/usr/lib/python2.7/dist-packages/simpy/rt.py is in python-simpy3 3.0.10-1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 | """Execution environment for events that synchronizes passing of time
with the real-time (aka *wall-clock time*).
"""
try:
# Python >= 3.3
from time import monotonic as time, sleep
except ImportError:
# Python < 3.3
from time import time, sleep
from simpy.core import Environment, EmptySchedule, Infinity
class RealtimeEnvironment(Environment):
"""Execution environment for an event-based simulation which is
synchronized with the real-time (also known as wall-clock time). A time
step will take *factor* seconds of real time (one second by default).
A step from ``0`` to ``3`` with a ``factor=0.5`` will, for example, take at
least
1.5 seconds.
The :meth:`step()` method will raise a :exc:`RuntimeError` if a time step
took too long to compute. This behaviour can be disabled by setting
*strict* to ``False``.
"""
def __init__(self, initial_time=0, factor=1.0, strict=True):
Environment.__init__(self, initial_time)
self.env_start = initial_time
self.real_start = time()
self._factor = factor
self._strict = strict
@property
def factor(self):
"""Scaling factor of the real-time."""
return self._factor
@property
def strict(self):
"""Running mode of the environment. :meth:`step()` will raise a
:exc:`RuntimeError` if this is set to ``True`` and the processing of
events takes too long."""
return self._strict
def sync(self):
"""Synchronize the internal time with the current wall-clock time.
This can be useful to prevent :meth:`step()` from raising an error if
a lot of time passes between creating the RealtimeEnvironment and
calling :meth:`run()` or :meth:`step()`.
"""
self.real_start = time()
def step(self):
"""Process the next event after enough real-time has passed for the
event to happen.
The delay is scaled according to the real-time :attr:`factor`. With
:attr:`strict` mode enabled, a :exc:`RuntimeError` will be raised, if
the event is processed too slowly.
"""
evt_time = self.peek()
if evt_time is Infinity:
raise EmptySchedule()
real_time = self.real_start + (evt_time - self.env_start) * self.factor
if self.strict and time() - real_time > self.factor:
# Events scheduled for time *t* may take just up to *t+1*
# for their computation, before an error is raised.
raise RuntimeError('Simulation too slow for real time (%.3fs).' % (
time() - real_time))
# Sleep in a loop to fix inaccuracies of windows (see
# http://stackoverflow.com/a/15967564 for details) and to ignore
# interrupts.
while True:
delta = real_time - time()
if delta <= 0:
break
sleep(delta)
return Environment.step(self)
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