204 lines
10 KiB
Python
204 lines
10 KiB
Python
import time
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import sys
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import datetime
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import threading
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class SimulationThread(threading.Thread):
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"""
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Singleton class for the simulation thread.
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Usage is the call the classmethod initialize first
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"""
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instance = None
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@classmethod
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def initialize(cls, periods, start_time=None, run_time=None, time_factor=1.0, verbose=False):
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"""
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Initializes the singleton Thread with the given values. The given arguments are passed directly to the instance constructor. See the `__init__` method for argument details.
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"""
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cls.instance = SimulationThread(periods, start_time, run_time, time_factor, verbose)
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@classmethod
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def get_instance(cls):
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"""
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Returns the simulation thread object, or None if initialize() has not been called.
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"""
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return cls.instance
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def __init__(self, periods, start_time, run_time, time_factor, verbose):
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"""
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Creates a simulation with the provided data and settings.
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Args:
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periods (list): A list of dictionaries that represent the traffic light periods (peak/off-peak etc) as specified in the problem description. See the provided `periods.json` file for the intended format, as this variable is intended to be a json.load() version of this data.
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start_time (datetime.time): The time at which the simulation should start.
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run_time (int): The amount of (real) time the simulation should run for before terminating. If None, run indefinitely or until signal_stop() is called.
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time_factor (float): The time "accelleration" factor at which the simulation should run. A value of 1.0 indicates indentity with real time, and higher values run faster (e.g. 4.0 = four simulated seconds for each real second).
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verbose (bool): If True, outputs progress information to stdout (for testing purposes only).
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"""
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# Parent constructor call (required). Uses parameter daemon=True to ensure thread shutdown when parent program finishes executing
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# See https://docs.python.org/3/library/threading.html
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super().__init__(daemon=True)
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self.mutex = threading.Lock()
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self.periods = periods
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self.start_simulation_time = start_time
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self.run_real_time = run_time
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self.time_factor = time_factor
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self.verbose = verbose
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# NOT a status variable, instead indicates whether signal_stop() has been called
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self.running = True
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self.current_period_index = 0
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self.current_state_index = 0
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self.next_changeover_real_time = None
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self.start_simulation_datetime = None
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self.current_simulation_datetime = None
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# For convenience, convert all ISO format times to datetime.time objects
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for period in self.periods:
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period["timestart"] = datetime.time.fromisoformat(period["timestart"])
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# Essential - periods are assumed to be in chronological order
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self.periods.sort(key=lambda x: x["timestart"])
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def signal_stop(self):
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"""
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Signals the thread to stop, regardless of run time
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"""
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self.mutex.acquire()
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self.running = False
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self.mutex.release()
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def force_to_time(self, new_time):
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"""
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Resets the simulation time to the provided time. This is for testing purposes; the current state is IGNORED and the sequence immediately resets to the beginning.
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"""
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new_simulation_datetime = datetime.datetime.fromisoformat("1900-01-01 " + new_time.isoformat())
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self.mutex.acquire()
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print()
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self.current_period_index = self._get_period_index(self.periods, new_simulation_datetime.time())
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self.current_state_index = 0
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self.next_changeover_real_time = time.time() + (self.periods[self.current_period_index]["states"][self.current_state_index]["duration"] / self.time_factor)
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self.mutex.release()
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def get_snapshot(self):
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"""
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Returns a dictionary of the current simulated state
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"""
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self.mutex.acquire()
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return_data = {
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"current_period_name": self.periods[self.current_period_index]["name"],
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"current_period_verbose_name": self.periods[self.current_period_index]["verbose-name"],
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"current_period_index": self.current_period_index,
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"current_state_index": self.current_state_index,
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"current_state_data": self.periods[self.current_period_index]["states"][self.current_state_index],
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"next_changeover_real_time": self.next_changeover_real_time,
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"simulation_time": self.current_simulation_datetime.time(),
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"time_remaining": (self.next_changeover_real_time - time.time()) * self.time_factor,
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}
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self.mutex.release()
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return return_data
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def _get_period_index(self, test_time: datetime.time):
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"""
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Returns the index of the period corresponding to the given time
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"""
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for i, period in enumerate(self.periods):
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if i == len(self.periods) - 1:
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return i
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if test_time >= period["timestart"] and \
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test_time < self.periods[i + 1]["timestart"]:
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return i
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# Should NOT be reached since last state assumed to last until midnight
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raise
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def run(self):
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"""
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Main thread loop. Note that this method should NOT be called directly: as a subclass of threading.Thread, the inherited start() method should be used instead.
