# Copyright 2015 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
import collections
import logging
import re
from autotest_lib.client.bin import utils
from autotest_lib.client.common_lib import error
def get_histogram_text(tab, histogram_name):
"""
This returns contents of the given histogram.
@param tab: object, Chrome tab instance
@param histogram_name: string, name of the histogram
@returns string: contents of the histogram
"""
docEle = 'document.documentElement'
tab.Navigate('chrome://histograms/%s' % histogram_name)
tab.WaitForDocumentReadyStateToBeComplete()
raw_text = tab.EvaluateJavaScript(
'{0} && {0}.innerText'.format(docEle))
# extract the contents of the histogram
histogram = raw_text[raw_text.find('Histogram:'):].strip()
if histogram:
logging.debug('chrome://histograms/%s:\n%s', histogram_name,
histogram)
else:
logging.debug('No histogram is shown in chrome://histograms/%s',
histogram_name)
return histogram
def loaded(tab, histogram_name, pattern):
"""
Checks if the histogram page has been fully loaded.
@param tab: object, Chrome tab instance
@param histogram_name: string, name of the histogram
@param pattern: string, required text to look for
@returns re.MatchObject if the given pattern is found in the text
None otherwise
"""
return re.search(pattern, get_histogram_text(tab, histogram_name))
def verify(cr, histogram_name, histogram_bucket_value):
"""
Verifies histogram string and success rate in a parsed histogram bucket.
The histogram buckets are outputted in debug log regardless of the
verification result.
Full histogram URL is used to load histogram. Example Histogram URL is :
chrome://histograms/Media.GpuVideoDecoderInitializeStatus
@param cr: object, the Chrome instance
@param histogram_name: string, name of the histogram
@param histogram_bucket_value: int, required bucket number to look for
@raises error.TestError if histogram is not successful
"""
bucket_pattern = '\n'+ str(histogram_bucket_value) +'.*100\.0%.*'
error_msg_format = ('{} not loaded or histogram bucket not found '
'or histogram bucket found at < 100%')
tab = cr.browser.tabs.New()
msg = error_msg_format.format(histogram_name)
utils.poll_for_condition(lambda : loaded(tab, histogram_name,
bucket_pattern),
exception=error.TestError(msg),
sleep_interval=1)
def is_bucket_present(cr,histogram_name, histogram_bucket_value):
"""
This returns histogram succes or fail to called function
@param cr: object, the Chrome instance
@param histogram_name: string, name of the histogram
@param histogram_bucket_value: int, required bucket number to look for
@returns True if histogram page was loaded and the bucket was found.
False otherwise
"""
try:
verify(cr,histogram_name, histogram_bucket_value)
except error.TestError:
return False
else:
return True
def is_histogram_present(cr, histogram_name):
"""
This checks if the given histogram is present and non-zero.
@param cr: object, the Chrome instance
@param histogram_name: string, name of the histogram
@returns True if histogram page was loaded and the histogram is present
False otherwise
"""
histogram_pattern = 'Histogram: '+ histogram_name + ' recorded ' + \
r'[1-9][0-9]*' + ' samples'
tab = cr.browser.tabs.New()
try:
utils.poll_for_condition(lambda : loaded(tab, histogram_name,
histogram_pattern),
timeout=2,
sleep_interval=0.1)
return True
except utils.TimeoutError:
# the histogram is not present, and then returns false
return False
def get_histogram(cr, histogram_name):
"""
This returns contents of the given histogram.
@param cr: object, the Chrome instance
@param histogram_name: string, name of the histogram
@returns string: contents of the histogram
"""
tab = cr.browser.tabs.New()
return get_histogram_text(tab, histogram_name)
def parse_histogram(histogram_text):
"""
Parses histogram text into bucket structure.
@param histogram_text: histogram raw text.
@returns dict(bucket_value, bucket_count)
"""
# Match separator line, e.g. "1 ..."
RE_SEPEARTOR = re.compile(r'\d+\s+\.\.\.')
