CS3305A Assignment 3 Solution

Purpose

The goals of this assignment are the following:
• Get experience with the pipe and pthread system functions.
• Learn how to create multiple threads for different tasks.
• Learn how to share data between threads using the pipe.
• Gain more experience with the C programming language from an OS perspective.

Inter-Thread Communications (100 points)

Write a C program that will accept two integers from the user as command-line arguments (for example, X and Y). The parent process will read X and Y from the command line. The parent process will create three threads with corresponding thread ID 100, 101, and 102, respectively. The parent process will write X and Y to the shared memory using pipe. The first thread (i.e., thread 100) will read X and Y from the pipe and perform the sum, S = X+Y, and then the result S will be written to the pipe. Next, the second thread (i.e., thread 101) will read the S from the pipe and determine whether S is an even or odd number, and then S will be written again to the pipe by the second thread. Finally, the third thread (i.e., thread 102) will read S from the pipe and count the total number of digits in S. The expected output from your program should look like the following (for this example below, X and Y represent 7 and 6, respectively):

1. parent (PID 2209) receives X = 7 and Y = 6 from the user
2. parent (PID 2209) writes X = 7 and Y = 6 to the pipe
3. thread (TID 100) reads X = 7 and Y = 6 from the pipe
4. thread (TID 100) writes X+Y = 13 to the pipe
5. thread (TID 101) reads X+Y = 13 from the pipe
6. thread (TID 101) identifies X+Y= 13 as an odd number
7. thread (TID 101) writes X+Y = 13 to the pipe
8. thread (TID 102) reads X+Y = 13 from the pipe
9. thread (TID 102) identifies X+Y=13 as a 2 digit number

In the above example, if the sum S is an even number, then the word “odd” in line number 6 above must be replaced with the word “even”. You must control the execution of the threads to follow the sequence according to the expected output above. You must not use more than one pipe for this assignment. In case of passing multiple parameters through a single pipe, concatenate the parameters using any delimiter so that you can parse it later accordingly. This assignment will be tested given only positive integers. Your implementation must have the following functions:

1. void *sum(void *thread_id): This function is executed by thread 100. This function reads X and Y from the pipe, performs addition i.e., S = X+Y, and writes S to the pipe.

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2. void *odd_even(void *thread_id): This function is executed by thread 101. This function reads S from the pipe and determines if the S is an even or odd number.

3. void *digit_count(void *thread_id): This function is executed by thread 102. This function determines the number of digits in S.

Mark Distribution


• Inter-Thread Communications (100 points)
a) Parent reads X and Y from user: 10 points
b) The first thread reads X & Y from user: 15 points
c) The first thread writes results to the pipe: 10 points
d) The second thread reads the result from the pipe: 10
e) The second thread identifies odd/even number: 15
f) The third thread reads the result from the pipe: 10
g) The third thread identifies the number of digits: 15
h) Control the thread execution flow: 15 points


Computing Platform for Assignments


• Students have virtual access to the MC 244 lab, which contains 30 Fedora 28 systems. Linux machines available to you are linux01.gaul.csd.uwo.ca through linux30.gaul.csd.uwo.ca.
• It is your responsibility to ensure that your code compiles and runs on the above systems. You can SSH into MC 244 machines (please see the Assignment 1 file transfer tutorial).
• If you are off-campus, you have to SSH to compute.gaul.csd.uwo.ca first (this server is also known as sylvia.gaul.csd.uwo.ca, in honor of Dr. Sylvia Osborn), and then to one of the MC 244 systems (linux01.gaul.csd.uwo.ca through linux30.gaul.csd.uwo.ca) [please see the Assignment 1 file transfer tutorial].
• https://wiki.sci.uwo.ca/sts/computer-science/gaul

Assignment Submission


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