def msg_reply(conf, msg_id, reply_q, connection_pool, reply=None,
failure=None, ending=False, log_failure=True):
"""Sends a reply or an error on the channel signified by msg_id.
Failure should be a sys.exc_info() tuple.
"""
with ConnectionContext(conf, connection_pool) as conn:
if failure:
failure = rpc_common.serialize_remote_exception(failure,
log_failure)
msg = {'result': reply, 'failure': failure}
if ending:
msg['ending'] = True
_add_unique_id(msg)
# If a reply_q exists, add the msg_id to the reply and pass the
# reply_q to direct_send() to use it as the response queue.
# Otherwise use the msg_id for backward compatibilty.
if reply_q:
msg['_msg_id'] = msg_id
conn.direct_send(reply_q, rpc_common.serialize_msg(msg))
else:
conn.direct_send(msg_id, rpc_common.serialize_msg(msg))
