example91.c

Linux网络编程教程适合初学者入门学习

/* example91.c */
#include	<stdio.h>
#include	<stdlib.h>
#include	<pthread.h>
#include	<errno.h>

#define		MAXNITEMS	1000000
#define		MAXNTHREADS	100

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

int	nitems;
struct {
	pthread_mutex_t	mutex;
	int		buff[MAXNITEMS];
	int		nput;
	int		nval;
}shared = {
	PTHREAD_MUTEX_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]);
	}
	Pthread_create(&tid_consume, NULL, consume, NULL);
	for (i=0; i<nthreads; i++) {
		Pthread_join(tid_produce[i], NULL);
		printf("count[%d] = %d\n", i, count[i]);
	}
	Pthread_join(tid_consume, NULL);
	exit(0);
}
void *
produce(void *arg)
{
	for( ; ; ) {
		pthread_mutex_lock(&shared.mutex);
		if (shared.nput >= nitems) {
			pthread_mutex_unlock(&shared.mutex);
			return(NULL);
		}
		shared.buff[shared.nput] = shared.nval;
		shared.nput++;
		shared.nval++;
		pthread_mutex_unlock(&shared.mutex);
		*((int *)arg) += 1;
	}
}
void
consume_wait(int i)
{
	for ( ; ; ) {
		pthread_mutex_lock(&shared.mutex);
		if (i < shared.nput) {
			pthread_mutex_unlock(&shared.mutex);
			return;
		}
		pthread_mutex_unlock(&shared.mutex);
	}
}
void *
consume(void *arg)
{
	int	i;
	for (i=0; i<nitems; i++) {
		consume_wait(i);
		if (shared.buff[i] != i)
			printf("buff[%d] = %d\n", i, shared.buff[i]);
	}
	return(NULL);
}