Add timeout to basic_publish and improve logging #732

[reidsunderland]

This makes some improvements but doesn't fix 732 yet.

It adds a timeout to publishing messages, which might help prevent hangs and improve error recovery when a broker isn't working. If the publish times out, it will raise an exception instead of hanging. The additional logging also helps troubleshooting - it was unclear where the publishing was getting stuck before.

The only thing missing is adding a timeout to the self.channel.tx_commit() call. We had talked about doing something similar to how timeouts are implemented here:

sarracenia/sarracenia/transfer/__init__.py

Line 60 in bcf4f47

def alarm_raise(n, f):

#732 (comment)