Improvement PageLayout Config Builder. Added save in cache config files.

app/code/Magento/Theme/Model/PageLayout/Config/Builder.php

@@ -12,6 +12,8 @@
  */
 class Builder implements \Magento\Framework\View\Model\PageLayout\Config\BuilderInterface
 {
+    const CACHE_KEY_LAYOUTS = 'THEME_LAYOUTS_FILES_MERGED';
+
     /**
      * @var \Magento\Framework\View\PageLayout\ConfigFactory
      */
@@ -32,19 +34,27 @@ class Builder implements \Magento\Framework\View\Model\PageLayout\Config\Builder
      */
     private $configFiles = [];
 
+    /**
+     * @var \Magento\Framework\App\Cache\Type\Layout
+     */
+    protected $cacheModel;
+
     /**
      * @param \Magento\Framework\View\PageLayout\ConfigFactory $configFactory
      * @param \Magento\Framework\View\PageLayout\File\Collector\Aggregated $fileCollector
      * @param \Magento\Theme\Model\ResourceModel\Theme\Collection $themeCollection
+     * @param \Magento\Framework\App\Cache\Type\Layout $cacheModel
      */
     public function __construct(
         \Magento\Framework\View\PageLayout\ConfigFactory $configFactory,
         \Magento\Framework\View\PageLayout\File\Collector\Aggregated $fileCollector,
-        \Magento\Theme\Model\ResourceModel\Theme\Collection $themeCollection
+        \Magento\Theme\Model\ResourceModel\Theme\Collection $themeCollection,
+        \Magento\Framework\App\Cache\Type\Layout $cacheModel
     ) {
         $this->configFactory = $configFactory;
         $this->fileCollector = $fileCollector;
         $this->themeCollection = $themeCollection;
+        $this->cacheModel = $cacheModel;
         $this->themeCollection->setItemObjectClass(\Magento\Theme\Model\Theme\Data::class);
     }
 
@@ -57,18 +67,25 @@ public function getPageLayoutsConfig()
     }
 
     /**
-     * Retrieve configuration files.
+     * Retrieve configuration files. Caches merged layouts.xml XML files.
      *
      * @return array
      */
     protected function getConfigFiles()
     {
         if (!$this->configFiles) {
             $configFiles = [];
-            foreach ($this->themeCollection->loadRegisteredThemes() as $theme) {
-                $configFiles[] = $this->fileCollector->getFilesContent($theme, 'layouts.xml');
+            $this->configFiles = $this->cacheModel->load(self::CACHE_KEY_LAYOUTS);
+            if (!empty($this->configFiles)) {
+                $this->configFiles = @unserialize($this->configFiles);//if value in cache is corrupted.
+            }
+            if (empty($this->configFiles)) {
+                foreach ($this->themeCollection->loadRegisteredThemes() as $theme) {
+                    $configFiles[] = $this->fileCollector->getFilesContent($theme, 'layouts.xml');
+                }
+                $this->configFiles = array_merge(...$configFiles);
+                $this->cacheModel->save(serialize($this->configFiles), self::CACHE_KEY_LAYOUTS);
             }
-            $this->configFiles = array_merge(...$configFiles);
         }
 
         return $this->configFiles;

app/code/Magento/Theme/Test/Unit/Model/PageLayout/Config/BuilderTest.php

@@ -10,14 +10,19 @@
  */
 namespace Magento\Theme\Test\Unit\Model\PageLayout\Config;
 
+use Magento\Framework\App\Cache\Type\FrontendPool;
+use Magento\Framework\App\Cache\Type\Layout as LayoutCache;
+use Magento\Framework\Cache\FrontendInterface;
 use Magento\Framework\TestFramework\Unit\Helper\ObjectManager;
 use Magento\Framework\View\PageLayout\Config;
 use Magento\Framework\View\PageLayout\File\Collector\Aggregated;
+use Magento\TestFramework\Helper\Bootstrap;
 use Magento\Theme\Model\PageLayout\Config\Builder;
 use Magento\Theme\Model\ResourceModel\Theme\Collection;
 use Magento\Theme\Model\Theme\Data;
 use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
+use Magento\Framework\App\Cache\Type\Layout;
 
 class BuilderTest extends TestCase
 {
@@ -41,6 +46,11 @@ class BuilderTest extends TestCase
      */
     protected $themeCollection;
 
+    /**
+     * @var Layout|MockObject
+     */
+    protected $cacheModel;
+
     /**
      * SetUp method
      *
@@ -58,21 +68,26 @@ protected function setUp(): void
         )->disableOriginalConstructor()
             ->getMock();
 
+        $helper = new ObjectManager($this);
         $this->themeCollection = $this->getMockBuilder(Collection::class)
             ->disableOriginalConstructor()
             ->getMock();
+        $this->cacheModel = $this->getMockBuilder(Layout::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+
         $this->themeCollection->expects($this->once())
             ->method('setItemObjectClass')
             ->with(Data::class)
             ->willReturnSelf();
-
         $helper = new ObjectManager($this);
         $this->builder = $helper->getObject(
             Builder::class,
             [
                 'configFactory' => $this->configFactory,
                 'fileCollector' => $this->fileCollector,
-                'themeCollection' => $this->themeCollection
+                'themeCollection' => $this->themeCollection,
+                'cacheModel' => $this->cacheModel,
             ]
         );
     }
@@ -84,6 +99,7 @@ protected function setUp(): void
      */
     public function testGetPageLayoutsConfig()
     {
+        $this->cacheModel->clean();
         $files1 = ['content layouts_1.xml', 'content layouts_2.xml'];
         $files2 = ['content layouts_3.xml', 'content layouts_4.xml'];