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examples/trafficlight_parallel/experiment.py

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+# 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
+#
+# 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 code for model simulation:
+from pypdevs.simulator import Simulator
+
+# Import the model to be simulated
+from model import TrafficSystem
+
+#    ======================================================================
+
+# 1. Instantiate the (Coupled or Atomic) DEVS at the root of the 
+#  hierarchical model. This effectively instantiates the whole model 
+#  thanks to the recursion in the DEVS model constructors (__init__).
+#
+trafficSystem = TrafficSystem(name="trafficSystem")
+
+#    ======================================================================
+
+# 2. Link the model to a DEVS Simulator: 
+#  i.e., create an instance of the 'Simulator' class,
+#  using the model as a parameter.
+sim = Simulator(trafficSystem)
+
+#    ======================================================================
+
+# 3. Perform all necessary configurations, the most commonly used are:
+
+# A. Termination time (or termination condition)
+#    Using a termination condition will execute a provided function at
+#    every simulation step, making it possible to check for certain states
+#    being reached.
+#    It should return True to stop simulation, or Falso to continue.
+def terminate_whenStateIsReached(clock, model):
+    return model.trafficLight.state.get() == "manual"
+sim.setTerminationCondition(terminate_whenStateIsReached)
+
+#    A termination time is prefered over a termination condition,
+#    as it is much simpler to use.
+#    e.g. to simulate until simulation time 400.0 is reached
+sim.setTerminationTime(400.0)
+
+# B. Set the use of a tracer to show what happened during the simulation run
+#    Both writing to stdout or file is possible:
+#    pass None for stdout, or a filename for writing to that file
+sim.setVerbose(None)
+
+#    ======================================================================
+
+# 4. Simulate the model
+sim.simulate()
+
+#    ======================================================================
+
+# 5. (optional) Extract data from the simulated model
+print("Simulation terminated with traffic light in state %s" % (trafficSystem.trafficLight.state.get()))

