47 lines
1.1 KiB
Python
47 lines
1.1 KiB
Python
from __future__ import annotations
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import time
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from typing import Optional
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__all__ = ["Deadline"]
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class Deadline:
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"""
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Manage timeouts across multiple steps.
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Args:
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timeout: Time available in seconds or :obj:`None` if there is no limit.
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"""
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def __init__(self, timeout: Optional[float]) -> None:
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self.deadline: Optional[float]
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if timeout is None:
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self.deadline = None
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else:
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self.deadline = time.monotonic() + timeout
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def timeout(self, *, raise_if_elapsed: bool = True) -> Optional[float]:
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"""
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Calculate a timeout from a deadline.
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Args:
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raise_if_elapsed (bool): Whether to raise :exc:`TimeoutError`
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if the deadline lapsed.
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Raises:
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TimeoutError: If the deadline lapsed.
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Returns:
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Time left in seconds or :obj:`None` if there is no limit.
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"""
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if self.deadline is None:
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return None
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timeout = self.deadline - time.monotonic()
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if raise_if_elapsed and timeout <= 0:
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raise TimeoutError("timed out")
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return timeout
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