# Match bucket line, e.g. "2 --O (46 = 1.5%) {46.1%}"
RE_BUCKET = re.compile(
r'(\d+)\s+\-*O\s+\((\d+) = (\d+\.\d+)%\).*')
result = {}
for line in histogram_text.splitlines():
if RE_SEPEARTOR.match(line):
continue
m = RE_BUCKET.match(line)
if m:
result[int(m.group(1))] = int(m.group(2))
return result
def subtract_histogram(minuend, subtrahend):
"""
Subtracts histogram: minuend - subtrahend
@param minuend: histogram bucket dict from which another is to be
subtracted.
@param subtrahend: histogram bucket dict to be subtracted from another.
@result difference of the two histograms in bucket dict. Note that
zero-counted buckets are removed.
"""
result = collections.defaultdict(int, minuend)
for k, v in subtrahend.iteritems():
result[k] -= v
# Remove zero counted buckets.
return {k: v for k, v in result.iteritems() if v}
def expect_sole_bucket(histogram_differ, bucket, bucket_name, timeout=10,
sleep_interval=1):
"""
Returns true if the given bucket solely exists in histogram differ.
@param histogram_differ: a HistogramDiffer instance used to get histogram
name and histogram diff multiple times.
@param bucket: bucket value.
@param bucket_name: bucket name to be shown on error message.
@param timeout: timeout in seconds.
@param sleep_interval: interval in seconds between getting diff.
@returns True if the given bucket solely exists in histogram.
@raises TestError if bucket doesn't exist or other buckets exist.
"""
timer = utils.Timer(timeout)
histogram = {}
histogram_name = histogram_differ.histogram_name
while timer.sleep(sleep_interval):
histogram = histogram_differ.end()
if histogram:
break
if bucket not in histogram:
raise error.TestError('Expect %s has %s. Histogram: %r' %
(histogram_name, bucket_name, histogram))
if len(histogram) > 1:
raise error.TestError('%s has bucket other than %s. Histogram: %r' %
(histogram_name, bucket_name, histogram))
return True
def poll_histogram_grow(histogram_differ, timeout=2, sleep_interval=0.1):
"""
Polls histogram to see if it grows within |timeout| seconds.
@param histogram_differ: a HistogramDiffer instance used to get histogram
name and histogram diff multiple times.
@param timeout: observation timeout in seconds.
@param sleep_interval: interval in seconds between getting diff.
@returns (True, histogram_diff) if the histogram grows.
(False, {}) if it does not grow in |timeout| seconds.
"""
timer = utils.Timer(timeout)
while timer.sleep(sleep_interval):
histogram_diff = histogram_differ.end()
if histogram_diff:
return (True, histogram_diff)
return (False, {})
class HistogramDiffer(object):
"""
Calculates a histogram's progress between begin() and end().
Usage:
differ = HistogramDiffer(cr, 'Media.GpuVideoDecoderError')
....
diff_gvd_error = differ.end()
"""
def __init__(self, cr, histogram_name, begin=True):
"""
Constructor.
@param: cr: object, the Chrome instance
@param: histogram_name: string, name of the histogram
@param: begin: if set, calls begin().
"""
self.cr = cr
self.histogram_name = histogram_name
self.begin_histogram_text = ''
self.end_histogram_text = ''
self.begin_histogram = {}
self.end_histogram = {}
if begin:
self.begin()
def _get_histogram(self):
"""
Gets current histogram bucket.
@returns (dict(bucket_value, bucket_count), histogram_text)
"""
tab = self.cr.browser.tabs.New()
text = get_histogram_text(tab, self.histogram_name)
tab.Close()
return (parse_histogram(text), text)
def begin(self):
"""
Takes a histogram snapshot as begin_histogram.
"""
(self.begin_histogram,
self.begin_histogram_text) = self._get_histogram()
logging.debug('begin histograms/%s: %r\nraw_text: %s',
self.histogram_name, self.begin_histogram,
self.begin_histogram_text)
def end(self):
"""
Takes a histogram snapshot as end_histogram.
@returns self.diff()
"""
self.end_histogram, self.end_histogram_text = self._get_histogram()
logging.debug('end histograms/%s: %r\nraw_text: %s',
self.histogram_name, self.end_histogram,
self.end_histogram_text)
diff = subtract_histogram(self.end_histogram, self.begin_histogram)
logging.debug('histogram diff: %r', diff)
return diff