type cleanups and refactoring

[totaam]

Mostly flagged by #3927, related to #3592.

A lot of the types from the typing module are now deprecated, see PEP 585:
https://docs.python.org/3/library/typing.html#typing.Tuple

This requires Python 3.9 (not a big problem for v6?)

• get_info server method signature mess:

xpra/platform/darwin/shadow_server.py:231: error: Signature of "get_info" incompatible with supertype "ServerBase"  [override]
xpra/platform/darwin/shadow_server.py:231: note:      Superclass:
xpra/platform/darwin/shadow_server.py:231: note:          def get_info(self, proto: Any = ..., client_uuids: Any = ...) -> dict[str, Any]
xpra/platform/darwin/shadow_server.py:231: note:      Subclass:
xpra/platform/darwin/shadow_server.py:231: note:          def get_info(self, proto: Any, *_args: Any) -> dict[str, Any]

• stricter packet parsing at network boundary, ie:
  xpra/x11/server.py:916: error: Cannot determine type of "wid" [has-type]
  Could this be introspected and changed to a positional packet function with default args?
• "client-window-base" missing attributes"
  xpra/client/gui/client_window_base.py:414: error: "ClientWindowBase" has no attribute "set_modal" [attr-defined]
• mixins cross domain dependencies:
  xpra/server/mixins/audio.py:216: error: "AudioServer" has no attribute "add_process" [attr-defined]
• SocketProtocol missing attributes: authenticators, encryption, ..
• XpraConfig class does not have any "real" attributes: convert to introspected hints?
• _id_to_window, readonly, ui_driver and friends
• Return a value of type "tuple[bool, bool]" instead of "NoneType" or update function "accept_data" type hint
• brain-overload: 164 functions have a cognitive complexity above 30 in sonarqube
• 41 FIXMEs and 38 TODOs
• 9 functions have too many arguments
  etc

[zatricky]

This seems also to be a problem for focal (Ubuntu 20.04 - corrected) as the latest version of xpra now requires python3.10+ due to using TypeAlias whereas focal ships with python3.8.10. I could be wrong about the exact versions needed/etc - here's the error at least:

2023-07-24 14:02:51,740 server error processing new connection from Protocol(socket socket:/run/user/<userid>/xpra/80/socket): cannot import name 'TypeAlias' from 'typing' (/usr/lib/python3.8/typing.py)
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/xpra/server/server_core.py", line 2245, in call_hello_oked
    self.hello_oked(proto, c, auth_caps)
  File "/usr/lib/python3/dist-packages/xpra/server/server_base.py", line 395, in hello_oked
    cc_class = self.get_client_connection_class(c)
  File "/usr/lib/python3/dist-packages/xpra/server/server_base.py", line 420, in get_client_connection_class
    return get_client_connection_class(caps)
  File "/usr/lib/python3/dist-packages/xpra/server/source/client_connection_factory.py", line 83, in get_client_connection_class
    CC_BASES = get_needed_based_classes(caps)
  File "/usr/lib/python3/dist-packages/xpra/server/source/client_connection_factory.py", line 71, in get_needed_based_classes
    from xpra.server.source.client_connection import ClientConnection
  File "/usr/lib/python3/dist-packages/xpra/server/source/client_connection.py", line 10, in <module>
    from typing import Dict, Any, Optional, Tuple, Callable, Union, TypeAlias
ImportError: cannot import name 'TypeAlias' from 'typing' (/usr/lib/python3.8/typing.py)
2023-07-24 14:02:51,741 Disconnecting client /run/user/<userid>/xpra/80/socket:
2023-07-24 14:02:51,741  ConnectionMessage.CONNECTION_ERROR (error accepting new connection)

[totaam]

@zatricky thanks for pointing that out, the workaround in d37fecb should work (not tested yet).
The requirement for Python 3.6+ in v5 is unchanged.

---

Edit:

This seems also to be a problem for focal (Ubuntu 22.04)

FYI: focal is 20.04.

[zatricky]

Oops! Yes, 20.04 ... :-|

[totaam]

With the switch to Python 3.10+, we can also take advantage of:

• contextlib.nullcontext to replace the dummy context
• contextlib.redirect_stdout to replace out custom context
• ipaddress.IPv4Network.supernet_of) to replace code from net_util?
• multiprocessing.Process.kill if terminate fails?
• queue.SimpleQueue
• the walrus "the walrus", incrementally
• self-documenting-expressions
• as_integer_ratio for scaling parser?
• importlib.metadata for getting version numbers?
• logging.basicConfig force force basic config?
• mmap.madvise with MADV_DONTDUMP for mmap area
• get_native_id expose it?
• dictionary-merge-update-operators
• string-methods-to-remove-prefixes
• sys.platlibdir
• typing.get_type_hints

[totaam]

Remaining items that might be of interest:

• monotonic_ns for a lot of performance data (window and source stats)
• dataclasses
• contextlib.suppress
• os.add_dll_directory
• os.memfd_create
• shlex.join for ssh command?
• has_dualstack_ipv6
• ipaddress
• The socket.if_nameindex(), socket.if_nametoindex(), and socket.if_indextoname() functions have been implemented on Windows
• typing.Literal
• math.isclose
• ConfigParser
• subprocess.run with capture_output
• set_start_method with spawn? (and pass file descriptors by hand?)

[totaam]

Regarding the switch to monotonic_ns, here is the type of bug we don't want to re-introduce: 5768677 / #2038