Issue #3281955 by prudloff: Add a way to debug big_pipe cache tags

3 files changed, 41 insertions, 1 deletions

diff --git a/core/modules/big_pipe/big_pipe.services.yml b/core/modules/big_pipe/big_pipe.services.yml
index 22d937a3d8ff..49e921d525f5 100644
--- a/core/modules/big_pipe/big_pipe.services.yml
+++ b/core/modules/big_pipe/big_pipe.services.yml
@@ -11,7 +11,7 @@ services:
       - { name: placeholder_strategy, priority: 0 }
   big_pipe:
     class: Drupal\big_pipe\Render\BigPipe
-    arguments: ['@renderer', '@session', '@request_stack', '@http_kernel', '@event_dispatcher', '@config.factory', '@messenger', '@router.request_context', '@logger.channel.php']
+    arguments: ['@renderer', '@session', '@request_stack', '@http_kernel', '@event_dispatcher', '@config.factory', '@messenger', '@router.request_context', '@logger.channel.php', '%http.response.debug_cacheability_headers%']
   Drupal\big_pipe\Render\BigPipe: '@big_pipe'
   html_response.attachments_processor.big_pipe:
     public: false
diff --git a/core/modules/big_pipe/src/Render/BigPipe.php b/core/modules/big_pipe/src/Render/BigPipe.php
index cefa77542f3f..1f24c409b76a 100644
--- a/core/modules/big_pipe/src/Render/BigPipe.php
+++ b/core/modules/big_pipe/src/Render/BigPipe.php
@@ -11,6 +11,7 @@ use Drupal\Core\Ajax\RedirectCommand;
 use Drupal\Core\Ajax\ReplaceCommand;
 use Drupal\Core\Asset\AttachedAssets;
 use Drupal\Core\Asset\AttachedAssetsInterface;
+use Drupal\Core\Cache\CacheableMetadata;
 use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\Form\EnforcedResponseException;
 use Drupal\Core\Messenger\MessengerInterface;
@@ -188,6 +189,7 @@ class BigPipe {
     protected MessengerInterface $messenger,
     protected RequestContext $requestContext,
     protected LoggerInterface $logger,
+    protected bool $debugCacheabilityHeaders = FALSE,
   ) {
   }
 
@@ -487,6 +489,9 @@ class BigPipe {
 
     // Create a Fiber for each placeholder.
     $fibers = [];
+
+    $cacheable_metadata = new CacheableMetadata();
+
     foreach ($placeholder_order as $placeholder_id) {
       if (!isset($placeholders[$placeholder_id])) {
         continue;
@@ -520,6 +525,11 @@ class BigPipe {
           }
           $elements = $fiber->getReturn();
           unset($fibers[$placeholder_id]);
+
+          if ($this->debugCacheabilityHeaders) {
+            $cacheable_metadata->addCacheableDependency(CacheableMetadata::createFromRenderArray($elements));
+          }
+
           // Create a new AjaxResponse.
           $ajax_response = new AjaxResponse();
           // JavaScript's querySelector automatically decodes HTML entities in
@@ -628,6 +638,11 @@ EOF;
       $iterations++;
     }
 
+    if ($this->debugCacheabilityHeaders) {
+      $this->sendChunk("\n<!-- big_pipe cache tags: " . implode(' ', $cacheable_metadata->getCacheTags()) . " -->\n");
+      $this->sendChunk("\n<!-- big_pipe cache contexts: " . implode(' ', $cacheable_metadata->getCacheContexts()) . " -->\n");
+    }
+
     // Send the stop signal.
     $this->sendChunk("\n" . static::STOP_SIGNAL . "\n");
   }
diff --git a/core/modules/big_pipe/tests/src/Functional/BigPipeTest.php b/core/modules/big_pipe/tests/src/Functional/BigPipeTest.php
index e6e2784fc11e..26e92fc14982 100644
--- a/core/modules/big_pipe/tests/src/Functional/BigPipeTest.php
+++ b/core/modules/big_pipe/tests/src/Functional/BigPipeTest.php
@@ -556,4 +556,29 @@ class BigPipeTest extends BrowserTestBase {
     $this->assertSession()->responseNotContains('<noscript><meta http-equiv="Refresh" content="0; URL=');
   }
 
+  /**
+   * Tests that response contains cacheability debug comments.
+   */
+  public function testDebugCacheability(): void {
+    $this->drupalLogin($this->rootUser);
+    $this->assertSessionCookieExists('1');
+    $this->assertBigPipeNoJsCookieExists('0');
+
+    // With debug_cacheability_headers enabled.
+    $this->drupalGet(Url::fromRoute('<front>'));
+    $this->assertBigPipeResponseHeadersPresent();
+    $this->assertSession()->responseContains('<!-- big_pipe cache tags:  -->');
+    $this->assertSession()
+      ->responseContains('<!-- big_pipe cache contexts: languages:language_interface theme user.permissions -->');
+
+    // With debug_cacheability_headers disabled.
+    $this->setContainerParameter('http.response.debug_cacheability_headers', FALSE);
+    $this->rebuildContainer();
+    $this->resetAll();
+    $this->drupalGet(Url::fromRoute('<front>'));
+    $this->assertSession()->responseNotContains('<!-- big_pipe cache tags:');
+    $this->assertSession()
+      ->responseNotContains('<!-- big_pipe cache contexts:');
+  }
+
 }