ansible/test/units/module_utils/facts/test_timeout.py
Toshio Kuratomi bd072fe83a
Make the timeout decorator raise an exception out of the function's scope (#49921)
* Revert "allow caller to deal with timeout (#49449)"

This reverts commit 63279823a7.

Flawed on many levels

* Adds poor API to a public function
* Papers over the fact that the public function is doing something bad
  by catching exceptions it cannot handle in the first place
* Papers over the real cause of the issue which is a bug in the timeout
  decorator
* Doesn't reraise properly
* Catches the wrong exception

Fixes #49824
Fixes #49817

* Make the timeout decorator properly raise an exception outside of the function's scope

signal handlers which raise exceptions will never work well because the
exception can be raised anywhere in the called code.  This leads to
exception race conditions where the exceptions could end up being
hanlded by unintended pieces of the called code.

The timeout decorator was using just that idiom.  It was especially bad
because the decorator syntactically occurs outside of the called code
but because of the signal handler, the exception was being raised inside
of the called code.

This change uses a thread instead of a signal to manage the timeout in
parallel to the execution of the decorated function.  Since raising of
the exception happens inside of the decorator, now, instead of inside of
a signal handler, the timeout exception is raised from outside of the
called code as expected which makes reasoning about where exceptions are
to be expected intuitive again.

Fixes #43884

* Add a common case test.

Adding an integration test driven from our unittests.  Most of the time
we'll timeout in run_command which is running things in a subprocess.
Create a test for that specific case in case anything funky comes up
between threading and execve.

* Don't use OSError-based TimeoutError as a base class

Unlike most standard exceptions, OSError has a specific parameter list
with specific meanings.  Instead follow the example of other stdlib
functions, concurrent.futures and multiprocessing and define a separate
TimeoutException.

* Add comment and docstring to point out that this is not hte Python3 TimeoutError
2018-12-18 18:01:46 -08:00

169 lines
5.2 KiB
Python

# -*- coding: utf-8 -*-
# (c) 2017, Toshio Kuratomi <tkuratomi@ansible.com>
#
# This file is part of Ansible
#
# Ansible is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Ansible is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Ansible. If not, see <http://www.gnu.org/licenses/>.
# Make coding more python3-ish
from __future__ import (absolute_import, division)
__metaclass__ = type
import sys
import time
import pytest
from ansible.module_utils.facts import timeout
@pytest.fixture
def set_gather_timeout_higher():
default_timeout = timeout.GATHER_TIMEOUT
timeout.GATHER_TIMEOUT = timeout.DEFAULT_GATHER_TIMEOUT + 5
yield
timeout.GATHER_TIMEOUT = default_timeout
@pytest.fixture
def set_gather_timeout_lower():
default_timeout = timeout.GATHER_TIMEOUT
timeout.GATHER_TIMEOUT = 2
yield
timeout.GATHER_TIMEOUT = default_timeout
@timeout.timeout
def sleep_amount_implicit(amount):
# implicit refers to the lack of argument to the decorator
time.sleep(amount)
return 'Succeeded after {0} sec'.format(amount)
@timeout.timeout(timeout.DEFAULT_GATHER_TIMEOUT + 5)
def sleep_amount_explicit_higher(amount):
# explicit refers to the argument to the decorator
time.sleep(amount)
return 'Succeeded after {0} sec'.format(amount)
@timeout.timeout(2)
def sleep_amount_explicit_lower(amount):
# explicit refers to the argument to the decorator
time.sleep(amount)
return 'Succeeded after {0} sec'.format(amount)
#
# Tests for how the timeout decorator is specified
#
def test_defaults_still_within_bounds():
# If the default changes outside of these bounds, some of the tests will
# no longer test the right thing. Need to review and update the timeouts
# in the other tests if this fails
assert timeout.DEFAULT_GATHER_TIMEOUT >= 4
def test_implicit_file_default_succeeds():
# amount checked must be less than DEFAULT_GATHER_TIMEOUT
assert sleep_amount_implicit(1) == 'Succeeded after 1 sec'
def test_implicit_file_default_timesout():
# sleep_time is greater than the default
sleep_time = timeout.DEFAULT_GATHER_TIMEOUT + 1
with pytest.raises(timeout.TimeoutError):
assert sleep_amount_implicit(sleep_time) == '(Not expected to succeed)'
def test_implicit_file_overridden_succeeds(set_gather_timeout_higher):
# Set sleep_time greater than the default timeout and less than our new timeout
sleep_time = timeout.DEFAULT_GATHER_TIMEOUT + 1
assert sleep_amount_implicit(sleep_time) == 'Succeeded after {0} sec'.format(sleep_time)
def test_implicit_file_overridden_timesout(set_gather_timeout_lower):
# Set sleep_time greater than our new timeout but less than the default
sleep_time = 3
with pytest.raises(timeout.TimeoutError):
assert sleep_amount_implicit(sleep_time) == '(Not expected to Succeed)'
def test_explicit_succeeds():
# Set sleep_time greater than the default timeout and less than our new timeout
sleep_time = timeout.DEFAULT_GATHER_TIMEOUT + 1
assert sleep_amount_explicit_higher(sleep_time) == 'Succeeded after {0} sec'.format(sleep_time)
def test_explicit_timeout():
# Set sleep_time greater than our new timeout but less than the default
sleep_time = 3
with pytest.raises(timeout.TimeoutError):
assert sleep_amount_explicit_lower(sleep_time) == '(Not expected to succeed)'
#
# Test that exception handling works
#
@timeout.timeout(1)
def function_times_out():
time.sleep(2)
# This is just about the same test as function_times_out but uses a separate process which is where
# we normally have our timeouts. It's more of an integration test than a unit test.
@timeout.timeout(1)
def function_times_out_in_run_command(am):
am.run_command([sys.executable, '-c', 'import time ; time.sleep(2)'])
@timeout.timeout(1)
def function_other_timeout():
raise TimeoutError('Vanilla Timeout')
@timeout.timeout(1)
def function_raises():
1 / 0
@timeout.timeout(1)
def function_catches_all_exceptions():
try:
time.sleep(10)
except BaseException:
raise RuntimeError('We should not have gotten here')
def test_timeout_raises_timeout():
with pytest.raises(timeout.TimeoutError):
assert function_times_out() == '(Not expected to succeed)'
@pytest.mark.parametrize('stdin', ({},), indirect=['stdin'])
def test_timeout_raises_timeout_integration_test(am):
with pytest.raises(timeout.TimeoutError):
assert function_times_out_in_run_command(am) == '(Not expected to succeed)'
def test_timeout_raises_other_exception():
with pytest.raises(ZeroDivisionError):
assert function_raises() == '(Not expected to succeed)'
def test_exception_not_caught_by_called_code():
with pytest.raises(timeout.TimeoutError):
assert function_catches_all_exceptions() == '(Not expected to succeed)'