This aides in detecting connection interruptions that would otherwise
go unnoticed.

Fixes bug #856764

Change-Id: Id4eb3d36036969b62890175d6a33b4e304be0527

This change replace sys.exit by a RPCException like the zmq
implementation does, to allow library users to handle the case of the
rpc failure in their applications.

Change-Id: Iafda7bfa20840fa5488dece1d5ad49e2b14b73b5

bug 1189711 Should RPC consume_in_thread() be more fault tolerant?

There are unprotected holes in the thread kicked off by RPC
consume_in_thread such that an exception will kill the thread.
This exists for both the service (TopicConsumer) and the new
reply proxy (DirectConsumer) consumers. This patch plugs
those holes as close to the base of the consumer thread as
possible by catching all non-caught exceptions and retrying
with sleeps between retries and some pacing of the log
output to prevent log flooding.

Change-Id: I0d6ec8a5e3a310314da201656ee862bb40b41616

The first commit of Nova contains this code as

 https://github.com/openstack/nova/blob/bf6e6e7/nova/rpc.py#L149

    try:
        publisher.send({'result': reply})
    except TypeError:
        publisher.send(
                {'result': dict((k, repr(v))
                                for k, v in reply.__dict__.iteritems())
                 })

but when the kombu driver was first added, it became:

 https://github.com/openstack/nova/blob/9cb46c48/nova/rpc/impl_kombu.py#L717

        try:
            msg = {'result': reply, 'failure': failure}
        except TypeError:
            msg = {'result': dict((k, repr(v))
                            for k, v in reply.__dict__.iteritems()),
                    'failure': failure}
        conn.direct_send(msg_id, msg)

Obviously, TypeError can't be raised with the current code and we dump
everything to json these days before passing down to kombu, qpid, etc.

Change-Id: I932fbfbbe824fbd9de8d31f070878e9db853ee45

Rather than blindly ack() all messages, consumers can be created
that reject() the message if an exception occurs in the callback.

Currently only implemented in kombu driver.

Change-Id: I308dd794b50966e3a189d31b2b51fdac36cd7d3a

Fixes bug #1188029

This relay functionality appears to be completely unused and untested
so just remove it. If we need it in future, we can restore it from the
git history.

Change-Id: I479d654aefdbd58c80946818b9a405eaa02644db