Initial commit

src/pypdevs/realtime/asynchronousComboGenerator.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 select
+import sys
+import threading
+import pypdevs.accurate_time as time
+from pypdevs.util import DEVSException
+
+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+    The name no longer represents what it actually is, as previously it also generated input from stdin (denoting the 'combo').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.
+    """
+    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)
+
+    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]
+
+    def getNextTime(self):
+        """
+        Return the time of the next event from this generator
+        """
+        return self.next_scheduled