tools/perf/metrics/network.py

   1 # Copyright 2015 The Chromium Authors. All rights reserved.
   2 # Use of this source code is governed by a BSD-style license that can be
   3 # found in the LICENSE file.
   4
   5 from telemetry.value import scalar
   6
   7 from metrics import Metric
   8
   9
  10 NETWORK_DATA_NOT_FOUND = 'Network data could not be found.'
  11
  12
  13 # This is experimental. crbug.com/480512
  14 # Will not be supported once network data is ported to TimelineBasedMetric.
  15 class NetworkMetric(Metric):
  16   """NetworkMetrics gathers network statistics."""
  17
  18   def __init__(self, platform):
  19     super(NetworkMetric, self).__init__()
  20     self._network_snd = None
  21     self._network_rcv = None
  22     self._platform = platform
  23     self._browser = None
  24
  25   def Start(self, _, tab):
  26     """Start the per-page preparation for this metric.
  27
  28     Here, this consists of recording the start value.
  29     """
  30     self._browser = tab.browser
  31     if not self._platform.CanMonitorNetworkData():
  32       return
  33
  34     data = self._platform.GetNetworkData(self._browser)
  35     if data is not None:
  36       self._network_snd, self._network_rcv = data
  37
  38   def Stop(self, _, tab):
  39     """Prepare the results for this page.
  40
  41     The results are the differences between the current values
  42     and the values when Start() was called.
  43     """
  44     if not self._platform.CanMonitorNetworkData():
  45       return
  46
  47     data = self._platform.GetNetworkData(self._browser)
  48     if data is not None:
  49       snd, rcv = data
  50       if self._network_snd is not None:
  51         self._network_snd = snd - self._network_snd
  52       if self._network_rcv is not None:
  53         self._network_rcv = rcv - self._network_rcv
  54     else: # If end data cannot be found, report none.
  55       self._network_snd = None
  56       self._network_rcv = None
  57
  58   def AddResults(self, tab, results):
  59     none_value_reason = (
  60         None if self._network_snd is not None else NETWORK_DATA_NOT_FOUND)
  61     results.AddValue(scalar.ScalarValue(
  62         results.current_page, 'network_data_sent', 'kb', self._network_snd,
  63         important=False, none_value_reason=none_value_reason))
  64     none_value_reason = (
  65         None if self._network_rcv is not None else NETWORK_DATA_NOT_FOUND)
  66     results.AddValue(scalar.ScalarValue(
  67         results.current_page, 'network_data_received', 'kb', self._network_rcv,
  68         important=False, none_value_reason=none_value_reason))