Module `Commands`

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# ****************************************************
# Copyright: 2020 Team Visualizer (Carlos Miguel Sayao, Connor Bettermann, Issac Greenfield, Madeleine Elyea, Tanner Sundwall, Ted Moore, Prerna Agarwal)
# License: MIT
# ****************************************************
# Purpose:  Global command buffer queue data structure.
#           When a command is registered, it is place on the queue.
#             If the queue is at max size, discard the command.
#           When a command is to be executed, dequeue and return command.
#             If queue is empty, enqueue a NONE to indicate no activity.
#             (Leader is constantly sending IDLE to show presence.)
# Sources:  Python doc: queue, https://docs.python.org/3.7/library/queue.html
#           GFG queue tutorial, https://www.geeksforgeeks.org/queue-in-python/
# ****************************************************

from datetime import datetime
from datetime import timedelta
from ErrorHandler import ErrorHandler
from OrderCode import *
from queue import Queue
from constants import *
from MessageMan import MessageMan

def init():
    global CommandQueue
    CommandQueue = Queue(maxsize=MAX_QUEUE_SIZE)
    header = MessageMan(ErrorHandler()).compose_message("", START_TIME, OrderCode.NONE)
    CommandQueue.put(header)
    global IsLeader
    IsLeader = False


class Commands:
    def __init__(self, error_handler=None):
        self.eh = error_handler
        
    def enqueue(self, to_queue):
        """ Places new commands on the queue. 

        Args:
            to_queue (dict): Command message to add.

        Returns:
            None 
        """
        # We don't want to try adding another one if the queue is full.
        if CommandQueue.qsize() < MAX_QUEUE_SIZE:
            CommandQueue.put_nowait(to_queue)

    def dequeue(self) -> dict:
        """ Pulls oldest command from the front of the queue. 

        Args:
            None

        Returns:
            dict: The dictionary that holds the command information
        """
        if CommandQueue.empty():
            header = MessageMan(self.eh).compose_message("", START_TIME, OrderCode.NONE)
            self.enqueue(header)
            return header
        return CommandQueue.get_nowait()

    def flush_queue(self):
        while not CommandQueue.empty():
            self.dequeue()

Functions

def init()

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def init():
    global CommandQueue
    CommandQueue = Queue(maxsize=MAX_QUEUE_SIZE)
    header = MessageMan(ErrorHandler()).compose_message("", START_TIME, OrderCode.NONE)
    CommandQueue.put(header)
    global IsLeader
    IsLeader = False

Classes

class Commands (error_handler=None)

Expand source code

class Commands:
    def __init__(self, error_handler=None):
        self.eh = error_handler
        
    def enqueue(self, to_queue):
        """ Places new commands on the queue. 

        Args:
            to_queue (dict): Command message to add.

        Returns:
            None 
        """
        # We don't want to try adding another one if the queue is full.
        if CommandQueue.qsize() < MAX_QUEUE_SIZE:
            CommandQueue.put_nowait(to_queue)

    def dequeue(self) -> dict:
        """ Pulls oldest command from the front of the queue. 

        Args:
            None

        Returns:
            dict: The dictionary that holds the command information
        """
        if CommandQueue.empty():
            header = MessageMan(self.eh).compose_message("", START_TIME, OrderCode.NONE)
            self.enqueue(header)
            return header
        return CommandQueue.get_nowait()

    def flush_queue(self):
        while not CommandQueue.empty():
            self.dequeue()

Methods

def dequeue(self)

Pulls oldest command from the front of the queue.

Args

None

Returns

dict: The dictionary that holds the command information

Expand source code

def dequeue(self) -> dict:
    """ Pulls oldest command from the front of the queue. 

    Args:
        None

    Returns:
        dict: The dictionary that holds the command information
    """
    if CommandQueue.empty():
        header = MessageMan(self.eh).compose_message("", START_TIME, OrderCode.NONE)
        self.enqueue(header)
        return header
    return CommandQueue.get_nowait()

def enqueue(self, to_queue)

Places new commands on the queue.

Args

to_queue : dict: Command message to add.

Returns

None

Expand source code

def enqueue(self, to_queue):
    """ Places new commands on the queue. 

    Args:
        to_queue (dict): Command message to add.

    Returns:
        None 
    """
    # We don't want to try adding another one if the queue is full.
    if CommandQueue.qsize() < MAX_QUEUE_SIZE:
        CommandQueue.put_nowait(to_queue)

def flush_queue(self)

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def flush_queue(self):
    while not CommandQueue.empty():
        self.dequeue()