DnsExt doesn't respect IDnsProvider.ManagerClass and always uses hard-coded SimpleDnsManager

[anpin]

DnsExt doesn't respect IDnsProvider.ManagerClass and always uses hard-coded SimpleDnsManager

Related to akkadotnet/Akka.Management#3365

akka.net/src/core/Akka/IO/Dns.cs

Line 278 in c10cfc1

return _manager = _manager ?? _system.SystemActorOf(Props.Create(() => new SimpleDnsManager(this))

For example with such config

akka.io.dns.resolver = async-dns
akka.io.dns.async-dns.provider-object = MyCustomDnsProviderFQDNClass, MyCustomDnsProviderAssembly 

and such class

public class MyCustomDnsProviderFQDNClass : IDnsProvider
{
    private readonly DnsBase _cache = new SimpleDnsCache();
    public DnsBase Cache => _cache;
    public Type ActorClass => typeof (DnsClientActor);
    public Type ManagerClass => typeof (DnsClientManager);
}

DnsExt will still use SimpleDnsManager. However SimpleDnsManager will use custom IDnsProvider.ActorClass and it will be instantiated if constructor has the same signature, but it will fail to work if messages sent to the SimpleDnsManager have different type.

[anpin]

in the linked PR I was able to workaround the issue by overriding DnsExt with such class

public class AsyncDnsExt : DnsExt
{
    public AsyncDnsExt(ExtendedActorSystem system) : base(system)
    {
        _system = system;
    }
    private readonly ExtendedActorSystem _system;
    private IActorRef? _manager; 
    public override IActorRef Manager 
    {
        get
        {
            // base implementation doesn't respect custom provider/manager settings, perhpaps on purpouse 
            return _manager = _manager ??  _system.SystemActorOf(Props.Create(Provider.ManagerClass, this)
                .WithDeploy(Deploy.Local)
                .WithDispatcher(Settings.Dispatcher));
        }
    }
}

[Aaronontheweb]

Yeah we should just fix this by changing the configuration - and, honestly, does the SimpleDnsManager suck? If so, we should deprecate it and try to remove it in v1.6

[Aaronontheweb]

@anpin merged your PR!