Ticket #42252: 42252.6.diff

src/wp-includes/class-wp-site-query.php

@@ -240 +240 @@
                  */
                 do_action_ref_array( 'pre_get_sites', array( &$this ) );
 
-                // $args can include anything. Only use the args defined in the query_var_defaults to compute the key.
-                $_args = wp_array_slice_assoc( $this->query_vars, array_keys( $this->query_var_defaults ) );
-
-                // Ignore the $fields argument as the queried result will be the same regardless.
-                unset( $_args['fields'] );
-
-                $key          = md5( serialize( $_args ) );
-                $last_changed = wp_cache_get_last_changed( 'sites' );
-
-                $cache_key   = "get_sites:$key:$last_changed";
+                $cache_key   = $this->get_cache_key( $this->query_vars );
                 $cache_value = wp_cache_get( $cache_key, 'sites' );
 
                 if ( false === $cache_value ) {
@@ -698 +689 @@
                         return 'DESC';
                 }
         }
+
+        /**
+         * Generates the cache key to lookup query results for a specific set of arguments.
+         *
+         * @since 5.0.0
+         *
+         * @param array $query_vars Array of WP_Site_Query arguments. See WP_Site_Query::__construct().
+         * @return string Cache key to use for the lookup.
+         */
+        protected function get_cache_key( $query_vars ) {
+                // $args can include anything. Only use the args defined in the query_var_defaults to compute the key.
+                $_args = wp_array_slice_assoc( $query_vars, array_keys( $this->query_var_defaults ) );
+
+                // Ignore the $fields argument as the queried result will be the same regardless.
+                unset( $_args['fields'] );
+
+                // Ignore the $update_site_cache as it does not affect the query.
+                unset( $_args['update_site_cache'] );
+
+                // Use the same cache key for array lookups with one element and single value lookups.
+                $single_multi_mappings = array(
+                        'ID'         => 'site__in',
+                        'network_id' => 'network__in',
+                        'domain'     => 'domain__in',
+                        'path'       => 'path__in',
+                        'lang_id'    => 'lang__in',
+                );
+                foreach ( $single_multi_mappings as $single_var => $multi_var ) {
+                        if ( empty( $_args[ $single_var ] ) && isset( $_args[ $multi_var ] ) && is_array( $_args[ $multi_var ] ) && count( $_args[ $multi_var ] ) === 1 ) {
+                                $_args[ $single_var ] = array_pop( $_args[ $multi_var ] );
+                                $_args[ $multi_var ] = '';
+                        }
+                }
+
+                $key = md5( serialize( $_args ) );
+
+                /* The following part of the code checks some common combinations of query vars.
+                 * If all non-empty values that actually affect the last_changed date for the query
+                 * belong to one of the special argument combinations, a more specific last_changed
+                 * cache key is used instead of the global one. */
+
+                // Only consider arguments that are not empty and have thus been passed to the query.
+                $used_args = array_filter( $_args );
+
+                // The following arguments affect the query result, but not its last_changed value.
+                $ignore_args = array( 'number', 'offset', 'no_found_rows', 'orderby', 'order', 'count' );
+                $used_args   = array_diff_key( $used_args, array_flip( $ignore_args ) );
+
+                // The following arguments are relevant for a special 'last_changed' prefix.
+                $last_changed_keys = array( 'domain', 'path', 'network_id' );
+
+                $last_changed_args = array();
+                foreach ( $last_changed_keys as $key ) {
+                        if ( isset( $used_args[ $key ] ) ) {
+                                $last_changed_args[ $key ] = (string) $used_args[ $key ];
+                                unset( $used_args[ $key ] );
+                        }
+                }
+
+                // Only use a special 'last_changed' prefix if no other arguments are present.
+                if ( ! empty( $last_changed_args ) && empty( $used_args ) ) {
+                        $last_changed_prefix = md5( serialize( $last_changed_args ) ) . '_';
+                } else {
+                        $last_changed_prefix = '';
+                }
+
+                $last_changed = wp_cache_get_last_changed( 'sites', $last_changed_prefix );
+
+                return "get_sites:$key:$last_changed";
+        }
 }

src/wp-includes/functions.php

@@ -5952 +5952 @@
  * Get last changed date for the specified cache group.
  *
  * @since 4.7.0
+ * @since 5.0.0 Now supports the $prefix parameter.
  *
- * @param string $group Where the cache contents are grouped.
+ * @param string $group  Where the cache contents are grouped.
+ * @param string $prefix Optional. Prefix to look for a specific last changed key. Default empty string.
  *
  * @return string $last_changed UNIX timestamp with microseconds representing when the group was last changed.
  */
-function wp_cache_get_last_changed( $group ) {
-        $last_changed = wp_cache_get( 'last_changed', $group );
+function wp_cache_get_last_changed( $group, $prefix = '' ) {
+        $key = $prefix . 'last_changed';
+
+        $last_changed = wp_cache_get( $key, $group );
 
         if ( ! $last_changed ) {
                 $last_changed = microtime();
-                wp_cache_set( 'last_changed', $last_changed, $group );
+                wp_cache_set( $key, $last_changed, $group );
         }
 
         return $last_changed;

src/wp-includes/ms-blogs.php

@@ -459 +459 @@
                                 'blog_id' => $blog_id,
                                 'domain'  => null,
                                 'path'    => null,
+                                'site_id' => get_current_network_id(),
                         )
                 );
         }
@@ -486 +487 @@
          */
         do_action( 'clean_site_cache', $blog_id, $blog, $domain_path_key );
 
-        wp_cache_set( 'last_changed', microtime(), 'sites' );
+        $current_time = microtime();
+
+        // The following arguments are relevant for a special 'last_changed' prefix.
+        $last_changed_args = array(
+                'domain'     => $blog->domain,
+                'path'       => $blog->path,
+                'network_id' => $blog->site_id,
+        );
+
+        $last_changed_prefixes = array( '' );
+
+        // Generate all possible variations.
+        $combinations = array( array() );
+        foreach ( $last_changed_args as $key => $value ) {
+                $value = (string) $value;
+
+                foreach ( $combinations as $combination ) {
+                        $current_args = array_merge( $combination, array( $key => $value ) );
+                        $last_changed_prefixes[] = md5( serialize( $current_args ) ) . '_';
+
+                        $combinations[] = $current_args;
+                }
+        }
+
+        foreach ( $last_changed_prefixes as $last_changed_prefix ) {
+                wp_cache_set( $last_changed_prefix . 'last_changed', $current_time, 'sites' );
+        }
 
         /**
          * Fires after the blog details cache is cleared.