OV-27. use semaphore to protect the read consistency of currentTime

bin/openVisualizerApp.py

@@ -12,6 +12,7 @@
 import os
 import logging
 import json
+import threading
 
 from openvisualizer.OVtracer import OVtracer
 
@@ -65,7 +66,10 @@ def __init__(self,confdir,datadir,logdir,simulatorMode,numMotes,trace,debug,useP
         if self.simulatorMode:
             from openvisualizer.SimEngine import SimEngine, MoteHandler
 
-            self.simengine        = SimEngine.SimEngine(simTopology)
+            # create semaphore  for reading the currentTime
+            self.currentTime_semaphore = threading.Semaphore()
+
+            self.simengine        = SimEngine.SimEngine(simTopology=simTopology, currentTime_semaphore=self.currentTime_semaphore)
             self.simengine.start()
 
         # import the number of motes from json file given by user (if the pathTopo option is enabled)
@@ -89,7 +93,7 @@ def __init__(self,confdir,datadir,logdir,simulatorMode,numMotes,trace,debug,useP
             MoteHandler.readNotifIds(os.path.join(self.datadir, 'sim_files', 'openwsnmodule_obj.h'))
             self.moteProbes       = []
             for _ in range(self.numMotes):
-                moteHandler       = MoteHandler.MoteHandler(oos_openwsn.OpenMote())
+                moteHandler       = MoteHandler.MoteHandler(oos_openwsn.OpenMote(), self.currentTime_semaphore)
                 self.simengine.indicateNewMote(moteHandler)
                 self.moteProbes  += [moteProbe.moteProbe(mqtt_broker_address, emulatedMote=moteHandler)]
         elif self.iotlabmotes:

openvisualizer/BspEmulator/BspUart.py

@@ -24,11 +24,12 @@ class BspUart(BspModule.BspModule):
     XONXOFF_ESCAPE  = 0x12
     XONXOFF_MASK    = 0x10
 
-    def __init__(self,motehandler):
+    def __init__(self,motehandler, currentTime_semaphore):
 
         # store params
         self.engine               = SimEngine.SimEngine()
         self.motehandler          = motehandler
+        self.ct_semaphore         = currentTime_semaphore
 
         # local variables
         self.timeline             = self.engine.timeline
@@ -357,9 +358,13 @@ def intr_rx(self):
     #======================== private =========================================
 
     def _scheduleNextTx(self):
+
+        self.ct_semaphore.acquire()
 
         # calculate time at which byte will get out
         timeNextTx           = self.timeline.getCurrentTime()+float(1.0/float(self.BAUDRATE))
+
+        self.ct_semaphore.release()
 
         # schedule that event
         self.timeline.scheduleEvent(

openvisualizer/SimEngine/MoteHandler.py

@@ -56,11 +56,12 @@ def notifId(s):
 
 class MoteHandler(threading.Thread):
 
-    def __init__(self,mote):
+    def __init__(self,mote, currentTime_semaphore):
 
         # store params
-        self.engine          = SimEngine.SimEngine()
+        self.engine          = SimEngine.SimEngine(currentTime_semaphore)
         self.mote            = mote
+        self.ct_semaphore    = currentTime_semaphore
 
         #=== local variables
         self.loghandler      = self.engine.loghandler
@@ -81,7 +82,7 @@ def __init__(self,mote):
         self.bspLeds         = BspLeds.BspLeds(self)
         self.bspSctimer      = BspSctimer.BspSctimer(self)
         self.bspRadio        = BspRadio.BspRadio(self)
-        self.bspUart         = BspUart.BspUart(self)
+        self.bspUart         = BspUart.BspUart(self, self.ct_semaphore)
         # status
         self.booted          = False
         self.cpuRunning      = threading.Lock()

openvisualizer/SimEngine/SimEngine.py

@@ -52,7 +52,7 @@ def __new__(cls, *args, **kwargs):
 
     #======================== main ============================================
 
-    def __init__(self,simTopology='',loghandler=logging.NullHandler()):
+    def __init__(self,simTopology='',loghandler=logging.NullHandler(), currentTime_semaphore=None):
 
         # don't re-initialize an instance (singleton pattern)
         if self._init:
@@ -61,10 +61,11 @@ def __init__(self,simTopology='',loghandler=logging.NullHandler()):
 
         # store params
         self.loghandler           = loghandler
+        self.ct_semaphore         = currentTime_semaphore
 
         # local variables
         self.moteHandlers         = []
-        self.timeline             = TimeLine.TimeLine()
+        self.timeline             = TimeLine.TimeLine(self.ct_semaphore)
         self.propagation          = Propagation.Propagation(simTopology)
         self.idmanager            = IdManager.IdManager()
         self.locationmanager      = LocationManager.LocationManager() 

openvisualizer/SimEngine/TimeLine.py

@@ -37,13 +37,15 @@ class TimeLine(threading.Thread):
     The timeline of the engine.
     '''
 
-    def __init__(self):
+    def __init__(self,ct_semaphore):
 
         # store params
-        self.engine               = SimEngine.SimEngine()
+        self.engine               = SimEngine.SimEngine(ct_semaphore)
+        self.ct_semaphore         = ct_semaphore
 
         # local variables
         self.currentTime          = 0   # current time
+        self.currentTimeLock      = threading.Lock()
         self.timeline             = []  # list of upcoming events
         self.firstEventPassed     = False
         self.firstEvent           = threading.Lock()
@@ -94,7 +96,15 @@ def run(self):
                 output += ' - currentTime='+str(self.getCurrentTime())+'\n'
                 self.log.warning(output)
                 raise StopIteration(output)
+
+            '''
+            use semaphore to resolve the inconsistant reading of currentTime 
+                - acquire right before a pop the next event
+                - release right after the currentTime is assigned.
+            '''
 
+            self.ct_semaphore.acquire()
+
             # pop the event at the head of the timeline
             event = self.timeline.pop(0)
 
@@ -103,6 +113,8 @@ def run(self):
 
             # record the current time
             self.currentTime = event.atTime
+
+            self.ct_semaphore.release()
 
             # log
             if self.log.isEnabledFor(logging.DEBUG):