Add option to bind mobility model ticks to real time clock.

Adds parameters 'use_rtc_model_mob' and 'rtc_model_mob_tick'
to mobility model code. When enabled, these will cause mobility
ticks to only occur every 'rtc_model_mob_tick' seconds as long as
the expected number of ticks for this time interval has occurred.

mn_wifi/mobility.py

@@ -381,6 +381,41 @@ def start_mob_mod(self, mob, nodes, draw):
             while self.pause_simulation:
                 pass
 
+class RTCModel(model):
+    def __init__(self, **kwargs):
+        self.tick_time = kwargs.get('rtc_model_mob_tick', 1)
+        super().__init__(**kwargs)
+
+    def start_mob_mod(self, mob, nodes, draw):
+        """
+        :param mob: mobility params
+        :param nodes: list of nodes
+        """
+        next_tick_time = time() + self.tick_time
+        for xy in mob:
+            for idx, node in enumerate(nodes):
+                pos = round(xy[idx][0], 2), round(xy[idx][1], 2), 0.0
+                self.set_pos(node, pos)
+                if draw:
+                    node.update_2d()
+            if draw:
+                PlotGraph.pause()
+            if self.pause_simulation:
+                while self.pause_simulation:
+                    pass
+                # When resuming simulation, reset the tick timing
+                next_tick_time = time() + self.tick_time
+                continue
+            # We try to use "best effort" scheduling- we want to have
+            # done as many ticks as there are elapsed seconds since we last
+            # performed a mobility tick and try to iterate the loop as consistently
+            # as possible
+            else:
+                while time() < next_tick_time:
+                    # If time() has been exceeded since the while loop check, don't sleep
+                    sleep(max(next_tick_time - time(), 0))
+            next_tick_time = next_tick_time + self.tick_time
+
 
 class Tracked(Mobility):
     "Used when the position of each node is previously defined"

mn_wifi/net.py

@@ -29,7 +29,7 @@
     master, managed, physicalMesh, PhysicalWifiDirectLink, _4addrClient, \
     _4addrAP, phyAP
 from mn_wifi.mobility import Tracked as TrackedMob, model as MobModel, \
-    Mobility as mob, ConfigMobility, ConfigMobLinks
+    Mobility as mob, ConfigMobility, ConfigMobLinks, RTCModel
 from mn_wifi.module import Mac80211Hwsim
 from mn_wifi.node import AP, Station, Car, OVSKernelAP, physicalAP
 from mn_wifi.plot import Plot2D, Plot3D, PlotGraph
@@ -145,6 +145,8 @@ def __init__(self, accessPoint=OVSKernelAP, station=Station, car=Car,
         self.wwan_module = wwan_module
         self.ifbIntf = 0
         self.mob_object = None
+        self.use_rtc_model_mob = False
+        self.rtc_model_mob_tick = 1.0
         self.mob_start_time = 0
         self.mob_stop_time = 0
         self.mob_rep = 1
@@ -1231,7 +1233,10 @@ def start_mobility(self, **kwargs):
         if self.roads:
             self.mob_object = vanet(**kwargs)
         else:
-            self.mob_object = MobModel(**kwargs)
+            if kwargs.get('use_rtc_model_mob'):
+                self.mob_object = RTCModel(**kwargs)
+            else:
+                self.mob_object = MobModel(**kwargs)
 
     def setMobilityModel(self, **kwargs):
         for key in kwargs:
@@ -1267,12 +1272,12 @@ def get_mobility_params(self):
                       'max_x', 'max_y', 'max_z',
                       'min_v', 'max_v', 'min_wt', 'max_wt',
                       'velocity_mean', 'alpha', 'variance', 'aggregation',
-                      'g_velocity']
+                      'g_velocity', 'rtc_model_mob_tick']
         args = ['stations', 'cars', 'aps', 'draw', 'seed',
                 'roads', 'mob_start_time', 'mob_stop_time',
                 'links', 'mob_model', 'mob_rep', 'reverse',
                 'ac_method', 'pointlist', 'n_groups', 'aggregation_epoch', 'epoch',
-                'velocity']
+                'velocity', 'use_rtc_model_mob']
         args += float_args
         for arg in args:
             if arg in float_args: