Update to Drupal 8.1.5. For more information, see https://www.drupal.org/project/drupal/releases/8.1.5

core/modules/big_pipe/src/Render/BigPipe.php

@@ -226,6 +226,13 @@ class BigPipe implements BigPipeInterface {
     $preg_placeholder_strings = array_map($prepare_for_preg_split, array_keys($no_js_placeholders));
     $fragments = preg_split('/' . implode('|', $preg_placeholder_strings) . '/', $html, NULL, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE);
 
+    // Determine how many occurrences there are of each no-JS placeholder.
+    $placeholder_occurrences = array_count_values(array_intersect($fragments, array_keys($no_js_placeholders)));
+
+    // Set up a variable to store the content of placeholders that have multiple
+    // occurrences.
+    $multi_occurrence_placeholders_content = [];
+
     foreach ($fragments as $fragment) {
       // If the fragment isn't one of the no-JS placeholders, it is the HTML in
       // between placeholders and it must be printed & flushed immediately. The
@@ -236,6 +243,15 @@ class BigPipe implements BigPipeInterface {
         continue;
       }
 
+      // If there are multiple occurrences of this particular placeholder, and
+      // this is the second occurrence, we can skip all calculations and just
+      // send the same content.
+      if ($placeholder_occurrences[$fragment] > 1 && isset($multi_occurrence_placeholders_content[$fragment])) {
+        print $multi_occurrence_placeholders_content[$fragment];
+        flush();
+        continue;
+      }
+
       $placeholder = $fragment;
       assert('isset($no_js_placeholders[$placeholder])');
       $token = Crypt::randomBytesBase64(55);
@@ -310,6 +326,13 @@ class BigPipe implements BigPipeInterface {
       // they can be sent in ::sendPreBody().
       $cumulative_assets->setAlreadyLoadedLibraries(array_merge($cumulative_assets->getAlreadyLoadedLibraries(), $html_response->getAttachments()['library']));
       $cumulative_assets->setSettings($html_response->getAttachments()['drupalSettings']);
+
+      // If there are multiple occurrences of this particular placeholder, track
+      // the content that was sent, so we can skip all calculations for the next
+      // occurrence.
+      if ($placeholder_occurrences[$fragment] > 1) {
+        $multi_occurrence_placeholders_content[$fragment] = $html_response->getContent();
+      }
     }
   }
 
@@ -508,7 +531,9 @@ EOF;
    *
    * @return array
    *   Indexed array; the order in which the BigPipe placeholders must be sent.
-   *   Values are the BigPipe placeholder IDs.
+   *   Values are the BigPipe placeholder IDs. Note that only unique
+   *   placeholders are kept: if the same placeholder occurs multiple times, we
+   *   only keep the first occurrence.
    */
   protected function getPlaceholderOrder($html) {
     $fragments = explode('<div data-big-pipe-placeholder-id="', $html);
@@ -521,7 +546,7 @@ EOF;
       $order[] = $placeholder;
     }
 
-    return $order;
+    return array_unique($order);
   }
 
 }

core/modules/big_pipe/src/Tests/BigPipeTest.php

@@ -269,6 +269,42 @@ class BigPipeTest extends WebTestBase {
     unlink(\Drupal::root() . '/' . $this->siteDirectory . '/error.log');
   }
 
