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      1 # Copyright (C) 2013 Google Inc. All rights reserved.
      2 #
      3 # Redistribution and use in source and binary forms, with or without
      4 # modification, are permitted provided that the following conditions are
      5 # met:
      6 #
      7 #     * Redistributions of source code must retain the above copyright
      8 # notice, this list of conditions and the following disclaimer.
      9 #     * Redistributions in binary form must reproduce the above
     10 # copyright notice, this list of conditions and the following disclaimer
     11 # in the documentation and/or other materials provided with the
     12 # distribution.
     13 #     * Neither the name of Google Inc. nor the names of its
     14 # contributors may be used to endorse or promote products derived from
     15 # this software without specific prior written permission.
     16 #
     17 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     18 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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     20 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     21 # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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     23 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     24 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     25 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     26 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     27 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     28 
     29 import logging
     30 import math
     31 import optparse
     32 import os
     33 import subprocess
     34 import sys
     35 
     36 from webkitpy.common.system.executive import Executive
     37 from webkitpy.common.system.filesystem import FileSystem
     38 from webkitpy.common.webkit_finder import WebKitFinder
     39 
     40 _log = logging.getLogger(__name__)
     41 
     42 
     43 class Bucket(object):
     44     def __init__(self, tests):
     45         self.tests = tests
     46 
     47     def size(self):
     48         return len(self.tests)
     49 
     50 
     51 class Bisector(object):
     52 
     53     def __init__(self, tests, is_debug):
     54         self.executive = Executive()
     55         self.tests = tests
     56         self.expected_failure = tests[-1]
     57         self.is_debug = is_debug
     58         self.webkit_finder = WebKitFinder(FileSystem())
     59 
     60     def bisect(self):
     61         if self.test_fails_in_isolation():
     62             self.buckets = [Bucket([self.expected_failure])]
     63             print '%s fails when run in isolation.' % self.expected_failure
     64             self.print_result()
     65             return 0
     66         if not self.test_fails(self.tests):
     67             _log.error('%s does not fail' % self.expected_failure)
     68             return 1
     69         # Split the list of test into buckets. Each bucket has at least one test required to cause
     70         # the expected failure at the end. Split buckets in half until there are only buckets left
     71         # with one item in them.
     72         self.buckets = [Bucket(self.tests[:-1]), Bucket([self.expected_failure])]
     73         while not self.is_done():
     74             self.print_progress()
     75             self.split_largest_bucket()
     76         self.print_result()
     77         self.verify_non_flaky()
     78         return 0
     79 
     80     def test_fails_in_isolation(self):
     81         return self.test_bucket_list_fails([Bucket([self.expected_failure])])
     82 
     83     def verify_non_flaky(self):
     84         print 'Verifying the failure is not flaky by running 10 times.'
     85         count_failures = 0
     86         for i in range(0, 10):
     87             if self.test_bucket_list_fails(self.buckets):
     88                 count_failures += 1
     89         print 'Failed %d/10 times' % count_failures
     90 
     91     def print_progress(self):
     92         count = 0
     93         for bucket in self.buckets:
     94             count += len(bucket.tests)
     95         print '%d tests left, %d buckets' % (count, len(self.buckets))
     96 
     97     def print_result(self):
     98         tests = []
     99         for bucket in self.buckets:
    100             tests += bucket.tests
    101         extra_args = ' --debug' if self.is_debug else ''
    102         print 'run-webkit-tests%s --child-processes=1 --order=none %s' % (extra_args, " ".join(tests))
    103 
    104     def is_done(self):
    105         for bucket in self.buckets:
    106             if bucket.size() > 1:
    107                 return False
    108         return True
    109 
    110     def split_largest_bucket(self):
    111         index = 0
    112         largest_index = 0
    113         largest_size = 0
    114         for bucket in self.buckets:
    115             if bucket.size() > largest_size:
    116                 largest_index = index
    117                 largest_size = bucket.size()
    118             index += 1
    119 
    120         bucket_to_split = self.buckets[largest_index]
    121         halfway_point = int(largest_size / 2)
    122         first_half = Bucket(bucket_to_split.tests[:halfway_point])
    123         second_half = Bucket(bucket_to_split.tests[halfway_point:])
    124 
    125         buckets_before = self.buckets[:largest_index]
    126         buckets_after = self.buckets[largest_index + 1:]
    127 
    128         # Do the second half first because it tends to be faster because the http tests are front-loaded and slow.
    129         new_buckets = buckets_before + [second_half] + buckets_after
    130         if self.test_bucket_list_fails(new_buckets):
    131             self.buckets = new_buckets
    132             return
    133 
    134         new_buckets = buckets_before + [first_half] + buckets_after
    135         if self.test_bucket_list_fails(new_buckets):
    136             self.buckets = new_buckets
    137             return
    138 
    139         self.buckets = buckets_before + [first_half, second_half] + buckets_after
    140 
    141     def test_bucket_list_fails(self, buckets):
    142         tests = []
    143         for bucket in buckets:
    144             tests += bucket.tests
    145         return self.test_fails(tests)
    146 
    147     def test_fails(self, tests):
    148         extra_args = ['--debug'] if self.is_debug else []
    149         path_to_run_webkit_tests = self.webkit_finder.path_from_webkit_base('Tools', 'Scripts', 'run-webkit-tests')
    150         output = self.executive.popen([path_to_run_webkit_tests, '--child-processes', '1', '--order', 'none', '--no-retry', '--no-show-results', '--verbose'] + extra_args + tests, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    151         failure_string = self.expected_failure + ' failed'
    152         if failure_string in output.stderr.read():
    153             return True
    154         return False
    155 
    156 
    157 def main(argv):
    158     logging.basicConfig()
    159 
    160     option_parser = optparse.OptionParser()
    161     option_parser.add_option('--test-list', action='store', help='file that list tests to bisect. The last test in the list is the expected failure.', metavar='FILE'),
    162     option_parser.add_option('--debug', action='store_true', default=False, help='whether to use a debug build'),
    163     options, args = option_parser.parse_args(argv)
    164 
    165     tests = open(options.test_list).read().strip().split('\n')
    166     bisector = Bisector(tests, is_debug=options.debug)
    167     return bisector.bisect()
    168 
    169 if __name__ == '__main__':
    170     sys.exit(main(sys.argv[1:]))
    171