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42d873c63a
The overflow occurs under some circumstances when a task or future recursively returns itself. Co-authored-by: Kyle Stanley <aeros167@gmail.com>
80 lines
2.5 KiB
Python
80 lines
2.5 KiB
Python
__all__ = ()
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import reprlib
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from _thread import get_ident
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from . import format_helpers
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# States for Future.
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_PENDING = 'PENDING'
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_CANCELLED = 'CANCELLED'
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_FINISHED = 'FINISHED'
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def isfuture(obj):
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"""Check for a Future.
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This returns True when obj is a Future instance or is advertising
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itself as duck-type compatible by setting _asyncio_future_blocking.
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See comment in Future for more details.
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"""
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return (hasattr(obj.__class__, '_asyncio_future_blocking') and
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obj._asyncio_future_blocking is not None)
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def _format_callbacks(cb):
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"""helper function for Future.__repr__"""
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size = len(cb)
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if not size:
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cb = ''
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def format_cb(callback):
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return format_helpers._format_callback_source(callback, ())
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if size == 1:
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cb = format_cb(cb[0][0])
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elif size == 2:
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cb = '{}, {}'.format(format_cb(cb[0][0]), format_cb(cb[1][0]))
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elif size > 2:
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cb = '{}, <{} more>, {}'.format(format_cb(cb[0][0]),
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size - 2,
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format_cb(cb[-1][0]))
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return f'cb=[{cb}]'
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# bpo-42183: _repr_running is needed for repr protection
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# when a Future or Task result contains itself directly or indirectly.
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# The logic is borrowed from @reprlib.recursive_repr decorator.
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# Unfortunately, the direct decorator usage is impossible because of
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# AttributeError: '_asyncio.Task' object has no attribute '__module__' error.
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#
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# After fixing this thing we can return to the decorator based approach.
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_repr_running = set()
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def _future_repr_info(future):
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# (Future) -> str
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"""helper function for Future.__repr__"""
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info = [future._state.lower()]
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if future._state == _FINISHED:
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if future._exception is not None:
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info.append(f'exception={future._exception!r}')
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else:
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key = id(future), get_ident()
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if key in _repr_running:
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result = '...'
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else:
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_repr_running.add(key)
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try:
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# use reprlib to limit the length of the output, especially
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# for very long strings
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result = reprlib.repr(future._result)
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finally:
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_repr_running.discard(key)
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info.append(f'result={result}')
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if future._callbacks:
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info.append(_format_callbacks(future._callbacks))
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if future._source_traceback:
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frame = future._source_traceback[-1]
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info.append(f'created at {frame[0]}:{frame[1]}')
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return info
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