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The loop executes until one of the following conditions is met:
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- The given run_time is exceeded (in real seconds), or
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- signal_stop() has been called
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- The executing program finishes (daemon=True)
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"""
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start_real_time = time.time()
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if self.start_simulation_time is None:
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self.start_simulation_datetime = datetime.datetime.now()
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else:
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self.start_simulation_datetime = datetime.datetime.fromisoformat(
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"1900-01-01 " + self.start_simulation_time.isoformat())
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self.current_period_index = self._get_period_index(self.start_simulation_datetime.time())
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self.current_state_index = 0
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self.next_changeover_real_time = start_real_time + (self.periods[self.current_period_index]["states"][self.current_state_index]["duration"] / self.time_factor)
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if self.verbose:
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print("Starting with simulation time {}".format(self.start_simulation_datetime.time()))
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print("Initial state data: {}".format(self.periods[self.current_period_index]["states"][self.current_state_index]))
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if self.run_real_time is None:
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print("No simulation time limit.")
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else:
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print("Simulation duration (in real second(s)): {}".format(self.run_real_time))
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print("Time compression factor: {}".format(self.time_factor))
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while (self.run_real_time is None) or (self.run_real_time is not None and time.time() < start_real_time + self.run_real_time):
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self.mutex.acquire()
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if not self.running:
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self.mutex.release()
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break
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now = time.time()
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self.current_simulation_datetime = self.start_simulation_datetime + datetime.timedelta(seconds=int((now - start_real_time) * self.time_factor))
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timed_period_index = self._get_period_index(self.current_simulation_datetime.time())
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if now >= self.next_changeover_real_time:
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timed_period_index = self._get_period_index(self.current_simulation_datetime.time())
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if timed_period_index != self.current_period_index and self.current_state_index == len(self.periods[self.current_period_index]["states"])-1:
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if self.verbose:
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print()
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print("{} : Changing PERIOD from {} to {}".format(self.current_simulation_datetime.time(), self.periods[self.current_period_index]["name"], self.periods[timed_period_index]["name"]))
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print(" Old state data: {}".format(self.periods[self.current_period_index]["states"][self.current_state_index]))
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# Safe to change period
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self.current_period_index = timed_period_index
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self.current_state_index = 0
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if self.verbose:
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print(" New state data: {}".format(self.periods[self.current_period_index]["states"][self.current_state_index]))
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print(" Next changeover in {} second(s)".format(self.periods[self.current_period_index]["states"][self.current_state_index]["duration"]))
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else:
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# Current sequence still completing, not safe to change to next period
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next_cycle_index = (self.current_state_index + 1) % len(self.periods[self.current_period_index]["states"])
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if self.verbose:
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print()
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print("{} : {} : Changing state from {} to {}".format(self.current_simulation_datetime.time(), self.periods[self.current_period_index]["name"], self.current_state_index, next_cycle_index))
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if self.current_period_index != timed_period_index:
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print(" [period change pending]")
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print(" Old state data: {}".format(self.periods[self.current_period_index]["states"][self.current_state_index]))
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print(" New state data: {}".format(self.periods[self.current_period_index]["states"][next_cycle_index]))
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print(" Next changeover in {} second(s)".format(self.periods[self.current_period_index]["states"][next_cycle_index]["duration"]))
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self.current_state_index = next_cycle_index
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# Ensure this calculation is done based on the PREVIOUS scheduled time to avoid "timing drift"
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self.next_changeover_real_time = self.next_changeover_real_time + (self.periods[self.current_period_index]["states"][self.current_state_index]["duration"] / self.time_factor)
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else:
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if self.verbose:
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print(".", end="")
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sys.stdout.flush()
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self.mutex.release()
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time.sleep(1.0 / self.time_factor)
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