class Dispatcher:
"""A dispatcher fulfills requests from riders and drivers for a
ride-sharing service.
When a rider requests a driver, the dispatcher assigns a driver to the
rider. If no driver is available, the rider is placed on a waiting
list for the next available driver. A rider that has not yet been
picked up by a driver may cancel their request.
When a driver requests a rider, the dispatcher assigns a rider from
the waiting list to the driver. If there is no rider on the waiting list
the dispatcher does nothing. Once a driver requests a rider, the driver
is registered with the dispatcher, and will be used to fulfill future
rider requests.
"""
def __init__(self):
"""Initialize a Dispatcher.
@type self: Dispatcher
@type _waitlist: Queue of Rider
@type _fleet: PriorityQueue of Driver
@rtype: None
"""
self._waitlist = Queue()
self._fleet = []
def request_driver(self, rider):
"""Return a driver for the rider, or None if no driver is available.
Add the rider to the waiting list if there is no available driver.
@type self: Dispatcher
@type rider: Rider
@rtype: Driver | None
>>> d = Dispatcher()
>>> d1 = Driver('a', Location(9,0), 1)
>>> d2 = Driver('b', Location(0,0), 1)
>>> d._fleet = [d1, d2]
>>> r1 = Rider('a', Location(0,0), Location(1,0), 3)
>>> print(d.request_driver(r1))
a
"""
fastest_driver = self._fleet[0]
for driver in self._fleet:
if not driver.is_idle:
self._waitlist.add(rider)
return None
else:
for i in range(len(self._fleet) - 1):
for j in range(len(self._fleet) - 1):
if self._fleet[i].get_travel_time(rider.origin) \
< self._fleet[j].get_travel_time(rider.origin):
fastest_driver = self._fleet[i]
else:
fastest_driver = self._fleet[j]
return fastest_driver
def request_rider(self, driver):
"""Return a rider for the driver, or None if no rider is available.
If this is a new driver, register the driver for future rider requests.
@type self: Dispatcher
@type driver: Driver
@rtype: Rider | None
>>> d = Dispatcher()
>>> r1 = Rider('a', Location(0,0), Location(1,0), 3)
>>> d._waitlist = Queue()
>>> d._waitlist.add(r1)
>>> d1 = Driver('a', Location(0,0), 1)
>>> d2 = Driver('b', Location(0,0), 1)
>>> d._fleet = [d1]
>>> print(d.request_rider(d2))
a
>>> print(d._fleet)
"""
if driver not in self._fleet:
self._fleet.append(driver)
# If waitlist is not empty, assign a rider
if not self._waitlist.is_empty():
return self._waitlist.remove()
else:
return None
def cancel_ride(self, rider):
"""Cancel the ride for rider and change their status to CANCELLED.
@type self: Dispatcher
@type rider: Rider
@rtype: None
"""
rider._status = CANCELLED
self._waitlist.remove(rider)
class Dispatcher:
"""A dispatcher fulfills requests from riders and drivers.
When a rider requests a driver, the dispatcher assigns a driver to the
rider. If no driver is available, the rider is placed on a waiting
list for the next available driver. A rider that has not yet been
picked up by a driver may cancel their request.
When a driver requests a rider, the dispatcher assigns a rider from
the waiting list to the driver. If there is no rider on the waiting list
the dispatcher does nothing. Once a driver requests a rider, the driver
is registered with the dispatcher, and will be used to fulfill future
rider requests.
"""
def __init__(self):
"""Initialize a Dispatcher.
@type self: Dispatcher
@type waiting_riders
@type availalbe_drivers
@rtype: None
"""
self._available_drivers = []
self._waiting_riders = Queue()
def __str__(self):
"""Return a string representation.
@type self: Dispatcher
@rtype: str
"""
return "Dispatcher:\n waiting_riders {0}, \n availalbe_drivers {1}"\
.format(self._waiting_riders, self._available_drivers)
def request_driver(self, rider):
"""Return a driver for the rider, or None if no driver is available.
Add the rider to the waiting list if there is no available driver.
If there are available drivers, return the one that can reach the driver fastest
@type self: Dispatcher
@type rider: Rider
@rtype: Driver | None
"""
if len(self._available_drivers) == 0:
self._waiting_riders.add(rider)
return None
DriverTimes = []
for driver in self._available_drivers:
if driver.is_idle:
DriverTimes.append(driver.get_travel_time(rider.origin))
shortestTime = min(DriverTimes)
for driver in self._available_drivers:
if driver.get_travel_time(rider.origin) == shortestTime:
return driver
def request_rider(self, driver):
"""Return a rider for the driver, or None if no rider is available.
If this is a new driver, register the driver for future rider requests.
Return None if no riders are available, otherwise return the longest waiting rider.
@type self: Dispatcher
@type driver: Driver
@rtype: Rider | None
"""
if not driver in self._available_drivers:
self._available_drivers.append(driver)
if self._waiting_riders.is_empty():
return None
# The longest waiting rider if the first element of self.waiting_riders
return self._waiting_riders.remove()
def cancel_ride(self, rider):
"""Cancel the ride for rider.
@type self: Dispatcher
@type rider: Rider
@rtype: None
>>> John = Dispatcher()
>>> Bobby = Rider('Bobby', Location(1,2), Location(3,4), 10)
>>> John._waiting_riders.items = [Bobby]
>>> John.cancel_ride(Bobby)
>>> print(John._waiting_riders.items)
[]
"""
if rider in self._waiting_riders.items:
self._waiting_riders.items.remove(rider)