FakeStatsdClient: Stop issuing DNS calls for host.

Running unittests on my home server, even though is a beast, would be
painfully slow. Running them on my laptop ran much faster. I tried
everything and couldn't figure it out.
Chris, co-author, dug in and after we ran out of options he fired up his
packet capture and realised most tests were issuing DNS queries for
`host.`. On my home server, it runs ipv6 dual stack, so these calls
would need to timeout before a test can continue.

On finding this `host.` Ben, another co-author, dug into the code and
found the only reference we have to `host` is in FakeStatsdClient.

Sure enough as I dug a little further it turns out our FakeStatsdClient
used to override a StatsdClient function `_determine_sock_family(self,
host, port)` to stop actually creating a real socket.
However, at some point the StatsdClient was refactored and that method
was renamed and changed. Which leads to a DNS lookup every time we
create a debug_logger as it brings up the socket.
As you can imagine, this happens alot!

This patch overrides the new function that handles to socket creation
`_set_sock_family_and_target(self, host, port)`. Which eliminates the
DNS call all together.

Co-Authored-By: Ben Formosa <[email protected]>
Co-Authored-By: Chris Smart <[email protected]>
Change-Id: Ie393075f79447627714692e3f01bb53e967a71e8

Author: 3 people

test/debug_logger.py

@@ -65,8 +65,8 @@ def wrapper(*args, **kwargs):
             return func(*args, **kwargs)
         return wrapper
 
-    def _determine_sock_family(self, host, port):
-        return None, None
+    def _set_sock_family_and_target(self, host, port):
+        self._target = (host, port)
 
     def _open_socket(self):
         return self.recording_socket
@@ -113,6 +113,7 @@ class CaptureLog(object):
     Captures log records passed to the ``handle`` method and provides accessor
     functions to the captured logs.
     """
+
     def __init__(self):
         self.clear()
 
@@ -280,6 +281,7 @@ class ForwardingLogHandler(logging.NullHandler):
     to a given handler function. This can be useful to forward records to a
     handler without the handler itself needing to subclass LogHandler.
     """
+
     def __init__(self, handler_fn):
         super(ForwardingLogHandler, self).__init__()
         self.handler_fn = handler_fn
@@ -293,6 +295,7 @@ class CaptureLogAdapter(utils.LogAdapter, CaptureLog):
     A LogAdapter that is capable of capturing logs for inspection via accessor
     methods.
     """
+
     def __init__(self, logger, name):
         super(CaptureLogAdapter, self).__init__(logger, name)
         self.clear()