muduo/base库学习笔记（6）-----CountDownLatch类

CountDownLatch

1 构造函数的实现

CountDownLatch::CountDownLatch(int count)
  : mutex_(),
    condition_(mutex_),
    count_(count)
{
}

2 普通成员函数的实现

void wait()函数的实现
这个函数主要是当条件不满足的时候，就阻塞等待条件满足

void CountDownLatch::wait()
{ 
//加锁
  MutexLockGuard lock(mutex_);
  while (count_ > 0)
  { 
  //如果条件满足，就一直阻塞等待
    condition_.wait();
  }
}

void countDown()，该函数主要实现对计数器的–操作

void CountDownLatch::countDown()
{
  MutexLockGuard lock(mutex_);
  --count_;
  //当计数器为0的时候，条件变量就通知所有线程
  if (count_ == 0)
  {
    condition_.notifyAll();
  }
}

int CountDownLatch::getCount()函数的实现

int CountDownLatch::getCount() const
{
//获取计数器的时候，首先进行加锁
  MutexLockGuard lock(mutex_);
  return count_;
}