threads/reader_writer.c - master - bvs22/draft

threads/reader_writer.c
87 строк2 KB
Batomunkuev Vladimir
solutions tasks reader and writer
27 ноя 2024, 17:30
27 ноя 2024, 17:30ebbcc80
#include <stdio.h>
#include <pthread.h>
#include <unistd.h>

#define READER_COUNT 5
#define BOOK_SIZE 10

pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t cond_reader = PTHREAD_COND_INITIALIZER;
pthread_cond_t cond_writer = PTHREAD_COND_INITIALIZER;
int book[BOOK_SIZE] = {0};
int written = 0;
int active_readers = 0;
int active_writers = 0;

void* reader_func(void* arg)
{
    int reader_id = *(int*)arg;

    for (int i = 0; i < BOOK_SIZE; i++)
    {
        pthread_mutex_lock(&mutex);
        while(active_writers || written <= i)
        {
            pthread_cond_wait(&cond_reader, &mutex);
        }
        active_readers++;

        printf("Прочитано читателем %d: %d\n", reader_id, book[i]);
        fflush(stdout);

        active_readers--;
        if(active_readers == 0)
        {
            pthread_cond_signal(&cond_writer);
        }
        pthread_mutex_unlock(&mutex);
    }
    pthread_exit(NULL);
}

void* writer_func(void* arg)
{
    for (int i = 0; i < BOOK_SIZE; i++)
    {
        pthread_mutex_lock(&mutex);
        while(active_readers > 0)
        {
            pthread_cond_wait(&cond_writer, &mutex);
        }
        active_writers++;

        book[i] = i;
        written++;
        printf("Произведено: %d\n", book[i]);
        fflush(stdout);

        active_writers = 0;
        pthread_cond_broadcast(&cond_reader);
        pthread_mutex_unlock(&mutex);
        sleep(1);
    }

    pthread_exit(NULL);
}

int main()
{
    pthread_t reader[READER_COUNT], writer;
    int reader_id[READER_COUNT] = {0};
    
    pthread_create(&writer, NULL, writer_func, NULL);
    for(int i = 0; i < READER_COUNT; i++)
    {
        reader_id[i] = i + 1;
        pthread_create(&reader[i], NULL, reader_func, &reader_id[i]);
    }

    for(int i = 0; i < READER_COUNT; i++) 
    {
        pthread_join(reader[i], NULL);
    }
    pthread_join(writer, NULL);

    printf("\n");
    return 0;
}