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#!/usr/bin/env python
from __future__ import absolute_import, division, print_function
from tornado import gen
from tornado.ioloop import IOLoop
from tornado.log import app_log
from tornado.stack_context import (StackContext, wrap, NullContext, StackContextInconsistentError,
ExceptionStackContext, run_with_stack_context, _state)
from tornado.testing import AsyncHTTPTestCase, AsyncTestCase, ExpectLog, gen_test
from tornado.test.util import unittest
from tornado.web import asynchronous, Application, RequestHandler
import contextlib
import functools
import logging
class TestRequestHandler(RequestHandler):
def __init__(self, app, request):
super(TestRequestHandler, self).__init__(app, request)
@asynchronous
def get(self):
logging.debug('in get()')
# call self.part2 without a self.async_callback wrapper. Its
# exception should still get thrown
IOLoop.current().add_callback(self.part2)
def part2(self):
logging.debug('in part2()')
# Go through a third layer to make sure that contexts once restored
# are again passed on to future callbacks
IOLoop.current().add_callback(self.part3)
def part3(self):
logging.debug('in part3()')
raise Exception('test exception')
def write_error(self, status_code, **kwargs):
if 'exc_info' in kwargs and str(kwargs['exc_info'][1]) == 'test exception':
self.write('got expected exception')
else:
self.write('unexpected failure')
class HTTPStackContextTest(AsyncHTTPTestCase):
def get_app(self):
return Application([('/', TestRequestHandler)])
def test_stack_context(self):
with ExpectLog(app_log, "Uncaught exception GET /"):
self.http_client.fetch(self.get_url('/'), self.handle_response)
self.wait()
self.assertEqual(self.response.code, 500)
self.assertTrue(b'got expected exception' in self.response.body)
def handle_response(self, response):
self.response = response
self.stop()
class StackContextTest(AsyncTestCase):
def setUp(self):
super(StackContextTest, self).setUp()
self.active_contexts = []
@contextlib.contextmanager
def context(self, name):
self.active_contexts.append(name)
yield
self.assertEqual(self.active_contexts.pop(), name)
# Simulates the effect of an asynchronous library that uses its own
# StackContext internally and then returns control to the application.
def test_exit_library_context(self):
def library_function(callback):
# capture the caller's context before introducing our own
callback = wrap(callback)
with StackContext(functools.partial(self.context, 'library')):
self.io_loop.add_callback(
functools.partial(library_inner_callback, callback))
def library_inner_callback(callback):
self.assertEqual(self.active_contexts[-2:],
['application', 'library'])
callback()
def final_callback():
# implementation detail: the full context stack at this point
# is ['application', 'library', 'application']. The 'library'
# context was not removed, but is no longer innermost so
# the application context takes precedence.
self.assertEqual(self.active_contexts[-1], 'application')
self.stop()
with StackContext(functools.partial(self.context, 'application')):
library_function(final_callback)
self.wait()
def test_deactivate(self):
deactivate_callbacks = []
def f1():
with StackContext(functools.partial(self.context, 'c1')) as c1:
deactivate_callbacks.append(c1)
self.io_loop.add_callback(f2)
def f2():
with StackContext(functools.partial(self.context, 'c2')) as c2:
deactivate_callbacks.append(c2)
self.io_loop.add_callback(f3)
def f3():
with StackContext(functools.partial(self.context, 'c3')) as c3:
deactivate_callbacks.append(c3)
self.io_loop.add_callback(f4)
def f4():
self.assertEqual(self.active_contexts, ['c1', 'c2', 'c3'])
deactivate_callbacks[1]()
# deactivating a context doesn't remove it immediately,
# but it will be missing from the next iteration
self.assertEqual(self.active_contexts, ['c1', 'c2', 'c3'])
self.io_loop.add_callback(f5)
def f5():
self.assertEqual(self.active_contexts, ['c1', 'c3'])
self.stop()
self.io_loop.add_callback(f1)
self.wait()
def test_deactivate_order(self):
# Stack context deactivation has separate logic for deactivation at
# the head and tail of the stack, so make sure it works in any order.
def check_contexts():
# Make sure that the full-context array and the exception-context
# linked lists are consistent with each other.
full_contexts, chain = _state.contexts
exception_contexts = []
while chain is not None:
exception_contexts.append(chain)
chain = chain.old_contexts[1]
self.assertEqual(list(reversed(full_contexts)), exception_contexts)
return list(self.active_contexts)
def make_wrapped_function():
"""Wraps a function in three stack contexts, and returns
the function along with the deactivation functions.
