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58 lines
1.8 KiB
Python
58 lines
1.8 KiB
Python
from ..vendor import monotonic
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class StopWatch(object):
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"""A simple timer/stopwatch helper class.
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Not thread-safe (when a single watch is mutated by multiple threads at
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the same time). Thread-safe when used by a single thread (not shared) or
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when operations are performed in a thread-safe manner on these objects by
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wrapping those operations with locks.
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It will use the `monotonic`_ pypi library to find an appropriate
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monotonically increasing time providing function (which typically varies
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depending on operating system and Python version).
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.. _monotonic: https://pypi.python.org/pypi/monotonic/
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"""
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def __init__(self):
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self._started_at = None
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self._stopped_at = None
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def start(self):
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"""Starts the watch."""
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self._started_at = monotonic.monotonic()
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return self
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def elapsed(self):
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"""Get how many seconds have elapsed.
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:return: Number of seconds elapsed
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:rtype: float
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"""
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# NOTE: datetime.timedelta does not support nanoseconds, so keep a float here
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if self._started_at is None:
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raise RuntimeError("Can not get the elapsed time of a stopwatch" " if it has not been started/stopped")
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if self._stopped_at is None:
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now = monotonic.monotonic()
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else:
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now = self._stopped_at
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return now - self._started_at
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def __enter__(self):
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"""Starts the watch."""
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self.start()
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return self
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def __exit__(self, tp, value, traceback):
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"""Stops the watch."""
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self.stop()
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def stop(self):
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"""Stops the watch."""
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if self._started_at is None:
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raise RuntimeError("Can not stop a stopwatch that has not been" " started")
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self._stopped_at = monotonic.monotonic()
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return self
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