code/pthread/example2.c

#include "example2.h"

void *produce(void *buf)
{
    buffer *buff;
    buff = (buffer *) buf;
    printf("\nproducer started");

    for (int i = 0; i < 20; i++) {
	sem_wait(&buff->full);
	pthread_mutex_lock(&buff->mutex);

	buff->data[buff->pos] = 0;
	buff->pos = buff->pos + 1;
	printf("\nproduced");

	sem_post(&buff->empty);
	pthread_mutex_unlock(&buff->mutex);

	sleep(1);
    }

    pthread_exit(0);
}

void *consume(void *buf)
{

    buffer *buff;
    buff = (buffer *) buf;
    printf("\nconsumer started");
    for (int i = 0; i < 20; i++) {
	sem_wait(&buff->empty);
	pthread_mutex_lock(&buff->mutex);

	buff->pos = buff->pos - 1;
	printf("\ngot value %d", buff->data[buff->pos]);

	printf("\nconsumed");

	sem_post(&buff->full);

	pthread_mutex_unlock(&buff->mutex);
	sleep(2);
    }
    pthread_exit(0);
}

void init_buffer(buffer * buf)
{

    sem_init(&buf->empty, 0, 0);
    sem_init(&buf->full, 0, BUFFER_SIZE);
    pthread_mutex_init(&buf->mutex, NULL);
    buf->pos = 0;

    for (int i = 0; i < BUFFER_SIZE; i++) {
	buf->data[i] = -1;
    }
}