C++生产者消费者模式（条件变量和互斥锁）

条件变量的wait操作：先释放互斥锁，将其放入互斥变量的等待队列中，等待其他线程唤醒，再放入互斥锁的等待队列中去获得锁进行操作。

#include<iostream>
#include<condition_variable>
#include<mutex>
#include<thread>
#include<queue>
using namespace std;
queue<int>sq;
const int maxsize = 30;
condition_variable  notempty;
condition_variable  notfull;
mutex  m;
int sumsize = 0;
void Producer()
{

	while (1)
	{
		std::unique_lock<mutex>lock(m);
		while (sumsize>=maxsize)
		{
			notfull.wait(lock);  //等待不为满，才可以进行生产
			                    //
		}
		sq.push(rand());
		sumsize++;
		cout << "Producer  " << sq.front() << endl;
		notempty.notify_all();
	}
}
void Consumer()
{
		while (1)
		{
			std::unique_lock<mutex>lock(m);
			while (sumsize == 0)
			{
				notempty.wait(lock);  //等待不为空  才可以进行消费
			}
			int tmp = sq.front();
			sq.pop();
			sumsize--;
			cout << "Consumer  " << tmp<< endl;
			notfull.notify_all();
		}

}
int main()
{
	thread th1(Producer);    //开启两个线程
	thread th2(Consumer);    //开启线程
	th1.join();
	th2.join();
	return 0;
}