+  /**
+   * Tests BigPipe with a multi-occurrence placeholder.
+   */
+  public function testBigPipeMultiOccurrencePlaceholders() {
+    $this->drupalLogin($this->rootUser);
+    $this->assertSessionCookieExists(TRUE);
+    $this->assertBigPipeNoJsCookieExists(FALSE);
+
+    // By not calling performMetaRefresh() here, we simulate JavaScript being
+    // enabled, because as far as the BigPipe module is concerned, JavaScript is
+    // enabled in the browser as long as the BigPipe no-JS cookie is *not* set.
+    // @see setUp()
+    // @see performMetaRefresh()
+
+    $this->drupalGet(Url::fromRoute('big_pipe_test_multi_occurrence'));
+    $big_pipe_placeholder_id = 'callback=Drupal%5CCore%5CRender%5CElement%5CStatusMessages%3A%3ArenderMessages&args[0]&token=a8c34b5e';
+    $expected_placeholder_replacement = '<script type="application/vnd.drupal-ajax" data-big-pipe-replacement-for-placeholder-with-id="' . $big_pipe_placeholder_id . '">';
+    $this->assertRaw('The count is 1.');
+    $this->assertNoRaw('The count is 2.');
+    $this->assertNoRaw('The count is 3.');
+    $raw_content = $this->getRawContent();
+    $this->assertTrue(substr_count($raw_content, $expected_placeholder_replacement) == 1, 'Only one placeholder replacement was found for the duplicate #lazy_builder arrays.');
+
+    // By calling performMetaRefresh() here, we simulate JavaScript being
+    // disabled, because as far as the BigPipe module is concerned, it is
+    // enabled in the browser when the BigPipe no-JS cookie is set.
+    // @see setUp()
+    // @see performMetaRefresh()
+    $this->performMetaRefresh();
+    $this->assertBigPipeNoJsCookieExists(TRUE);
+    $this->drupalGet(Url::fromRoute('big_pipe_test_multi_occurrence'));
+    $this->assertRaw('The count is 1.');
+    $this->assertNoRaw('The count is 2.');
+    $this->assertNoRaw('The count is 3.');
+  }
+
   protected function assertBigPipeResponseHeadersPresent() {
     $this->pass('Verifying BigPipe response headers…', 'Debug');
     $this->assertTrue(FALSE !== strpos($this->drupalGetHeader('Cache-Control'), 'private'), 'Cache-Control header set to "private".');

core/modules/big_pipe/tests/modules/big_pipe_test/big_pipe_test.routing.yml

@@ -15,3 +15,12 @@ no_big_pipe:
     _no_big_pipe: TRUE
   requirements:
     _access: 'TRUE'
+
+big_pipe_test_multi_occurrence:
+  path: '/big_pipe_test_multi_occurrence'
+  defaults:
+    _controller: '\Drupal\big_pipe_test\BigPipeTestController::multiOccurrence'
+    _title: 'BigPipe test multiple occurrences of the same placeholder'
+  requirements:
+    _access: 'TRUE'
+

core/modules/big_pipe/tests/modules/big_pipe_test/src/BigPipeTestController.php

@@ -52,6 +52,30 @@ class BigPipeTestController {
     return ['#markup' => '<p>Nope.</p>'];
   }
 
+  /**
+   * A page with multiple occurrences of the same placeholder.
+   *
+   * @see \Drupal\big_pipe\Tests\BigPipeTest::testBigPipeMultipleOccurrencePlaceholders()
+   *
+   * @return array
+   */
+  public function multiOccurrence() {
+    return [
+      'item1' => [
+        '#lazy_builder' => [static::class . '::counter', []],
+        '#create_placeholder' => TRUE,
+      ],
+      'item2' => [
+        '#lazy_builder' => [static::class . '::counter', []],
+        '#create_placeholder' => TRUE,
+      ],
+      'item3' => [
+        '#lazy_builder' => [static::class . '::counter', []],
+        '#create_placeholder' => TRUE,
+      ],
+    ];
+  }
+
   /**
    * #lazy_builder callback; builds <time> markup with current time.
    *
@@ -98,4 +122,31 @@ class BigPipeTestController {
     return ['#plain_text' => BigPipeTestSubscriber::CONTENT_TRIGGER_EXCEPTION];
   }
 
+  /**
+   * #lazy_builder callback; returns the current count.
+   *
+   * @see \Drupal\big_pipe\Tests\BigPipeTest::testBigPipeMultipleOccurrencePlaceholders()
+   *
+   * @return array
+   *   The render array.
+   */
+  public static function counter() {
+    // Lazy builders are not allowed to build their own state like this function
+    // does, but in this case we're intentionally doing that for testing
+    // purposes: so we can ensure that each lazy builder is only ever called
+    // once with the same parameters.
+    static $count;
+
+    if (!isset($count)) {
+      $count = 0;
+    }
+
+    $count++;
+
+    return [
+      '#markup' => BigPipeMarkup::create("<p>The count is $count.</p>"),
+      '#cache' => ['max-age' => 0],
+    ];
+  }
+
 }

