-   * Cache expiration is not implemented for PHP ArrayBackend as this backend
-   * only persists during a single request and expiration are done using
+   * Cache expiration is not implemented for MemoryBackend as this backend only
+   * persists during a single request and expiration are done using
    * REQUEST_TIME.
    */
-  public function expire() {
+  public function deleteExpired() {
   }
 
   /**
-   * Checks to see if any of the tags associated with a cache object have been
-   * invalidated.
-   *
-   * @param object @cache
-   *   An cache object to calculate and compare it's original checksum for.
-   *
-   * @return boolean
-   *   TRUE if the a tag has been invalidated, FALSE otherwise.
+   * Implements Drupal\Core\Cache\CacheBackendInterface::invalidate().
+   */
+  public function invalidate($cid) {
+    $this->cache[$cid]->expire = REQUEST_TIME - 1;
+  }
+
+  /**
+   * Implements Drupal\Core\Cache\CacheBackendInterface::invalidateMultiple().
    */
-  protected function hasInvalidatedTags($cache) {
-    if ($cache->checksum != $this->checksum($this->flattenTags($cache->tags))) {
-      return TRUE;
+  public function invalidateMultiple(array $cids) {
+    foreach ($cids as $cid) {
+      $this->cache[$cid]->expire = REQUEST_TIME - 1;
     }
-    return FALSE;
   }
 
   /**
-   * Flattens a tags array into a numeric array suitable for string storage.
+   * Implements Drupal\Core\Cache\CacheBackendInterface::invalidateTags().
+   */
+  public function invalidateTags(array $tags) {
+    $flat_tags = $this->flattenTags($tags);
+    foreach ($this->cache as $cid => $item) {
+      if (array_intersect($flat_tags, $item->tags)) {
+        $this->cache[$cid]->expire = REQUEST_TIME - 1;
+      }
+    }
+  }
+
+  /**
+   * Implements Drupal\Core\Cache\CacheBackendInterface::invalidateAll().
+   */
+  public function invalidateAll() {
+    foreach ($this->cache as $cid => $item) {
+      $this->cache[$cid]->expire = REQUEST_TIME - 1;
+    }
+  }
+
+  /**
+   * 'Flattens' a tags array into an array of strings.
    *
    * @param array $tags
    *   Associative array of tags to flatten.
    *
-   * @return
-   *   An array of flattened tag identifiers.
+   * @return array
+   *   An indexed array of strings.
    */
   protected function flattenTags(array $tags) {
     if (isset($tags[0])) {
@@ -200,20 +213,6 @@ protected function flattenTags(array $tags) {
     return $flat_tags;
   }
 
-  /**
-   * Implements Drupal\Core\Cache\CacheBackendInterface::invalidateTags().
-   */
-  public function invalidateTags(array $tags) {
-    foreach ($this->flattenTags($tags) as $tag) {
-      if (isset($this->invalidatedTags[$tag])) {
-        $this->invalidatedTags[$tag] = $this->invalidatedTags[$tag] + 1;
-      }
-      else {
-        $this->invalidatedTags[$tag] = 1;
-      }
-    }
-  }
-
   /**
    * Implements Drupal\Core\Cache\CacheBackendInterface::isEmpty().
    */

core/lib/Drupal/Core/Cache/NullBackend.php

@@ -31,14 +31,14 @@ public function __construct($bin) {}
   /**
    * Implements Drupal\Core\Cache\CacheBackendInterface::get().
    */
-  public function get($cid) {
+  public function get($cid, $allow_invalid = FALSE) {
     return FALSE;
   }
 
   /**
    * Implements Drupal\Core\Cache\CacheBackendInterface::getMultiple().
    */
-  public function getMultiple(&$cids) {
+  public function getMultiple(&$cids, $allow_invalid = FALSE) {
     return array();
   }
 
@@ -58,25 +58,45 @@ public function delete($cid) {}
   public function deleteMultiple(array $cids) {}
 
   /**
-   * Implements Drupal\Core\Cache\CacheBackendInterface::flush().
+   * Implements Drupal\Core\Cache\CacheBackendInterface::deleteAll().
    */
-  public function flush() {}
+  public function deleteAll() {}
 
   /**
-   * Implements Drupal\Core\Cache\CacheBackendInterface::expire().
+   * Implements Drupal\Core\Cache\CacheBackendInterface::deleteExpired().
    */
-  public function expire() {}
+  public function deleteExpired() {}
 
   /**
-   * Implements Drupal\Core\Cache\CacheBackendInterface::garbageCollection().
+   * Implements Drupal\Core\Cache\CacheBackendInterface::deleteTags().
    */
-  public function garbageCollection() {}
+  public function deleteTags(array $tags) {}
+