82 lines
3.4 KiB
Python
82 lines
3.4 KiB
Python
# Copyright 2014 Modelling, Simulation and Design Lab (MSDL) at
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# McGill University and the University of Antwerp (http://msdl.cs.mcgill.ca/)
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import select
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import sys
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import threading
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import pypdevs.accurate_time as time
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from pypdevs.util import DEVSException
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class AsynchronousComboGenerator(object):
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"""
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The asynchronous combo generator: it generates events from file input
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The name no longer represents what it actually is, as previously it also generated input from stdin (denoting the 'combo').
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It does NOT use the default *interrupt()* calls for the threading backend, as this would require the generator to run
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on a different thread. The generator should be called at every iteration and its *getNextTime()* value should be taken into
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account by every *wait()* call.
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"""
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def __init__(self, filename, backend):
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"""
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Constructor.
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:param filename: the name of the input file to use for file input. None for no file input.
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:param backend: subsystem to use for threading
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.. note:: *filename* parameter should not be a file handle
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"""
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self.backend = backend
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if filename is not None:
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self.infile = open(filename, 'r')
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else:
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self.infile = None
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self.next_scheduled = float('inf')
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self.file_event = None
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# Call this here already for time 0, to schedule the first event
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self.checkInterrupt(0)
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def checkInterrupt(self, current_time):
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"""
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Checks for whether an interrupt should happen at this time; if so, it also reschedules the next one.
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This method must be called before the internal interrupt is fetched, as otherwise it will not be taken into account.
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:param current_time: the current simulation time to check for interrupts
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"""
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if self.infile is not None:
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# First check for if the scheduled message happened
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if (self.next_scheduled - current_time) <= 0:
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if self.backend.setInterrupt(self.file_event):
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self.next_scheduled = float('inf')
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self.file_event = None
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# Now check for the next one
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if self.next_scheduled == float('inf'):
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# We don't have a scheduled event, so fetch one
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line = self.infile.readline()
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if line == "":
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self.infile.close()
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self.infile = None
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else:
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event = line.split(" ", 1)
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if len(event) != 2:
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raise DEVSException(
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"Inproperly formatted input in file: %s" % event)
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self.next_scheduled = float(event[0])
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self.file_event = event[1].rstrip()
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def getNextTime(self):
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"""
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Return the time of the next event from this generator
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"""
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return self.next_scheduled
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