Index: src/wp-includes/class-wp-site-query.php =================================================================== --- src/wp-includes/class-wp-site-query.php (revision 42373) +++ src/wp-includes/class-wp-site-query.php (working copy) @@ -240,16 +240,7 @@ */ 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 ) { @@ -698,4 +689,74 @@ 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"; + } } Index: src/wp-includes/functions.php =================================================================== --- src/wp-includes/functions.php (revision 42373) +++ src/wp-includes/functions.php (working copy) @@ -5952,17 +5952,21 @@ * 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; Index: src/wp-includes/ms-blogs.php =================================================================== --- src/wp-includes/ms-blogs.php (revision 42373) +++ src/wp-includes/ms-blogs.php (working copy) @@ -459,6 +459,7 @@ 'blog_id' => $blog_id, 'domain' => null, 'path' => null, + 'site_id' => get_current_network_id(), ) ); } @@ -486,7 +487,33 @@ */ 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.