greendeck/greendeck/timer.py

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2022-12-13 14:25:50 -06:00
import functools
import time
from dataclasses import dataclass, field
from typing import Callable, ClassVar, Dict, Optional
class TimerError(Exception):
"""A custom exception used to report errors in use of Timer class."""
pass
@dataclass
class Timer:
"""Time a section of code."""
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:
"""Add timer to dict of timers after initialization."""
if self.name is not None:
self.timers.setdefault(self.name, 0)
def __enter__(self):
"""Start a new timer as a context manager."""
self.start()
return self
def __exit__(self, *exc_info):
"""Stop the context manager timer."""
self.stop()
def __call__(self, func):
"""Support using Timer as a decorator."""
@functools.wraps(func)
def wrapper_timer(*args, **kwargs):
with self:
return func(*args, **kwargs)
return wrapper_timer
def start(self) -> None:
"""Start a new timer."""
if self._start_time is not None:
raise TimerError("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("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