tor-browser

The Tor Browser
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json_perf_parser.py (4355B)

      1 # Copyright 2013 The Chromium Authors
      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 """A helper module for parsing JSON objects from perf tests results."""
      7 
      8 
      9 import json
     10 
     11 
     12 def GetAverageRunInfo(json_data, name):
     13  """Summarizes TraceEvent JSON data for performance metrics.
     14 
     15  Example JSON Inputs (More tags can be added but these are required):
     16  Measuring Duration:
     17  [
     18    { "cat": "Java",
     19      "ts": 10000000000,
     20      "ph": "S",
     21      "name": "TestTrace"
     22    },
     23    { "cat": "Java",
     24      "ts": 10000004000,
     25      "ph": "F",
     26      "name": "TestTrace"
     27    },
     28    ...
     29  ]
     30 
     31  Measuring Call Frequency (FPS):
     32  [
     33    { "cat": "Java",
     34      "ts": 10000000000,
     35      "ph": "I",
     36      "name": "TestTraceFPS"
     37    },
     38    { "cat": "Java",
     39      "ts": 10000004000,
     40      "ph": "I",
     41      "name": "TestTraceFPS"
     42    },
     43    ...
     44  ]
     45 
     46  Args:
     47    json_data: A list of dictonaries each representing a JSON object.
     48    name: The 'name' tag to filter on in the JSON file.
     49 
     50  Returns:
     51    A dictionary of result data with the following tags:
     52      min: The minimum value tracked.
     53      max: The maximum value tracked.
     54      average: The average of all the values tracked.
     55      count: The number of times the category/name pair was tracked.
     56      type: The type of tracking ('Instant' for instant tags and 'Span' for
     57            begin/end tags.
     58      category: The passed in category filter.
     59      name: The passed in name filter.
     60      data_points: A list of all of the times used to generate this data.
     61      units: The units for the values being reported.
     62 
     63  Raises:
     64    Exception: if entry contains invalid data.
     65  """
     66 
     67  def EntryFilter(entry):
     68    return entry['cat'] == 'Java' and entry['name'] == name
     69  filtered_entries = [j for j in json_data if EntryFilter(j)]
     70 
     71  result = {}
     72 
     73  result['min'] = -1
     74  result['max'] = -1
     75  result['average'] = 0
     76  result['count'] = 0
     77  result['type'] = 'Unknown'
     78  result['category'] = 'Java'
     79  result['name'] = name
     80  result['data_points'] = []
     81  result['units'] = ''
     82 
     83  total_sum = 0
     84 
     85  last_val = 0
     86  val_type = None
     87  for entry in filtered_entries:
     88    if not val_type:
     89      if 'mem' in entry:
     90        val_type = 'mem'
     91 
     92        def GetVal(entry):
     93          return entry['mem']
     94 
     95        result['units'] = 'kb'
     96      elif 'ts' in entry:
     97        val_type = 'ts'
     98 
     99        def GetVal(entry):
    100          return float(entry['ts']) / 1000.0
    101 
    102        result['units'] = 'ms'
    103      else:
    104        raise Exception('Entry did not contain valid value info: %s' % entry)
    105 
    106    if not val_type in entry:
    107      raise Exception('Entry did not contain expected value type "%s" '
    108                      'information: %s' % (val_type, entry))
    109    val = GetVal(entry)
    110    if (entry['ph'] == 'S' and
    111        (result['type'] == 'Unknown' or result['type'] == 'Span')):
    112      result['type'] = 'Span'
    113      last_val = val
    114    elif ((entry['ph'] == 'F' and result['type'] == 'Span') or
    115          (entry['ph'] == 'I' and (result['type'] == 'Unknown' or
    116                                   result['type'] == 'Instant'))):
    117      if last_val > 0:
    118        delta = val - last_val
    119        if result['min'] == -1 or result['min'] > delta:
    120          result['min'] = delta
    121        if result['max'] == -1 or result['max'] < delta:
    122          result['max'] = delta
    123        total_sum += delta
    124        result['count'] += 1
    125        result['data_points'].append(delta)
    126      if entry['ph'] == 'I':
    127        result['type'] = 'Instant'
    128        last_val = val
    129  if result['count'] > 0:
    130    result['average'] = total_sum / result['count']
    131 
    132  return result
    133 
    134 
    135 def GetAverageRunInfoFromJSONString(json_string, name):
    136  """Returns the results from GetAverageRunInfo using a JSON string.
    137 
    138  Args:
    139    json_string: The string containing JSON.
    140    name: The 'name' tag to filter on in the JSON file.
    141 
    142  Returns:
    143    See GetAverageRunInfo Returns section.
    144  """
    145  return GetAverageRunInfo(json.loads(json_string), name)
    146 
    147 
    148 def GetAverageRunInfoFromFile(json_file, name):
    149  """Returns the results from GetAverageRunInfo using a JSON file.
    150 
    151  Args:
    152    json_file: The path to a JSON file.
    153    name: The 'name' tag to filter on in the JSON file.
    154 
    155  Returns:
    156    See GetAverageRunInfo Returns section.
    157  """
    158  with open(json_file, 'r') as f:
    159    data = f.read()
    160    perf = json.loads(data)
    161 
    162  return GetAverageRunInfo(perf, name)