Source code for pypdevs.realtime.asynchronousComboGenerator

# Copyright 2014 Modelling, Simulation and Design Lab (MSDL) at 
# McGill University and the University of Antwerp (http://msdl.cs.mcgill.ca/)
# 
# 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
#
#    http://www.apache.org/licenses/LICENSE-2.0
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# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
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import select
import sys
import threading
import pypdevs.accurate_time as time
from pypdevs.util import DEVSException

[docs]class AsynchronousComboGenerator(object): """ The asynchronous combo generator: it generates events from file input The name no longer represents what it actually is, as previously it also generated input from stdin (denoting the 'combo'). It does NOT use the default *interrupt()* calls for the threading backend, as this would require the generator to run on a different thread. The generator should be called at every iteration and its *getNextTime()* value should be taken into account by every *wait()* call. """
[docs] def __init__(self, filename, backend): """ Constructor. :param filename: the name of the input file to use for file input. None for no file input. :param backend: subsystem to use for threading .. note:: *filename* parameter should not be a file handle """ self.backend = backend if filename is not None: self.infile = open(filename, 'r') else: self.infile = None self.next_scheduled = float('inf') self.file_event = None # Call this here already for time 0, to schedule the first event self.checkInterrupt(0)
[docs] def checkInterrupt(self, current_time): """ Checks for whether an interrupt should happen at this time; if so, it also reschedules the next one. This method must be called before the internal interrupt is fetched, as otherwise it will not be taken into account. :param current_time: the current simulation time to check for interrupts """ if self.infile is not None: # First check for if the scheduled message happened if (self.next_scheduled - current_time) <= 0: if self.backend.setInterrupt(self.file_event): self.next_scheduled = float('inf') self.file_event = None # Now check for the next one if self.next_scheduled == float('inf'): # We don't have a scheduled event, so fetch one line = self.infile.readline() if line == "": self.infile.close() self.infile = None else: event = line.split(" ", 1) if len(event) != 2: raise DEVSException( "Inproperly formatted input in file: %s" % event) self.next_scheduled = float(event[0]) self.file_event = event[1][:-1]
[docs] def getNextTime(self): """ Return the time of the next event from this generator """ return self.next_scheduled