Cache block asset resource hints (#51874)

* Cache block asset resource hints

* Combine resource hints under single cache transient

* Add AssetController tests

* Add changelog entry

* Skip cache use in development mode

* Fix up lint errors

* Revert init method back to protected and ignore linting

Co-authored-by: Mike Jolley <mike.jolley@me.com>

---------

Co-authored-by: Mike Jolley <mike.jolley@me.com>

plugins/woocommerce/changelog/update-49230

@@ -0,0 +1,4 @@
+Significance: patch
+Type: performance
+
+Cache block asset resource hints

plugins/woocommerce/src/Blocks/AssetsController.php

@@ -1,4 +1,6 @@
 <?php
+declare( strict_types = 1 );
+
 namespace Automattic\WooCommerce\Blocks;
 
 use Automattic\WooCommerce\Blocks\Assets\Api as AssetApi;
@@ -31,7 +33,7 @@ final class AssetsController {
 	/**
 	 * Initialize class features.
 	 */
-	protected function init() {
+	protected function init() { // phpcs:ignore WooCommerce.Functions.InternalInjectionMethod.MissingPublic
 		add_action( 'init', array( $this, 'register_assets' ) );
 		add_action( 'enqueue_block_editor_assets', array( $this, 'register_and_enqueue_site_editor_assets' ) );
 		add_filter( 'wp_resource_hints', array( $this, 'add_resource_hints' ), 10, 2 );
@@ -196,6 +198,50 @@ final class AssetsController {
 		return $urls;
 	}
 
+	/**
+	 * Get the block asset resource hints in the cache or null if not found.
+	 *
+	 * @return array|null Array of resource hints.
+	 */
+	private function get_block_asset_resource_hints_cache() {
+		if ( wp_is_development_mode( 'plugin' ) ) {
+			return null;
+		}
+
+		$cache = get_site_transient( 'woocommerce_block_asset_resource_hints' );
+
+		$current_version = array(
+			'woocommerce' => WOOCOMMERCE_VERSION,
+			'wordpress'   => get_bloginfo( 'version' ),
+		);
+
+		if ( isset( $cache['version'] ) && $cache['version'] === $current_version ) {
+			return $cache['files'];
+		}
+
+		return null;
+	}
+
+	/**
+	 * Set the block asset resource hints in the cache.
+	 *
+	 * @param string $filename File name.
+	 * @param array  $data Array of resource hints.
+	 */
+	private function set_block_asset_resource_hints_cache( $filename, $data ) {
+		$cache   = $this->get_block_asset_resource_hints_cache();
+		$updated = array(
+			'files'   => $cache ?? array(),
+			'version' => array(
+				'woocommerce' => WOOCOMMERCE_VERSION,
+				'wordpress'   => get_bloginfo( 'version' ),
+			),
+		);
+
+		$updated['files'][ $filename ] = $data;
+		set_site_transient( 'woocommerce_block_asset_resource_hints', $updated, WEEK_IN_SECONDS );
+	}
+
 	/**
 	 * Get resource hint for a block by name.
 	 *
@@ -206,6 +252,13 @@ final class AssetsController {
 		if ( ! $filename ) {
 			return array();
 		}
+
+		$cached = $this->get_block_asset_resource_hints_cache();
+
+		if ( isset( $cached[ $filename ] ) ) {
+			return $cached[ $filename ];
+		}
+
 		$script_data = $this->api->get_script_data(
 			$this->api->get_block_asset_build_path( $filename )
 		);
@@ -213,7 +266,8 @@ final class AssetsController {
 			array( esc_url( add_query_arg( 'ver', $script_data['version'], $script_data['src'] ) ) ),
 			$this->get_script_dependency_src_array( $script_data['dependencies'] )
 		);
-		return array_map(
+
+		$data = array_map(
 			function ( $src ) {
 				return array(
 					'href' => $src,
@@ -222,6 +276,10 @@ final class AssetsController {
 			},
 			array_unique( array_filter( $resources ) )
 		);
+
+		$this->set_block_asset_resource_hints_cache( $filename, $data );
+
+		return $data;
 	}
 
