clovis: Report the number and cost of DNS requests.

tools/android/loading/metrics.py

 # Copyright 2016 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.
 
 """Descriptive metrics for Clovis.
 
 When executed as a script, prints the amount of data attributed to Ads, and
 shows a graph of the amount of data to download for a new visit to the same
 page, with a given time interval.
 """
@@ skipping 88 matching lines @@
   Returns:
     (uploaded_bytes (int), downloaded_bytes (int))
   """
   content_lens = (
       content_classification_lens.ContentClassificationLens.WithRulesFiles(
           trace, ad_rules_filename, tracking_rules_filename))
   requests = content_lens.AdAndTrackingRequests()
   return TransferSize(requests)
 
 
+def DnsRequestsAndCost(trace):
+  """Returns the number and cost of DNS requests for a trace."""
+  requests = trace.request_track.GetEvents()
+  requests_with_dns = [r for r in requests if r.timing.dns_start != -1]
+  dns_requests_count = len(requests_with_dns)
+  dns_cost = sum(r.timing.dns_end - r.timing.dns_start
+                 for r in requests_with_dns)
+  return (dns_requests_count, dns_cost)
+
+
 def PlotTransferSizeVsTimeBetweenVisits(trace):
   times = [10, 60, 300, 600, 3600, 4 * 3600, 12 * 3600, 24 * 3600]
   labels = ['10s', '1m', '10m', '1h', '4h', '12h', '1d']
   (_, total_downloaded) = TotalTransferSize(trace)
   downloaded = [TransferredDataRevisit(trace, delta_t)[1] for delta_t in times]
   plt.figure()
   plt.title('Amount of data to download for a revisit - %s' % trace.url)
   plt.xlabel('Time between visits (log)')
   plt.ylabel('Amount of data (bytes)')
   plt.plot(times, downloaded, 'k+--')
@@ skipping 17 matching lines @@
 if __name__ == '__main__':
   import sys
   from matplotlib import pylab as plt
   import loading_trace
   if len(sys.argv) != 4:
     print (
         'Usage: %s trace_filename ad_rules_filename tracking_rules_filename'
         % sys.argv[0])
     sys.exit(0)
   main(*sys.argv[1:])