IO进程线程day9

1.将一个文件中的数据打印到终端上，类似cat一个文件，要求如下

a.A线程读取文件中的数据

b.B线程将A线程读取到的数据打印到终端上

c.文件打印完毕后，结束进程

#include <stdio.h>
#include<string.h>
#include <unistd.h>
#include <pthread.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <semaphore.h>
//临界资源
sem_t  sem1,sem2;
char c=0;
int fd_r;
void* callback1(void* arg)
{
    int fd_r=*(int *)arg;
    ssize_t res;
    while (1)
    {
        // printf("1\n");
        /*********临界区************/
         sem_wait(&sem1);//P操作
         res=read(fd_r,&c,1);
        sem_post(&sem2);//V操作
        if(res==0)
        {
            //pthread_exit(NULL);
            break;
        
        }
        /*********临界区************/
    }
    pthread_exit(NULL);
}
void*callback2(void*arg)
{
    char temp=0;
    while(1)
    {
       // printf("2\n");
        /*********临界区************/
        sem_wait(&sem2);//P操作
        printf("%c",c);
       sem_post(&sem1); //V操作
    /*********临界区************/
    }
        pthread_exit(NULL);
}
int main(int argc, char const *argv[])
{
    //打开文件
   int fd_r=open("./01.c",O_RDONLY);
   //创建2个信号量
    if(sem_init(&sem1,0,1)<0)
    {
            perror("sem_init");
            return -1;
    }    
     if(sem_init(&sem2,0,0)<0)
    {
            perror("sem_init");
            return -1;
    }
    //创建2个线程
    pthread_t tid1,tid2;
    if(pthread_create(&tid1,NULL,callback1,&fd_r)!=0)
        {
                fprintf(stderr,"pthread_create failed\n");
                return -1;
         }
    pthread_detach(tid1);
    if(pthread_create(&tid2,NULL,callback2,NULL)!=0)
        {
                fprintf(stderr,"pthread_create failed\n");
                return -1;
        }
        pthread_join(tid1,NULL);
        pthread_join(tid2,NULL);
        //销毁信号量
        sem_destroy(&sem1);
        sem_destroy(&sem2);
        //关闭文件
        close(fd_r);
    return 0;
}

2.用条件变量实现，有编号为ABC的3个线程，线程内分别打印自己的线程编号，要求打印顺序为ABC

a.提示：多个条件变量

#include <stdio.h>
#include<string.h>
#include <unistd.h>
#include <pthread.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <semaphore.h>
//创建初始化条件变量
pthread_cond_t cond=PTHREAD_COND_INITIALIZER;
pthread_cond_t cond1=PTHREAD_COND_INITIALIZER;
pthread_cond_t cond2=PTHREAD_COND_INITIALIZER;
//创建锁
pthread_mutex_t mutex=PTHREAD_MUTEX_INITIALIZER;
int flag=0;

void* callback1(void* arg)
{
    while (1)
    {
        pthread_mutex_lock(&mutex);
        if(flag!=0)
        {
            pthread_cond_wait(&cond,&mutex);

        }
        printf("%c",'A');
        flag=1;
        pthread_cond_signal(&cond1);
        pthread_mutex_unlock(&mutex);
      
    }
    pthread_exit(NULL);
}
void*callback2(void*arg)
{
    while (1)
    {
        pthread_mutex_lock(&mutex);
        if(flag!=1)
        {
            pthread_cond_wait(&cond1,&mutex);

        }
        printf("%c",'B');
        flag =2;
        pthread_cond_signal(&cond2);
        pthread_mutex_unlock(&mutex); 
    }
    pthread_exit(NULL);
}
void*callback3(void*arg)
{
   while (1)
    {
        pthread_mutex_lock(&mutex);
        if(flag!=2)
        {
            pthread_cond_wait(&cond2,&mutex);

        }
        printf("%c\n",'C');
        sleep(1);
        flag=0;
        pthread_cond_signal(&cond);
        pthread_mutex_unlock(&mutex);  
    }
    pthread_exit(NULL);
}
int main(int argc, char const *argv[])
{
    
    //创建3个线程
    pthread_t tid1,tid2,tid3;
    if(pthread_create(&tid1,NULL,callback1,NULL)!=0)
        {
                fprintf(stderr,"pthread_create failed\n");
                return -1;
         }
    pthread_detach(tid1);
    if(pthread_create(&tid2,NULL,callback2,NULL)!=0)
        {
                fprintf(stderr,"pthread_create failed\n");
                return -1;
        }
        if(pthread_create(&tid3,NULL,callback3,NULL)!=0)
        {
                fprintf(stderr,"pthread_create failed\n");
                return -1;
         }
        pthread_cond_init(&cond,NULL);
        pthread_mutex_init(&mutex,NULL);

        pthread_join(tid1,NULL);
        pthread_join(tid2,NULL);
        pthread_join(tid3,NULL);

    return 0;
}