#include <pthread.h>
#include <stdio.h>
#include <malloc.h>
#include <stdlib.h>

pthread_rwlock_t rwlock = PTHREAD_RWLOCK_INITIALIZER;
int num_readers = 0;
int num_writers = 0;

void *reader (int p) {
	while (1) {
		printf("Reader %d ready\n", p);
		pthread_rwlock_rdlock(&rwlock);
		num_readers++;
		printf("Reader %d started  (num. readers = %d)\n", p, num_readers);
		usleep(2000000);
		num_readers--;
		printf("Reader %d finished (num. readers = %d)\n", p, num_readers);
		pthread_rwlock_unlock(&rwlock);
		usleep(1000000 * p);
	}
}
void *writer (int p) {
	while (1) {
		printf("Writer %d ready\n", p);
		pthread_rwlock_wrlock(&rwlock);
		num_writers++;
		printf("Writer %d started  (num. writers = %d)\n", p, num_writers);
		usleep(1000000);
		num_writers--;
		printf("Writer %d finished (num. writers = %d)\n", p, num_writers);
		pthread_rwlock_unlock(&rwlock);
		usleep(1000000 * p * 5);
	}
}

int main () {
	pthread_t thr_id;
	pthread_attr_t attr;

	pthread_attr_init(&attr);
	pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);

	pthread_create(&thr_id, &attr, reader, (void *) 1);
	pthread_create(&thr_id, &attr, reader, (void *) 2);
	pthread_create(&thr_id, &attr, reader, (void *) 3);
	pthread_create(&thr_id, &attr, reader, (void *) 4);
	pthread_create(&thr_id, &attr, reader, (void *) 5);

	pthread_create(&thr_id, &attr, writer, (void *) 1);
	pthread_create(&thr_id, &attr, writer, (void *) 2);
		
	usleep(50000000); //simulation time

	return 0;
}