4:8
     ˆÇË„e§Ê¿Í ?÷     """Selector and proactor event loops for Windows."""

import sys

if sys.platform != 'win32':  # pragma: no cover
    raise ImportError('win32 only')

import _overlapped
import _winapi
import errno
import math
import msvcrt
import socket
import struct
import time
import weakref

from . import events
from . import base_subprocess
from . import futures
from . import exceptions
from . import proactor_events
from . import selector_events
from . import tasks
from . import windows_utils
from .log import logger


__all__ = (
    'SelectorEventLoop', 'ProactorEventLoop', 'IocpProactor',
    'DefaultEventLoopPolicy', 'WindowsSelectorEventLoopPolicy',
    'WindowsProactorEventLoopPolicy',
)


NULL = _winapi.NULL
INFINITE = _winapi.INFINITE
ERROR_CONNECTION_REFUSED = 1225
ERROR_CONNECTION_ABORTED = 1236

# Initial delay in seconds for connect_pipe() before retrying to connect
CONNECT_PIPE_INIT_DELAY = 0.001

# Maximum delay in seconds for connect_pipe() before retrying to connect
CONNECT_PIPE_MAX_DELAY = 0.100


class _OverlappedFuture(futures.Future):
    """Subclass of Future which represents an overlapped operation.

    Cancelling it will immediately cancel the overlapped operation.
    """

    def __init__(self, ov, *, loop=None):
        super().__init__(loop=loop)
        if self._source_traceback:
            del self._source_traceback[-1]
        self._ov = ov

    def _repr_info(self):
        info = super()._repr_info()
        if self._ov is not None:
            state = 'pending' if self._ov.pending else 'completed'
            info.insert(1, f'overlapped=<{state}, {self._ov.address:#x}>')
        return info

    def _cancel_overlapped(self):
        if self._ov is None:
            return
        try:
            self._ov.cancel()
        except OSError as exc:
            context = {
                'message': 'Cancelling an overlapped future failed',
                'exception': exc,
                'future': self,
            }
            if self._source_traceback:
                context['source_traceback'] = self._source_traceback
            self._loop.call_exception_handler(context)
        self._ov = None

    def cancel(self, msg=None):
        self._cancel_overlapped()
        return super().cancel(msg=msg)

    def set_exception(self, exception):
        super().set_exception(exception)
        self._cancel_overlapped()

    def set_result(self, result):
        super().set_result(result)
        self._ov = None


class _BaseWaitHandleFuture(futures.Future):
    """Subclass of Future which represents a wait handle."""

    def __init__(self, ov, handle, wait_handle, *, loop=None):
        super().__init__(loop=loop)
        if self._source_traceback:
            del self._source_traceback[-1]
        # Keep a reference to the Overlapped object to keep it alive until the
        # wait is unregistered
        self._ov = ov
        self._handle = handle
        self._wait_handle = wait_handle

        # Should we call UnregisterWaitEx() if the wait completes
        # or is cancelled?
        self._registered = True

    def _poll(self):
        # non-blocking wait: use a timeout of 0 millisecond
        return (_winapi.WaitForSingleObject(self._handle, 0) ==
                _winapi.WAIT_OBJECT_0)

    def _repr_info(self):
        info = super()._repr_info()
        info.append(f'handle={self._handle:#x}')
        if self._handle is not None:
            state = 'signaled' if self._poll() else 'waiting'
            info.append(state)
        if self._wait_handle is not None:
            info.append(f'wait_handle={self._wait_handle:#x}')
        return info

    def _unregister_wait_cb(self, fut):
        # The wait was unregistered: it's not safe to destroy the Overlapped
        # object
        self._ov = None

    def _unregister_wait(self):
        if not self._registered:
            return
        self._registered = False

        wait_handle = self._wait_handle
        self._wait_handle = None
        try:
            _overlapped.UnregisterWait(wait_handle)