临界区的同步操作-------------使用信号量 实现

                   同步模型: 

 　　          

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <pthread.h>
#include <semaphore.h>

//#define	EXIT_SUCCESS	0
//#define	EXIT_FAILURE	1
//假设有6个同学{姜涵,张柏芝,刘思思，孙燕姿,赵敏，马苏}，依次按照顺序报数
//f(x) = f(x+6)   周期性
// 关键是理解 临界区需要怎么去操作   选择什么样技术

static int  pthread_run = 1;
static void  print(char*s);
static sem_t sem[6];
//sem_init(&sem, 0, 0)

static void* J_H_Pthread(void *arg)
{
    int a ;
    while(pthread_run)
    {
       //printf("pthread run
");
       sem_wait(&sem[0]);
       print(__func__);
       sem_post(&sem[1]);

    }

    return (void*)NULL;
}

static void* Z_B_Z_Pthread(void *arg)
{
    int a ;
    while(pthread_run)
    {
       //printf("pthread run
");
       sem_wait(&sem[1]);
       print(__func__);
       sem_post(&sem[2]);

    }

    return (void*)NULL;
}

static void* L_S_SPthread(void *arg)
{
    int a ;
    while(pthread_run)
    {
       //printf("pthread run
");
       sem_wait(&sem[2]);
       print(__func__);
       sem_post(&sem[3]);

    }

    return (void*)NULL;
}

static void* S_Y_Zthread(void *arg)
{
    int a ;
    while(pthread_run)
    {
       //printf("pthread run
");
       sem_wait(&sem[3]);
       print(__func__);
       sem_post(&sem[4]);

    }

    return (void*)NULL;
}

static void* Z_M_Pthread(void *arg)
{
    int a ;
    while(pthread_run)
    {
       //printf("pthread run
");
       sem_wait(&sem[4]);
       print(__func__);
       sem_post(&sem[5]);

    }

    return (void*)NULL;
}

static void* M_S_Pthread(void *arg)
{
    int a ;
    while(pthread_run)
    {
       //printf("pthread run
");
       sem_wait(&sem[5]);
       print(__func__);
       sem_post(&sem[0]);
    }

    return (void*)NULL;
}

// 定义一个临界区资源
static void  print(char*s)
{
   if(s==NULL)
   {
      printf("int value error
");
      return 0;
   }
   printf("I'm here %s
",s);
}

int main()
{


    printf("EXIT_SUCCESS is %d
",EXIT_SUCCESS);
    printf("EXIT_FAILURE is %d
",EXIT_FAILURE);
    int ret = -1;
    pthread_t  j_h_ptid,z_b_ztid,l_s_stid,s_yztid,z_mtid,m_stid;
    //int ret = pthread_create(&tid,NULL,Noise_USB_Pthread,NULL);
    //printf("ret is %d
",ret);
    //ret = pthread_join(tid,NULL);
    //printf("ret is %d
",ret);
    int i;
    for(i =0;i<6;i++)
    {
        if(i==0)
          sem_init(&sem[i],0,1);
        else
          sem_init(&sem[i],0,0);
    }

    ret = pthread_create(&j_h_ptid,NULL,J_H_Pthread,NULL);
    printf("ret is %d
",ret);
    ret = pthread_create(&z_b_ztid,NULL,Z_B_Z_Pthread,NULL);
    printf("ret is %d
",ret);
    ret = pthread_create(&l_s_stid,NULL,L_S_SPthread,NULL);
    printf("ret is %d
",ret);
    ret = pthread_create(&s_yztid,NULL,S_Y_Zthread,NULL);
    printf("ret is %d
",ret);
    ret = pthread_create(&z_mtid,NULL,Z_M_Pthread,NULL);
    printf("ret is %d
",ret);
    ret = pthread_create(&m_stid,NULL,M_S_Pthread,NULL);
    printf("ret is %d
",ret);

    pthread_join(j_h_ptid,NULL);
    pthread_join(z_b_ztid,NULL);
    pthread_join(l_s_stid,NULL);
    pthread_join(s_yztid,NULL);
    pthread_join(s_yztid,NULL);
    pthread_join(m_stid,NULL);

    for(i =0;i<6;i++)
    {
        sem_destroy(&sem[i]);
    }

    while(1);

    return 0;
}

　　同步模型