Posts, Post Types: Avoid unnecessarily parsing blocks twice in `wp_tr…

…im_excerpt()`.

All blocks relevant for the excerpt are already being parsed in `excerpt_remove_blocks()`. Therefore running `do_blocks()` on the post content only to create the excerpt is unnecessary and wasteful from a performance perspective.

Props thekt12, spacedmonkey, mukesh27, joemcgill.
Fixes #58682.


git-svn-id: https://develop.svn.wordpress.org/trunk@56560 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/blocks.php

@@ -956,6 +956,10 @@ function filter_block_kses_value( $value, $allowed_html, $allowed_protocols = ar
  * @return string The parsed and filtered content.
  */
 function excerpt_remove_blocks( $content ) {
+	if ( ! has_blocks( $content ) ) {
+		return $content;
+	}
+
 	$allowed_inner_blocks = array(
 		// Classic blocks have their blockName set to null.
 		null,

src/wp-includes/formatting.php

@@ -3980,18 +3980,29 @@ function wp_trim_excerpt( $text = '', $post = null ) {
 		 * within the excerpt are stripped out. Modifying the tags here
 		 * is wasteful and can lead to bugs in the image counting logic.
 		 */
-		$filter_removed = remove_filter( 'the_content', 'wp_filter_content_tags' );
+		$filter_image_removed = remove_filter( 'the_content', 'wp_filter_content_tags' );
+
+		/*
+		 * Temporarily unhook do_blocks() since excerpt_remove_blocks( $text )
+		 * handels block rendering needed for excerpt.
+		 */
+		$filter_block_removed = remove_filter( 'the_content', 'do_blocks', 9 );
 
 		/** This filter is documented in wp-includes/post-template.php */
 		$text = apply_filters( 'the_content', $text );
 		$text = str_replace( ']]>', ']]>', $text );
 
-		/**
+		// Restore the original filter if removed.
+		if ( $filter_block_removed ) {
+			add_filter( 'the_content', 'do_blocks', 9 );
+		}
+
+		/*
 		 * Only restore the filter callback if it was removed above. The logic
 		 * to unhook and restore only applies on the default priority of 10,
 		 * which is generally used for the filter callback in WordPress core.
 		 */
-		if ( $filter_removed ) {
+		if ( $filter_image_removed ) {
 			add_filter( 'the_content', 'wp_filter_content_tags' );
 		}
 

tests/phpunit/tests/formatting/wpTrimExcerpt.php

@@ -148,4 +148,85 @@ public function test_wp_trim_excerpt_does_not_restore_wp_filter_content_tags_if_
 		// Assert that the filter callback was not restored after running 'the_content'.
 		$this->assertFalse( has_filter( 'the_content', 'wp_filter_content_tags' ) );
 	}
+
+	/**
+	 * Tests that `wp_trim_excerpt()` does process valid blocks.
+	 *
+	 * @ticket 58682
+	 *
+	 * @covers ::wp_trim_excerpt
+	 */
+	public function test_wp_trim_excerpt_check_if_block_renders() {
+		$post = self::factory()->post->create(
+			array(
+				'post_content' => '<!-- wp:paragraph --> <p>A test paragraph</p> <!-- /wp:paragraph -->',
+			)
+		);
+
+		$output_text = wp_trim_excerpt( '', $post );
+
+		$this->assertSame( 'A test paragraph', $output_text, 'wp_trim_excerpt() did not process paragraph block.' );
+	}
+
+	/**
+	 * Tests that `wp_trim_excerpt()` unhooks `do_blocks()` from 'the_content' filter.
+	 *
+	 * @ticket 58682
+	 *
+	 * @covers ::wp_trim_excerpt
+	 */
+	public function test_wp_trim_excerpt_unhooks_do_blocks() {
+		$post = self::factory()->post->create();
+
+		/*
+		 * Record that during 'the_content' filter run by wp_trim_excerpt() the
+		 * do_blocks() callback is not used.
+		 */
+		$has_filter = true;
+		add_filter(
+			'the_content',
+			static function( $content ) use ( &$has_filter ) {
+				$has_filter = has_filter( 'the_content', 'do_blocks' );
+				return $content;
+			}
+		);
+
+		wp_trim_excerpt( '', $post );
+
+		$this->assertFalse( $has_filter, 'do_blocks() was not unhooked in wp_trim_excerpt()' );
+	}
+
+	/**
+	 * Tests that `wp_trim_excerpt()` doesn't permanently unhook `do_blocks()` from 'the_content' filter.
+	 *
+	 * @ticket 58682
+	 *
+	 * @covers ::wp_trim_excerpt
+	 */
+	public function test_wp_trim_excerpt_should_not_permanently_unhook_do_blocks() {
+		$post = self::factory()->post->create();
+
+		wp_trim_excerpt( '', $post );
+
+		$this->assertSame( 9, has_filter( 'the_content', 'do_blocks' ), 'do_blocks() was not restored in wp_trim_excerpt()' );
+	}
+
+	/**
+	 * Tests that `wp_trim_excerpt()` doesn't restore `do_blocks()` if it was previously unhooked.
+	 *
+	 * @ticket 58682
+	 *
+	 * @covers ::wp_trim_excerpt
+	 */
+	public function test_wp_trim_excerpt_does_not_restore_do_blocks_if_previously_unhooked() {
+		$post = self::factory()->post->create();
+
+		// Remove do_blocks() from 'the_content' filter generally.
+		remove_filter( 'the_content', 'do_blocks', 9 );
+
+		wp_trim_excerpt( '', $post );
+
+		// Assert that the filter callback was not restored after running 'the_content'.
+		$this->assertFalse( has_filter( 'the_content', 'do_blocks' ) );
+	}
 }