sync, mutex. unix network programming p161

다시 thread로 돌아왔다.

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <pthread.h>
#define	MAXNITEMS 		1000000
#define	MAXNTHREADS			100
#define MIN(X,Y) ((X)<(Y) ? (X) : (Y))



//gcc -lpthread 옵션으로 컴파일.
int		nitems;			/* read-only by producer and consumer */


//shared를 초기화 하는데,
//맨 처음에 mutext가 있음.
//나머지는 0으로 초기화됨..
struct {
  pthread_mutex_t	mutex;
  int	buff[MAXNITEMS];
  int	nput;
  int	nval;
} shared = { PTHREAD_MUTEX_INITIALIZER };

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


int
main(int argc, char **argv)
{
	int			i, nthreads, count[MAXNTHREADS];
	pthread_t	tid_produce[MAXNTHREADS], tid_consume;
	//앞에서부터 초기화.
	struct test {
		int no1;
		int no2;
	} teststruct = {10};

	if (argc != 3)
		perror("usage: prodcons2 <#items> <#threads>");
	nitems = MIN(atoi(argv[1]), MAXNITEMS);
	nthreads = MIN(atoi(argv[2]), MAXNTHREADS);

	//pthread_setconcurrency();
		/* 4start all the producer threads */
	for (i = 0; i < nthreads; i++) {
		count[i] = 0;
		pthread_create(&tid_produce[i], NULL, produce, &count[i]);
	}

		/* 4wait for all the producer threads */
	for (i = 0; i < nthreads; i++) {
		pthread_join(tid_produce[i], NULL);
		printf("count[%d] = %d\n", i, count[i]);	
	}

		/* 4start, then wait for the consumer thread */
	pthread_create(&tid_consume, NULL, consume, NULL);
	pthread_join(tid_consume, NULL);

	exit(0);
}
/* end main */

/* include producer */
void *
produce(void *arg)
{
	for ( ; ; ) {
		pthread_mutex_lock(&shared.mutex);
		if (shared.nput >= nitems) {
			pthread_mutex_unlock(&shared.mutex);
			return(NULL);		/* array is full, we're done */
		}
		shared.buff[shared.nput] = shared.nval;
		shared.nput++;
		shared.nval++;
		pthread_mutex_unlock(&shared.mutex);
		*((int *) arg) += 1;
	}
}

void *
consume(void *arg)
{
	int		i;

	for (i = 0; i < nitems; i++) {
		if (shared.buff[i] != i)
			printf("buff[%d] = %d\n", i, shared.buff[i]);
	}
	return(NULL);
}
/* end producer */