examples/trafficlight_parallel/model.py

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+# 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
+#
+# 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 code for DEVS model representation:
+from pypdevs.DEVS import *
+from pypdevs.infinity import INFINITY
+
+class TrafficLightMode:
+    """
+    Encapsulates the system's state
+    """
+
+    def __init__(self, current="red"):
+        """
+        Constructor (parameterizable).
+        """
+        self.set(current)
+
+    def set(self, value="red"):
+        self.__colour=value
+
+    def get(self):
+        return self.__colour
+
+    def __str__(self):
+        return self.get()
+
+class TrafficLight(AtomicDEVS):
+    """
+    A traffic light 
+    """
+  
+    def __init__(self, name=None):
+        """
+        Constructor (parameterizable).
+        """
+        # Always call parent class' constructor FIRST:
+        AtomicDEVS.__init__(self, name)
+    
+        # STATE:
+        #  Define 'state' attribute (initial sate):
+        self.state = TrafficLightMode("red") 
+
+        # ELAPSED TIME:
+        #  Initialize 'elapsed time' attribute if required
+        #  (by default, value is 0.0):
+        self.elapsed = 1.5 
+        # with elapsed time initially 1.5 and initially in 
+        # state "red", which has a time advance of 60,
+        # there are 60-1.5 = 58.5time-units  remaining until the first 
+        # internal transition 
+    
+        # PORTS:
+        #  Declare as many input and output ports as desired
+        #  (usually store returned references in local variables):
+        self.INTERRUPT = self.addInPort(name="INTERRUPT")
+        self.OBSERVED = self.addOutPort(name="OBSERVED")
+
+    def extTransition(self, inputs):
+        """
+        External Transition Function.
+        """
+        # Compute the new state 'Snew' based (typically) on current
+        # State, Elapsed time parameters and calls to 'self.peek(self.IN)'.
+        input = inputs.get(self.INTERRUPT)[0]
+
+        state = self.state.get()
+
+        if input == "toManual":
+            if state == "manual":
+                # staying in manual mode
+                return TrafficLightMode("manual")
+            elif state in ("red", "green", "yellow"):
+                return TrafficLightMode("manual")
+        elif input == "toAutonomous":
+            if state == "manual":
+                return TrafficLightMode("red")
+            elif state in ("red", "green", "yellow"):
+                # If toAutonomous is given while still autonomous, just stay in this state
+                return self.state
+        raise DEVSException(\
+            "unknown state <%s> in TrafficLight external transition function"\
+            % state) 
+
+    def intTransition(self):
+        """
+        Internal Transition Function.
+        """
+
+        state = self.state.get()
+
+        if state == "red":
+            return TrafficLightMode("green")
+        elif state == "green":
+            return TrafficLightMode("yellow")
+        elif state == "yellow":
+            return TrafficLightMode("red")
+        else:
+            raise DEVSException(\
+                "unknown state <%s> in TrafficLight internal transition function"\
+                % state)
+  
+    def outputFnc(self):
+        """
+        Output Funtion.
+        """
+   
+        # A colourblind observer sees "grey" instead of "red" or "green".
+ 
+        # BEWARE: ouput is based on the OLD state
+        # and is produced BEFORE making the transition.
+        # We'll encode an "observation" of the state the
+        # system will transition to !
+
+        # Send messages (events) to a subset of the atomic-DEVS' 
+        # output ports by means of the 'poke' method, i.e.:
+        # The content of the messages is based (typically) on current State.
+ 
+        state = self.state.get()
+
+        if state == "red":
+            return {self.OBSERVED: ["grey"]}
+        elif state == "green":
+            return {self.OBSERVED: ["yellow"]}
+        elif state == "yellow":
+            return {self.OBSERVED: ["grey"]}
+        else:
+            raise DEVSException(\
+                "unknown state <%s> in TrafficLight external transition function"\
+                % state)
+    
+    def timeAdvance(self):
+        """
+        Time-Advance Function.
+        """
+        # Compute 'ta', the time to the next scheduled internal transition,
+        # based (typically) on current State.
+        state = self.state.get()
+        if state == "red":
+            return 60 
+        elif state == "green":
+            return 50 
+        elif state == "yellow":
+            return 10 
+        elif state == "manual":
+            return INFINITY 
+        else:
+            raise DEVSException(\
+                "unknown state <%s> in TrafficLight time advance transition function"\
+                % state)
+
+class PolicemanMode:
+    """
+    Encapsulates the Policeman's state
+    """
+    def __init__(self, current="idle"):
+        """
+        Constructor (parameterizable).
+        """
+        self.set(current)
+
+    def set(self, value="idle"):
+        self.__mode=value
+
+    def get(self):
+        return self.__mode
+
+    def __str__(self):
+        return self.get()
+
+class Policeman(AtomicDEVS):
+    """
+    A policeman producing "toManual" and "toAutonomous" events:
+    "toManual" when going from "idle" to "working" mode
+    "toAutonomous" when going from "working" to "idle" mode
+    """
+    def __init__(self, name=None):
+        """
+        Constructor (parameterizable).
+        """
+    
+        # Always call parent class' constructor FIRST:
+        AtomicDEVS.__init__(self, name)
+    
+        # STATE:
+        #  Define 'state' attribute (initial sate):
+        self.state = PolicemanMode("idle") 
+
+        # ELAPSED TIME:
+        #  Initialize 'elapsed time' attribute if required
+        #  (by default, value is 0.0):
+        self.elapsed = 0 
+    
+        # PORTS:
+        #  Declare as many input and output ports as desired
+        #  (usually store returned references in local variables):
+        self.OUT = self.addOutPort(name="OUT")
+
+    def intTransition(self):
+        """
+        Internal Transition Function.
+        The policeman works forever, so only one mode. 
+        """
+  
+        state = self.state.get()
+
+        if state == "idle":
+            return PolicemanMode("working")
+        elif state == "working":
+            return PolicemanMode("idle")
+        else:
+            raise DEVSException(\
+                "unknown state <%s> in Policeman internal transition function"\
+                % state)
+    
+    def outputFnc(self):
+        """
+        Output Funtion.
+        """
+        # Send messages (events) to a subset of the atomic-DEVS' 
+        # output ports by means of the 'poke' method, i.e.:
+        # The content of the messages is based (typically) on current State.
+        state = self.state.get()
+        if state == "idle":
+            return {self.OUT: ["toManual"]}
+        elif state == "working":
+            return {self.OUT: ["toAutonomous"]}
+        else:
+            raise DEVSException(\
+                "unknown state <%s> in Policeman output function"\
+                % state)
+    
+    def timeAdvance(self):
+        """
+        Time-Advance Function.
+        """
+        # Compute 'ta', the time to the next scheduled internal transition,
+        # based (typically) on current State.
+    
+        state = self.state.get()
+
+        if state == "idle":
+            return 200 
+        elif state == "working":
+            return 100 
+        else:
+            raise DEVSException(\
+                "unknown state <%s> in Policeman time advance function"\
+                % state)
+
+class TrafficSystem(CoupledDEVS):
+    def __init__(self, name=None):
+        """
+        A simple traffic system consisting of a Policeman and a TrafficLight.
+        """
+        # Always call parent class' constructor FIRST:
+        CoupledDEVS.__init__(self, name)
+
+        # Declare the coupled model's output ports:
+        # Autonomous, so no output ports
+
+        # Declare the coupled model's sub-models:
+
+        # The Policeman generating interrupts 
+        self.policeman = self.addSubModel(Policeman(name="policeman"))
+
+        # The TrafficLight 
+        self.trafficLight = self.addSubModel(TrafficLight(name="trafficLight"))
+
+        # Only connect ...
+        self.connectPorts(self.policeman.OUT, self.trafficLight.INTERRUPT)
+