c – 如何使用pthreads屏障？

概述嗨很抱歉发布了一大堆代码,但我是C代码的新手,基本上我正在做大学的任务,我必须实现一个“pthread_barrier”,现在我理解了障碍的概念(或者在至少我认为我这样做但是我只是不确定我应该把它放在哪里.作业说明： “使用pthread_barrier_init和pthread_barrier_wait确保所有生产者/消费者线程同时开始生产/消费.” 顺便说一下,这是作业的额外学分 #inclu 嗨很抱歉发布了一大堆代码,但我是C代码的新手,基本上我正在做大学的任务,我必须实现一个“pthread_barrIEr”,现在我理解了障碍的概念(或者在至少我认为我这样做但是我只是不确定我应该把它放在哪里.作业说明：

“使用pthread_barrIEr_init和pthread_barrIEr_wait确保所有生产者/消费者线程同时开始生产/消费.”

顺便说一下,这是作业的额外学分

#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 2typedef 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 intinit(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);}intmain(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,(voID *)&cp);  pthread_create(&c,consumer,(voID *)&cp);  pthread_create(&m,monitor,(voID *)&cp);  /* Wait for our threads */  pthread_join(p,NulL);  pthread_join(p,NulL);  pthread_join(c,NulL);  pthread_join(m,NulL);  return (0);}

解决方法 我可能会给你完整的答案,但我害怕Lasse V. Karlsen.所以我会给你提示.

>您的struct cp_t中已经可以访问屏障对象栏
>使用pthread_barrIEr_init初始化它,就像初始化互斥锁一样.计数与演员数量之间存在对应关系.
>在开始生产/消费之前,生产者和消费者都需要wait.得到它 ？

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