Incorporate page state into ETag computation

plugins/embed-optimizer/tests/test-optimization-detective.php

@@ -18,6 +18,7 @@ public function set_up(): void {
 		if ( ! defined( 'OPTIMIZATION_DETECTIVE_VERSION' ) ) {
 			$this->markTestSkipped( 'Optimization Detective is not active.' );
 		}
+		$GLOBALS['template'] = '/path/to/theme/index.php';
 
 		// Normalize the data for computing the current URL Metrics ETag to work around the issue where there is no
 		// global variable storing the OD_Tag_Visitor_Registry instance along with any registered tag visitors, so
@@ -26,6 +27,14 @@ public function set_up(): void {
 		add_filter( 'od_current_url_metrics_etag_data', '__return_empty_array' );
 	}
 
+	/**
+	 * Runs the routine after each test is executed.
+	 */
+	public function tear_down(): void {
+		unset( $GLOBALS['template'] );
+		parent::tear_down();
+	}
+
 	/**
 	 * Tests embed_optimizer_register_tag_visitors().
 	 *

plugins/image-prioritizer/tests/test-helper.php

@@ -15,6 +15,7 @@ class Test_Image_Prioritizer_Helper extends WP_UnitTestCase {
 	 */
 	public function set_up(): void {
 		parent::set_up();
+		$GLOBALS['template'] = '/path/to/theme/index.php';
 
 		// Normalize the data for computing the current URL Metrics ETag to work around the issue where there is no
 		// global variable storing the OD_Tag_Visitor_Registry instance along with any registered tag visitors, so
@@ -23,6 +24,14 @@ public function set_up(): void {
 		add_filter( 'od_current_url_metrics_etag_data', '__return_empty_array' );
 	}
 
+	/**
+	 * Runs the routine after each test is executed.
+	 */
+	public function tear_down(): void {
+		unset( $GLOBALS['template'] );
+		parent::tear_down();
+	}
+
 	/**
 	 * @return array<string, array<string, mixed>>
 	 */

plugins/optimization-detective/optimization.php

@@ -170,10 +170,16 @@ function od_is_response_html_content_type(): bool {
  * @since 0.1.0
  * @access private
  *
+ * @global WP_Query $wp_the_query            WP_Query object.
+ * @global string   $_wp_current_template_id Current template ID.
+ * @global string   $template                Template file path.
+ *
  * @param string $buffer Template output buffer.
  * @return string Filtered template output buffer.
  */
 function od_optimize_template_output_buffer( string $buffer ): string {
+	global $wp_the_query, $_wp_current_template_id, $template;
+
 	// If the content-type is not HTML or the output does not start with '<', then abort since the buffer is definitely not HTML.
 	if (
 		! od_is_response_html_content_type() ||
@@ -206,7 +212,15 @@ function od_optimize_template_output_buffer( string $buffer ): string {
 	 */
 	do_action( 'od_register_tag_visitors', $tag_visitor_registry );
 
-	$current_etag         = od_get_current_url_metrics_etag( $tag_visitor_registry );
+	$current_template = null;
+	if ( wp_is_block_theme() && isset( $_wp_current_template_id ) ) {
+		$current_template = get_block_template( $_wp_current_template_id, 'wp_template' );
+	}
+	if ( null === $current_template && isset( $template ) && is_string( $template ) ) {
+		$current_template = basename( $template );
+	}
+
+	$current_etag         = od_get_current_url_metrics_etag( $tag_visitor_registry, $wp_the_query, $current_template );
 	$group_collection     = new OD_URL_Metric_Group_Collection(
 		$post instanceof WP_Post ? OD_URL_Metrics_Post_Type::get_url_metrics_from_post( $post ) : array(),
 		$current_etag,

