Major fixes and new features

venv/lib/python3.12/site-packages/asyncpg/_asyncio_compat.py

@@ -0,0 +1,87 @@
+# Backports from Python/Lib/asyncio for older Pythons
+#
+# Copyright (c) 2001-2023 Python Software Foundation; All Rights Reserved
+#
+# SPDX-License-Identifier: PSF-2.0
+
+
+import asyncio
+import functools
+import sys
+
+if sys.version_info < (3, 11):
+    from async_timeout import timeout as timeout_ctx
+else:
+    from asyncio import timeout as timeout_ctx
+
+
+async def wait_for(fut, timeout):
+    """Wait for the single Future or coroutine to complete, with timeout.
+
+    Coroutine will be wrapped in Task.
+
+    Returns result of the Future or coroutine.  When a timeout occurs,
+    it cancels the task and raises TimeoutError.  To avoid the task
+    cancellation, wrap it in shield().
+
+    If the wait is cancelled, the task is also cancelled.
+
+    If the task supresses the cancellation and returns a value instead,
+    that value is returned.
+
+    This function is a coroutine.
+    """
+    # The special case for timeout <= 0 is for the following case:
+    #
+    # async def test_waitfor():
+    #     func_started = False
+    #
+    #     async def func():
+    #         nonlocal func_started
+    #         func_started = True
+    #
+    #     try:
+    #         await asyncio.wait_for(func(), 0)
+    #     except asyncio.TimeoutError:
+    #         assert not func_started
+    #     else:
+    #         assert False
+    #
+    # asyncio.run(test_waitfor())
+
+    if timeout is not None and timeout <= 0:
+        fut = asyncio.ensure_future(fut)
+
+        if fut.done():
+            return fut.result()
+
+        await _cancel_and_wait(fut)
+        try:
+            return fut.result()
+        except asyncio.CancelledError as exc:
+            raise TimeoutError from exc
+
+    async with timeout_ctx(timeout):
+        return await fut
+
+
+async def _cancel_and_wait(fut):
+    """Cancel the *fut* future or task and wait until it completes."""
+
+    loop = asyncio.get_running_loop()
+    waiter = loop.create_future()
+    cb = functools.partial(_release_waiter, waiter)
+    fut.add_done_callback(cb)
+
+    try:
+        fut.cancel()
+        # We cannot wait on *fut* directly to make
+        # sure _cancel_and_wait itself is reliably cancellable.
+        await waiter
+    finally:
+        fut.remove_done_callback(cb)
+
+
+def _release_waiter(waiter, *args):
+    if not waiter.done():
+        waiter.set_result(None)