Issue #2543332 by Wim Leers, effulgentsia, Fabianx, Crell, dawehner,...

Issue #2543332 by Wim Leers, effulgentsia, Fabianx, Crell, dawehner, borisson_: Auto-placeholdering for #lazy_builder without bubbling

core/core.services.yml

@@ -3,6 +3,10 @@ parameters:
   twig.config: {}
   renderer.config:
     required_cache_contexts: ['languages:language_interface', 'theme', 'user.permissions']
+    auto_placeholder_conditions:
+      max-age: 0
+      contexts: ['session', 'user']
+      tags: []
   factory.keyvalue:
     default: keyvalue.database
   factory.keyvalue.expirable:

core/lib/Drupal/Core/Render/Renderer.php

@@ -170,6 +170,9 @@ protected function renderPlaceholder($placeholder, array $elements) {
     // Get the render array for the given placeholder
     $placeholder_elements = $elements['#attached']['placeholders'][$placeholder];
 
+    // Prevent the render array from being auto-placeholdered again.
+    $placeholder_elements['#create_placeholder'] = FALSE;
+
     // Render the placeholder into markup.
     $markup = $this->renderPlain($placeholder_elements);
 
@@ -337,6 +340,10 @@ protected function doRender(&$elements, $is_root_call = FALSE) {
         throw new \DomainException(sprintf('When a #lazy_builder callback is specified, no properties can exist; all properties must be generated by the #lazy_builder callback. You specified the following properties: %s.', implode(', ', $unsupported_keys)));
       }
     }
+    // Determine whether to do auto-placeholdering.
+    if (isset($elements['#lazy_builder']) && (!isset($elements['#create_placeholder']) || $elements['#create_placeholder'] !== FALSE) && $this->shouldAutomaticallyPlaceholder($elements)) {
+      $elements['#create_placeholder'] = TRUE;
+    }
     // If instructed to create a placeholder, and a #lazy_builder callback is
     // present (without such a callback, it would be impossible to replace the
     // placeholder), replace the current element with a placeholder.
@@ -635,6 +642,37 @@ protected function replacePlaceholders(array &$elements) {
     return TRUE;
   }
 
+  /**
+   * Whether the given render array should be automatically placeholdered.
+   *
+   * @param array $element
+   *   The render array whose cacheability to analyze.
+   *
+   * @return bool
+   *   Whether the given render array's cacheability meets the placeholdering
+   *   conditions.
+   */
+  protected function shouldAutomaticallyPlaceholder(array $element) {
+    $conditions = $this->rendererConfig['auto_placeholder_conditions'];
+
+    // Auto-placeholder if max-age is at or below the configured threshold.
+    if (isset($element['#cache']['max-age']) && $element['#cache']['max-age'] !== Cache::PERMANENT && $element['#cache']['max-age'] <= $conditions['max-age']) {
+      return TRUE;
+    }
+
+    // Auto-placeholder if a high-cardinality cache context is set.
+    if (isset($element['#cache']['contexts']) && array_intersect($element['#cache']['contexts'], $conditions['contexts'])) {
+      return TRUE;
+    }
+
+    // Auto-placeholder if a high-invalidation frequency cache tag is set.
+    if (isset($element['#cache']['tags']) && array_intersect($element['#cache']['tags'], $conditions['tags'])) {
+      return TRUE;
+    }
+
+    return FALSE;
+  }
+
   /**
    * Turns this element into a placeholder.
    *

core/modules/comment/src/CommentForm.php

@@ -78,6 +78,16 @@ public function form(array $form, FormStateInterface $form_state) {
     $field_definition = $this->entityManager->getFieldDefinitions($entity->getEntityTypeId(), $entity->bundle())[$comment->getFieldName()];
     $config = $this->config('user.settings');
 
+    // In several places within this function, we vary $form on:
+    // - The current user's permissions.
+    // - Whether the current user is authenticated or anonymous.
+    // - The 'user.settings' configuration.
+    // - The comment field's definition.
+    $form['#cache']['contexts'][] = 'user.permissions';
+    $form['#cache']['contexts'][] = 'user.roles:authenticated';
+    $this->renderer->addCacheableDependency($form, $config);
+    $this->renderer->addCacheableDependency($form, $field_definition->getConfig($entity->bundle()));
+
     // Use #comment-form as unique jump target, regardless of entity type.
     $form['#id'] = Html::getUniqueId('comment_form');
     $form['#theme'] = array('comment_form__' . $entity->getEntityTypeId() . '__' . $entity->bundle() . '__' . $field_name, 'comment_form');
@@ -90,10 +100,6 @@ public function form(array $form, FormStateInterface $form_state) {
       $form['#attributes']['data-user-info-from-browser'] = TRUE;
     }
 
