Source code
Revision control
Copy as Markdown
Other Tools
# Copyright 2013 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.
"""A helper module for parsing JSON objects from perf tests results."""
import json
def GetAverageRunInfo(json_data, name):
"""Summarizes TraceEvent JSON data for performance metrics.
Example JSON Inputs (More tags can be added but these are required):
Measuring Duration:
[
{ "cat": "Java",
"ts": 10000000000,
"ph": "S",
"name": "TestTrace"
},
{ "cat": "Java",
"ts": 10000004000,
"ph": "F",
"name": "TestTrace"
},
...
]
Measuring Call Frequency (FPS):
[
{ "cat": "Java",
"ts": 10000000000,
"ph": "I",
"name": "TestTraceFPS"
},
{ "cat": "Java",
"ts": 10000004000,
"ph": "I",
"name": "TestTraceFPS"
},
...
]
Args:
json_data: A list of dictonaries each representing a JSON object.
name: The 'name' tag to filter on in the JSON file.
Returns:
A dictionary of result data with the following tags:
min: The minimum value tracked.
max: The maximum value tracked.
average: The average of all the values tracked.
count: The number of times the category/name pair was tracked.
type: The type of tracking ('Instant' for instant tags and 'Span' for
begin/end tags.
category: The passed in category filter.
name: The passed in name filter.
data_points: A list of all of the times used to generate this data.
units: The units for the values being reported.
Raises:
Exception: if entry contains invalid data.
"""
def EntryFilter(entry):
return entry['cat'] == 'Java' and entry['name'] == name
filtered_entries = [j for j in json_data if EntryFilter(j)]
result = {}
result['min'] = -1
result['max'] = -1
result['average'] = 0
result['count'] = 0
result['type'] = 'Unknown'
result['category'] = 'Java'
result['name'] = name
result['data_points'] = []
result['units'] = ''
total_sum = 0
last_val = 0
val_type = None
for entry in filtered_entries:
if not val_type:
if 'mem' in entry:
val_type = 'mem'
def GetVal(entry):
return entry['mem']
result['units'] = 'kb'
elif 'ts' in entry:
val_type = 'ts'
def GetVal(entry):
return float(entry['ts']) / 1000.0
result['units'] = 'ms'
else:
raise Exception('Entry did not contain valid value info: %s' % entry)
if not val_type in entry:
raise Exception('Entry did not contain expected value type "%s" '
'information: %s' % (val_type, entry))
val = GetVal(entry)
if (entry['ph'] == 'S' and
(result['type'] == 'Unknown' or result['type'] == 'Span')):
result['type'] = 'Span'
last_val = val
elif ((entry['ph'] == 'F' and result['type'] == 'Span') or
(entry['ph'] == 'I' and (result['type'] == 'Unknown' or
result['type'] == 'Instant'))):
if last_val > 0:
delta = val - last_val
if result['min'] == -1 or result['min'] > delta:
result['min'] = delta
if result['max'] == -1 or result['max'] < delta:
result['max'] = delta
total_sum += delta
result['count'] += 1
result['data_points'].append(delta)
if entry['ph'] == 'I':
result['type'] = 'Instant'
last_val = val
if result['count'] > 0:
result['average'] = total_sum / result['count']
return result
def GetAverageRunInfoFromJSONString(json_string, name):
"""Returns the results from GetAverageRunInfo using a JSON string.
Args:
json_string: The string containing JSON.
name: The 'name' tag to filter on in the JSON file.
Returns:
See GetAverageRunInfo Returns section.
"""
return GetAverageRunInfo(json.loads(json_string), name)
def GetAverageRunInfoFromFile(json_file, name):
"""Returns the results from GetAverageRunInfo using a JSON file.
Args:
json_file: The path to a JSON file.
name: The 'name' tag to filter on in the JSON file.
Returns:
See GetAverageRunInfo Returns section.
"""
with open(json_file, 'r') as f:
data = f.read()
perf = json.loads(data)
return GetAverageRunInfo(perf, name)