Reference no: EM132472230

Problem

A bakery shop has to provide a stream of muffins for customers. The muffins are made by a baker in the kitchen and placed on a conveyor belt. The conveyor belt carries the muffins to where the customers are waiting to buy them.

This scenario has been simulated using two processes: the baker and customer, and a shared conveyor belt implemented as a circular array called conveyor, where each space in the array can hold one muffin. There are two shared general semaphores, empty and full, and a mutex buffer_mutex. In this scenario, there is only multiple bakers and a single customer.

The pseudo-code for the baker is as follows. The baker makes use of an integer variable in for noting the next available space on the conveyor belt.
1. while(true){
2.   muffin = makeMuffin(); // Create a muffin
3.   wait(empty);
4.   wait(buffer_mutex);
5.   conveyor[in] = muffin; // Put the muffin on the conveyor belt
6.   in = (in + 1) mod n;
7.   signal(buffer_mutex);
8.   signal(full);
9. }
The pseudo-code for the customer is as follows. The customer makes use of an integer variable out for noting the next location on the conveyor belt that contains a muffin.
1. while(true){
2.   wait(full);
3.   muffin = conveyor[out]; // Get a muffin from the conveyor belt
4.   conveyor[out] = null;
5.   out = (out + 1) mod n;
6.   signal(empty);
7.   eat(muffin); // Eat the muffin
8. }

This code should be familiar to you as it is similar to the example of the Producer-Consumer problem. Only a few sentences are required for each of the questions below.

Q1: Explain, in words, the purpose of the mod n statement. Explain what is the purpose of mutex buffer_mutex. What problems solves? You may wish to include simple examples.

Q2: Explain what will happen if the order of semaphores in the customer changes. So, we have in line 2  signal(empty) and in line 6  wait(full). Now assume that there is a single baker and a single customer, with an infinite buffer. Explain, in words, what changes should be made and why.