From 4258f31a3b6a44e195f78e3a45c9282e0693715c Mon Sep 17 00:00:00 2001
From: Peter Wilson <wilson@peterwilson.cc>
Date: Thu, 12 Oct 2023 23:41:23 +0000
Subject: [PATCH] Query: Cache post parent IDs in `posts` group.

Move the cache of post parent IDs from the dedicated group `post_parents` to `posts`. This maintains backward compatibility for clearing all post object related data by calling `wp_cache_flush_group( 'posts' )`.

Post parent IDs are now cached with with the prefix `post_parent:` in the `posts` group.

Follow up to [56763].

Props spacedmonkey, joemcgill, peterwilsoncc.
See #59188.

Built from https://develop.svn.wordpress.org/trunk@56925


git-svn-id: http://core.svn.wordpress.org/trunk@56436 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/class-wp-query.php | 22 +++++++++++++++-------
 wp-includes/post.php           | 28 ++++++++++++++++++++++++----
 wp-includes/version.php        |  2 +-
 3 files changed, 40 insertions(+), 12 deletions(-)

diff --git a/wp-includes/class-wp-query.php b/wp-includes/class-wp-query.php
index e79f460fc5..a9ed269d72 100644
--- a/wp-includes/class-wp-query.php
+++ b/wp-includes/class-wp-query.php
@@ -3192,12 +3192,17 @@ class WP_Query {
 					} elseif ( 'id=>parent' === $q['fields'] ) {
 						_prime_post_parent_id_caches( $post_ids );
 
-						/** @var int[] */
-						$post_parents = wp_cache_get_multiple( $post_ids, 'post_parent' );
+						$post_parent_cache_keys = array();
+						foreach ( $post_ids as $post_id ) {
+							$post_parent_cache_keys[] = 'post_parent:' . (string) $post_id;
+						}
 
-						foreach ( $post_parents as $id => $post_parent ) {
+						/** @var int[] */
+						$post_parents = wp_cache_get_multiple( $post_parent_cache_keys, 'posts' );
+
+						foreach ( $post_parents as $cache_key => $post_parent ) {
 							$obj              = new stdClass();
-							$obj->ID          = (int) $id;
+							$obj->ID          = (int) str_replace( 'post_parent:', '', $cache_key );
 							$obj->post_parent = (int) $post_parent;
 
 							$this->posts[] = $obj;
@@ -3245,8 +3250,9 @@ class WP_Query {
 			$this->set_found_posts( $q, $limits );
 
 			/** @var int[] */
-			$post_parents = array();
-			$post_ids     = array();
+			$post_parents       = array();
+			$post_ids           = array();
+			$post_parents_cache = array();
 
 			foreach ( $this->posts as $key => $post ) {
 				$this->posts[ $key ]->ID          = (int) $post->ID;
@@ -3254,9 +3260,11 @@ class WP_Query {
 
 				$post_parents[ (int) $post->ID ] = (int) $post->post_parent;
 				$post_ids[]                      = (int) $post->ID;
+
+				$post_parents_cache[ 'post_parent:' . (string) $post->ID ] = (int) $post->post_parent;
 			}
 			// Prime post parent caches, so that on second run, there is not another database query.
-			wp_cache_add_multiple( $post_parents, 'post_parent' );
+			wp_cache_add_multiple( $post_parents_cache, 'posts' );
 
 			if ( $q['cache_results'] && $id_query_is_cacheable ) {
 				$cache_value = array(
diff --git a/wp-includes/post.php b/wp-includes/post.php
index c3910d2b3a..edad5218fa 100644
--- a/wp-includes/post.php
+++ b/wp-includes/post.php
@@ -7270,8 +7270,8 @@ function clean_post_cache( $post ) {
 	}
 
 	wp_cache_delete( $post->ID, 'posts' );
+	wp_cache_delete( 'post_parent:' . (string) $post->ID, 'posts' );
 	wp_cache_delete( $post->ID, 'post_meta' );
-	wp_cache_delete( $post->ID, 'post_parent' );
 
 	clean_object_term_cache( $post->ID, $post->post_type );
 
@@ -7817,17 +7817,37 @@ function _prime_post_caches( $ids, $update_term_cache = true, $update_meta_cache
 function _prime_post_parent_id_caches( array $ids ) {
 	global $wpdb;
 
-	$non_cached_ids = _get_non_cached_ids( $ids, 'post_parent' );
+	$ids = array_filter( $ids, '_validate_cache_id' );
+	$ids = array_unique( array_map( 'intval', $ids ), SORT_NUMERIC );
+
+	if ( empty( $ids ) ) {
+		return;
+	}
+
+	$cache_keys = array();
+	foreach ( $ids as $id ) {
+		$cache_keys[ $id ] = 'post_parent:' . (string) $id;
+	}
+
+	$cached_data = wp_cache_get_multiple( array_values( $cache_keys ), 'posts' );
+
+	$non_cached_ids = array();
+	foreach ( $cache_keys as $id => $cache_key ) {
+		if ( false === $cached_data[ $cache_key ] ) {
+			$non_cached_ids[] = $id;
+		}
+	}
+
 	if ( ! empty( $non_cached_ids ) ) {
 		$fresh_posts = $wpdb->get_results( sprintf( "SELECT $wpdb->posts.ID, $wpdb->posts.post_parent FROM $wpdb->posts WHERE ID IN (%s)", implode( ',', $non_cached_ids ) ) );
 
 		if ( $fresh_posts ) {
 			$post_parent_data = array();
 			foreach ( $fresh_posts as $fresh_post ) {
-				$post_parent_data[ (int) $fresh_post->ID ] = (int) $fresh_post->post_parent;
+				$post_parent_data[ 'post_parent:' . (string) $fresh_post->ID ] = (int) $fresh_post->post_parent;
 			}
 
-			wp_cache_add_multiple( $post_parent_data, 'post_parent' );
+			wp_cache_add_multiple( $post_parent_data, 'posts' );
 		}
 	}
 }
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 6c571591b5..16a9fdd027 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.4-beta4-56923';
+$wp_version = '6.4-beta4-56925';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.