51 lines
1.9 KiB
Python
51 lines
1.9 KiB
Python
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# Copyright 2013 The Chromium Authors. All rights reserved.
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# Use of this source code is governed by a BSD-style license that can be
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# found in the LICENSE file.
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import json
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import logging
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def SubtractHistogram(histogram_json, start_histogram_json):
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"""Subtracts a previous histogram from a histogram. Both parameters are json
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serializations of histograms."""
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start_histogram = json.loads(start_histogram_json)
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# It's ok if the start histogram is empty (we had no data, maybe even no
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# histogram at all, at the start of the test).
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if 'buckets' not in start_histogram:
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return histogram_json
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histogram = json.loads(histogram_json)
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if ('pid' in start_histogram and 'pid' in histogram
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and start_histogram['pid'] != histogram['pid']):
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raise Exception(
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'Trying to compare histograms from different processes (%d and %d)'
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% (start_histogram['pid'], histogram['pid']))
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start_histogram_buckets = dict()
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for b in start_histogram['buckets']:
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start_histogram_buckets[b['low']] = b['count']
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new_buckets = []
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for b in histogram['buckets']:
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new_bucket = b
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low = b['low']
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if low in start_histogram_buckets:
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new_bucket['count'] = b['count'] - start_histogram_buckets[low]
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if new_bucket['count'] < 0:
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logging.error('Histogram subtraction error, starting histogram most '
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'probably invalid.')
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if new_bucket['count']:
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new_buckets.append(new_bucket)
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histogram['buckets'] = new_buckets
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histogram['count'] -= start_histogram['count']
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return json.dumps(histogram)
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def GetHistogramFromDomAutomation(function, name, tab):
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# TODO(jeremy): Remove references to
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# domAutomationController when we update the reference builds.
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js = ('(window.statsCollectionController ? '
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'statsCollectionController : '
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'domAutomationController).%s("%s")' %
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(function, name))
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return tab.EvaluateJavaScript(js)
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