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      1 # Copyright (c) 2012 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 
      8 import json
      9 
     10 
     11 def 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: result['average'] = total_sum / result['count']
    129 
    130   return result
    131 
    132 
    133 def GetAverageRunInfoFromJSONString(json_string, name):
    134   """Returns the results from GetAverageRunInfo using a JSON string.
    135 
    136   Args:
    137     json_string: The string containing JSON.
    138     name: The 'name' tag to filter on in the JSON file.
    139 
    140   Returns:
    141     See GetAverageRunInfo Returns section.
    142   """
    143   return GetAverageRunInfo(json.loads(json_string), name)
    144 
    145 
    146 def GetAverageRunInfoFromFile(json_file, name):
    147   """Returns the results from GetAverageRunInfo using a JSON file.
    148 
    149   Args:
    150     json_file: The path to a JSON file.
    151     name: The 'name' tag to filter on in the JSON file.
    152 
    153   Returns:
    154     See GetAverageRunInfo Returns section.
    155   """
    156   with open(json_file, 'r') as f:
    157     data = f.read()
    158     perf = json.loads(data)
    159 
    160   return GetAverageRunInfo(perf, name)
    161