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      1 # Copyright 2014 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 
      6 class TimelineBasedMetricException(Exception):
      7   """Exception that can be thrown from metrics that implements
      8      TimelineBasedMetric to indicate a problem arose when computing the metric.
      9      """
     10 
     11 
     12 def _TimeRangesHasOverlap(iterable_time_ranges):
     13   """ Returns True if there is are overlapped ranges in time ranges.
     14   iterable_time_ranges: an iterable of time ranges. Each time range is a
     15   tuple (start time, end time).
     16   """
     17   # Sort the ranges by the start time
     18   sorted_time_ranges = sorted(iterable_time_ranges)
     19   last_range = sorted_time_ranges[0]
     20   for current_range in sorted_time_ranges[1:]:
     21     start_current_range = current_range[0]
     22     end_last_range = last_range[1]
     23     if start_current_range < end_last_range:
     24       return True
     25     last_range = current_range
     26   return False
     27 
     28 
     29 def IsEventInInteractions(event, interaction_records):
     30   """ Return True if event is in any of the interaction records' time range.
     31 
     32   Args:
     33     event: an instance of telemetry.timeline.event.TimelineEvent.
     34     interaction_records: a list of interaction records, whereas each record is
     35       an instance of
     36       telemetry.web_perf.timeline_interaction_record.TimelineInteractionRecord.
     37 
     38   Returns:
     39     True if |event|'s start & end time is in any of the |interaction_records|'s
     40     time range.
     41   """
     42   return any(ir.start <= event.start and ir.end >= event.end for ir
     43              in interaction_records)
     44 
     45 
     46 class TimelineBasedMetric(object):
     47 
     48   def __init__(self):
     49     """Computes metrics from a telemetry.timeline Model and a range
     50 
     51     """
     52     super(TimelineBasedMetric, self).__init__()
     53 
     54   def AddResults(self, model, renderer_thread, interaction_records, results):
     55     """Computes and adds metrics for the interaction_records' time ranges.
     56 
     57     The override of this method should compute results on the data **only**
     58     within the interaction_records' start and end time ranges.
     59 
     60     Args:
     61       model: An instance of telemetry.timeline.model.TimelineModel.
     62       interaction_records: A list of instances of TimelineInteractionRecord. If
     63         the override of this method doesn't support overlapped ranges, use
     64         VerifyNonOverlappedRecords to check that no records are overlapped.
     65       results: An instance of page.PageTestResults.
     66 
     67     """
     68     raise NotImplementedError()
     69 
     70   def AddWholeTraceResults(self, model, results):
     71     """Computes and adds metrics corresponding to the entire trace.
     72 
     73     Override this method to compute results that correspond to the whole trace.
     74 
     75     Args:
     76       model: An instance of telemetry.timeline.model.TimelineModel.
     77       results: An instance of page.PageTestResults.
     78     """
     79     pass
     80 
     81   def VerifyNonOverlappedRecords(self, interaction_records):
     82     """This raises exceptions if interaction_records contain overlapped ranges.
     83     """
     84     if _TimeRangesHasOverlap(((r.start, r.end) for r in interaction_records)):
     85       raise TimelineBasedMetricException(
     86           'This metric does not support interaction records with overlapped '
     87           'time range.')
     88