stack_context_test.py
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00001 #!/usr/bin/env python
00002 from __future__ import absolute_import, division, print_function, with_statement
00003 
00004 from tornado import gen
00005 from tornado.log import app_log
00006 from tornado.stack_context import (StackContext, wrap, NullContext, StackContextInconsistentError,
00007                                    ExceptionStackContext, run_with_stack_context, _state)
00008 from tornado.testing import AsyncHTTPTestCase, AsyncTestCase, ExpectLog, gen_test
00009 from tornado.test.util import unittest
00010 from tornado.web import asynchronous, Application, RequestHandler
00011 import contextlib
00012 import functools
00013 import logging
00014 
00015 
00016 class TestRequestHandler(RequestHandler):
00017     def __init__(self, app, request, io_loop):
00018         super(TestRequestHandler, self).__init__(app, request)
00019         self.io_loop = io_loop
00020 
00021     @asynchronous
00022     def get(self):
00023         logging.debug('in get()')
00024         # call self.part2 without a self.async_callback wrapper.  Its
00025         # exception should still get thrown
00026         self.io_loop.add_callback(self.part2)
00027 
00028     def part2(self):
00029         logging.debug('in part2()')
00030         # Go through a third layer to make sure that contexts once restored
00031         # are again passed on to future callbacks
00032         self.io_loop.add_callback(self.part3)
00033 
00034     def part3(self):
00035         logging.debug('in part3()')
00036         raise Exception('test exception')
00037 
00038     def write_error(self, status_code, **kwargs):
00039         if 'exc_info' in kwargs and str(kwargs['exc_info'][1]) == 'test exception':
00040             self.write('got expected exception')
00041         else:
00042             self.write('unexpected failure')
00043 
00044 
00045 class HTTPStackContextTest(AsyncHTTPTestCase):
00046     def get_app(self):
00047         return Application([('/', TestRequestHandler,
00048                              dict(io_loop=self.io_loop))])
00049 
00050     def test_stack_context(self):
00051         with ExpectLog(app_log, "Uncaught exception GET /"):
00052             self.http_client.fetch(self.get_url('/'), self.handle_response)
00053             self.wait()
00054         self.assertEqual(self.response.code, 500)
00055         self.assertTrue(b'got expected exception' in self.response.body)
00056 
00057     def handle_response(self, response):
00058         self.response = response
00059         self.stop()
00060 
00061 
00062 class StackContextTest(AsyncTestCase):
00063     def setUp(self):
00064         super(StackContextTest, self).setUp()
00065         self.active_contexts = []
00066 
00067     @contextlib.contextmanager
00068     def context(self, name):
00069         self.active_contexts.append(name)
00070         yield
00071         self.assertEqual(self.active_contexts.pop(), name)
00072 
00073     # Simulates the effect of an asynchronous library that uses its own
00074     # StackContext internally and then returns control to the application.
00075     def test_exit_library_context(self):
00076         def library_function(callback):
00077             # capture the caller's context before introducing our own
00078             callback = wrap(callback)
00079             with StackContext(functools.partial(self.context, 'library')):
00080                 self.io_loop.add_callback(
00081                     functools.partial(library_inner_callback, callback))
00082 
00083         def library_inner_callback(callback):
00084             self.assertEqual(self.active_contexts[-2:],
00085                              ['application', 'library'])
00086             callback()
00087 
00088         def final_callback():
00089             # implementation detail:  the full context stack at this point
00090             # is ['application', 'library', 'application'].  The 'library'
00091             # context was not removed, but is no longer innermost so
00092             # the application context takes precedence.
00093             self.assertEqual(self.active_contexts[-1], 'application')
00094             self.stop()
00095         with StackContext(functools.partial(self.context, 'application')):
00096             library_function(final_callback)
00097         self.wait()
00098 
00099     def test_deactivate(self):
00100         deactivate_callbacks = []
00101 
00102         def f1():
00103             with StackContext(functools.partial(self.context, 'c1')) as c1:
00104                 deactivate_callbacks.append(c1)
00105                 self.io_loop.add_callback(f2)
00106 
00107         def f2():
00108             with StackContext(functools.partial(self.context, 'c2')) as c2:
00109                 deactivate_callbacks.append(c2)
00110                 self.io_loop.add_callback(f3)
00111 
00112         def f3():
00113             with StackContext(functools.partial(self.context, 'c3')) as c3:
00114                 deactivate_callbacks.append(c3)
00115                 self.io_loop.add_callback(f4)
00116 
00117         def f4():
00118             self.assertEqual(self.active_contexts, ['c1', 'c2', 'c3'])
00119             deactivate_callbacks[1]()
00120             # deactivating a context doesn't remove it immediately,
00121             # but it will be missing from the next iteration
00122             self.assertEqual(self.active_contexts, ['c1', 'c2', 'c3'])
00123             self.io_loop.add_callback(f5)
00124 
00125         def f5():
00126             self.assertEqual(self.active_contexts, ['c1', 'c3'])
00127             self.stop()
00128         self.io_loop.add_callback(f1)
00129         self.wait()
00130 
00131     def test_deactivate_order(self):
00132         # Stack context deactivation has separate logic for deactivation at
00133         # the head and tail of the stack, so make sure it works in any order.
00134         def check_contexts():
00135             # Make sure that the full-context array and the exception-context
00136             # linked lists are consistent with each other.
00137             full_contexts, chain = _state.contexts
00138             exception_contexts = []
00139             while chain is not None:
00140                 exception_contexts.append(chain)
00141                 chain = chain.old_contexts[1]
00142             self.assertEqual(list(reversed(full_contexts)), exception_contexts)
00143             return list(self.active_contexts)
00144 
00145         def make_wrapped_function():
00146             """Wraps a function in three stack contexts, and returns
00147             the function along with the deactivation functions.