-    // Vary per role, because we check a permission above and attach an asset
-    // library only for authenticated users.
-    $form['#cache']['contexts'][] = 'user.roles';
-
     // If not replying to a comment, use our dedicated page callback for new
     // Comments on entities.
     if (!$comment->id() && !$comment->hasParentComment()) {
@@ -164,6 +170,7 @@ public function form(array $form, FormStateInterface $form_state) {
       $form['author']['name']['#value'] = $form['author']['name']['#default_value'];
       $form['author']['name']['#theme'] = 'username';
       $form['author']['name']['#account'] = $this->currentUser;
+      $form['author']['name']['#cache']['contexts'][] = 'user';
     }
     elseif($this->currentUser->isAnonymous()) {
       $form['author']['name']['#attributes']['data-drupal-default-value'] = $config->get('anonymous');
@@ -210,10 +217,6 @@ public function form(array $form, FormStateInterface $form_state) {
       '#access' => $is_admin,
     );
 
-    $this->renderer->addCacheableDependency($form, $config);
-    // The form depends on the field definition.
-    $this->renderer->addCacheableDependency($form, $field_definition->getConfig($entity->bundle()));
-
     return parent::form($form, $form_state, $comment);
   }
 

core/modules/comment/src/Plugin/Field/FieldFormatter/CommentDefaultFormatter.php

@@ -184,30 +184,23 @@ public function viewElements(FieldItemListInterface $items) {
         // Only show the add comment form if the user has permission.
         $elements['#cache']['contexts'][] = 'user.roles';
         if ($this->currentUser->hasPermission('post comments')) {
-          // All users in the "anonymous" role can use the same form: it is fine
-          // for this form to be stored in the render cache.
-          if ($this->currentUser->isAnonymous()) {
-            $comment = $this->storage->create(array(
-              'entity_type' => $entity->getEntityTypeId(),
-              'entity_id' => $entity->id(),
-              'field_name' => $field_name,
-              'comment_type' => $this->getFieldSetting('comment_type'),
-              'pid' => NULL,
-            ));
-            $output['comment_form'] = $this->entityFormBuilder->getForm($comment);
-          }
-          // All other users need a user-specific form, which would break the
-          // render cache: hence use a #lazy_builder callback.
-          else {
-            $output['comment_form'] = [
-              '#lazy_builder' => ['comment.lazy_builders:renderForm', [
-                $entity->getEntityTypeId(),
-                $entity->id(),
-                $field_name,
-                $this->getFieldSetting('comment_type'),
-              ]],
-              '#create_placeholder' => TRUE,
-            ];
+          $output['comment_form'] = [
+            '#lazy_builder' => ['comment.lazy_builders:renderForm', [
+              $entity->getEntityTypeId(),
+              $entity->id(),
+              $field_name,
+              $this->getFieldSetting('comment_type'),
+            ]],
+          ];
+
+          // @todo Remove this in https://www.drupal.org/node/2543334. Until
+          //   then, \Drupal\Core\Render\Renderer::hasPoorCacheability() isn't
+          //   integrated with cache context bubbling, so this duplicates the
+          //   contexts added by \Drupal\comment\CommentForm::form().
+          $output['comment_form']['#cache']['contexts'][] = 'user.permissions';
+          $output['comment_form']['#cache']['contexts'][] = 'user.roles:authenticated';
+          if ($this->currentUser->isAuthenticated()) {
+            $output['comment_form']['#cache']['contexts'][] = 'user';
           }
         }
       }

core/modules/comment/src/Tests/CommentDefaultFormatterCacheTagsTest.php

@@ -70,8 +70,7 @@ public function testCacheTags() {
       ->getViewBuilder('entity_test')
       ->view($commented_entity);
     $renderer->renderRoot($build);
-    $cache_context_tags = \Drupal::service('cache_contexts_manager')->convertTokensToKeys($build['#cache']['contexts'])->getCacheTags();
-    $expected_cache_tags = Cache::mergeTags($cache_context_tags, [
+    $expected_cache_tags = [
       'entity_test_view',
       'entity_test:'  . $commented_entity->id(),
       'comment_list',
@@ -80,7 +79,7 @@ public function testCacheTags() {
       'config:field.field.entity_test.entity_test.comment',
       'config:field.storage.comment.comment_body',
       'config:user.settings',
-    ]);
+    ];
     sort($expected_cache_tags);
     $this->assertEqual($build['#cache']['tags'], $expected_cache_tags);
 
