python/aqmp: add asyncio compatibility wrappers

Python 3.6 does not have all of the goodies that Python 3.7 does, and we
need to support both. Add some compatibility wrappers needed for this
purpose.

(Note: Python 3.6 is EOL December 2021.)

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 20210915162955.333025-5-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
This commit is contained in:
John Snow 2021-09-15 12:29:32 -04:00
parent 35b9a85ade
commit a07616d612
1 changed files with 89 additions and 0 deletions

89
python/qemu/aqmp/util.py Normal file
View File

@ -0,0 +1,89 @@
"""
Miscellaneous Utilities
This module provides asyncio utilities and compatibility wrappers for
Python 3.6 to provide some features that otherwise become available in
Python 3.7+.
"""
import asyncio
import sys
from typing import (
Any,
Coroutine,
Optional,
TypeVar,
)
T = TypeVar('T')
# -------------------------------
# Section: Compatibility Wrappers
# -------------------------------
def create_task(coro: Coroutine[Any, Any, T],
loop: Optional[asyncio.AbstractEventLoop] = None
) -> 'asyncio.Future[T]':
"""
Python 3.6-compatible `asyncio.create_task` wrapper.
:param coro: The coroutine to execute in a task.
:param loop: Optionally, the loop to create the task in.
:return: An `asyncio.Future` object.
"""
if sys.version_info >= (3, 7):
if loop is not None:
return loop.create_task(coro)
return asyncio.create_task(coro) # pylint: disable=no-member
# Python 3.6:
return asyncio.ensure_future(coro, loop=loop)
def is_closing(writer: asyncio.StreamWriter) -> bool:
"""
Python 3.6-compatible `asyncio.StreamWriter.is_closing` wrapper.
:param writer: The `asyncio.StreamWriter` object.
:return: `True` if the writer is closing, or closed.
"""
if sys.version_info >= (3, 7):
return writer.is_closing()
# Python 3.6:
transport = writer.transport
assert isinstance(transport, asyncio.WriteTransport)
return transport.is_closing()
async def wait_closed(writer: asyncio.StreamWriter) -> None:
"""
Python 3.6-compatible `asyncio.StreamWriter.wait_closed` wrapper.
:param writer: The `asyncio.StreamWriter` to wait on.
"""
if sys.version_info >= (3, 7):
await writer.wait_closed()
return
# Python 3.6
transport = writer.transport
assert isinstance(transport, asyncio.WriteTransport)
while not transport.is_closing():
await asyncio.sleep(0)
# This is an ugly workaround, but it's the best I can come up with.
sock = transport.get_extra_info('socket')
if sock is None:
# Our transport doesn't have a socket? ...
# Nothing we can reasonably do.
return
while sock.fileno() != -1:
await asyncio.sleep(0)