Updates for PR 6392

src/wp-includes/global-styles-and-settings.php

@@ -307,8 +307,41 @@ function wp_add_global_styles_for_blocks() {
 
 	$tree        = WP_Theme_JSON_Resolver::get_merged_data();
 	$block_nodes = $tree->get_styles_block_nodes();
+
+	$can_use_cached = ! wp_is_development_mode( 'theme' );
+	if ( $can_use_cached ) {
+		// md5 is a costly operation, so we hashing global settings and block_node in a single call.
+		$hash = md5(
+			wp_json_encode(
+				array(
+					'global_setting' => wp_get_global_settings(),
+					'block_nodes'    => $block_nodes,
+				)
+			)
+		);
+
+		$cache_key = "wp_styles_for_blocks:$hash";
+		$cached    = get_site_transient( $cache_key );
+		if ( ! is_array( $cached ) ) {
+			$cached = array();
+		}
+	}
+
+	$update_cache = false;
+
 	foreach ( $block_nodes as $metadata ) {
-		$block_css = $tree->get_styles_for_block( $metadata );
+
+		if ( $can_use_cached && isset( $metadata['name'] ) ) {
+			if ( isset( $cached[ $metadata['name'] ] ) ) {
+				$block_css = $cached[ $metadata['name'] ];
+			} else {
+				$block_css                   = $tree->get_styles_for_block( $metadata );
+				$cached[ $metadata['name'] ] = $block_css;
+				$update_cache                = true;
+			}
+		} else {
+			$block_css = $tree->get_styles_for_block( $metadata );
+		}
 
 		if ( ! wp_should_load_separate_core_block_assets() ) {
 			wp_add_inline_style( 'global-styles', $block_css );
@@ -354,6 +387,10 @@ function wp_add_global_styles_for_blocks() {
 			}
 		}
 	}
+
+	if ( $update_cache ) {
+		set_site_transient( $cache_key, $cached, HOUR_IN_SECONDS );
+	}
 }
 
 /**

tests/phpunit/tests/theme/wpAddGlobalStylesForBlocks.php

@@ -75,6 +75,87 @@ public function test_third_party_blocks_inline_styles_get_registered_to_global_s
 		);
 	}
 
+	/**
+	 * Ensure that the block cache is set for global styles.
+	 *
+	 * @ticket 59595
+	 */
+	public function test_styles_for_blocks_cache_is_set() {
+		$this->set_up_third_party_block();
+
+		wp_register_style( 'global-styles', false, array(), true, true );
+
+		$cache_key                = $this->get_wp_styles_for_blocks_cache_key();
+		$styles_for_blocks_before = get_site_transient( $cache_key );
+		$this->assertFalse( $styles_for_blocks_before );
+
+		wp_add_global_styles_for_blocks();
+
+		$styles_for_blocks_after = get_site_transient( $cache_key );
+		$this->assertNotEmpty( $styles_for_blocks_after );
+	}
+
+	/**
+	 * Confirm that the block cache is skipped when in dev mode for themes.
+	 *
+	 * @ticket 59595
+	 */
+	public function test_styles_for_blocks_skips_cache_in_dev_mode() {
+		global $_wp_tests_development_mode;
+
+		$orig_dev_mode = $_wp_tests_development_mode;
+
+		// Setting development mode to theme should skip the cache.
+		$_wp_tests_development_mode = 'theme';
+
+		wp_register_style( 'global-styles', false, array(), true, true );
+
+		// Initial register of global styles.
+		wp_add_global_styles_for_blocks();
+
+		$cache_key                 = $this->get_wp_styles_for_blocks_cache_key();
+		$styles_for_blocks_initial = get_site_transient( $cache_key );
+
+		// Cleanup.
+		$_wp_tests_development_mode = $orig_dev_mode;
+
+		$this->assertFalse( $styles_for_blocks_initial );
+	}
+
+	/**
+	 * Confirm that the block cache is updated if the block meta has changed.
+	 *
+	 * @ticket 59595
+	 */
+	public function test_styles_for_blocks_cache_is_skipped() {
+		wp_register_style( 'global-styles', false, array(), true, true );
+
+		// Initial register of global styles.
+		wp_add_global_styles_for_blocks();
+
+		$cache_key                 = $this->get_wp_styles_for_blocks_cache_key();
+		$styles_for_blocks_initial = get_site_transient( $cache_key );
+		$this->assertNotEmpty( $styles_for_blocks_initial, 'Initial cache was not set.' );
+
+		$this->set_up_third_party_block();
+
+		/*
+		 * Call register of global styles again to ensure the cache is updated.
+		 * In normal conditions, this function is only called once per request.
+		 */
+		wp_add_global_styles_for_blocks();
+
+		$cache_key                 = $this->get_wp_styles_for_blocks_cache_key();
+		$styles_for_blocks_updated = get_site_transient( $cache_key );
+		$this->assertNotEmpty( $styles_for_blocks_updated, 'Updated cache was not set.' );
+
+		$this->assertNotEquals(
+			$styles_for_blocks_initial,
+			$styles_for_blocks_updated,
+			'Block style cache was not updated.'
+		);
+	}
+
 	/**
 	 * @ticket 56915
 	 * @ticket 61165
@@ -253,4 +334,25 @@ private function get_global_styles() {
 		$actual = wp_styles()->get_data( 'global-styles', 'after' );
 		return is_array( $actual ) ? $actual : array();
 	}
+
+	/**
+	 * Get cache key for `wp_styles_for_blocks`.
+	 *
+	 * @return string The cache key.
+	 */
+	private function get_wp_styles_for_blocks_cache_key() {
+		$tree        = WP_Theme_JSON_Resolver::get_merged_data();
+		$block_nodes = $tree->get_styles_block_nodes();
+		// md5 is a costly operation, so we hashing global settings and block_node in a single call.
+		$hash = md5(
+			wp_json_encode(
+				array(
+					'global_setting' => wp_get_global_settings(),
+					'block_nodes'    => $block_nodes,
+				)
+			)
+		);
+
+		return "wp_styles_for_blocks:$hash";
+	}
 }