plugins/optimization-detective/storage/data.php

@@ -143,19 +143,55 @@ function od_get_url_metrics_slug( array $query_vars ): string {
 /**
  * Gets the current ETag for URL Metrics.
  *
- * The ETag is a hash based on the IDs of the registered tag visitors
- * in the current environment. It is used for marking the URL Metrics as stale
- * when its value changes.
+ * Generates a hash based on the IDs of registered tag visitors, the queried object,
+ * posts in The Loop, and theme information in the current environment. This ETag
+ * is used to assess if the URL Metrics are stale when its value changes.
  *
  * @since n.e.x.t
  * @access private
  *
- * @param OD_Tag_Visitor_Registry $tag_visitor_registry Tag visitor registry.
+ * @param OD_Tag_Visitor_Registry       $tag_visitor_registry Tag visitor registry.
+ * @param WP_Query                      $wp_query             The WP_Query instance.
+ * @param string|WP_Block_Template|null $current_template     The current template being used.
  * @return non-empty-string Current ETag.
  */
-function od_get_current_url_metrics_etag( OD_Tag_Visitor_Registry $tag_visitor_registry ): string {
+function od_get_current_url_metrics_etag( OD_Tag_Visitor_Registry $tag_visitor_registry, WP_Query $wp_query, $current_template ): string {
+	$queried_object      = $wp_query->get_queried_object();
+	$queried_object_data = array(
+		'id'            => null,
+		'type'          => null,
+		'last_modified' => null,
+	);
+
+	if ( $queried_object instanceof WP_Post ) {
+		$queried_object_data['id']            = $queried_object->ID;
+		$queried_object_data['type']          = 'post';
+		$queried_object_data['last_modified'] = $queried_object->post_modified_gmt;
+	} elseif ( $queried_object instanceof WP_Term ) {
+		$queried_object_data['id']   = $queried_object->term_id;
+		$queried_object_data['type'] = 'term';
+	} elseif ( $queried_object instanceof WP_User ) {
+		$queried_object_data['id']   = $queried_object->ID;
+		$queried_object_data['type'] = 'user';
+	} elseif ( $wp_query->is_post_type_archive() ) {
+		$queried_object_data['type'] = $wp_query->get( 'post_type' );
+	}
+
 	$data = array(
-		'tag_visitors' => array_keys( iterator_to_array( $tag_visitor_registry ) ),
+		'tag_visitors'     => array_keys( iterator_to_array( $tag_visitor_registry ) ),
+		'queried_object'   => $queried_object_data,
+		'queried_posts'    => wp_list_pluck( $wp_query->posts, 'post_modified_gmt', 'ID' ),
+		'active_theme'     => array(
+			'template'   => array(
+				'name'    => get_template(),
+				'version' => wp_get_theme( get_template() )->get( 'Version' ),
+			),
+			'stylesheet' => array(
+				'name'    => get_stylesheet(),
+				'version' => wp_get_theme()->get( 'Version' ),
+			),
+		),
+		'current_template' => $current_template,
 	);
 
 	/**

plugins/optimization-detective/tests/storage/test-data.php

@@ -293,7 +293,10 @@ public function test_od_get_url_metrics_slug(): void {
 	 */
 	public function test_od_get_current_url_metrics_etag(): void {
 		remove_all_filters( 'od_current_url_metrics_etag_data' );
-		$registry = new OD_Tag_Visitor_Registry();
+		$post_ids         = self::factory()->post->create_many( 3 );
+		$registry         = new OD_Tag_Visitor_Registry();
+		$wp_the_query     = new WP_Query();
+		$current_template = 'index.php';
 
 		$captured_etag_data = array();
 		add_filter(
@@ -304,35 +307,174 @@ static function ( array $data ) use ( &$captured_etag_data ) {
 			},
 			PHP_INT_MAX
 		);
-		$etag1 = od_get_current_url_metrics_etag( $registry );
+		add_filter(
+			'od_current_url_metrics_etag_data',
+			static function ( $data ) {
+				$data['active_theme'] = array(
+					'template'   => array(
+						'name'    => 'od-theme',
+						'version' => '1.0.0',
+					),
+					'stylesheet' => array(
+						'name'    => 'od-theme',
+						'version' => '1.0.0',
+					),
+				);
+				return $data;
+			}
+		);
+
+		$wp_the_query->query( array() );
+		$etag1 = od_get_current_url_metrics_etag( $registry, $wp_the_query, $current_template );
 		$this->assertMatchesRegularExpression( '/^[a-z0-9]{32}\z/', $etag1 );
-		$etag2 = od_get_current_url_metrics_etag( $registry );
+
+		$etag2 = od_get_current_url_metrics_etag( $registry, $wp_the_query, $current_template );
 		$this->assertSame( $etag1, $etag2 );
 		$this->assertCount( 2, $captured_etag_data );
-		$this->assertSame( array( 'tag_visitors' => array() ), $captured_etag_data[0] );
+		$this->assertSame(
+			array(
+				'tag_visitors'     => array(),
+				'queried_object'   => array(
+					'id'            => null,
+					'type'          => null,
+					'last_modified' => null,
+				),
+				'queried_posts'    => wp_list_pluck( $wp_the_query->posts, 'post_modified_gmt', 'ID' ),
+				'active_theme'     => array(
+					'template'   => array(
+						'name'    => 'od-theme',
+						'version' => '1.0.0',
+					),
+					'stylesheet' => array(
+						'name'    => 'od-theme',
+						'version' => '1.0.0',
+					),
+				),
+				'current_template' => 'index.php',
+			),
+			$captured_etag_data[0]
+		);
 		$this->assertSame( $captured_etag_data[ count( $captured_etag_data ) - 2 ], $captured_etag_data[ count( $captured_etag_data ) - 1 ] );
 
