Issue #2752961 by dawehner, Wim Leers, Jo Fitzgerald, bradjones1, chr.fritsch, greg.1.anderson, anavarre, Berdir, moshe weitzman, bkosborne, alexpott, Crell, catch, msonnabaum, lauriii, joelpittet, deviantintegral, cilefen, effulgentsia, xjm: No reliable method exists for clearing the Twig cache

core/includes/common.inc

@@ -17,7 +17,6 @@ use Drupal\Core\Cache\Cache;
 use Drupal\Core\Render\Element\Link;
 use Drupal\Core\Render\Markup;
 use Drupal\Core\StringTranslation\TranslatableMarkup;
-use Drupal\Core\PhpStorage\PhpStorageFactory;
 use Drupal\Core\StringTranslation\PluralTranslatableMarkup;
 use Drupal\Core\Render\BubbleableMetadata;
 use Drupal\Core\Render\Element;
@@ -1117,7 +1116,7 @@ function drupal_flush_all_caches() {
   \Drupal::service('kernel')->invalidateContainer();
 
   // Wipe the Twig PHP Storage cache.
-  PhpStorageFactory::get('twig')->deleteAll();
+  \Drupal::service('twig')->invalidate();
 
   // Rebuild module and theme data.
   $module_data = system_rebuild_module_data();

core/includes/utility.inc

@@ -5,7 +5,6 @@
  * Miscellaneous functions.
  */
 
-use Drupal\Core\PhpStorage\PhpStorageFactory;
 use Drupal\Core\Cache\Cache;
 use Drupal\Core\DrupalKernel;
 use Symfony\Component\HttpFoundation\Request;
@@ -30,7 +29,7 @@ function drupal_rebuild($class_loader, Request $request) {
   restore_exception_handler();
 
   // Force kernel to rebuild php cache.
-  PhpStorageFactory::get('twig')->deleteAll();
+  \Drupal::service('twig')->invalidate();
 
   // Bootstrap up to where caches exist and clear them.
   $kernel = new DrupalKernel('prod', $class_loader);

core/lib/Drupal/Core/Template/TwigEnvironment.php

@@ -3,6 +3,7 @@
 namespace Drupal\Core\Template;
 
 use Drupal\Core\Cache\CacheBackendInterface;
+use Drupal\Core\PhpStorage\PhpStorageFactory;
 use Drupal\Core\Render\Markup;
 use Drupal\Core\State\StateInterface;
 
@@ -16,6 +17,18 @@ use Drupal\Core\State\StateInterface;
  */
 class TwigEnvironment extends \Twig_Environment {
 
+  /**
+   * Key name of the Twig cache prefix metadata key-value pair in State.
+   */
+  const CACHE_PREFIX_METADATA_KEY = 'twig_extension_hash_prefix';
+
+  /**
+   * The state service.
+   *
+   * @var \Drupal\Core\State\StateInterface
+   */
+  protected $state;
+
   /**
    * Static cache of template classes.
    *
@@ -43,6 +56,8 @@ class TwigEnvironment extends \Twig_Environment {
    *   The options for the Twig environment.
    */
   public function __construct($root, CacheBackendInterface $cache, $twig_extension_hash, StateInterface $state, \Twig_LoaderInterface $loader = NULL, $options = []) {
+    $this->state = $state;
+
     // Ensure that twig.engine is loaded, given that it is needed to render a
     // template because functions like TwigExtension::escapeFilter() are called.
     require_once $root . '/core/themes/engines/twig/twig.engine';
@@ -63,7 +78,7 @@ class TwigEnvironment extends \Twig_Environment {
     $this->addExtension($sandbox);
 
     if ($options['cache'] === TRUE) {
-      $current = $state->get('twig_extension_hash_prefix', ['twig_extension_hash' => '']);
+      $current = $state->get(static::CACHE_PREFIX_METADATA_KEY, ['twig_extension_hash' => '']);
       if ($current['twig_extension_hash'] !== $twig_extension_hash || empty($current['twig_cache_prefix'])) {
         $current = [
           'twig_extension_hash' => $twig_extension_hash,
@@ -71,7 +86,7 @@ class TwigEnvironment extends \Twig_Environment {
           'twig_cache_prefix' => uniqid(),
 
         ];
-        $state->set('twig_extension_hash_prefix', $current);
+        $state->set(static::CACHE_PREFIX_METADATA_KEY, $current);
       }
       $this->twigCachePrefix = $current['twig_cache_prefix'];
 
@@ -82,6 +97,18 @@ class TwigEnvironment extends \Twig_Environment {
     parent::__construct($this->loader, $options);
   }
 
+  /**
+   * Invalidates all compiled Twig templates.
+   *
+   * @see \drupal_flush_all_caches
+   */
+  public function invalidate() {
+    PhpStorageFactory::get('twig')->deleteAll();
+    $this->templateClasses = [];
+    $this->loadedTemplates = [];
+    $this->state->delete(static::CACHE_PREFIX_METADATA_KEY);
+  }
+
   /**
    * Get the cache prefixed used by \Drupal\Core\Template\TwigPhpStorageCache
    *

core/tests/Drupal/KernelTests/Core/Theme/TwigEnvironmentTest.php

@@ -4,9 +4,11 @@ namespace Drupal\KernelTests\Core\Theme;
 
 use Drupal\Component\Utility\Crypt;
 use Drupal\Component\Utility\Html;
+use Drupal\Core\DependencyInjection\ContainerBuilder;
 use Drupal\Core\Site\Settings;
 use Drupal\Core\Template\TwigPhpStorageCache;
 use Drupal\KernelTests\KernelTestBase;
+use Symfony\Component\DependencyInjection\Definition;
 
 /**
  * Tests the twig environment.
@@ -143,4 +145,52 @@ class TwigEnvironmentTest extends KernelTestBase {
     $this->assertNotEqual($new_extension_filename, $original_filename);
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function register(ContainerBuilder $container) {
+    parent::register($container);
+
+    $container->setDefinition('twig_loader__file_system', new Definition('Twig_Loader_Filesystem', [[sys_get_temp_dir()]]))
+      ->addTag('twig.loader');
+  }
+
+
+  /**
+   * Test template invalidation.
+   */
+  public function testTemplateInvalidation() {
+    $template_before = <<<TWIG
+<div>Hello before</div>
+TWIG;
+    $template_after = <<<TWIG
+<div>Hello after</div>
+TWIG;
+
+    $tempfile = tempnam(sys_get_temp_dir(), '__METHOD__') . '.html.twig';
+    file_put_contents($tempfile, $template_before);
+
+    /** @var \Drupal\Core\Template\TwigEnvironment $environment */
+    $environment = \Drupal::service('twig');
+
+    $output = $environment->load(basename($tempfile))->render();
+    $this->assertEquals($template_before, $output);
+
+    file_put_contents($tempfile, $template_after);
+    $output = $environment->load(basename($tempfile))->render();
+    $this->assertEquals($template_before, $output);
+
+    $environment->invalidate();
+    // Manually change $templateClassPrefix to force a different template
+    // classname, as the other class is still loaded. This wouldn't be a problem
+    // on a real site where you reload the page.
+    $reflection = new \ReflectionClass($environment);
+    $property_reflection = $reflection->getProperty('templateClassPrefix');
+    $property_reflection->setAccessible(TRUE);
+    $property_reflection->setValue($environment, 'otherPrefix');
+
+    $output = $environment->load(basename($tempfile))->render();
+    $this->assertEquals($template_after, $output);
+  }
+
 }