Source

File: wp-includes/comment.php

function wp_update_comment_count_now( $post_id ) {
	global $wpdb;
	$post_id = (int) $post_id;
	if ( ! $post_id ) {
		return false;
	}

	wp_cache_delete( 'comments-0', 'counts' );
	wp_cache_delete( "comments-{$post_id}", 'counts' );

	$post = get_post( $post_id );
	if ( ! $post ) {
		return false;
	}

	$old = (int) $post->comment_count;

	/**
	 * Filters a post's comment count before it is updated in the database.
	 *
	 * @since 4.5.0
	 *
	 * @param int|null $new     The new comment count. Default null.
	 * @param int      $old     The old comment count.
	 * @param int      $post_id Post ID.
	 */
	$new = apply_filters( 'pre_wp_update_comment_count_now', null, $old, $post_id );

	if ( is_null( $new ) ) {
		$new = (int) $wpdb->get_var( $wpdb->prepare( "SELECT COUNT(*) FROM $wpdb->comments WHERE comment_post_ID = %d AND comment_approved = '1'", $post_id ) );
	} else {
		$new = (int) $new;
	}

	$wpdb->update( $wpdb->posts, array( 'comment_count' => $new ), array( 'ID' => $post_id ) );

	clean_post_cache( $post );

	/**
	 * Fires immediately after a post's comment count is updated in the database.
	 *
	 * @since 2.3.0
	 *
	 * @param int $post_id Post ID.
	 * @param int $new     The new comment count.
	 * @param int $old     The old comment count.
	 */
	do_action( 'wp_update_comment_count', $post_id, $new, $old );

	/** This action is documented in wp-includes/post.php */
	do_action( "edit_post_{$post->post_type}", $post_id, $post );

	/** This action is documented in wp-includes/post.php */
	do_action( 'edit_post', $post_id, $post );

	return true;
}