Add support for Tornado 6 #1

owais · 2020-03-12T04:03:50Z

This PR adds support for Tornado 6 by conditionally using different
scope manager, context manager and tracing implementation depending
on the version of Tornado and Python being used.

It does not require existing users to change anything other than upgrade
to the latest version of this package.

This package used to use the TornadoScopeManager shipped by
opentracing-python. The scope manager used tornado.stack_context
which was deprecated in Tornado 5 and removed in Tornado 6. Tornado
now recommends using contextvars package introduced in Python3.7.
opentracing-python already provides a ContextVarsScopeManager that
builds on top of the contextvars package. It also implements
AsyncioScopeManager which builds on top of asyncio and falls back
on thread local storage to implement context propagation. We fallback on
this for Python 3.6 and older when using Tornado 6 and newer.

The package also had seen some decay and some tests were not passing.
This PR updates the test suite and unit tests to get them working again.

Changes this PR introduces:

Default to ContextVarsScopeManager instead of TornadoScopeManager.
Fallback on TornadoScopeManager or AsyncioScopeManager based on the
Tornado and Python version.
Added tox support to enable easier testing across Python and Tornado
versions.
Updated travis config to work with tox environments. Now each travis
build will run tests on every supported python version in parallel. Each
parallel test will run all tests for all versions of tornado serially.
The PR add some code that uses the new async/await syntax. Such code
is invalid for older versions of python. To make it works for all
versions, we conditionally import modules depending on the Python
interpreter version.
To preserve backward compatibility and to keep using common code for
all tornado versions, we've added some noop implementations that are not
to be used with newer versions of tornado.
tornado.gen.coroutine was deprecated in favour of async/await but we
still support it where we can. There is a bug in Tornado 6 that prevents
us from support the deprecated feature on Python3.7 with
ContextVarsScopeManager.
(Run tornado gen.coroutines in the context of a task. tornadoweb/tornado#2716)
Python3.4 also does not pass the tests for tornado.gen.coroutine but
it is not a regression caused by this PR. Testing on master results in
the same behavior. For now, I've added skip markers to these tests on
Python3.4. If needed, we can look into supporting these in future in a
separate PR.

tests/helpers.py

tests/_test_case_base.py

rmfitzpatrick · 2020-03-12T14:27:54Z

tornado_opentracing/handlers.py

+    def wrapper(self, *args, **kwargs):
+        tracing = self.settings.get('opentracing_tracing')
+        attrs = self.settings.get('opentracing_traced_attributes', [])
+        tracing._apply_tracing(self, attrs)


tracing may be None here

tornado_opentracing/__init__.py

setup.py

tornado_opentracing/_tracing.py

tornado_opentracing/context_manager.py

tornado_opentracing/initialization.py

This PR adds support for Tornado 6 by conditionally using different scope manager, context manager and tracing implementation depending on the version of Tornado and Python being used. It does not require existing users to change anything other than upgrade to the latest version of this package. This package used to use the TornadoScopeManager shipped by opentracing-python. The scope manager used `tornado.stack_context` which was deprecated in Tornado 5 and removed in Tornado 6. Tornado now recommends using contextvars package introduced in Python3.7. opentracing-python already provides a ContextVarsScopeManager that builds on top of the contextvars package. It also implements AsyncioScopeManager which builds on top of asyncio and falls back on thread local storage to implement context propagation. We fallback on this for Python 3.6 and older when using Tornado 6 and newer. The package also had seen some decay and some tests were not passing. This PR updates the test suite and unit tests to get them working again. Changes this PR introduces: - Default to ContextVarsScopeManager instead of TornadoScopeManager. Fallback on TornadoScopeManager or AsyncioScopeManager based on the Tornado and Python version. - Added tox support to enable easier testing across Python and Tornado versions. - Updated travis config to work with tox environments. Now each travis build will run tests on every supported python version in parallel. Each parallel test will run all tests for all versions of tornado serially. - The PR add some code that uses the new async/await syntax. Such code is invalid for older versions of python. To make it works for all versions, we conditionally import modules depending on the Python interpreter version. - To preserve backward compatibility and to keep using common code for all tornado versions, we've added some noop implementations that are not to be used with newer versions of tornado. - `tornado.gen.coroutine` was deprecated in favour of async/await but we still support it where we can. There is a bug in Tornado 6 that prevents us from support the deprecated feature on Python3.7 with ContextVarsScopeManager. (tornadoweb/tornado#2716) - Python3.4 also does not pass the tests for `tornado.gen.coroutine` but it is not a regression caused by this PR. Testing on master results in the same behavior. For now, I've added skip markers to these tests on Python3.4. If needed, we can look into supporting these in future in a separate PR.

rmfitzpatrick

Very nice!

owais requested a review from rmfitzpatrick March 12, 2020 04:05