Rewrote is_flaky.py with use of multiprocessinng

Rewrote is_flaky.py with use of multiprocessing and added tests

BUG=387410
R=qyearsley@chromium.org, ojan@chromium.org

Committed: https://crrev.com/f7d01c8e5e8608298ec83b5aa856672f9c1df897
Cr-Commit-Position: refs/heads/master@{#295741}

[qyearsley, 2014-09-16 18:52:10]

https://codereview.chromium.org/560123004/diff/40001/tools/flakiness/is_flaky.py
File tools/flakiness/is_flaky.py (right):

https://codereview.chromium.org/560123004/diff/40001/tools/flakiness/is_flaky...
tools/flakiness/is_flaky.py:45: if num_passed == 0 or num_failed == 0:
You could also omit `or num_failed == 0`, since it would be same either way.

https://codereview.chromium.org/560123004/diff/40001/tools/flakiness/is_flaky...
File tools/flakiness/is_flaky_test.py (right):

https://codereview.chromium.org/560123004/diff/40001/tools/flakiness/is_flaky...
tools/flakiness/is_flaky_test.py:15: """Tests for the is_flaky.py functions."""
Ojan might think that this docstring is redundant/unnecessary :-)

https://codereview.chromium.org/560123004/diff/40001/tools/flakiness/is_flaky...
tools/flakiness/is_flaky_test.py:34: subprocess.check_call =
self.mock_check_call
An alternative to this way is using the "mock" module
(http://www.voidspace.org.uk/python/mock/), but that's not necessarily easier to
understand.

https://codereview.chromium.org/560123004/diff/40001/tools/flakiness/is_flaky...
tools/flakiness/is_flaky_test.py:40: subprocess.check_call =
self.original_subprocess_check_call
setUp and tearDown could also be put at the top of the class, above
mock_check_call and mock_load_options, but if you feel this order makes more
sense then this is OK.

https://codereview.chromium.org/560123004/diff/40001/tools/flakiness/is_flaky...
tools/flakiness/is_flaky_test.py:64: self.assertEqual(ret_code, 0)
You might note that this failure rate of 2/10 is lower than the the threshold in
the options returned by mock_load_options.

[Sergiy Byelozyorov, 2014-09-17 15:49:34]

https://codereview.chromium.org/560123004/diff/40001/tools/flakiness/is_flaky.py
File tools/flakiness/is_flaky.py (right):

https://codereview.chromium.org/560123004/diff/40001/tools/flakiness/is_flaky...
tools/flakiness/is_flaky.py:45: if num_passed == 0 or num_failed == 0:
On 2014/09/16 18:52:09, qyearsley wrote:
> You could also omit `or num_failed == 0`, since it would be same either way.

Done.

https://codereview.chromium.org/560123004/diff/40001/tools/flakiness/is_flaky...
File tools/flakiness/is_flaky_test.py (right):

https://codereview.chromium.org/560123004/diff/40001/tools/flakiness/is_flaky...
tools/flakiness/is_flaky_test.py:15: """Tests for the is_flaky.py functions."""
On 2014/09/16 18:52:09, qyearsley wrote:
> Ojan might think that this docstring is redundant/unnecessary :-)

Done.

https://codereview.chromium.org/560123004/diff/40001/tools/flakiness/is_flaky...
tools/flakiness/is_flaky_test.py:34: subprocess.check_call =
self.mock_check_call
On 2014/09/16 18:52:09, qyearsley wrote:
> An alternative to this way is using the "mock" module
> (http://www.voidspace.org.uk/python/mock/), but that's not necessarily easier
to
> understand.
I'd love that, but mock module is not installed by default on the bots.

https://codereview.chromium.org/560123004/diff/40001/tools/flakiness/is_flaky...
tools/flakiness/is_flaky_test.py:40: subprocess.check_call =
self.original_subprocess_check_call
On 2014/09/16 18:52:09, qyearsley wrote:
> setUp and tearDown could also be put at the top of the class, above
> mock_check_call and mock_load_options, but if you feel this order makes more
> sense then this is OK.

Done.

https://codereview.chromium.org/560123004/diff/40001/tools/flakiness/is_flaky...
tools/flakiness/is_flaky_test.py:64: self.assertEqual(ret_code, 0)
On 2014/09/16 18:52:09, qyearsley wrote:
> You might note that this failure rate of 2/10 is lower than the the threshold
in
> the options returned by mock_load_options.
That's right. That's why the return code is 0 - test is not considered flaky.

[qyearsley, 2014-09-19 06:41:39]

lgtm, Ojan might have suggestions

[ojan, 2014-09-19 17:31:06]

The CQ bit was checked by ojan@chromium.org

[ojan, 2014-09-19 17:31:06]

lgtm

[commit-bot: I haz the power, 2014-09-19 17:32:33]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/560123004/60001

[commit-bot: I haz the power, 2014-09-19 18:23:28]

Committed patchset #4 (id:60001) as 0de95b25bdb7b74ce7968ec20e04ba4440bbfd2b

[commit-bot: I haz the power, 2014-09-19 18:24:24]

Patchset 4 (id:??) landed as
https://crrev.com/f7d01c8e5e8608298ec83b5aa856672f9c1df897
Cr-Commit-Position: refs/heads/master@{#295741}