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--- lab7 [2016/02/24 14:05] – created franck
+++ lab7 [2019/03/14 01:13] (current) – franck
@@ Line 1: / Line 1: @@
-Consider the following app.
+====== Lab 7 ======
-<html>
-<pre>
+You are asked to implement a solution to the sleeping barber problem in Java.  Some Java code has already been developed (see below).  First, we describe the problem.
-public class ComputeSquareRoot {
-    public static void main(String[] args) {
+The barber has one barber's chair and a waiting room containing a number of chairs in it.  When the barber finishes cutting a customer's hair, he dismisses the customer and goes to the waiting room to see if there are others waiting.  If there are, he brings one of them back to the chairs and cut their hair.  If there are none, he returns to the chair and sleeps in it.
-          double data = 3.1415926;
-          System.out.println("The square root of " + data + " is " + StrictMath.sqrt(data));
+Each customer, when they arrive, looks to see what the barber is doing.  If the barber is sleeping, the customer wakes him up.  If the barber is cutting hair, the customer stays in the waiting room.  If there is a free chair in the waiting room, the customer sits in it and waits their turn.  If there is no free chair, the customer leaves.
-    }
-}
+The waiting room is represented by the class WaitingRoom and the barber and the customers are represented by Barber and Customer threads.  The API of these classes can be found [[http://www.eecs.yorku.ca/course_archive/2018-19/W/4315/lab7/barber.api/index.html|here]].  Implement the classes WaitingRoom and Barber.  An implementation of the Customer class can be found [[http://www.eecs.yorku.ca/course_archive/2018-19/W/4315/lab7/Customer.java.txt|here]].  The sleeping barber app can be found [[http://www.eecs.yorku.ca/course_archive/2018-19/W/4315/lab7/Main.java.txt|here]].
-</pre>
-</html>
+Since randomization is used in some of the classes, different runs of the app may produce different outputs.
+<code>
+Barber sleeps
+Customer 4 enters
+Customer 4 sits down
+Barber wakes up
+Customer 4 gets a haircut
+Customer 4 leaves
+Customer 3 enters
+Customer 3 sits down
+Customer 1 enters
+Customer 1 sits down
+Customer 3 gets a haircut
+Customer 3 leaves
+Customer 0 enters
+Customer 0 sits down
+Customer 2 enters
+Customer 2 sits down
+Customer 1 gets a haircut
+Customer 1 leaves
+Customer 0 gets a haircut
+Customer 0 leaves
+Customer 2 gets a haircut
+Customer 2 leaves
+Barber is done for the day
+</code>
+In the above run, there are never more than three customers in the waiting room and therefore all customers get a haircut.
+<code>
+Barber sleeps
+Customer 1 enters
+Customer 1 sits down
+Barber wakes up
+Customer 2 enters
+Customer 2 sits down
+Customer 3 enters
+Customer 3 sits down
+Customer 4 enters
+Customer 4 leaves because no chair is free
+Customer 0 enters
+Customer 0 leaves because no chair is free
+Customer 1 gets a haircut
+Customer 1 leaves
+Customer 2 gets a haircut
+Customer 2 leaves
+Customer 3 gets a haircut
+Customer 3 leaves
+Barber is done for the day
+</code>
+In the above run, customers 4 and 0 leave before getting a haircut since all chairs in the waiting room are occupied.
+To receive feedback, submit your code **before** March 23 using the submit command:\\
+<code>
+submit 4315 lab7 <name of class>.java
+</code>
-  - Develop a model class so that the above app can be verified with JPF.  [[https://en.wikipedia.org/wiki/Methods_of_computing_square_roots|This]] Wikipedia page might be helpful.
-  - Develop a native peer so that the above app can be verified with JPF.