From 723ac9580b5e1d348d9d495a98dc88da48cf2639 Mon Sep 17 00:00:00 2001
From: Nathaniel Catchpole <catch@35733.no-reply.drupal.org>
Date: Tue, 16 Dec 2014 18:03:51 +0000
Subject: [PATCH] Issue #2392235 by Berdir: ChainedFastBackend shouldn't write
 cache tags to the fast cache back-end

---
 core/lib/Drupal/Core/Cache/ChainedFastBackend.php   | 13 +++++++++++--
 .../Tests/Cache/GenericCacheBackendUnitTestBase.php |  1 -
 .../Tests/Core/Cache/ChainedFastBackendTest.php     |  2 +-
 3 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/core/lib/Drupal/Core/Cache/ChainedFastBackend.php b/core/lib/Drupal/Core/Cache/ChainedFastBackend.php
index 1523ea2a965..559cff78403 100644
--- a/core/lib/Drupal/Core/Cache/ChainedFastBackend.php
+++ b/core/lib/Drupal/Core/Cache/ChainedFastBackend.php
@@ -160,7 +160,9 @@ class ChainedFastBackend implements CacheBackendInterface {
     if ($cids) {
       foreach ($this->consistentBackend->getMultiple($cids, $allow_invalid) as $item) {
         $cache[$item->cid] = $item;
-        $this->fastBackend->set($item->cid, $item->data, $item->expire, $item->tags);
+        // Don't write the cache tags to the fast backend as any cache tag
+        // invalidation results in an invalidation of the whole fast backend.
+        $this->fastBackend->set($item->cid, $item->data, $item->expire);
       }
     }
 
@@ -173,7 +175,9 @@ class ChainedFastBackend implements CacheBackendInterface {
   public function set($cid, $data, $expire = Cache::PERMANENT, array $tags = array()) {
     $this->consistentBackend->set($cid, $data, $expire, $tags);
     $this->markAsOutdated();
-    $this->fastBackend->set($cid, $data, $expire, $tags);
+    // Don't write the cache tags to the fast backend as any cache tag
+    // invalidation results in an invalidation of the whole fast backend.
+    $this->fastBackend->set($cid, $data, $expire);
   }
 
   /**
@@ -182,6 +186,11 @@ class ChainedFastBackend implements CacheBackendInterface {
   public function setMultiple(array $items) {
     $this->consistentBackend->setMultiple($items);
     $this->markAsOutdated();
+    // Don't write the cache tags to the fast backend as any cache tag
+    // invalidation results in an invalidation of the whole fast backend.
+    foreach ($items as &$item) {
+      unset($item['tags']);
+    }
     $this->fastBackend->setMultiple($items);
   }
 
diff --git a/core/modules/system/src/Tests/Cache/GenericCacheBackendUnitTestBase.php b/core/modules/system/src/Tests/Cache/GenericCacheBackendUnitTestBase.php
index 97d7ccd6113..d6f31bfcc28 100644
--- a/core/modules/system/src/Tests/Cache/GenericCacheBackendUnitTestBase.php
+++ b/core/modules/system/src/Tests/Cache/GenericCacheBackendUnitTestBase.php
@@ -411,7 +411,6 @@ abstract class GenericCacheBackendUnitTestBase extends KernelTestBase {
     $this->assertEqual($cached['cid_4']->expire, $future_expiration, 'Cache expiration has been correctly set.');
 
     $this->assertEqual($cached['cid_5']->data, $items['cid_5']['data'], 'New cache item set correctly.');
-    $this->assertEqual($cached['cid_5']->tags, array('test:a', 'test:b'));
 
     // Calling ::setMultiple() with invalid cache tags.
     try {
diff --git a/core/tests/Drupal/Tests/Core/Cache/ChainedFastBackendTest.php b/core/tests/Drupal/Tests/Core/Cache/ChainedFastBackendTest.php
index 798f37d7d76..c2640f2c56e 100644
--- a/core/tests/Drupal/Tests/Core/Cache/ChainedFastBackendTest.php
+++ b/core/tests/Drupal/Tests/Core/Cache/ChainedFastBackendTest.php
@@ -103,7 +103,7 @@ class ChainedFastBackendTest extends UnitTestCase {
     // We should get a call to set the cache item on the fast backend.
     $fast_cache->expects($this->once())
       ->method('set')
-      ->with($cache_item->cid, $cache_item->data, $cache_item->expire, $cache_item->tags);
+      ->with($cache_item->cid, $cache_item->data, $cache_item->expire);
 
     $chained_fast_backend = new ChainedFastBackend(
       $consistent_cache,