make version of ts_mon compatible with appengine

infra_libs/ts_mon/interface.py

Index: infra_libs/ts_mon/interface.py
diff --git a/infra_libs/ts_mon/interface.py b/infra_libs/ts_mon/interface.py
index e24bf14d120309f21c77e967f35908a3c5d31741..2e3d498375bd32dd2a273ed2b602a346215df379 100644
--- a/infra_libs/ts_mon/interface.py
+++ b/infra_libs/ts_mon/interface.py
@@ -39,7 +39,7 @@ import time
 
 from monacq.proto import metrics_pb2
 
-from infra_libs.ts_mon import errors
+from infra_libs.ts_mon.common import errors
 
 # The maximum number of MetricsData messages to include in each HTTP request.
 # MetricsCollections larger than this will be split into multiple requests.
@@ -116,8 +116,9 @@ def register(metric):
   """
   # If someone is registering the same metric object twice, that's okay, but
   # registering two different metric objects with the same metric name is not.
-  if metric in state.metrics:
-    return
+  for m in state.metrics:
+    if metric == m:
+      return

[agable, 2015/08/19 01:14:42]

I don't think this does what we want: This means that the registration will be
successful, but the newly-created Metric object will not be added to the global
state, so when flush() is called any data points which have been added to it
won't get sent.

I think what we actually want to do is

here:
if metric == m:
  return m

and in the Metric constructor call interface.register() and if that returns
something then replace ourselves with that. Note that this may require
implementing __new__ as well as __init__.

   if any([metric._name == m._name for m in state.metrics]):
     raise errors.MonitoringDuplicateRegistrationError(metric._name)