+		// Add new post.
+		$post_ids[] = self::factory()->post->create();
+		$wp_the_query->query( array() );
+		$etag3 = od_get_current_url_metrics_etag( $registry, $wp_the_query, $current_template );
+		$this->assertNotEquals( $etag2, $etag3 ); // Etag should change.
+		$this->assertNotEquals( $captured_etag_data[ count( $captured_etag_data ) - 2 ], $captured_etag_data[ count( $captured_etag_data ) - 1 ] );
+
+		// Update the post content.
+		usleep( 1000000 ); // Sleep for 1 second to ensure the post_modified_gmt is different from the previous value.
+		wp_update_post(
+			array(
+				'ID'           => $post_ids[0],
+				'post_content' => 'Updated post content',
+			)
+		);
+		$wp_the_query->query( array() );
+		$etag4 = od_get_current_url_metrics_etag( $registry, $wp_the_query, $current_template );
+		$this->assertNotEquals( $etag3, $etag4 );
+		$this->assertNotEquals( $captured_etag_data[ count( $captured_etag_data ) - 2 ], $captured_etag_data[ count( $captured_etag_data ) - 1 ] );
+
+		// Register new tag visitors.
 		$registry->register( 'foo', static function (): void {} );
 		$registry->register( 'bar', static function (): void {} );
 		$registry->register( 'baz', static function (): void {} );
-		$etag3 = od_get_current_url_metrics_etag( $registry );
-		$this->assertNotEquals( $etag2, $etag3 );
+		$etag5 = od_get_current_url_metrics_etag( $registry, $wp_the_query, $current_template );
+		$this->assertNotEquals( $etag4, $etag5 );
 		$this->assertNotEquals( $captured_etag_data[ count( $captured_etag_data ) - 2 ], $captured_etag_data[ count( $captured_etag_data ) - 1 ] );
-		$this->assertSame( array( 'tag_visitors' => array( 'foo', 'bar', 'baz' ) ), $captured_etag_data[ count( $captured_etag_data ) - 1 ] );
+		$this->assertSame(
+			array(
+				'tag_visitors'     => array( 'foo', 'bar', 'baz' ),
+				'queried_object'   => array(
+					'id'            => null,
+					'type'          => null,
+					'last_modified' => null,
+				),
+				'queried_posts'    => wp_list_pluck( $wp_the_query->posts, 'post_modified_gmt', 'ID' ),
+				'active_theme'     => array(
+					'template'   => array(
+						'name'    => 'od-theme',
+						'version' => '1.0.0',
+					),
+					'stylesheet' => array(
+						'name'    => 'od-theme',
+						'version' => '1.0.0',
+					),
+				),
+				'current_template' => 'index.php',
+			),
+			$captured_etag_data[ count( $captured_etag_data ) - 1 ]
+		);
+
+		// Modify data using filters.
+		add_filter(
+			'od_current_url_metrics_etag_data',
+			static function ( $data ) {
+				$data['active_theme']['template']['version']   = '2.0.0';
+				$data['active_theme']['stylesheet']['version'] = '2.0.0';
+				return $data;
+			}
+		);
+		$etag6 = od_get_current_url_metrics_etag( $registry, $wp_the_query, $current_template );
+		$this->assertNotEquals( $etag5, $etag6 );
+		$this->assertNotEquals( $captured_etag_data[ count( $captured_etag_data ) - 2 ], $captured_etag_data[ count( $captured_etag_data ) - 1 ] );
+		$this->assertSame(
+			array(
+				'tag_visitors'     => array( 'foo', 'bar', 'baz' ),
+				'queried_object'   => array(
+					'id'            => null,
+					'type'          => null,
+					'last_modified' => null,
+				),
+				'queried_posts'    => wp_list_pluck( $wp_the_query->posts, 'post_modified_gmt', 'ID' ),
+				'active_theme'     => array(
+					'template'   => array(
+						'name'    => 'od-theme',
+						'version' => '2.0.0',
+					),
+					'stylesheet' => array(
+						'name'    => 'od-theme',
+						'version' => '2.0.0',
+					),
+				),
+				'current_template' => 'index.php',
+			),
+			$captured_etag_data[ count( $captured_etag_data ) - 1 ]
+		);
+
 		add_filter(
 			'od_current_url_metrics_etag_data',
 			static function ( $data ): array {
-				$data['last_modified'] = '2024-03-02T01:00:00';
+				$data['queried_object'] = array(
+					'ID'            => 99,
+					'last_modified' => '2024-03-02T01:00:00',
+				);
 				return $data;
 			}
 		);
-		$etag4 = od_get_current_url_metrics_etag( $registry );
-		$this->assertNotEquals( $etag3, $etag4 );
+		$etag7 = od_get_current_url_metrics_etag( $registry, $wp_the_query, $current_template );
+		$this->assertNotEquals( $etag6, $etag7 );
 		$this->assertNotEquals( $captured_etag_data[ count( $captured_etag_data ) - 2 ], $captured_etag_data[ count( $captured_etag_data ) - 1 ] );
 		$this->assertSame(
 			array(
-				'tag_visitors'  => array( 'foo', 'bar', 'baz' ),
-				'last_modified' => '2024-03-02T01:00:00',
+				'tag_visitors'     => array( 'foo', 'bar', 'baz' ),
+				'queried_object'   => array(
+					'ID'            => 99,
+					'last_modified' => '2024-03-02T01:00:00',
+				),
+				'queried_posts'    => wp_list_pluck( $wp_the_query->posts, 'post_modified_gmt', 'ID' ),
+				'active_theme'     => array(
+					'template'   => array(
+						'name'    => 'od-theme',
+						'version' => '2.0.0',
+					),
+					'stylesheet' => array(
+						'name'    => 'od-theme',
+						'version' => '2.0.0',
+					),
+				),
+				'current_template' => 'index.php',
 			),
 			$captured_etag_data[ count( $captured_etag_data ) - 1 ]
 		);

