Ceph » Messengers

wip-7888 handles this for MonClient. We can do the same with Objecter, but this is less critical because we will find out via the osdmap if they are really down.

There is a bit of a concern about this whole approach, though: if the server isn't reading data because it has hit its memory throttle, the client may time out and reconnect, resending a bunch of the same messages, making the memory pressure even worse. It really is better if this can be handled a bit lower down in the protocol layer.

Alternatively, the Messenger throttle could be redone so that it is cooperative and never stops reading data off the socket. But then we end up having to implement all the same flow control that TCP is already giving us... meh!