IO作业5

设置双信号实现交替生产者线程和消费者线程

#include <myhead.h>
int n=0;
pthread_mutex_t fastmutex;//定义互斥锁
pthread_cond_t cond;//定义条件变量
pthread_cond_t cond2;
void *product()
{int i;for(i=0;i<10;i++){n++;printf("我生产了一台特斯拉n=%d\n",n);pthread_cond_signal(&cond);pthread_cond_wait(&cond2,&fastmutex);pthread_mutex_unlock(&fastmutex);//每次循环都唤醒一个消费者}pthread_exit(NULL);
}	
void *custom()
{pthread_cond_wait(&cond,&fastmutex);//让消费者处于等待状态n--;printf("我消费了一台特斯拉n=%d\n",n);pthread_mutex_unlock(&fastmutex);pthread_cond_signal(&cond2);pthread_exit(NULL);
}
int main(int argc, const char *argv[])
{pthread_mutex_init(&fastmutex,NULL);//初始化互斥锁pthread_cond_init(&cond,NULL);//初始化条件变量pthread_cond_init(&cond2,NULL);//初始化条件变量pthread_t tid1,tid2[10];if(pthread_create(&tid1,NULL,product,NULL)!=0){perror("pthread_create");return -1;}int i;for(i=0;i<10;i++){if(pthread_create(&tid2[i],NULL,custom,NULL)!=0){perror("pthread_create");return -1;}}pthread_join(tid1,NULL);for(i=0;i<10;i++){pthread_join(tid2[i],NULL);}return 0;
}

#include <myhead.h>
void *fun1()
{printf("子线程1\n");int fp3=open("./3.txt",O_CREAT|O_RDWR|O_TRUNC,0664);if(fp3==-1){perror("打开文件3失败\n");return NULL;}int fp4=open("./4.txt",O_RDONLY);if(fp4==-1){perror("打开文件4失败\n");return NULL;}char buf[100];int sum=0;
int len=lseek(fp4,0,SEEK_END);
lseek(fp4,0,SEEK_SET);
while(1)
{
int a=read(fp4,buf,len/2);
sum+=a;
int k=a-(sum-len/2);if(sum>=len/2){
write(fp3,buf,k);break;}
write(fp3,buf,a);  
}
close(fp3);
close(fp4);
}
void *fun2()
{sleep(2);printf("子线程2\n");int fp3=open("./3.txt",O_RDWR|O_APPEND,0664);if(fp3==-1){perror("打开文件3失败\n");return NULL;}int fp4=open("./4.txt",O_RDONLY);if(fp4==-1){perror("打开文件4失败\n");return NULL;}char buf[100];int len=lseek(fp4,0,SEEK_END);lseek(fp4,len/2,SEEK_SET);while(1){int a=read(fp4,buf,len-len/2);if(a<0){break;}write(fp3,buf,a);}close(fp3);close(fp4);}
int main(int argc, const char *argv[])
{
pthread_t tid1;
pthread_t tid2;
int k1=pthread_create(&tid1,NULL,fun1,NULL);if(k1!=0){printf("创建线程1失败\n");exit(1);}
int k2=pthread_create(&tid2,NULL,fun2,NULL);if(k2!=0){printf("创建线程2失败\n");exit(1);}sleep(3);return 0;
}

#include <myhead.h>
#define MAX 5
#define SIZE 1000000
int n=0;
pthread_mutex_t fastmutex;//定义互斥锁
//pthread_mutex_t fastmutex=PTHREAD_MUTEX_INITIALIZER;
//静态初始化互斥锁
void *fun1()
{pthread_mutex_lock(&fastmutex);//上锁int i;for(i=0;i<SIZE;i++){n+=1;}
pthread_mutex_unlock(&fastmutex);
//解锁pthread_exit(NULL);
}
int main(int argc, const char *argv[])
{//没有互斥锁时多线程产生竞态的现象pthread_t tid[MAX];pthread_mutex_init(&fastmutex,NULL);//动态初始化互斥锁，默认属性int i;for(i=0;i<MAX;i++){int k=pthread_create(&tid[i],NULL,fun1,NULL);if(k!=0){perror("pthread_create");return -1;} }
for(i=0;i<MAX;i++)
{pthread_join(tid[i],NULL);//循环回收线程资源
}
printf("预期的结果：5000000\n");
printf("实际的结果：%d\n",n);
pthread_mutex_destroy(&fastmutex);return 0;
}

#include <myhead.h>
//创建一个生产者生产10台特斯拉
//创建10个消费者线程，使用信号量每次只允许一个消费者区消费特斯拉
int n1=0;
sem_t sem;//定义无名信号量
void *product()
{int i;for(i=0;i<10;i++){n1+=1;printf("n=%d生产者生产一台特斯拉\n",n1);}sem_post(&sem);//生产者完成后,释放无名信号量//sem=sem+1;pthread_exit(NULL);//生产者线程退出
}
void *custom()
{sem_wait(&sem);//消费者线程申请无名信号量//sem=sem-1;printf("n=%d消费者消费了一台特斯拉\n",n1);n1--;sem_post(&sem);//消费者线程释放无名信号量//sem=sem+1pthread_exit(NULL);//消费者线程退出
}
int main(int argc, const char *argv[])
{
pthread_t tid1,tid2[10];
sem_init(&sem,0,0);//初始化无名信号量0
//表示所有线程没有申请权限
int k1=pthread_create(&tid1,NULL,product,NULL);
if(k1!=0)
{perror("pthread_create");return -1;
}
int i;
for(i=0;i<10;i++)
{int k2=pthread_create(&tid2[i],NULL,custom,NULL);//消费者线程函数if(k2!=0){perror("pthread_create");return -1;}
}
pthread_join(tid1,NULL);//回收生产者线程
for(i=0;i<10;i++)
{pthread_join(tid2[i],NULL);
}
sem_destroy(&sem);//销毁无名信号量return 0;
}