用条件变量代替忙等待

Question

如何用条件变量替换下面的忙等待？

while (this_thread != pthread_self()){
        pthread_mutex_lock(&lock);
        if(this_thread == -1)
            this_thread = get_id();
        pthread_mutex_unlock(&lock);
    }

谢谢！

Answer 1

假设 get_id() 返回的值仅通过一个名为 set_id() 的函数设置，请看这个伪代码：

全局变量

Mutex mutex
Condition cond
Id id

代码

set_id(id_in)
{
  mutex_lock
  id = id_in
  cond_signal
  mutex_unlock
}

test()
{
  mutex_lock
  while ((this_thread = get_id()) != pthread_self())
    cond_wait
  mutex_unlock
}

用条件变量代替忙等待

Replace busy waiting with condition variable

pthreads