vendor asynccontextmanager outside of greenlet dependency

Fixed installation issue where the ``sqlalchemy.dialects.mysql`` module
would not be importable if "greenlet" were not installed.

This was actually breaking the sphinx build for when greenlet
were not installed.

Fixes: #7204
Change-Id: Ia351c124a2f1ca44bafe20a97267ce20cb55808f

diff --git a/doc/build/changelog/unreleased_14/7204.rst b/doc/build/changelog/unreleased_14/7204.rst
new file mode 100644 (file)
index 0000000..2f02d50
--- /dev/null
+++ b/doc/build/changelog/unreleased_14/7204.rst
@@ -0,0 +1,6 @@
+.. change::
+    :tags: bug, mysql
+    :tickets: 7204
+
+    Fixed installation issue where the ``sqlalchemy.dialects.mysql`` module
+    would not be importable if "greenlet" were not installed.

diff --git a/lib/sqlalchemy/util/_compat_py3k.py b/lib/sqlalchemy/util/_compat_py3k.py
new file mode 100644 (file)
index 0000000..cd9f3eb
--- /dev/null
+++ b/lib/sqlalchemy/util/_compat_py3k.py
@@ -0,0 +1,67 @@
+# util/_compat_py3k.py
+# Copyright (C) 2005-2021 the SQLAlchemy authors and contributors
+# <see AUTHORS file>
+#
+# This module is part of SQLAlchemy and is released under
+# the MIT License: https://www.opensource.org/licenses/mit-license.php
+
+from functools import wraps
+
+# vendored from py3.7
+
+
+class _AsyncGeneratorContextManager:
+    """Helper for @asynccontextmanager."""
+
+    def __init__(self, func, args, kwds):
+        self.gen = func(*args, **kwds)
+        self.func, self.args, self.kwds = func, args, kwds
+        doc = getattr(func, "__doc__", None)
+        if doc is None:
+            doc = type(self).__doc__
+        self.__doc__ = doc
+
+    async def __aenter__(self):
+        try:
+            return await self.gen.__anext__()
+        except StopAsyncIteration:
+            raise RuntimeError("generator didn't yield") from None
+
+    async def __aexit__(self, typ, value, traceback):
+        if typ is None:
+            try:
+                await self.gen.__anext__()
+            except StopAsyncIteration:
+                return
+            else:
+                raise RuntimeError("generator didn't stop")
+        else:
+            if value is None:
+                value = typ()
+            # See _GeneratorContextManager.__exit__ for comments on subtleties
+            # in this implementation
+            try:
+                await self.gen.athrow(typ, value, traceback)
+                raise RuntimeError("generator didn't stop after athrow()")
+            except StopAsyncIteration as exc:
+                return exc is not value
+            except RuntimeError as exc:
+                if exc is value:
+                    return False
+                if isinstance(value, (StopIteration, StopAsyncIteration)):
+                    if exc.__cause__ is value:
+                        return False
+                raise
+            except BaseException as exc:
+                if exc is not value:
+                    raise
+
+
+# using the vendored version in all cases at the moment to establish
+# full test coverage
+def asynccontextmanager(func):
+    @wraps(func)
+    def helper(*args, **kwds):
+        return _AsyncGeneratorContextManager(func, args, kwds)
+
+    return helper

diff --git a/lib/sqlalchemy/util/_concurrency_py3k.py b/lib/sqlalchemy/util/_concurrency_py3k.py
index 7a4a2c361b71ccbc8fda71a6aa058c29e7ce4a01..55fe87c6a78ba109517ce0e9ce505b84245cde7e 100644 (file)
--- a/lib/sqlalchemy/util/_concurrency_py3k.py
+++ b/lib/sqlalchemy/util/_concurrency_py3k.py
@@ -1,5 +1,11 @@
+# util/_concurrency_py3k.py
+# Copyright (C) 2005-2021 the SQLAlchemy authors and contributors
+# <see AUTHORS file>
+#
+# This module is part of SQLAlchemy and is released under
+# the MIT License: https://www.opensource.org/licenses/mit-license.php
+
 import asyncio
-from functools import wraps
 import sys
 from typing import Any
 from typing import Callable
@@ -194,63 +200,3 @@ def get_event_loop():
             return asyncio.get_event_loop_policy().get_event_loop()
     else:
         return asyncio.get_event_loop()
-
-
-# vendored from py3.7
-
-
-class _AsyncGeneratorContextManager:
-    """Helper for @asynccontextmanager."""
-
-    def __init__(self, func, args, kwds):
-        self.gen = func(*args, **kwds)
-        self.func, self.args, self.kwds = func, args, kwds
-        doc = getattr(func, "__doc__", None)
-        if doc is None:
-            doc = type(self).__doc__
-        self.__doc__ = doc
-
-    async def __aenter__(self):
-        try:
-            return await self.gen.__anext__()
-        except StopAsyncIteration:
-            raise RuntimeError("generator didn't yield") from None
-
-    async def __aexit__(self, typ, value, traceback):
-        if typ is None:
-            try:
-                await self.gen.__anext__()
-            except StopAsyncIteration:
-                return
-            else:
-                raise RuntimeError("generator didn't stop")
-        else:
-            if value is None:
-                value = typ()
-            # See _GeneratorContextManager.__exit__ for comments on subtleties
-            # in this implementation
-            try:
-                await self.gen.athrow(typ, value, traceback)
-                raise RuntimeError("generator didn't stop after athrow()")
-            except StopAsyncIteration as exc:
-                return exc is not value
-            except RuntimeError as exc:
-                if exc is value:
-                    return False
-                if isinstance(value, (StopIteration, StopAsyncIteration)):
-                    if exc.__cause__ is value:
-                        return False
-                raise
-            except BaseException as exc:
-                if exc is not value:
-                    raise
-
-
-# using the vendored version in all cases at the moment to establish
-# full test coverage
-def asynccontextmanager(func):
-    @wraps(func)
-    def helper(*args, **kwds):
-        return _AsyncGeneratorContextManager(func, args, kwds)
-
-    return helper

diff --git a/lib/sqlalchemy/util/concurrency.py b/lib/sqlalchemy/util/concurrency.py
index 5d15e06dec0ce3bc088257a379898cb0910aead0..37ecfdbc338a2192e5370e748effedc8c6ea2fab 100644 (file)
--- a/lib/sqlalchemy/util/concurrency.py
+++ b/lib/sqlalchemy/util/concurrency.py
@@ -1,3 +1,10 @@
+# util/concurrency.py
+# Copyright (C) 2005-2021 the SQLAlchemy authors and contributors
+# <see AUTHORS file>
+#
+# This module is part of SQLAlchemy and is released under
+# the MIT License: https://www.opensource.org/licenses/mit-license.php
+
 from . import compat
 
 have_greenlet = False
@@ -19,7 +26,9 @@ if compat.py3k:
             _util_async_run_coroutine_function,
         )  # noqa F401, E501
         from ._concurrency_py3k import asyncio  # noqa F401
-        from ._concurrency_py3k import asynccontextmanager
+
+    # does not need greennlet, just Python 3
+    from ._compat_py3k import asynccontextmanager  # noqa F401
 
 if not have_greenlet:
 
@@ -58,6 +67,3 @@ if not have_greenlet:
 
     def _util_async_run_coroutine_function(fn, *arg, **kw):  # noqa F81
         _not_implemented()
-
-    def asynccontextmanager(fn, *arg, **kw):  # noqa F81
-        _not_implemented()