Source code for spinn_utilities.timer
# Copyright (c) 2017 The University of Manchester
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import sys
import time
from datetime import timedelta
if sys.version_info >= (3, 7):
# acquire the most accurate measurement available (perf_counter_ns)
_now = time.perf_counter_ns
# conversion factor
_NANO_TO_MICRO = 1000.0
def _convert_to_timedelta(time_diff):
"""
Have to convert to a timedelta for rest of code to read.
As perf_counter_ns is nano seconds, and time delta lowest is micro,
need to convert.
"""
return timedelta(microseconds=time_diff / _NANO_TO_MICRO)
else:
# acquire the most accurate measurement available (perf_counter)
_now = time.perf_counter
def _convert_to_timedelta(time_diff):
"""
Have to convert to a timedelta for rest of code to read.
As perf_counter is fractional seconds, put into correct time delta.
"""
return timedelta(seconds=time_diff)
[docs]class Timer(object):
"""
A timer used for performance measurements.
Recommended usage::
with Timer() as timer:
... do stuff that takes time ...
elapsed_time = timer.measured_interval
or alternatively::
timer = Timer()
timer.start_timing()
... do stuff that takes time ...
elapsed_time = timer.take_sample()
Mixing these two styles is *not recommended*.
"""
__slots__ = [
# The start time when the timer was set off
"_start_time",
# The time in the measured section
"_measured_section_interval"
]
def __init__(self):
self._start_time = None
self._measured_section_interval = None
[docs] def start_timing(self):
"""
Start the timing. Use :py:meth:`take_sample` to get the end.
"""
self._start_time = _now()
[docs] def take_sample(self):
"""
Describes how long has elapsed since the instance that the
:py:meth:`start_timing` method was last called.
:rtype: datetime.timedelta
"""
time_now = _now()
diff = time_now - self._start_time
return _convert_to_timedelta(diff)
def __enter__(self):
self.start_timing()
return self
def __exit__(self, *_args):
self._measured_section_interval = self.take_sample()
return False
@property
def measured_interval(self):
"""
Get how long elapsed during the measured section.
:rtype: datetime.timedelta
"""
return self._measured_section_interval