@@ -113,8 +112,7 @@ public function testCacheTags() {
       ->getViewBuilder('entity_test')
       ->view($commented_entity);
     $renderer->renderRoot($build);
-    $cache_context_tags = \Drupal::service('cache_contexts_manager')->convertTokensToKeys($build['#cache']['contexts'])->getCacheTags();
-    $expected_cache_tags = Cache::mergeTags($cache_context_tags, [
+    $expected_cache_tags = [
       'entity_test_view',
       'entity_test:' . $commented_entity->id(),
       'comment_list',
@@ -128,7 +126,7 @@ public function testCacheTags() {
       'config:field.field.entity_test.entity_test.comment',
       'config:field.storage.comment.comment_body',
       'config:user.settings',
-    ]);
+    ];
     sort($expected_cache_tags);
     $this->assertEqual($build['#cache']['tags'], $expected_cache_tags);
   }

core/modules/comment/src/Tests/CommentTranslationUITest.php

@@ -38,10 +38,9 @@ class CommentTranslationUITest extends ContentTranslationUITestBase {
   protected $defaultCacheContexts = [
     'languages:language_interface',
     'theme',
-    'user.permissions',
     'timezone',
     'url.query_args.pagers:0',
-    'user.roles'
+    'user'
   ];
 
   /**

core/modules/node/src/Tests/NodeTranslationUITest.php

@@ -27,13 +27,12 @@ class NodeTranslationUITest extends ContentTranslationUITestBase {
   protected $defaultCacheContexts = [
     'languages:language_interface',
     'theme',
-    'user.permissions',
     'route.menu_active_trails:account',
     'route.menu_active_trails:footer',
     'route.menu_active_trails:main',
     'route.menu_active_trails:tools',
     'timezone',
-    'user.roles'
+    'user'
   ];
 
   /**

core/tests/Drupal/Tests/Core/Render/RendererTestBase.php

@@ -89,6 +89,11 @@ class RendererTestBase extends UnitTestCase {
       'languages:language_interface',
       'theme',
     ],
+    'auto_placeholder_conditions' => [
+      'max-age' => 0,
+      'contexts' => ['session', 'user'],
+      'tags' =>  ['current-temperature'],
+    ],
   ];
 
   /**

sites/default/default.services.yml

@@ -84,6 +84,37 @@ parameters:
     #
     # @default ['languages:language_interface', 'theme', 'user.permissions']
     required_cache_contexts: ['languages:language_interface', 'theme', 'user.permissions']
+    # Renderer automatic placeholdering conditions:
+    #
+    # Drupal allows portions of the page to be automatically deferred when
+    # rendering to improve cache performance. That is especially helpful for
+    # cache contexts that vary widely, such as the active user. On some sites
+    # those may be different, however, such as sites with only a handful of
+    # users. If you know what the high-cardinality cache contexts are for your
+    # site, specify those here. If you're not sure, the defaults are fairly safe
+    # in general.
+    #
+    # For more information about rendering optimizations see
+    # https://www.drupal.org/developing/api/8/render/arrays/cacheability#optimizing
+    auto_placeholder_conditions:
+      # Max-age at or below which caching is not considered worthwhile.
+      #
+      # Disable by setting to -1.
+      #
+      # @default 0
+      max-age: 0
+      # Cache contexts with a high cardinality.
+      #
+      # Disable by setting to [].
+      #
+      # @default ['session', 'user']
+      contexts: ['session', 'user']
+      # Tags with a high invalidation frequency.
+      #
+      # Disable by setting to [].
+      #
+      # @default []
+      tags: []
   factory.keyvalue:
     {}
     # Default key/value storage service to use.