Linux读写锁实现多线程读写示例

linux 读写锁应用实例
/*使用读写锁实现四个线程读写一段程序的实例，共创建了四个新的线程，其中两个线程用来读取数据，另外两个线程用来写入数据。在任意时刻，如果有一个线程在写数据，将阻塞所有其他线程的任何操作。*/
#include <errno.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <bits/pthreadtypes.h>

static pthread_rwlock_t rwlock;//读写锁对象

#define WORK_SIZE 1024
char work_area[WORK_SIZE];
int time_to_exit;

void *thread_function_read_o(void *arg);//读线程1
void *thread_function_read_t(void *arg);//读线程2
void *thread_function_write_o(void *arg);//写线程1
void *thread_function_write_t(void *arg);//写线程2
   

int main(int argc,char *argv[])
{
    int res;
    pthread_t a_thread,b_thread,c_thread,d_thread;
    void *thread_result;

    res=pthread_rwlock_init(&rwlock,NULL);//初始化读写锁
    if (res != 0)
    {
        perror("rwlock initialization failed");

        exit(EXIT_FAILURE);
    }
    res = pthread_create(&a_thread, NULL, thread_function_read_o, NULL);//create new thread创建线程
    if (res != 0)
    {
        perror("Thread creation failed");
        exit(EXIT_FAILURE);
    }

     res = pthread_create(&b_thread, NULL, thread_function_read_t, NULL);//create new thread
    if (res != 0)
    {
        perror("Thread creation failed");
        exit(EXIT_FAILURE);
    }
    res = pthread_create(&c_thread, NULL, thread_function_write_o, NULL);//create new thread
    if (res != 0)
    {
        perror("Thread creation failed");
        exit(EXIT_FAILURE);
    }
    res = pthread_create(&d_thread, NULL, thread_function_write_t, NULL);//create new thread
    if (res != 0)
    {
        perror("Thread creation failed");
        exit(EXIT_FAILURE);
    }
   
     res = pthread_join(a_thread, &thread_result);//等待a_thread线程结束           
     if (res != 0)