private async IAsyncEnumerable <CommandResponse> InvokeCore(CommandRequest request, bool relayEvents, [EnumeratorCancellation] CancellationToken cancellationToken = default)
{
if (request.CommandTypeName == null)
{
throw new ArgumentException("Command type is not specified.", nameof(request));
}
var commandType = Type.GetType(request.CommandTypeName + "," + s_serviceContractAssemblyName, throwOnError: true) !;
if (!commandType.HasInterface(typeof(ICommand)))
{
throw new ArgumentException("Command type is invalid.", nameof(request));
}
var command = (ICommand)ServiceHostContractSerializer.Default.Deserialize(request.SerializedCommand ?? Array.Empty <byte>(), commandType);
ServiceErrorException?errorException = null;
object?key = null;
Action <ICommand, object>?handleKeyGenerated;
var keyGeneratorCommand = command as IKeyGeneratorCommand;
if (keyGeneratorCommand != null)
{
handleKeyGenerated = (_, k) => key = k;
keyGeneratorCommand.OnKeyGenerated += handleKeyGenerated;
}
else
{
handleKeyGenerated = null;
}
try
{
Task dispatchTask;
if (relayEvents && command is IEventProducerCommand eventProducerCommand)
{
var eventChannel = Channel.CreateUnbounded <Event>(s_eventChannelOptions);
eventProducerCommand.OnEvent = (_, @event) => eventChannel.Writer.TryWrite(@event);
dispatchTask = Task.Run(async() =>
{
try { await _commandDispatcher.DispatchAsync(command, cancellationToken); }
finally { eventChannel.Writer.Complete(); }
});
while (await eventChannel.Reader.WaitToReadAsync(cancellationToken))
{
while (eventChannel.Reader.TryRead(out var @event))
{
yield return new CommandResponse.Notification
{
Event = new EventData {
Value = @event
}
}
}
}
;
}
else
{
dispatchTask = _commandDispatcher.DispatchAsync(command, cancellationToken);
}
try { await dispatchTask; }
catch (ServiceErrorException ex) { errorException = ex; }
}
finally
{
if (keyGeneratorCommand != null)
{
keyGeneratorCommand.OnKeyGenerated -= handleKeyGenerated;
}
}
if (errorException != null)
{
yield return new CommandResponse.Failure {
Error = errorException.ToData()
}
}
;
else
{
yield return new CommandResponse.Success {
Key = key != null?KeyData.From(key) : null
}
};
}