时间锁
#include <pthread.h>
#include <time.h>
int pthread_mutex_timedlock(pthread_mutex_t * restrict mutex, const struct timespec *restrict tsptr);
愿意等待timespec描述的时间，达到时间返回错误码ETIMEOUT
一个例子
// APUE example11-13
// pthread_mutex_timedlock
// lcl 20190325
//
#include "../myapue.h"
#include <pthread.h>
#include <time.h>
int main (void)
{
int err;
struct timespec tout;
struct tm *tmp;
char buf[64];
pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
pthread_mutex_lock(&lock);
printf("the mutex now is locked\n");
clock_gettime(CLOCK_REALTIME, &tout);
tmp = localtime(&tout.tv_sec);
strftime(buf, sizeof(buf), "%r", tmp);
printf("current time is %s\n",buf);
tout.tv_sec += 10;
err = pthread_mutex_timedlock(&lock,&tout);
clock_gettime(CLOCK_REALTIME, &tout);
tmp = localtime(&tout.tv_sec);
strftime(buf,sizeof(buf), "%r", tmp);
printf("the time is now %s\n",buf);
if(err == 0)
printf("mutex locked again!\n");
else
printf("can't lock mutex again:%s\n",strerror(err));
exit(0);
}
运行结果：
the mutex now is locked
current time is 01:08:51 PM
the time is now 01:09:01 PM
can't lock mutex again:Connection timed out
读写锁，三种状态读加锁、写加锁和不加锁
#include <pthread.h>
int pthread_rwlock_init(pthread_rwlock_t *restrict rwlock,
const pthread_rwlockattr_t *restrict attr);
int pthread_rwlock_destory(pthread_rwlock_t *rwlock);
int pthread_rwlock_rdlock(pthread_rwlock_t *rwlock)
int pthread_rwlock_wrlock(pthread_rwlock_t *rwlock)
int pthread_rwlock_unlock(pthread_rwlock_t *rwlock)
如上，函数名可以很好的反映函数的功能。
- 写锁阻塞其他加锁
- 读锁阻塞写锁但不阻塞读锁
- 写锁在阻塞时，不再响应其他读锁请求。
