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63 lines
2.0 KiB
Python
63 lines
2.0 KiB
Python
import math
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from . import _timeouts
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import trio
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from ._core._windows_cffi import (
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ffi,
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kernel32,
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ErrorCodes,
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raise_winerror,
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_handle,
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)
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async def WaitForSingleObject(obj):
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"""Async and cancellable variant of WaitForSingleObject. Windows only.
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Args:
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handle: A Win32 handle, as a Python integer.
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Raises:
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OSError: If the handle is invalid, e.g. when it is already closed.
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"""
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# Allow ints or whatever we can convert to a win handle
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handle = _handle(obj)
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# Quick check; we might not even need to spawn a thread. The zero
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# means a zero timeout; this call never blocks. We also exit here
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# if the handle is already closed for some reason.
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retcode = kernel32.WaitForSingleObject(handle, 0)
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if retcode == ErrorCodes.WAIT_FAILED:
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raise_winerror()
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elif retcode != ErrorCodes.WAIT_TIMEOUT:
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return
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# Wait for a thread that waits for two handles: the handle plus a handle
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# that we can use to cancel the thread.
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cancel_handle = kernel32.CreateEventA(ffi.NULL, True, False, ffi.NULL)
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try:
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await trio.to_thread.run_sync(
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WaitForMultipleObjects_sync,
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handle,
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cancel_handle,
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cancellable=True,
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limiter=trio.CapacityLimiter(math.inf),
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)
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finally:
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# Clean up our cancel handle. In case we get here because this task was
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# cancelled, we also want to set the cancel_handle to stop the thread.
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kernel32.SetEvent(cancel_handle)
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kernel32.CloseHandle(cancel_handle)
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def WaitForMultipleObjects_sync(*handles):
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"""Wait for any of the given Windows handles to be signaled."""
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n = len(handles)
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handle_arr = ffi.new("HANDLE[{}]".format(n))
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for i in range(n):
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handle_arr[i] = handles[i]
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timeout = 0xFFFFFFFF # INFINITE
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retcode = kernel32.WaitForMultipleObjects(n, handle_arr, False, timeout) # blocking
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if retcode == ErrorCodes.WAIT_FAILED:
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raise_winerror()
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