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@TVect
Created July 27, 2022 00:57
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Python Timer Functions: Three Ways to Monitor Your Code https://realpython.com/python-timer/
import time
from contextlib import ContextDecorator
from dataclasses import dataclass, field
from typing import Any, Callable, ClassVar, Dict, Optional
class TimerError(Exception):
"""A custom exception used to report errors in use of Timer class"""
@dataclass
class Timer(ContextDecorator):
"""Time your code using a class, context manager, or decorator"""
timers: ClassVar[Dict[str, float]] = {}
name: Optional[str] = None
text: str = "Elapsed time: {:0.4f} seconds"
logger: Optional[Callable[[str], None]] = print
_start_time: Optional[float] = field(default=None, init=False, repr=False)
def __post_init__(self) -> None:
"""Initialization: add timer to dict of timers"""
if self.name:
self.timers.setdefault(self.name, 0)
def start(self) -> None:
"""Start a new timer"""
if self._start_time is not None:
raise TimerError(f"Timer is running. Use .stop() to stop it")
self._start_time = time.perf_counter()
def stop(self) -> float:
"""Stop the timer, and report the elapsed time"""
if self._start_time is None:
raise TimerError(f"Timer is not running. Use .start() to start it")
# Calculate elapsed time
elapsed_time = time.perf_counter() - self._start_time
self._start_time = None
# Report elapsed time
if self.logger:
self.logger(self.text.format(elapsed_time))
if self.name:
self.timers[self.name] += elapsed_time
return elapsed_time
def __enter__(self) -> "Timer":
"""Start a new timer as a context manager"""
self.start()
return self
def __exit__(self, *exc_info: Any) -> None:
"""Stop the context manager timer"""
self.stop()
if __name__ == "__main__":
# 1. As a class:
t = Timer(name="class")
t.start()
# Do something
t.stop()
# 2. As a context manager:
with Timer(name="context manager"):
# Do something
pass
# 3. As a decorator:
@Timer(name="decorator")
def stuff():
# Do something
pass
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