你好，很抱歉发布了一大堆代码，但我对C语言非常陌生。基本上我正在为大学作业而做一些事情，并且我必须实现一个“pthread_barrier”，现在我理解屏障的概念（至少我认为我理解了），但我不确定应该把它放在哪里。作业规定如下：
“使用pthread_barrier_init和pthread_barrier_wait确保所有生成者/消费者线程同时开始生成/消费。”
顺便说一下，这是作业的额外学分部分。
#include <pthread.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#define SIXTY_SECONDS 60000000
#define ONE_SECOND 1000000
#define RANGE 10
#define PERIOD 2
typedef struct {
int *carpark;
int capacity;
int occupied;
int nextin;
int nextout;
int cars_in;
int cars_out;
pthread_mutex_t lock;
pthread_cond_t space;
pthread_cond_t car;
pthread_barrier_t bar;
} cp_t;
/* Our producer threads will each execute this function */
static void *
producer(void *cp_in)
{
cp_t *cp;
unsigned int seed;
/* Convert what was passed in to a pointer to a bounded buffer */
cp = (cp_t *)cp_in;
/* Loop */
while (1) {
/* Sleep for up to 1s */
usleep(rand_r(&seed) % ONE_SECOND);
/* Acquire the lock */
pthread_mutex_lock(&cp->lock);
/* While full wait until there is room available */
while (cp->occupied == cp->capacity) {
pthread_cond_wait(&cp->car, &cp->lock);
}
/* Insert an item */
cp->carpark[cp->nextin] = rand_r(&seed) % RANGE;
/* Increment counters */
cp->occupied++;
cp->nextin++;
cp->nextin %= cp->capacity;
cp->cars_in++;
/* Someone may be waiting on data to become available */
pthread_cond_signal(&cp->space);
/* Release the lock */
pthread_mutex_unlock(&cp->lock);
}
return ((void *)NULL);
}
/* Our consumer threads will each execute this function */
static void *
consumer(void *cp_in)
{
cp_t *cp;
unsigned int seed;
/* Convert what was passed in to a pointer to a bounded buffer */
cp = (cp_t *)cp_in;
while (1) {
/* Sleep for up to 1s */
usleep(rand_r(&seed) % ONE_SECOND);
/* Acquire the lock */
pthread_mutex_lock(&cp->lock);
/* While empty wait until there is data available */
while (cp->occupied == 0) {
pthread_cond_wait(&cp->space, &cp->lock);
}
/* Increment counters */
cp->occupied--;
cp->nextout++;
cp->nextout %= cp->capacity;
cp->cars_out++;
/* Someone may be waiting on room to become available */
pthread_cond_signal(&cp->car);
/* Release the lock */
pthread_mutex_unlock(&cp->lock);
}
return ((void *)NULL);
}
/* Our monitor thread will each execute this function */
static void *
monitor(void *cp_in)
{
cp_t *cp;
/* Convert what was passed in to a pointer to a bounded buffer */
cp = (cp_t *)cp_in;
while (1) {
/* Pause */
sleep(PERIOD);
/* Acquire the lock */
pthread_mutex_lock(&cp->lock);
printf("Delta: %d\n", cp->cars_in - cp->cars_out);
/* Release the lock */
pthread_mutex_unlock(&cp->lock);
}
return ((void *)NULL);
}
/* Initialisation */
static int
init(cp_t *cp, int capacity)
{
/* Set up the bounded buffer internals */
cp->occupied = cp->nextin = cp->nextout = cp->cars_in = cp->cars_out = 0;
cp->capacity = capacity;
/* Initialise our data structure */
cp->carpark = (int *)malloc(cp->capacity * sizeof (*cp->carpark));
/* Check malloc succeeded */
if (cp->carpark == NULL) {
perror("malloc()");
exit(EXIT_FAILURE);
}
/* Initialise lock and condition variables */
pthread_mutex_init(&cp->lock, NULL);
pthread_cond_init(&cp->space, NULL);
pthread_cond_init(&cp->car, NULL);
/* Seed random number generator */
srand((unsigned int)getpid());
return (0);
}
int
main(int argc, char *argv[])
{
pthread_t p, c, m;
cp_t cp;
/* Check usage */
if (argc != 2) {
printf("Usage: %s buffer_size\n", argv[0]);
exit(EXIT_FAILURE);
}
/* Initialise */
init(&cp, atoi(argv[1]));
/* Create our threads */
pthread_create(&p, NULL, producer, (void *)&cp);
pthread_create(&p, NULL, producer, (void *)&cp);
pthread_create(&c, NULL, consumer, (void *)&cp);
pthread_create(&c, NULL, consumer, (void *)&cp);
pthread_create(&m, NULL, monitor, (void *)&cp);
/* Wait for our threads */
pthread_join(p, NULL);
pthread_join(p, NULL);
pthread_join(c, NULL);
pthread_join(c, NULL);
pthread_join(m, NULL);
return (0);
}