#include <pthread.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#define check(return_val, msg) { if (return_val != 0) printf("%s",msg); }

unsigned long int condivisa[] = {0,0,0,0,0,0,0,0,0,0}; int ncondivisa = 0;/* Variabili condivise */
pthread_mutex_t Mutex = PTHREAD_MUTEX_INITIALIZER; /* lock per accesso memoria */ 
void *aggiorna ( int dim);  /* aggiornamento casuale */
int main(){
	pthread_t tid1,tid2;
	int retcode, k, dim=sizeof(condivisa)/sizeof(int);

	retcode=pthread_create(&tid1,NULL,(void *)aggiorna,(void *) dim);check(retcode,"errore create");
	retcode=pthread_create(&tid2,NULL,(void *)aggiorna,(void *) dim);check(retcode,"errore create");

	retcode = pthread_join(tid1,NULL);   check(retcode, "join failed");
	retcode = pthread_join(tid2,NULL);   check(retcode, "join failed");
	for(k=0; k<dim; k++)	printf("condivisa[%d]=%lu\n", k,condivisa[k]);
	exit(0);
}

void * aggiorna(int dim){
	int i; 	int sl; srand(getpid());
	printf("processo=%d,thread=%lu\n",getpid(),pthread_self());
	pthread_mutex_lock( &Mutex );
	for(i=0; i<dim/2 ; i++) {
		sl = 1 + (int) (5.0 * rand()/(RAND_MAX+1.0));
		usleep(sl*1000);
		//pthread_mutex_lock( &Mutex );
		condivisa[ncondivisa]=pthread_self();
		ncondivisa++;
		//pthread_mutex_unlock( &Mutex );
	}
	pthread_mutex_unlock( &Mutex );
	return( (void *) NULL);
}