1 files changed, 73 insertions, 0 deletions
diff --git a/lib/sqlalchemy/util/concurrency.py b/lib/sqlalchemy/util/concurrency.py
new file mode 100644
index 0000000..e900b43
--- /dev/null
+++ b/lib/sqlalchemy/util/concurrency.py
@@ -0,0 +1,73 @@
+# util/concurrency.py
+# Copyright (C) 2005-2022 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
+greenlet_error = None
+
+if compat.py3k:
+    try:
+        import greenlet  # noqa: F401
+    except ImportError as e:
+        greenlet_error = str(e)
+    else:
+        have_greenlet = True
+        from ._concurrency_py3k import await_only
+        from ._concurrency_py3k import await_fallback
+        from ._concurrency_py3k import greenlet_spawn
+        from ._concurrency_py3k import is_exit_exception
+        from ._concurrency_py3k import AsyncAdaptedLock
+        from ._concurrency_py3k import _util_async_run  # noqa: F401
+        from ._concurrency_py3k import (
+            _util_async_run_coroutine_function,
+        )  # noqa: F401, E501
+        from ._concurrency_py3k import asyncio  # noqa: F401
+
+    # does not need greennlet, just Python 3
+    from ._compat_py3k import asynccontextmanager  # noqa: F401
+
+if not have_greenlet:
+
+    asyncio = None  # noqa: F811
+
+    def _not_implemented():
+        # this conditional is to prevent pylance from considering
+        # greenlet_spawn() etc as "no return" and dimming out code below it
+        if have_greenlet:
+            return None
+
+        if not compat.py3k:
+            raise ValueError("Cannot use this function in py2.")
+        else:
+            raise ValueError(
+                "the greenlet library is required to use this function."
+                " %s" % greenlet_error
+                if greenlet_error
+                else ""
+            )
+
+    def is_exit_exception(e):  # noqa: F811
+        return not isinstance(e, Exception)
+
+    def await_only(thing):  # noqa: F811
+        _not_implemented()
+
+    def await_fallback(thing):  # noqa: F811
+        return thing
+
+    def greenlet_spawn(fn, *args, **kw):  # noqa: F811
+        _not_implemented()
+
+    def AsyncAdaptedLock(*args, **kw):  # noqa: F811
+        _not_implemented()
+
+    def _util_async_run(fn, *arg, **kw):  # noqa: F811
+        return fn(*arg, **kw)
+
+    def _util_async_run_coroutine_function(fn, *arg, **kw):  # noqa: F811
+        _not_implemented()