/// <summary>
/// Enqueues <paramref name="msg"/> at the first position in the mailbox. If the message contained in
/// the envelope is a <see cref="Terminated"/> message, it will be ensured that it can be re-received
/// by the actor.
/// </summary>
private void EnqueueFirst(Envelope msg)
{
Mailbox.EnqueueFirst(msg);
var terminatedMessage = msg.Message as Terminated;
if (terminatedMessage != null)
{
_actorCell.TerminatedQueuedFor(terminatedMessage.ActorRef);
}
}