example92.c

Linux网络编程教程适合初学者入门学习

/* example92.c */
#include	<pthread.h>
#include	<errno.h>

#define		MAXNITEMS	1000000
#define		MAXNTHREADS	100

#define min(a,b)        ((a) < (b) ? (a) : (b))

int	nitems;
int	buff[MAXNITEMS];

struct {
	pthread_mutex_t	mutex;
	int		nput;
	int		nval;
}put = {
	PTHREAD_MUTEX_INITIALIZER
};

struct {
	pthread_mutex_t	mutex;
	pthread_cond_t	cond;
	int		nready;
}nready = {
	PTHREAD_MUTEX_INITIALIZER,PTHREAD_COND_INITIALIZER
};

void	*produce(void *);
void	*consume(void *);


void
Pthread_create(pthread_t *tid, const pthread_attr_t *attr,
		                                           void * (*func)(void *), void *arg)
{
	int             n;

	if ( (n = pthread_create(tid, attr, func, arg)) == 0)
		return;

	errno = n;
	printf("pthread_create error");
}

void
Pthread_join(pthread_t tid, void **status)
{

	int             n;

	if ( (n = pthread_join(tid, status)) == 0)
		return;
	errno = n;
	printf("pthread_join error");
}


int
set_concurrency(int level)
{
#ifdef  HAVE_THR_SETCONCURRENCY_PROTO

	int             thr_setconcurrency(int);

	return(thr_setconcurrency(level));
#else
	return(0);
#endif
}

void
Set_concurrency(int level)
{

	if (set_concurrency(level) != 0)
		printf("set_concurrency error");
}

int
main(int argc, char **argv)
{
	int	i, nthreads, count[MAXNTHREADS];
	pthread_t	tid_produce[MAXNTHREADS], tid_consume;
	if (argc != 3) {
		printf("usage: prodcons3 <#items> <#threads>\n");
		return 0;
	}
	nitems = min(atoi(argv[1]), MAXNITEMS);
	nthreads = min(atoi(argv[2]), MAXNTHREADS);
	set_concurrency(nthreads + 1);
	for (i=0; i<nthreads; i++) {
		count[i] = 0;
		Pthread_create(&tid_consume, NULL, produce, &count[i]);
	}
	for (i=0; i<nthreads; i++) {
		Pthread_join(tid_produce[i], NULL);
		printf("count[%d] = %d\n", i, count[i]);
	}
	Pthread_create(&tid_consume, NULL, consume, NULL);
	Pthread_join(tid_consume, NULL);
	
	exit(0);
}
void *
produce(void *arg)
{
	for( ; ; ) {
		pthread_mutex_lock(&put.mutex);
		if (put.nput >= nitems) {
			pthread_mutex_unlock(&put.mutex);
			return(NULL);
		}
		buff[put.nput] = put.nval;
		put.nput++;
		put.nval++;
		pthread_mutex_unlock(&put.mutex);
		pthread_mutex_lock(&nready.mutex);
		if (nready.nready == 0)
			pthread_cond_signal(&nready.cond);
		nready.nready++;
		pthread_mutex_unlock(&nready.mutex);
		*((int *)arg) += 1;
	}
}
void *
consume(void *arg)
{
	int	i;
	for (i=0; i<nitems; i++) {
		pthread_mutex_lock(&nready.mutex);
		while (nready.nready == 0)
			pthread_cond_wait(&nready.cond, &nready.mutex);
		nready.nready--;
		pthread_mutex_unlock(&nready.mutex);
		if (buff[i] != i)
			printf("buff[%d] = %d\n", i, buff[i]);
	}
	return(NULL);
}