线程1——互斥锁

头文件：

#include <pthread.h>

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创建新线程函数：

int pthread_create(pthread_t *thread, const pthread_attr_t *attr,void *(*start_routine) (void *), void *arg);

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结束线程函数：

void pthread_exit(void *retval);

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等待线程结束：

int pthread_join(pthread_t thread, void **retval);

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创建互斥锁
pthread_mutex_t *mutex
pthread_mutex_init(互斥锁指针,NULL)

//线程互斥锁加锁
int pthread_mutex_lock(pthread_mutex_t *mutex)

//线程互斥锁解锁
int pthread_mutex_unlock(pthread_mutex_t *mutex)

//线程互斥锁销毁
int pthread_mutex_distory(pthread_mutex_t *mutex)

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案例：分别用三个线程打出1-30报数

#include <pthread.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
//声明三个新进程
void* task1(void *arg);
void* task2(void *arg);
void* task3(void *arg);
pthread_mutex_t lock;    //互斥锁指针
static int buf[30]={1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30};



int main(void)
{
    int ret;
    
    //创建初始化互斥锁
    pthread_mutex_init(&lock,NULL);
    
    //声明三个指针，指向线程的id
    pthread_t tid1,tid2,tid3;
    //创建三个新线程，用刚才的指针，
    pthread_create(&tid1,NULL,task1,(void*)5);
    pthread_create(&tid2,NULL,task2,(void*)6);
    pthread_create(&tid3,NULL,task3,(void*)7);
    
    printf("Main thread
");
    //等待线程结束运行
    pthread_join(tid1,(void **)&ret);
    pthread_join(tid2,(void **)&ret);
    pthread_join(tid3,(void **)&ret);
    
    sleep(1);
    printf("New thread1 id:%ld
",tid1);
    printf("New thread2 id:%ld
",tid2);
    printf("New thread3 id:%ld
",tid3);
    
    //销毁互斥锁
    pthread_mutex_destroy(&lock);
    
}

    int i = 0;

void* task1(void *arg)
{
    while(i<30){
    
    //上锁
    pthread_mutex_lock(&lock);
    printf("task1:%d
",buf[i]);
    i += 1;
    //解锁
    pthread_mutex_unlock(&lock);
    usleep(1);
    }
    pthread_exit(NULL);
}


void* task2(void *arg)
{
    
    while(i<30)
    {
    
    //上锁
    pthread_mutex_lock(&lock);
    printf("task2:%d
",buf[i]);
    i += 1;
    //解锁
    pthread_mutex_unlock(&lock);
    usleep(1);
    }
    pthread_exit(NULL);
}

void* task3(void *arg)
{
    
    while(i<30)
    {
    
    //上锁
    pthread_mutex_lock(&lock);
    printf("task3:%d
",buf[i]);
    i += 1;
    //解锁
    pthread_mutex_unlock(&lock);
    usleep(1);
    }
    pthread_exit(NULL);
}

上锁和解锁，要放在使用公共资源的前后，比如例中的 i 前后。