task.txt

This Lab will require you to implement a concurrent program 
in Java. Please make sure that you have the computing 
environment for building and testing your program properly 
configured on your computer before beginning.

In this assignment, you are asked to implement two different 
types of concurrent queues to determine which is most 
efficient.

The first queue should be implemented in a class called 
BankQueue, and is modeled after the lineup found in most 
banks. In such a queue implementation, there is only one 
lineup, and as soon as one teller becomes free, the first 
person in the queue proceeds to be served.

The second type of queue should be implemented in a class 
called GroceryQueues, which will be array of type 
GroceryQueue, and is modeled after the lineups in many 
grocery stores and supermarkets. In this queue 
implementation, there will be several lineups, one for 
each cashier. When a customer arrives, they join the queue 
with the fewest number of people waiting. If there are 
two such queues, it chooses one at random.

For the purposes of this assignment, you may assume that it 
takes between 60 and 300 seconds to serve any customer 
(uniform distribution), and that new customers arrive 
between every 20 and 60 seconds (also uniformly distributed).
The constructor for the GroceryQueues class should take the 
number of GroceryQueue’s and the maximum length of each 
queue (excluding the customer being served) as input 
parameters.
Similarly, the constructor for BankQueue should take the 
number of tellers and the maximum length of the single 
queue as parameters.

In the case of GroceryQueues, if a customer arrives, and 
no queue exists with any space, then he/she waits until a 
queue becomes available until a maximum of 10 seconds and 
then promptly leaves. For the BankQueue, a customer 
departs immediately if the queue is full.

You should also implement a Customer class which at the 
very minimum keeps track of the customer’s arrival time, 
and the time needed for it to be served. If it was not 
served because all queues were at maximum capacity, then 
this fact should also be recorded. 

There should also be a QueueSimulator class which accepts 
events from customers, contains a clock which ticks every 
second, and processes any events that occurred in the last 
clock tick.

Your main program should take as parameter the number of 
minutes you wish to simulate the two queue types, and for 
each type of queue, output the total number of customers 
that arrived, the total number of customers who were 
forced to leave without being served, the total number 
of customers served, and the average amount of time taken 
to serve each customer.

You are expected to submit your source code, along with the 
program’s output for 2 hours of the simulation when there 
are exactly 3 tellers in the case of the BankQueue class 
and 3 cashiers (and thus 3 queues) in the case of the 
GroceryQueues class, and when the maximum length of a 
BankQueue is 5, while the maximum length of a GroceryQueue 
is just 2 (this excludes the customer being served).

You can use synchronization mechanisms such as locks, 
semaphores and monitors to implement your solution.