plugins/optimization-detective/tests/test-optimization.php

@@ -27,17 +27,19 @@ class Test_OD_Optimization extends WP_UnitTestCase {
 	private $default_mimetype;
 
 	public function set_up(): void {
+		parent::set_up();
 		$this->original_request_uri    = $_SERVER['REQUEST_URI'];
 		$this->original_request_method = $_SERVER['REQUEST_METHOD'];
 		$this->default_mimetype        = (string) ini_get( 'default_mimetype' );
-		parent::set_up();
+		$GLOBALS['template']           = '/path/to/theme/index.php';
 	}
 
 	public function tear_down(): void {
 		$_SERVER['REQUEST_URI']    = $this->original_request_uri;
 		$_SERVER['REQUEST_METHOD'] = $this->original_request_method;
 		ini_set( 'default_mimetype', $this->default_mimetype ); // phpcs:ignore WordPress.PHP.IniSet.Risky
 		unset( $GLOBALS['wp_customize'] );
+		unset( $GLOBALS['template'] );
 		parent::tear_down();
 	}
 

tests/class-optimization-detective-test-helpers.php

@@ -27,7 +27,7 @@ trait Optimization_Detective_Test_Helpers {
 	 */
 	public function populate_url_metrics( array $elements, bool $complete = true ): void {
 		$slug        = od_get_url_metrics_slug( od_get_normalized_query_vars() );
-		$etag        = od_get_current_url_metrics_etag( new OD_Tag_Visitor_Registry() ); // Note: Tests rely on the od_current_url_metrics_etag_data filter to set the desired value.
+		$etag        = od_get_current_url_metrics_etag( new OD_Tag_Visitor_Registry(), new WP_Query(), 'index.php' ); // Note: Tests rely on the od_current_url_metrics_etag_data filter to set the desired value.
 		$sample_size = $complete ? od_get_url_metrics_breakpoint_sample_size() : 1;
 		foreach ( array_merge( od_get_breakpoint_max_widths(), array( 1000 ) ) as $viewport_width ) {
 			for ( $i = 0; $i < $sample_size; $i++ ) {
@@ -81,7 +81,7 @@ public function get_sample_dom_rect(): array {
 	public function get_sample_url_metric( array $params ): OD_URL_Metric {
 		$params = array_merge(
 			array(
-				'etag'           => od_get_current_url_metrics_etag( new OD_Tag_Visitor_Registry() ), // Note: Tests rely on the od_current_url_metrics_etag_data filter to set the desired value.
+				'etag'           => od_get_current_url_metrics_etag( new OD_Tag_Visitor_Registry(), new WP_Query(), 'index.php' ), // Note: Tests rely on the od_current_url_metrics_etag_data filter to set the desired value.
 				'url'            => home_url( '/' ),
 				'viewport_width' => 480,
 				'elements'       => array(),