Improve Communication between LustreFileCreationCheckTask and Pushgateway Client

[gabrieleiannetti]

LustreFileCreationCheckTask just sends asynchronous task result to Pushgateway Client without getting an answer back. So the task cannot determine if the Pushgateway Client received the result.

The Communication BaseHandler class could be extended with a pair of methods for synchronized message exchange wrapping the underlying calls to recv+send and send+recv calls e.g.

• task.sync_send()

1. send()
2. recv()

• pushgateway_client.sync_recv()

1. recv()
2. send()