make version of ts_mon compatible with appengine

infra_libs/ts_mon/interface.py

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Classes representing the monitoring interface for tasks or devices.
 
 Usage:
   import argparse
   from infra_libs import ts_mon
 
@@ skipping 21 matching lines @@
 """
 
 import logging
 import os
 import random
 import threading
 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.
 METRICS_DATA_LENGTH_LIMIT = 5000
 
 
 class State(object):
   """Package-level state is stored here so that it is easily accessible.
 
   Configuration is kept in this one object at the global level so that all
@@ skipping 51 matching lines @@
   for metric in state.metrics:
     metric.serialize_to(proto, default_target=state.default_target,
                         loop_action=loop_action)
 
   state.global_monitor.send(proto)
 
 
 def register(metric):
   """Adds the metric to the list of metrics sent by flush().
 
-  This is called automatically by Metric's constructor - you don't need to call
-  it manually.
+  This is called automatically by Metric's constructor.
   """
   # 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:
+      state.metrics.remove(m)
+      state.metrics.add(metric)
+      return
   if any([metric._name == m._name for m in state.metrics]):
     raise errors.MonitoringDuplicateRegistrationError(metric._name)
 
   state.metrics.add(metric)
 
-
 def unregister(metric):
   """Removes the metric from the list of metrics sent by flush()."""
   state.metrics.remove(metric)
 
 
 def close():
   """Stops any background threads and waits for them to exit."""
   if state.flush_thread is not None:
     state.flush_thread.stop()
 
@@ skipping 39 matching lines @@
             'Last monitoring flush took %f seconds (longer than '
             '--ts-mon-flush-interval-secs = %f seconds)',
             flush_duration, self.interval_secs)
         next_timeout = 0
 
   def stop(self):
     """Stops the background thread and performs a final flush."""
 
     self.stop_event.set()
     self.join()