commit

StartingPoint/lib/realtime/event_loop.py

@@ -0,0 +1,67 @@
+from lib.controller import Controller
+from lib.realtime.realtime import WallClock, AbstractRealTimeSimulation
+import time
+import abc
+
+class AbstractEventLoop:
+    # delay in nanoseconds
+    # should be non-blocking
+    # should return timer ID
+    @abc.abstractmethod
+    def schedule(self, delay, callback):
+        pass
+
+    @abc.abstractmethod
+    def cancel(self, timer_id):
+        pass
+
+# Runs virtual (simulated) time as close as possible to (scaled) wall-clock time.
+# Depending on how fast your computer is, simulated time will always run a tiny bit behind wall-clock time, but this error will NOT grow over time.
+class EventLoopRealTimeSimulation(AbstractRealTimeSimulation):
+
+    def __init__(self, controller: Controller, event_loop: AbstractEventLoop, wall_clock: WallClock, termination_condition=lambda: False, time_advance_callback=lambda simtime:None):
+        self.controller = controller
+        self.event_loop = event_loop
+
+        self.wall_clock = wall_clock
+
+        self.termination_condition = termination_condition
+
+        # Just a callback indicating that the current simulated time has changed.
+        # Can be useful for displaying the simulated time in a GUI or something
+        self.time_advance_callback = time_advance_callback
+
+        # At most one timer will be scheduled at the same time
+        self.scheduled_id = None
+
+    def poke(self):
+        if self.scheduled_id is not None:
+            self.event_loop.cancel(self.scheduled_id)
+
+        self.controller.run_until(self.wall_clock.time_since_start()) # this call may actually consume some time
+
+        self.time_advance_callback(self.controller.simulated_time)
+
+        if self.termination_condition():
+            print("Termination condition satisfied. Stop mainloop.")
+            return
+
+        if self.controller.have_event():
+            # schedule next wakeup
+            sleep_duration = self.wall_clock.sleep_duration_until(self.controller.get_earliest())
+            self.scheduled_id = self.event_loop.schedule(sleep_duration, self.poke)
+            # print("sleeping for", pretty_time(sleep_duration))
+        else:
+            # print("sleeping until woken up")
+            pass
+
+    # generate input event at the current wall clock time
+    # this method should be used for generating events that represent e.g., button clicks, key presses
+    def add_input_now(self, sc, event, value=None):
+        self.controller.add_input(sc, event, timestamp=self.wall_clock.time_since_start(), value=value)
+        self.poke()
+
+    # for events that need to happen immediately, at the current point in simulated time
+    def add_input_sync(self, sc, event, value=None):
+        self.controller.add_input_relative(sc, event, value=value)
+        self.poke()