Project

CS 5500 Advanced Operating Systems

Programming Project

by Hyungbae Park

Main function

• int main(int argc, char *argv[]) { // Initialize your variables

// Create TA thread sleep(1); for(i=0;i<MAX;i++) {

sleep(1); // Create students threads

}

for(j=0;j<MAX;j++) { // Join all the threads

} }

Semaphore wait() function

• void wait(int sema, int param) {

while(sema == 0) {} if(param == 0)

printf("[SEMAPHORE] TA gets the lock!\n");

else printf("[SEMAPHORE] Student %d gets

the lock!\n",param); sema--;

}

Semaphore signal() function

• void signal(int sema, int param) {

if(param == 0) printf("[SEMAPHORE] TA releases the

lock!\n"); else

printf("[SEMAPHORE] Student %d releases the lock!\n",param);

sema++; }

Thread sleepingta() function

• void *sleepingta(void *param) { // Wait & get the lock printf("[TA THREAD] TA is in the office.\n"); // Release the lock while(ENDOFPROGRAM) {

// Add your logic } // End thread

}

Thread student() function

• void *student(void *param) { // Wait & get the lock printf("[STUDENT THREAD] Student %d is

coming!\n",*(int*)param);

// Add your logic

// Release the lock // End thread

}

Variables

• #include <pthread.h> #include <stdio.h>

#define SLEEP 0 #define WAKEUP 1

int semaphore; int MAX, TA, TTL; int ENDOFPROGRAM; int curstudent; int waitinglist;

Flowchart - main()

MAIN START

Create TA thread (TA is sleeping)

Get user input (Number of students)

Create student threads

MAIN END

Flowchart – sleepingta()

TA THREAD START

TA is sleeping

Student wakes TA up

No students in 10 seconds

Help the student

Waiting students

TA THREAD END

YesNo

Yes

No

Flowchart – student()

STUDENT THREAD START

Student wakes TA up

Thee waiting students

Seat on the chair and wait

Helped by TA

STUDENT THREAD END

Is TA sleeping

Yes

No

Yes No

Results

• [SEMAPHORE] TA gets the lock! [TA THREAD] TA is in the office. [SEMAPHORE] TA releases the lock! [TA THREAD] Waiting students = 0, Student in the office = 0 [SEMAPHORE] Student 1 gets the lock! [STUDENT THREAD] Student 1 is coming! [STUDENT THREAD] Waiting students = 0, Student in the office = 1 [STUDENT THREAD] Student 1 wakes up TA and gets help. [SEMAPHORE] Student 1 releases the lock! [SEMAPHORE] Student 2 gets the lock! [STUDENT THREAD] Student 2 is coming! [STUDENT THREAD] Student 2 is seating on the waiting chair #1. [STUDENT THREAD] Waiting students = 1, Student in the office = 1 [SEMAPHORE] Student 2 releases the lock! [TA THREAD] TA is helping a student... [SEMAPHORE] Student 3 gets the lock! [STUDENT THREAD] Student 3 is coming! [STUDENT THREAD] Student 3 is seating on the waiting chair #2. [STUDENT THREAD] Waiting students = 2, Student in the office = 1 [SEMAPHORE] Student 3 releases the lock! [SEMAPHORE] Student 4 gets the lock! [STUDENT THREAD] Student 4 is coming! [STUDENT THREAD] Student 4 is seating on the waiting chair #3. [STUDENT THREAD] Waiting students = 3, Student in the office = 1 [SEMAPHORE] Student 4 releases the lock!

Results – cont'd

• [SEMAPHORE] Student 5 gets the lock! [STUDENT THREAD] Student 5 is coming! [STUDENT THREAD] Student 5 is waiting. [TA THREAD] TA is done with the student! [TA THREAD] Waiting students = 2, Student in the office = 1 [TA THREAD] TA is helping a student... [STUDENT THREAD] Student 5 is seating on the waiting chair #3. [STUDENT THREAD] Waiting students = 3, Student in the office = 1 [SEMAPHORE] Student 5 releases the lock! [TA THREAD] TA is done with the student! [TA THREAD] Waiting students = 2, Student in the office = 1 [TA THREAD] TA is helping a student... [TA THREAD] TA is done with the student! [TA THREAD] Waiting students = 1, Student in the office = 1 [TA THREAD] TA is helping a student... [TA THREAD] TA is done with the student! [TA THREAD] Waiting students = 0, Student in the office = 1 [TA THREAD] TA is helping a student... [TA THREAD] TA is done with the student! [TA THREAD] Waiting students = 0, Student in the office = 0

Submission

• It should be YOUR OWN WORK

• Please submit your original source code! – DO NOT copy & paste your source code to any text

editors

– If you submit non-compilable files, then you will get zero for the project

• Submission link is available on Blackboard

• Extra credit (+5) for the submission by 6/11 11:59 pm