VS2022连接Linux操作pthread_rwlock_t等显示未定义标识符

Question

使用VS2022社区版远程连接LInux（CentOS7）操作时，已经加入头文件#include<pthread.h>的情况下，VS中使用pthread_rwlock_t 出现了未定义标识符的错误

Answer 1

• 这篇文章：C语言中的读写锁pthread_rwlock_t及使用方法介绍 也许能够解决你的问题，你可以看下
• 除此之外, 这篇博客: Linux系统编程学习笔记中的 读写锁pthread_rwlock_t 部分也许能够解决你的问题, 你可以仔细阅读以下内容或跳转源博客中阅读:
  

• 读写锁与互斥量类似, 但读写锁允许更高的并行性, 其特性为

  1. 写独占, 读共享
  2. 写锁优先级高(读写锁一起过来时)
  3. 锁只有一把

  读写锁只有一把, 但其具备两种状态:

  • 读模式下加锁状态(读锁)
  • 写模式下加锁状态(写锁)

  
  当读线程远大于写线程, 可以调高访问效率

  读写锁操作函数:

  /*定义一个读写锁变量*/
  pthread_rwlock_t rwlock;
  
  int pthread_rwlock_init(&rwlock,NULL);
  int pthread_rwlock_destory(&rwlock);
  int pthread_rwlock_rdlock(&rwlock);
  int pthread_rwlock_wrlock(&rwlock);
  int pthread_rwlock_tryrdlock(&rwlock);
  int pthread_rwlock_trywrlock(&rwlock);
  int pthread_rwlock_unlock(&rwlock);
  

  都是成功返回0, 失败直接返回错误号

  读写锁代码示例：

  int cnt = 0;
  pthread_rwlock_t rwlock;
  
  void* writer(void* arg) {
  	long i = (long)arg;
  	while (1) {
  		pthread_rwlock_wrlock(&rwlock);
  		usleep(10000);
  		int t = cnt;
  		printf("I'm writer %ld, cnt = %d, ++cnt = %d\n", i, t, ++cnt);
  		pthread_rwlock_unlock(&rwlock);
  		usleep(100000);
  	}
  	return NULL;
  }
  
  void* reader(void* arg) {
  	long i = (long)arg;
  	while (1) {
  		pthread_rwlock_rdlock(&rwlock);
  		printf("I'm reader %ld, cnt = %d\n", i, cnt);
  		pthread_rwlock_unlock(&rwlock);
  		usleep(20000);
  	}
  	return NULL;
  }
  
  int main() {
  	pthread_rwlock_init(&rwlock, NULL);
  	pthread_t tid[8];
  	long i = 0;
  	for (; i < 3; ++i) {
  		pthread_create(tid + i, NULL, writer, (void*)i);
  	}
  	for (; i < 8; ++i) {
  		pthread_create(tid + 3 + i, NULL, reader, (void*)i);
  	}
  	for (i = 0; i < 8; ++i) {
  		pthread_join(tid[i], NULL);
  	}
  	pthread_rwlock_destroy(&rwlock);
  }
  

  现象:

  I'm writer 0, cnt = 0, ++cnt = 1
  I'm reader 3, cnt = 1
  I'm reader 4, cnt = 1
  I'm reader 5, cnt = 1
  I'm reader 6, cnt = 1
  I'm reader 7, cnt = 1
  I'm writer 1, cnt = 1, ++cnt = 2
  I'm writer 2, cnt = 2, ++cnt = 3
  I'm reader 6, cnt = 3
  I'm reader 3, cnt = 3
  I'm reader 5, cnt = 3
  I'm reader 4, cnt = 3
  I'm reader 7, cnt = 3
  I'm reader 3, cnt = 3
  I'm reader 5, cnt = 3
  I'm reader 6, cnt = 3
  I'm reader 4, cnt = 3
  I'm reader 7, cnt = 3
  I'm reader 6, cnt = 3
  I'm reader 5, cnt = 3
  I'm reader 4, cnt = 3
  I'm reader 3, cnt = 3
  I'm reader 7, cnt = 3
  I'm reader 4, cnt = 3
  I'm reader 5, cnt = 3
  I'm reader 3, cnt = 3
  I'm reader 6, cnt = 3
  I'm reader 7, cnt = 3
  I'm writer 0, cnt = 3, ++cnt = 4
  I'm reader 5, cnt = 4
  I'm reader 3, cnt = 4
  I'm reader 4, cnt = 4
  I'm reader 6, cnt = 4
  I'm reader 7, cnt = 4
  I'm writer 1, cnt = 4, ++cnt = 5
  I'm writer 2, cnt = 5, ++cnt = 6
  I'm reader 5, cnt = 6
  I'm reader 3, cnt = 6
  I'm reader 4, cnt = 6
  I'm reader 6, cnt = 6
  I'm reader 7, cnt = 6
  I'm reader 4, cnt = 6
  I'm reader 5, cnt = 6
  I'm reader 3, cnt = 6