00148             """
00149             # Remove the test's stack context to make sure we can cover
00150             # the case where the last context is deactivated.
00151             with NullContext():
00152                 partial = functools.partial
00153                 with StackContext(partial(self.context, 'c0')) as c0:
00154                     with StackContext(partial(self.context, 'c1')) as c1:
00155                         with StackContext(partial(self.context, 'c2')) as c2:
00156                             return (wrap(check_contexts), [c0, c1, c2])
00157 
00158         # First make sure the test mechanism works without any deactivations
00159         func, deactivate_callbacks = make_wrapped_function()
00160         self.assertEqual(func(), ['c0', 'c1', 'c2'])
00161 
00162         # Deactivate the tail
00163         func, deactivate_callbacks = make_wrapped_function()
00164         deactivate_callbacks[0]()
00165         self.assertEqual(func(), ['c1', 'c2'])
00166 
00167         # Deactivate the middle
00168         func, deactivate_callbacks = make_wrapped_function()
00169         deactivate_callbacks[1]()
00170         self.assertEqual(func(), ['c0', 'c2'])
00171 
00172         # Deactivate the head
00173         func, deactivate_callbacks = make_wrapped_function()
00174         deactivate_callbacks[2]()
00175         self.assertEqual(func(), ['c0', 'c1'])
00176 
00177     def test_isolation_nonempty(self):
00178         # f2 and f3 are a chain of operations started in context c1.
00179         # f2 is incidentally run under context c2, but that context should
00180         # not be passed along to f3.
00181         def f1():
00182             with StackContext(functools.partial(self.context, 'c1')):
00183                 wrapped = wrap(f2)
00184             with StackContext(functools.partial(self.context, 'c2')):
00185                 wrapped()
00186 
00187         def f2():
00188             self.assertIn('c1', self.active_contexts)
00189             self.io_loop.add_callback(f3)
00190 
00191         def f3():
00192             self.assertIn('c1', self.active_contexts)
00193             self.assertNotIn('c2', self.active_contexts)
00194             self.stop()
00195 
00196         self.io_loop.add_callback(f1)
00197         self.wait()
00198 
00199     def test_isolation_empty(self):
00200         # Similar to test_isolation_nonempty, but here the f2/f3 chain
00201         # is started without any context.  Behavior should be equivalent
00202         # to the nonempty case (although historically it was not)
00203         def f1():
00204             with NullContext():
00205                 wrapped = wrap(f2)
00206             with StackContext(functools.partial(self.context, 'c2')):
00207                 wrapped()
00208 
00209         def f2():
00210             self.io_loop.add_callback(f3)
00211 
00212         def f3():
00213             self.assertNotIn('c2', self.active_contexts)
00214             self.stop()
00215 
00216         self.io_loop.add_callback(f1)
00217         self.wait()
00218 
00219     def test_yield_in_with(self):
00220         @gen.engine
00221         def f():
00222             self.callback = yield gen.Callback('a')
00223             with StackContext(functools.partial(self.context, 'c1')):
00224                 # This yield is a problem: the generator will be suspended
00225                 # and the StackContext's __exit__ is not called yet, so
00226                 # the context will be left on _state.contexts for anything
00227                 # that runs before the yield resolves.
00228                 yield gen.Wait('a')
00229 
00230         with self.assertRaises(StackContextInconsistentError):
00231             f()
00232             self.wait()
00233         # Cleanup: to avoid GC warnings (which for some reason only seem
00234         # to show up on py33-asyncio), invoke the callback (which will do
00235         # nothing since the gen.Runner is already finished) and delete it.
00236         self.callback()
00237         del self.callback
00238 
00239     @gen_test
00240     def test_yield_outside_with(self):
00241         # This pattern avoids the problem in the previous test.
00242         cb = yield gen.Callback('k1')
00243         with StackContext(functools.partial(self.context, 'c1')):
00244             self.io_loop.add_callback(cb)
00245         yield gen.Wait('k1')
00246 
00247     def test_yield_in_with_exception_stack_context(self):
00248         # As above, but with ExceptionStackContext instead of StackContext.
00249         @gen.engine
00250         def f():
00251             with ExceptionStackContext(lambda t, v, tb: False):
00252                 yield gen.Task(self.io_loop.add_callback)
00253 
00254         with self.assertRaises(StackContextInconsistentError):
00255             f()
00256             self.wait()
00257 
00258     @gen_test
00259     def test_yield_outside_with_exception_stack_context(self):
00260         cb = yield gen.Callback('k1')
00261         with ExceptionStackContext(lambda t, v, tb: False):
00262             self.io_loop.add_callback(cb)
00263         yield gen.Wait('k1')
00264 
00265     @gen_test
00266     def test_run_with_stack_context(self):
00267         @gen.coroutine
00268         def f1():
00269             self.assertEqual(self.active_contexts, ['c1'])
00270             yield run_with_stack_context(
00271                 StackContext(functools.partial(self.context, 'c2')),
00272                 f2)
00273             self.assertEqual(self.active_contexts, ['c1'])
00274 
00275         @gen.coroutine
00276         def f2():
00277             self.assertEqual(self.active_contexts, ['c1', 'c2'])
00278             yield gen.Task(self.io_loop.add_callback)
00279             self.assertEqual(self.active_contexts, ['c1', 'c2'])
00280 
00281         self.assertEqual(self.active_contexts, [])
00282         yield run_with_stack_context(
00283             StackContext(functools.partial(self.context, 'c1')),
00284             f1)
00285         self.assertEqual(self.active_contexts, [])
00286 
00287 if __name__ == '__main__':
00288     unittest.main()


rosbridge_server
Author(s): Jonathan Mace
autogenerated on Thu Aug 27 2015 14:50:40