ex2 w6 worker.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <time.h>
#include <stdbool.h>

// 6 digits for big triangular numbers like 113050
#define TRI_BASE 1000000

// Current process pid (which executed this program)
pid_t pid;

// Current process idx (starts from 0)
int process_idx;

// Number of triangular numbers found so far
long tris;

bool is_triangular(long n) {
    for (long i = 1; i <= n; i++) {
        if (i * (i + 1) == 2 * n) {
            return true;
        }
    }
    return false;
}

void signal_handler(int signum) {
    switch (signum) {
        case SIGTSTP:
            // Pause the process indefinitely
            printf("Process %d: stopping....\n", process_idx);
            pause();
            break;
        case SIGCONT:
            // Continue the process
            printf("Process %d: resuming....\n", process_idx);
            break;
        case SIGTERM:
            // Terminate the process
            printf("Process %d: terminating....\n", process_idx);
            exit(EXIT_SUCCESS);
            break;
        default:
            break;
    }
}

// Generates a big number n
long big_n() {
    time_t t;
    long n = 0;
    srand((unsigned)time(&t));
    while (n < TRI_BASE)
        n += rand();
    return n % TRI_BASE;
}

int main(int argc, char *argv[]) {
    if (argc != 2) {
        fprintf(stderr, "Usage: %s <process_idx>\n", argv[0]);
        exit(EXIT_FAILURE);
    }

    process_idx = atoi(argv[1]); // Get process_idx from command line argument
    pid = getpid();

    // Register signal handlers
    signal(SIGTSTP, signal_handler);
    signal(SIGCONT, signal_handler);
    signal(SIGTERM, signal_handler);

    long next_n = big_n() + 1;

    printf("Process %d (PID=%d): has been started\n", process_idx, pid);
    printf("Process %d (PID=%d): will find the next triangular number from [%ld, inf)\n", process_idx, pid, next_n);

    // Initialize counter
    tris = 0;

    while (true) {
        if (is_triangular(next_n)) {
            tris++;
            printf("Process %d (PID=%d): I found this triangular number %ld\n", process_idx, pid, next_n);
        }
        next_n++;
    }

    return 0;
}