Support Trio out-of-the-box, take 2 (#463)

* Support Trio out-of-the-box

This PR makes `@retry` just work when running under Trio.

* Add a no-trio test environment

* Switch to only testing trio in one environment

* bump releasenote so it is later in history->reno puts it in the correct place in the changelog

* fix mypy & pep8 checks

* Update doc/source/index.rst

fix example

Co-authored-by: Julien Danjou <julien@danjou.info>

* Update tests/test_tornado.py

* Update tests/test_tornado.py

* make _portably_async_sleep a sync function that returns an async function

---------

Co-authored-by: Nathaniel J. Smith <njs@pobox.com>
Co-authored-by: Julien Danjou <julien@danjou.info>

.github/workflows/ci.yaml

@@ -27,7 +27,7 @@ jobs:
           - python: "3.11"
             tox: py311
           - python: "3.12"
-            tox: py312
+            tox: py312,py312-trio
           - python: "3.12"
             tox: pep8
           - python: "3.11"

doc/source/index.rst

@@ -568,28 +568,34 @@ in retry strategies like ``retry_if_result``. This can be done accessing the
 Async and retry
 ~~~~~~~~~~~~~~~
 
-Finally, ``retry`` works also on asyncio and Tornado (>= 4.5) coroutines.
+Finally, ``retry`` works also on asyncio, Trio, and Tornado (>= 4.5) coroutines.
 Sleeps are done asynchronously too.
 
 .. code-block:: python
 
     @retry
-    async def my_async_function(loop):
+    async def my_asyncio_function(loop):
         await loop.getaddrinfo('8.8.8.8', 53)
 
+.. code-block:: python
+
+    @retry
+    async def my_async_trio_function():
+        await trio.socket.getaddrinfo('8.8.8.8', 53)
+
 .. code-block:: python
 
     @retry
     @tornado.gen.coroutine
-    def my_async_function(http_client, url):
+    def my_async_tornado_function(http_client, url):
         yield http_client.fetch(url)
 
-You can even use alternative event loops such as `curio` or `Trio` by passing the correct sleep function:
+You can even use alternative event loops such as `curio` by passing the correct sleep function:
 
 .. code-block:: python
 
-    @retry(sleep=trio.sleep)
-    async def my_async_function(loop):
+    @retry(sleep=curio.sleep)
+    async def my_async_curio_function():
         await asks.get('https://example.org')
 
 Contribute

releasenotes/notes/trio-support-retry-22bd544800cd1f36.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    If you're using `Trio <https://trio.readthedocs.io>`__, then
+    ``@retry`` now works automatically. It's no longer necessary to
+    pass ``sleep=trio.sleep``.

tenacity/asyncio/__init__.py

@@ -46,19 +46,30 @@
 WrappedFn = t.TypeVar("WrappedFn", bound=t.Callable[..., t.Awaitable[t.Any]])
 
 
-def asyncio_sleep(duration: float) -> t.Awaitable[None]:
+def _portable_async_sleep(seconds: float) -> t.Awaitable[None]:
+    # If trio is already imported, then importing it is cheap.
+    # If trio isn't already imported, then it's definitely not running, so we
+    # can skip further checks.
+    if "trio" in sys.modules:
+        # If trio is available, then sniffio is too
+        import trio
+        import sniffio
+
+        if sniffio.current_async_library() == "trio":
+            return trio.sleep(seconds)
+    # Otherwise, assume asyncio
     # Lazy import asyncio as it's expensive (responsible for 25-50% of total import overhead).
     import asyncio
 
-    return asyncio.sleep(duration)
+    return asyncio.sleep(seconds)
 
 
 class AsyncRetrying(BaseRetrying):
     def __init__(
         self,
         sleep: t.Callable[
             [t.Union[int, float]], t.Union[None, t.Awaitable[None]]
-        ] = asyncio_sleep,
+        ] = _portable_async_sleep,
         stop: "StopBaseT" = tenacity.stop.stop_never,
         wait: "WaitBaseT" = tenacity.wait.wait_none(),
         retry: "t.Union[SyncRetryBaseT, RetryBaseT]" = tenacity.retry_if_exception_type(),

tests/test_asyncio.py

@@ -18,6 +18,13 @@
 import unittest
 from functools import wraps
 
+try:
+    import trio
+except ImportError:
+    have_trio = False
+else:
+    have_trio = True
+
 import pytest
 
 import tenacity
@@ -55,7 +62,7 @@ async def _retryable_coroutine_with_2_attempts(thing):
     thing.go()
 
 
-class TestAsync(unittest.TestCase):
+class TestAsyncio(unittest.TestCase):
     @asynctest
     async def test_retry(self):
         thing = NoIOErrorAfterCount(5)
@@ -138,6 +145,21 @@ def after(retry_state):
         assert list(attempt_nos2) == [1, 2, 3]
 
 
+@unittest.skipIf(not have_trio, "trio not installed")
+class TestTrio(unittest.TestCase):
+    def test_trio_basic(self):
+        thing = NoIOErrorAfterCount(5)
+
+        @retry
+        async def trio_function():
+            await trio.sleep(0.00001)
+            return thing.go()
+
+        trio.run(trio_function)
+
+        assert thing.counter == thing.count
+
+
 class TestContextManager(unittest.TestCase):
     @asynctest
     async def test_do_max_attempts(self):

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py3{8,9,10,11,12}, pep8, pypy3
+envlist = py3{8,9,10,11,12,12-trio}, pep8, pypy3
 skip_missing_interpreters = True
 
 [testenv]
@@ -8,6 +8,7 @@ sitepackages = False
 deps =
     .[test]
     .[doc]
+    trio: trio
 commands =
     py3{8,9,10,11,12},pypy3: pytest {posargs}
     py3{8,9,10,11,12},pypy3: sphinx-build -a -E -W -b doctest doc/source doc/build
@@ -24,10 +25,11 @@ commands =
 deps =
     mypy>=1.0.0
     pytest # for stubs
+    trio
 commands =
     mypy {posargs}
 
 [testenv:reno]
 basepython = python3
 deps = reno
-commands = reno {posargs}
+commands = reno {posargs}