 	/**

plugins/woocommerce/tests/php/src/Blocks/AssetsController.php

@@ -0,0 +1,254 @@
+<?php
+declare( strict_types = 1 );
+
+namespace Automattic\WooCommerce\Tests\Blocks;
+
+use Automattic\WooCommerce\Blocks\Assets\Api;
+use Automattic\WooCommerce\Blocks\AssetsController as TestedAssetsController;
+
+/**
+ * Unit tests for the PatternRegistry class.
+ */
+class AssetsController extends \WP_UnitTestCase {
+
+	/**
+	 * Holds the mock Api instance.
+	 *
+	 * @var Api The mock API.
+	 */
+	private $api;
+
+	/**
+	 * Holds the AssetsController under test.
+	 *
+	 * @var TestedAssetsController The AssetsController under test.
+	 */
+	private $block_types_controller;
+
+	/**
+	 * Sets up a new TestedAssetsController so it can be tested.
+	 *
+	 * @return void
+	 */
+	protected function setUp(): void {
+		parent::setUp();
+		$this->api               = $this->createMock( Api::class );
+		$this->assets_controller = new TestedAssetsController( $this->api );
+
+		// A block checkout or cart page must exist in order to have resource hints.
+		$page    = array(
+			'name'    => 'block-checkout',
+			'title'   => 'Block Checkout',
+			'content' => '<!-- wp:woocommerce/checkout -->',
+		);
+		$page_id = wc_create_page( $page['name'], 'woocommerce_checkout_page_id', $page['title'], $page['content'] );
+
+		// Ensure a product exists in the cart unless the test specifies otherwise.
+		$product = \WC_Helper_Product::create_simple_product();
+		wc()->cart->add_to_cart( $product->get_id() );
+
+		// Set up some mock dependencies.
+		global $wp_scripts;
+		$wp_scripts->registered['mock-dependency']     = (object) array(
+			'ver'  => '1.2.3',
+			'src'  => 'http://test.local/wp-content/plugins/woocommerce/assets/client/block/mock-dependency.js',
+			'deps' => array(
+				'mock-sub-dependency',
+			),
+		);
+		$wp_scripts->registered['mock-sub-dependency'] = (object) array(
+			'ver'  => '1.2.3',
+			'src'  => 'http://test.local/wp-content/plugins/woocommerce/assets/client/block/mock-sub-dependency.js',
+			'deps' => array(),
+		);
+	}
+
+	/**
+	 * Clean up mock dependencies and pages after each test.
+	 *
+	 * @return void
+	 */
+	public function tearDown(): void {
+		parent::tearDown();
+
+		wp_delete_post( get_option( 'woocommerce_checkout_page_id' ), true );
+		delete_option( 'woocommerce_checkout_page_id' );
+
+		wc()->cart->empty_cart();
+
+		global $wp_scripts;
+		unset( $wp_scripts->registered['mock-dependency'] );
+		unset( $wp_scripts->registered['mock-sub-dependency'] );
+	}
+
+	/**
+	 * Tests that no additional resource hints are added on non-prefetch, non-prerender relations.
+	 *
+	 * @return void
+	 */
+	public function test_no_additional_resource_hints_added() {
+		$mock_urls = array(
+			array(
+				'href' => 'http://test.local/wp-content/plugins/woocommerce/assets/client/blocks/mock.js?ver=1.1.0',
+				'as'   => 'script',
+			),
+		);
+		$urls      = $this->assets_controller->add_resource_hints( $mock_urls, 'mock_relation' );
+
+		$this->assertEquals( $mock_urls, $urls );
+	}
+
+	/**
+	 * Tests that no additional resource hints are added on non-prefetch, non-prerender relations.
+	 *
+	 * @return void
+	 */
+	public function test_no_additional_resource_hints_added_on_non_prefetch_prerender_relation() {
+		$mock_urls = array(
+			array(
+				'href' => 'http://test.local/wp-content/plugins/woocommerce/assets/client/blocks/mock.js?ver=1.1.0',
+				'as'   => 'script',
+			),
+		);
+		$urls      = $this->assets_controller->add_resource_hints( $mock_urls, 'mock_relation' );
+
+		$this->assertEquals( $mock_urls, $urls );
+	}
+
+	/**
+	 * Tests that no additional resource hints are added on empty carts.
+	 *
+	 * @return void
+	 */
+	public function test_no_additional_resource_hints_added_on_empty_cart() {
