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