69 lines
1.9 KiB
Python
69 lines
1.9 KiB
Python
import functools
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import time
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from dataclasses import dataclass, field
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from typing import Callable, ClassVar, Dict, Optional
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class TimerError(Exception):
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"""A custom exception used to report errors in use of Timer class."""
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pass
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@dataclass
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class Timer:
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"""Time a section of code."""
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timers: ClassVar[Dict[str, float]] = {}
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name: Optional[str] = None
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text: str = "Elapsed time: {:0.4f} seconds"
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logger: Optional[Callable[[str], None]] = print
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_start_time: Optional[float] = field(default=None, init=False, repr=False)
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def __post_init__(self) -> None:
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"""Add timer to dict of timers after initialization."""
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if self.name is not None:
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self.timers.setdefault(self.name, 0)
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def __enter__(self):
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"""Start a new timer as a context manager."""
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self.start()
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return self
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def __exit__(self, *exc_info):
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"""Stop the context manager timer."""
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self.stop()
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def __call__(self, func):
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"""Support using Timer as a decorator."""
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@functools.wraps(func)
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def wrapper_timer(*args, **kwargs):
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with self:
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return func(*args, **kwargs)
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return wrapper_timer
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def start(self) -> None:
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"""Start a new timer."""
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if self._start_time is not None:
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raise TimerError("Timer is running. Use .stop() to stop it")
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self._start_time = time.perf_counter()
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def stop(self) -> float:
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"""Stop the timer, and report the elapsed time."""
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if self._start_time is None:
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raise TimerError("Timer is not running. Use .start() to start it")
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# Calculate elapsed time
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elapsed_time = time.perf_counter() - self._start_time
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self._start_time = None
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# Report elapsed time
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if self.logger:
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self.logger(self.text.format(elapsed_time))
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if self.name:
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self.timers[self.name] += elapsed_time
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return elapsed_time
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