blob: b754519066011419a69e5ef4e34e9eff13d5ae1a [file] [log] [blame]
// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import 'dart:collection';
import 'resource_record.dart';
/// Cache for resource records that have been received.
/// There can be multiple entries for the same name and type.
/// The cache is updated with a list of records, because it needs to remove
/// all entries that correspond to the name and type of the name/type
/// combinations of records that should be updated. For example, a host may
/// remove one of its IP addresses and report the remaining address as a
/// response - then we need to clear all previous entries for that host before
/// updating the cache.
class ResourceRecordCache {
/// Creates a new ResourceRecordCache.
final Map<int, SplayTreeMap<String, List<ResourceRecord>>> _cache =
<int, SplayTreeMap<String, List<ResourceRecord>>>{};
/// The number of entries in the cache.
int get entryCount {
int count = 0;
for (final SplayTreeMap<String, List<ResourceRecord>> map
in _cache.values) {
for (final List<ResourceRecord> records in map.values) {
count += records.length;
return count;
/// Update the records in this cache.
void updateRecords(List<ResourceRecord> records) {
// TODO(karlklose): include flush bit in the record and only flush if
// necessary.
// Clear the cache for all name/type combinations to be updated.
final Map<int, Set<String>> seenRecordTypes = <int, Set<String>>{};
for (final ResourceRecord record in records) {
// TODO(dnfield): Update this to use set literal syntax when we're able to bump the SDK constraint.
seenRecordTypes[record.resourceRecordType] ??=
Set<String>(); // ignore: prefer_collection_literals
if (seenRecordTypes[record.resourceRecordType]!.add( {
_cache[record.resourceRecordType] ??=
SplayTreeMap<String, List<ResourceRecord>>();
_cache[record.resourceRecordType]![] = <ResourceRecord>[
} else {
/// Get a record from this cache.
void lookup<T extends ResourceRecord>(
String name, int type, List<T> results) {
final int time =;
final SplayTreeMap<String, List<ResourceRecord>>? candidates = _cache[type];
if (candidates == null) {
final List<ResourceRecord>? candidateRecords = candidates[name];
if (candidateRecords == null) {
.removeWhere((ResourceRecord candidate) => candidate.validUntil < time);