core/modules/big_pipe/tests/src/FunctionalJavascript/BigPipeRegressionTest.php

@@ -0,0 +1,117 @@
+<?php
+
+namespace Drupal\Tests\big_pipe\FunctionalJavascript;
+
+use Drupal\comment\CommentInterface;
+use Drupal\comment\Entity\Comment;
+use Drupal\comment\Plugin\Field\FieldType\CommentItemInterface;
+use Drupal\comment\Tests\CommentTestTrait;
+use Drupal\editor\Entity\Editor;
+use Drupal\filter\Entity\FilterFormat;
+use Drupal\FunctionalJavascriptTests\JavascriptTestBase;
+use Drupal\simpletest\ContentTypeCreationTrait;
+use Drupal\simpletest\NodeCreationTrait;
+
+/**
+ * BigPipe regression tests.
+ *
+ * @group big_pipe
+ */
+class BigPipeRegressionTest extends JavascriptTestBase {
+
+  use CommentTestTrait;
+  use ContentTypeCreationTrait;
+  use NodeCreationTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = [
+    'node',
+    'comment',
+    'big_pipe',
+    'history',
+    'editor',
+    'ckeditor',
+    'filter',
+  ];
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setUp() {
+    parent::setUp();
+
+    // Use the big_pipe_test_theme theme.
+    $this->container->get('theme_installer')->install(['big_pipe_test_theme']);
+    $this->container->get('config.factory')->getEditable('system.theme')->set('default', 'big_pipe_test_theme')->save();
+  }
+
+  /**
+   * Ensure comment form works with history and big_pipe modules.
+   *
+   * @see https://www.drupal.org/node/2698811
+   */
+  public function testCommentForm_2698811() {
+    // Ensure an `article` node type exists.
+    $this->createContentType(['type' => 'article']);
+    $this->addDefaultCommentField('node', 'article');
+
+    // Enable CKEditor.
+    $format = $this->randomMachineName();
+    FilterFormat::create([
+      'format' => $format,
+      'name' => $this->randomString(),
+      'weight' => 1,
+      'filters' => [],
+    ])->save();
+    $settings['toolbar']['rows'] = [
+      [
+        [
+          'name' => 'Links',
+          'items' => [
+            'DrupalLink',
+            'DrupalUnlink',
+          ],
+        ],
+      ],
+    ];
+    $editor = Editor::create([
+      'format' => $format,
+      'editor' => 'ckeditor',
+    ]);
+    $editor->setSettings($settings);
+    $editor->save();
+
+    $admin_user = $this->drupalCreateUser([
+      'access comments',
+      'post comments',
+      'use text format ' . $format,
+    ]);
+    $this->drupalLogin($admin_user);
+
+    $node = $this->createNode([
+      'type' => 'article',
+      'comment' => CommentItemInterface::OPEN,
+    ]);
+    // Create some comments.
+    foreach (range(1, 5) as $i) {
+      $comment = Comment::create([
+        'status' => CommentInterface::PUBLISHED,
+        'field_name' => 'comment',
+        'entity_type' => 'node',
+        'entity_id' => $node->id(),
+      ]);
+      $comment->save();
+    }
+    $this->drupalGet($node->toUrl()->toString());
+    // Confirm that CKEditor loaded.
+    $javascript = <<<JS
+    (function(){
+      return Object.keys(CKEDITOR.instances).length > 0;
+    }());
+JS;
+    $this->assertJsCondition($javascript);
+  }
+
+}

core/modules/big_pipe/tests/themes/big_pipe_test_theme/big_pipe_test_theme.info.yml

@@ -0,0 +1,5 @@
+name: 'BigPipe test theme'
+type: theme
+description: 'Theme for testing BigPipe edge cases.'
+version: VERSION
+core: 8.x

core/modules/big_pipe/tests/themes/big_pipe_test_theme/templates/field--comment.html.twig

@@ -0,0 +1,13 @@
+{#
+/**
+ * @file
+ * Test that comments still work with the form above instead of below.
+ *
+ * @see \Drupal\Tests\big_pipe\FunctionalJavascript\BigPipeRegressionTest::testCommentForm_2698811()
+ */
+#}
+<section{{ attributes }}>
+  {{ comment_form }}
+
+  {{ comments }}
+</section>