COMP 322 - Assignment 1: Process Creation Hierarchy

Course Title: Intro to Operating Systems & Architecture
Semester: Fall 2021

Objective

To simulate process creation and destruction when implemented with a dynamic array.

Specification

The program creates/destroys child processes based on choosing from a menu of choices, where each choice calls the appropriate procedure, where the choices are:

Enter parameters
Create a new child process
Destroy all descendants of a process
Quit program and free memory

Assignment

Create a process creation hierarchy as a dynamic array of length n which references the process control blocks (PCBs), indexed 0 to n-1. Each PCB is a structure consisting of four fields:

parent: a PCB index corresponding to the current process’ creator
first_child: the first child process (if any) of the current process
older_sibling: a process (if any) that was created immediately before the current process and shares the same parent
younger_sibling: a process (if any) that was created immediately after the current process and shares the same parent

Functions

The necessary functions are simplified as follows:

`create()`

Represents the create function, which prompts for the parent process PCB[p]. The function creates a new child process PCB[q] of process PCB[p] by performing the following tasks:

record the parent's index, p, in PCB[q]
initialize the first_child and younger_sibling fields of PCB[q] to -1 (empty)
record the older_sibling field of PCB[q] as t, where t is the located older sibling of q (if any)
record the younger_sibling field of PCB[t] (if it exists) as q, where t is the located older sibling of q (if any)

`destroy()`

Represents the destroy function, which prompts for the parent process PCB[p]. The function recursively destroys all descendent processes (child, grandchild, etc.) of process PCB[p] by performing the following tasks:

initially call the recursive procedure on the first_child field of PCB[p]
call the recursive procedure on the younger sibling of PCB[q] (this continues until the youngest sibling is reached)
call the recursive procedure on each younger sibling’s first_child field
set all fields of the current process to -1 (parent, first_child, younger_sibling, older_sibling)

What Not to Do

Any violation will result in an automatic score of 0 on the assignment.

Do NOT modify the choice values (1,2,3,4) or input characters and then try to convert them to integers - the test script used for grading your assignment will not work correctly.
Do NOT turn in an alternate version of the assignment downloaded from the Internet (coursehero, chegg, reddit, github, etc.) or submitted from you or another student from a previous semester.
Do NOT turn in your assignment coded in another programming language (C++, C#, Java).

What to Turn In

The source code as a C file uploaded to Canvas by the deadline of 11:59pm PST (50% off one day late, grade of 0% two or more days late)
Make sure your code compiles with the online C compiler before submitting.
Code that is unable to compile will receive an automatic grade of 0%. (Crashes during runtime are acceptable for partial credit.)

Sample Output

Process creation and destruction
--------------------------------
1) Enter parameters
2) Create a new child process
3) Destroy all descendants of a process
4) Quit program and free memory


Enter selection: 1
Enter maximum number of processes: 5


Process creation and destruction
--------------------------------
1) Enter parameters
2) Create a new child process
3) Destroy all descendants of a process
4) Quit program and free memory


Enter selection: 2
Enter the parent process index: 0

i       Parent  First   Older   Younger
--------------------------------------
0       0       1
1       0


Process creation and destruction
--------------------------------
1) Enter parameters
2) Create a new child process
3) Destroy all descendants of a process
4) Quit program and free memory


Enter selection: 2
Enter the parent process index: 0

i       Parent  First   Older   Younger
--------------------------------------
0       0       1
1       0                      2
2       0              1


Process creation and destruction
--------------------------------
1) Enter parameters
2) Create a new child process
3) Destroy all descendants of a process
4) Quit program and free memory


Enter selection: 2
Enter the parent process index: 2

i       Parent  First   Older   Younger
--------------------------------------
0       0       1
1       0                      2
2       0       3       1
3       2


Process creation and destruction
--------------------------------
1) Enter parameters
2) Create a new child process
3) Destroy all descendants of a process
4) Quit program and free memory


Enter selection: 2
Enter the parent process index: 0

i       Parent  First   Older   Younger
--------------------------------------
0       0       1
1       0                      2
2       0       3       1       4
3       2
4       0              2


Process creation and destruction
--------------------------------
1) Enter parameters
2) Create a new child process
3) Destroy all descendants of a process
4) Quit program and free memory


Enter selection: 3
Enter the process whose descendants are to be destroyed: 0

i       Parent  First   Older   Younger
--------------------------------------
0       0


Process creation and destruction
--------------------------------
1) Enter parameters
2) Create a new child process
3) Destroy all descendants of a process
4) Quit program and free memory


Enter selection: 4
Quitting program...

MarkKoz / comp-322