WP_Comment_Query::fill_descendants( WP_Comment[] $comments ): array

1038	protected function fill_descendants( $comments ) {1039		$levels = array(1040			0 => wp_list_pluck( $comments, 'comment_ID' ),1041		);1042 1043		$key          = md5( serialize( wp_array_slice_assoc( $this->query_vars, array_keys( $this->query_var_defaults ) ) ) );1044		$last_changed = wp_cache_get_last_changed( 'comment' );1045 1046		// Fetch an entire level of the descendant tree at a time.1047		$level        = 0;1048		$exclude_keys = array( 'parent', 'parent__in', 'parent__not_in' );1049		do {1050			// Parent-child relationships may be cached. Only query for those that are not.1051			$child_ids           = array();1052			$uncached_parent_ids = array();1053			$_parent_ids         = $levels[ $level ];1054			if ( $_parent_ids ) {1055				$cache_keys = array();1056				foreach ( $_parent_ids as $parent_id ) {1057					$cache_keys[ $parent_id ] = "get_comment_child_ids:$parent_id:$key";1058				}1059				$cache_data = wp_cache_get_multiple_salted( array_values( $cache_keys ), 'comment-queries', $last_changed );1060				foreach ( $_parent_ids as $parent_id ) {1061					$parent_child_ids = $cache_data[ $cache_keys[ $parent_id ] ];1062					if ( false !== $parent_child_ids ) {1063						$child_ids = array_merge( $child_ids, $parent_child_ids );1064					} else {1065						$uncached_parent_ids[] = $parent_id;1066					}1067				}1068			}1069 1070			if ( $uncached_parent_ids ) {1071				// Fetch this level of comments.1072				$parent_query_args = $this->query_vars;1073				foreach ( $exclude_keys as $exclude_key ) {1074					$parent_query_args[ $exclude_key ] = '';1075				}1076				$parent_query_args['parent__in']    = $uncached_parent_ids;1077				$parent_query_args['no_found_rows'] = true;1078				$parent_query_args['hierarchical']  = false;1079				$parent_query_args['offset']        = 0;1080				$parent_query_args['number']        = 0;1081 1082				$level_comments = get_comments( $parent_query_args );1083 1084				// Cache parent-child relationships.1085				$parent_map = array_fill_keys( $uncached_parent_ids, array() );1086				foreach ( $level_comments as $level_comment ) {1087					$parent_map[ $level_comment->comment_parent ][] = $level_comment->comment_ID;1088					$child_ids[]                                    = $level_comment->comment_ID;1089				}1090 1091				$data = array();1092				foreach ( $parent_map as $parent_id => $children ) {1093					$cache_key          = "get_comment_child_ids:$parent_id:$key";1094					$data[ $cache_key ] = $children;1095				}1096				wp_cache_set_multiple_salted( $data, 'comment-queries', $last_changed );1097			}1098 1099			++$level;1100			$levels[ $level ] = $child_ids;1101		} while ( $child_ids );1102 1103		// Prime comment caches for non-top-level comments.1104		$descendant_ids = array();1105		for ( $i = 1, $c = count( $levels ); $i < $c; $i++ ) {1106			$descendant_ids = array_merge( $descendant_ids, $levels[ $i ] );1107		}1108 1109		_prime_comment_caches( $descendant_ids, $this->query_vars['update_comment_meta_cache'] );1110 1111		// Assemble a flat array of all comments + descendants.1112		$all_comments = $comments;1113		foreach ( $descendant_ids as $descendant_id ) {1114			$all_comments[] = get_comment( $descendant_id );1115		}1116 1117		// If a threaded representation was requested, build the tree.