"""
# Remove the test's stack context to make sure we can cover
# the case where the last context is deactivated.
with NullContext():
partial = functools.partial
with StackContext(partial(self.context, 'c0')) as c0:
with StackContext(partial(self.context, 'c1')) as c1:
with StackContext(partial(self.context, 'c2')) as c2:
return (wrap(check_contexts), [c0, c1, c2])
# First make sure the test mechanism works without any deactivations
func, deactivate_callbacks = make_wrapped_function()
self.assertEqual(func(), ['c0', 'c1', 'c2'])
# Deactivate the tail
func, deactivate_callbacks = make_wrapped_function()
deactivate_callbacks[0]()
self.assertEqual(func(), ['c1', 'c2'])
# Deactivate the middle
func, deactivate_callbacks = make_wrapped_function()
deactivate_callbacks[1]()
self.assertEqual(func(), ['c0', 'c2'])
# Deactivate the head
func, deactivate_callbacks = make_wrapped_function()
deactivate_callbacks[2]()
self.assertEqual(func(), ['c0', 'c1'])
def test_isolation_nonempty(self):
# f2 and f3 are a chain of operations started in context c1.
# f2 is incidentally run under context c2, but that context should
# not be passed along to f3.
def f1():
with StackContext(functools.partial(self.context, 'c1')):
wrapped = wrap(f2)
with StackContext(functools.partial(self.context, 'c2')):
wrapped()
def f2():
self.assertIn('c1', self.active_contexts)
self.io_loop.add_callback(f3)
def f3():
self.assertIn('c1', self.active_contexts)
self.assertNotIn('c2', self.active_contexts)
self.stop()
self.io_loop.add_callback(f1)
self.wait()
def test_isolation_empty(self):
# Similar to test_isolation_nonempty, but here the f2/f3 chain
# is started without any context. Behavior should be equivalent
# to the nonempty case (although historically it was not)
def f1():
with NullContext():
wrapped = wrap(f2)
with StackContext(functools.partial(self.context, 'c2')):
wrapped()
def f2():
self.io_loop.add_callback(f3)
def f3():
self.assertNotIn('c2', self.active_contexts)
self.stop()
self.io_loop.add_callback(f1)
self.wait()
def test_yield_in_with(self):
@gen.engine
def f():
self.callback = yield gen.Callback('a')
with StackContext(functools.partial(self.context, 'c1')):
# This yield is a problem: the generator will be suspended
# and the StackContext's __exit__ is not called yet, so
# the context will be left on _state.contexts for anything
# that runs before the yield resolves.
yield gen.Wait('a')
with self.assertRaises(StackContextInconsistentError):
f()
self.wait()
# Cleanup: to avoid GC warnings (which for some reason only seem
# to show up on py33-asyncio), invoke the callback (which will do
# nothing since the gen.Runner is already finished) and delete it.
self.callback()
del self.callback
@gen_test
def test_yield_outside_with(self):
# This pattern avoids the problem in the previous test.
cb = yield gen.Callback('k1')
with StackContext(functools.partial(self.context, 'c1')):
self.io_loop.add_callback(cb)
yield gen.Wait('k1')
def test_yield_in_with_exception_stack_context(self):
# As above, but with ExceptionStackContext instead of StackContext.
@gen.engine
def f():
with ExceptionStackContext(lambda t, v, tb: False):
yield gen.Task(self.io_loop.add_callback)
with self.assertRaises(StackContextInconsistentError):
f()
self.wait()
@gen_test
def test_yield_outside_with_exception_stack_context(self):
cb = yield gen.Callback('k1')
with ExceptionStackContext(lambda t, v, tb: False):
self.io_loop.add_callback(cb)
yield gen.Wait('k1')
@gen_test
def test_run_with_stack_context(self):
@gen.coroutine
def f1():
self.assertEqual(self.active_contexts, ['c1'])
yield run_with_stack_context(
StackContext(functools.partial(self.context, 'c2')),
f2)
self.assertEqual(self.active_contexts, ['c1'])
@gen.coroutine
def f2():
self.assertEqual(self.active_contexts, ['c1', 'c2'])
yield gen.Task(self.io_loop.add_callback)
self.assertEqual(self.active_contexts, ['c1', 'c2'])
self.assertEqual(self.active_contexts, [])
yield run_with_stack_context(
StackContext(functools.partial(self.context, 'c1')),
f1)
self.assertEqual(self.active_contexts, [])
if __name__ == '__main__':
unittest.main()