Please enter the code where it says TODO Working with Pthreads - Peterson’s Solu
ID: 3889106 • Letter: P
Question
Please enter the code where it says TODO
Working with Pthreads - Peterson’s Solution & Mutex
The goal of the assignment is for you to practice and use functions related to POSIX threads or Pthreads creation & handling in Unix based OSs. An online version of the Linux manual can be found here:http://linux.die.net/man/.
For this activity, you will need to refer to the phtreads section of the Linux manual, available here:https://linux.die.net/man/7/pthreads
Part 1: Peterson’s Solution
Execute the peterson program several times.
Examine the output carefully. You should notice a problem in the implementation. Make sure to follow the logic in main() and to read the comments carefully.
Review Peterson’s solution to achieve mutual exclusion. Pay special attention to the algorithm and code used to implement it.
You may want to refer to the prep materials for background info (section 2.3.3 in the textbook).
Correct the problem. Look for the // TODO comments and address them (i.e., implement the functionality described in the comments).
#include <iostream>
#include <pthread.h>
#define TOTAL_THREADS 2
int count;
int turn; // Shared variable, indicates
// whose turn it is to execute
bool interested[TOTAL_THREADS]; // Shared variable, indicates
// processes interested in executing
// The thread_id will be either 0 or 1
void enter_region(int thread_id)
{
int other; // ID of the other thread
other = 1 - thread_id; // The opposite of thread_id
// TODO: Add the code to indicate the
// thread's interest in executing.
// TODO: Indicate the thread's turn to execute next
// TODO: Busy wait until it is the thread's turn to execute
}
void leave_region(int thread_id)
{
// TODO: Add the code to set the flag
// indicating that the thread has
// exited the critical region.
}
void* myFunction(void* arg)
{
int thread_id = *((int*) arg);
for(unsigned int i = 0; i < 10; ++i) {
// TODO:
// Make sure that the thread waits for its turn
// before it enters the critical region.
//
// HINT: You need one function call
// Beginning of the critical region
count++;
std::cout << "Thread #" << thread_id << " count = " << count << std::endl;
// End of the critical region
// TODO:
// Make sure that the other thread gets a turn
//
// HINT: You need one function call
}
pthread_exit(NULL);
}
// HINT: It is not necessary to make any changes in main()
int main()
{
int rc[TOTAL_THREADS];
pthread_t ids[TOTAL_THREADS];
int args[TOTAL_THREADS];
count = 0;
for(unsigned int i = 0; i < TOTAL_THREADS; ++i) {
args[i] = i;
rc[i] = pthread_create(&ids[i], NULL, myFunction, (void*) &args[i]);
}
for(unsigned int i = 0; i < TOTAL_THREADS; ++i) {
pthread_join(ids[i], NULL);
}
std::cout << "Final count = " << count << std::endl;
pthread_exit(NULL);
}
Thread #0 count = 1 Thread #1 count = 2 Thread #0 count = 3 Thread #1 count = 4 Thread #0 count = 5 Thread #1 count = 6 Thread #0 count = 7 Thread #1 count = 8 Thread #0 count = 9 Thread #1 count = 10 Thread #0 count = 11 Thread #1 count = 12 Thread #0 count = 13 Thread #1 count = 14 Thread #0 count = 15 Thread #1 count = 16 Thread #0 count = 17 Thread #1 count = 18 Thread #0 count = 19 Thread #1 count = 20 Final count = 20