Reference no: EM132470610
Problem 1
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 Problems 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.