const envoy::extensions::common::dynamic_forward_proxy::v3::DnsCacheConfig& config) {

  const auto& existing_cache = caches_.find(config.name());

  if (existing_cache != caches_.end()) {

    if (!Protobuf::util::MessageDifferencer::Equivalent(config, existing_cache->second.config_)) {

      return absl::InvalidArgumentError(

          fmt::format("config specified DNS cache '{}' with different settings", config.name()));

    }

    return existing_cache->second.cache_;

  }

  auto cache_or_status = DnsCacheImpl::createDnsCacheImpl(context_, config);

  RETURN_IF_NOT_OK_REF(cache_or_status.status());

  DnsCacheSharedPtr new_cache = std::move(cache_or_status.value());

  caches_.emplace(config.name(), ActiveCache{config, new_cache});

  return new_cache;

}

DnsCacheSharedPtr DnsCacheManagerImpl::lookUpCacheByName(absl::string_view cache_name) {

  ASSERT(context_.serverFactoryContext().mainThreadDispatcher().isThreadSafe());

  const auto& existing_cache = caches_.find(cache_name);

  if (existing_cache != caches_.end()) {

    return existing_cache->second.cache_;

  }

  return nullptr;

}

DnsCacheManagerSharedPtr DnsCacheManagerFactoryImpl::get() {

  return context_.serverFactoryContext().singletonManager().getTyped<DnsCacheManager>(

      SINGLETON_MANAGER_REGISTERED_NAME(dns_cache_manager),

      [this] { return std::make_shared<DnsCacheManagerImpl>(context_); });

}