worker_pool.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/wait.h>

#define MAX_LINE 1024
#define MAX_WORKERS 10

typedef struct {
    int lines;
    int words;
    int chars;
    int vowels;
} result_t;

int count_words(char *line) {
    int count = 0;
    char *token = strtok(line, " \n");
    while (token != NULL) {
        count++;
        token = strtok(NULL, " \n");
    }
    return count;
}

int count_vowels(char *line) {
    int v = 0;
    for (int i = 0; line[i]; i++) {
        char c = line[i];
        if (c=='a'||c=='e'||c=='i'||c=='o'||c=='u'||
            c=='A'||c=='E'||c=='I'||c=='O'||c=='U') {
            v++;
        }
    }
    return v;
}

int main(int argc, char *argv[]) {
    int n = 2;
    char *filename = NULL;

    // parse args
    for (int i = 1; i < argc; i++) {
        if (strcmp(argv[i], "-n") == 0) {
            n = atoi(argv[++i]);
        } else if (strcmp(argv[i], "-f") == 0) {
            filename = argv[++i];
        }
    }

    if (n < 1 || n > MAX_WORKERS) {
        fprintf(stderr, "Error: workers must be 1-%d\n", MAX_WORKERS);
        return 1;
    }

    FILE *fp = stdin;

    if (filename != NULL) {
        fp = fopen(filename, "r");
        if (fp == NULL) {
            perror("fopen");
            return 1;
        }
    }

    int task_pipe[MAX_WORKERS][2];
    int result_pipe[MAX_WORKERS][2];
    pid_t workers[MAX_WORKERS];

    // create workers
    for (int i = 0; i < n; i++) {

        if (pipe(task_pipe[i]) < 0) {
            perror("pipe");
            exit(1);
        }

        if (pipe(result_pipe[i]) < 0) {
            perror("pipe");
            exit(1);
        }

        workers[i] = fork();

        if (workers[i] < 0) {
            perror("fork");
            exit(1);
        }

        if (workers[i] == 0) {
            // child

            close(task_pipe[i][1]);
            close(result_pipe[i][0]);

            char line[MAX_LINE];

            while (1) {
                int nread = read(task_pipe[i][0], line, MAX_LINE);

                if (nread < 0) {
                    perror("read");
                    exit(1);
                }

                if (nread == 0) break;

                result_t r;
                r.lines = 1;

                char temp[MAX_LINE];
                strcpy(temp, line);

                r.words = count_words(temp);
                r.chars = strlen(line);
                r.vowels = count_vowels(line);

                if (write(result_pipe[i][1], &r, sizeof(r)) < 0) {
                    perror("write");
                    exit(1);
                }
            }

            close(task_pipe[i][0]);
            close(result_pipe[i][1]);
            exit(0);
        } else {
            // parent
            close(task_pipe[i][0]);
            close(result_pipe[i][1]);
        }
    }

    // distribute tasks
    char line[MAX_LINE];
    int current = 0;
    int tasks_sent = 0;

    while (fgets(line, MAX_LINE, fp) != NULL) {

        if (write(task_pipe[current][1], line, MAX_LINE) < 0) {
            perror("write");
            exit(1);
        }

        current = (current + 1) % n;
        tasks_sent++;
    }

    // close task pipes
    for (int i = 0; i < n; i++) {
        close(task_pipe[i][1]);
    }

    // collect results
    int total_lines = 0;
    int total_words = 0;
    int total_chars = 0;
    int total_vowels = 0;
    int results_received = 0;
    int worker_usage[MAX_WORKERS] = {0};

    result_t r;

    for (int i = 0; i < n; i++) {

        while (1) {
            int nread = read(result_pipe[i][0], &r, sizeof(r));

            if (nread < 0) {
                perror("read");
                exit(1);
            }

            if (nread == 0) break;

            total_lines += r.lines;
            total_words += r.words;
            total_chars += r.chars;
            total_vowels += r.vowels;

            worker_usage[i]++;
            results_received++;
        }

        close(result_pipe[i][0]);
    }

    // wait children
    for (int i = 0; i < n; i++) {
        wait(NULL);
    }

    // print summary
    printf("\n========== FINAL SUMMARY ==========\n");
    printf("Run status      : completed normally\n");
    printf("Tasks sent      : %d\n", tasks_sent);
    printf("Results received: %d\n", results_received);
    printf("Total lines     : %d\n", total_lines);
    printf("Total words     : %d\n", total_words);
    printf("Total chars     : %d\n", total_chars);
    printf("Total vowels    : %d\n", total_vowels);

    printf("\nWorker usage:\n");
    for (int i = 0; i < n; i++) {
        printf("  Worker %d processed %d task(s)\n", i, worker_usage[i]);
    }

    printf("===================================\n");

    return 0;
}