+		wc()->cart->empty_cart();
+		$mock_urls = array(
+			array(
+				'href' => 'http://test.local/wp-content/plugins/woocommerce/assets/client/blocks/mock.js?ver=1.1.0',
+				'as'   => 'script',
+			),
+		);
+		$urls      = $this->assets_controller->add_resource_hints( $mock_urls, 'prefetch' );
+
+		$this->assertEquals( $mock_urls, $urls );
+	}
+
+	/**
+	 * Tests that no additional resource hints are added on empty carts.
+	 *
+	 * @return void
+	 */
+	public function test_additional_resource_hints_added_when_block_cart_exists() {
+		$this->api->expects( $this->once() )
+			->method( 'get_script_data' )
+			->willReturn(
+				array(
+					'version'      => '1.2.3',
+					'src'          => 'http://test.local/wp-content/plugins/woocommerce/assets/client/block/checkout.js',
+					'dependencies' => array(
+						'mock-dependency',
+					),
+				)
+			);
+
+		$mock_urls = array(
+			array(
+				'href' => 'http://test.local/wp-content/plugins/woocommerce/assets/client/blocks/mock.js?ver=1.1.0',
+				'as'   => 'script',
+			),
+		);
+		$urls      = $this->assets_controller->add_resource_hints( $mock_urls, 'prefetch' );
+
+		$this->assertEquals(
+			array_merge(
+				$mock_urls,
+				array(
+					array(
+						'href' => 'http://test.local/wp-content/plugins/woocommerce/assets/client/block/checkout.js?ver=1.2.3',
+						'as'   => 'script',
+					),
+					array(
+						'href' => 'http://test.local/wp-content/plugins/woocommerce/assets/client/block/mock-dependency.js?ver=1.2.3',
+						'as'   => 'script',
+					),
+					array(
+						'href' => 'http://test.local/wp-content/plugins/woocommerce/assets/client/block/mock-sub-dependency.js?ver=1.2.3',
+						'as'   => 'script',
+					),
+				)
+			),
+			$urls,
+		);
+	}
+
+	/**
+	 * Tests that the additional resource hints uses the cache when available.
+	 *
+	 * @return void
+	 */
+	public function test_additional_resource_hints_cache() {
+		$mock_cache = array(
+			'files'   => array(
+				'checkout-frontend' => array(
+					'href' => 'http://test.local/wp-content/plugins/woocommerce/assets/client/block/mock-cached.js?ver=1.2.3',
+					'as'   => 'script',
+				),
+			),
+			'version' => array(
+				'woocommerce' => WOOCOMMERCE_VERSION,
+				'wordpress'   => get_bloginfo( 'version' ),
+			),
+		);
+		set_site_transient( 'woocommerce_block_asset_resource_hints', $mock_cache );
+
+		$urls = $this->assets_controller->add_resource_hints( array(), 'prefetch' );
+
+		$this->assertEquals(
+			$mock_cache['files']['checkout-frontend'],
+			$urls,
+		);
+	}
+
+	/**
+	 * Tests that the additional resource hints don't use the cache when the version is invalid.
+	 *
+	 * @return void
+	 */
+	public function test_additional_resource_hints_invalid_cache() {
+		$this->api->expects( $this->once() )
+			->method( 'get_script_data' )
+			->willReturn(
+				array(
+					'version'      => '1.2.3',
+					'src'          => 'http://test.local/wp-content/plugins/woocommerce/assets/client/block/checkout.js',
+					'dependencies' => array(),
+				)
+			);
+
+		$mock_cache = array(
+			'files'   => array(
+				'checkout-frontend' => array(
+					'href' => 'http://test.local/wp-content/plugins/woocommerce/assets/client/block/mock-cached.js?ver=1.2.3',
+					'as'   => 'script',
+				),
+			),
+			'version' => array(
+				'woocommerce' => WOOCOMMERCE_VERSION,
+				'wordpress'   => '0.1.0-old',
+			),
+		);
+		set_site_transient( 'woocommerce_block_asset_resource_hints', $mock_cache );
+
+		$urls = $this->assets_controller->add_resource_hints( array(), 'prefetch' );
+
+		$this->assertEquals(
+			array(
+				array(
+					'href' => 'http://test.local/wp-content/plugins/woocommerce/assets/client/block/checkout.js?ver=1.2.3',
+					'as'   => 'script',
+				),
+			),
+			$urls,
+		);
+	}
+}