C++实现生产者消费者模型

#include <iostream>
#include <mutex>
#include <queue>
#include <thread>
using namespace std;

//缓冲区大小
#define BufferSize 10

//使用缓冲区需要加锁
mutex mtxBuffer;
//条件变量，生产者等待缓冲区不为满，消费者等待缓冲区为满
condition_variable cvNotFull, cvFull;
//缓冲区
queue<int> buffer;
//产品编号
int i = 0;
void producer() {
	unique_lock<mutex> ulock(mtxBuffer, defer_lock);
	while (true) {
		ulock.lock();
		if (buffer.size() >= BufferSize) {
			cvNotFull.wait(ulock, []() {
				return buffer.size() < BufferSize;
			});
		}
		cout << "生产者放入" << i << "产品" << endl;
		buffer.push(i++);

		//因为是死循环，并且notify是不解锁的，所以需要手动解锁，不然只能等到缓冲区满了wait解锁
		//unlock在notify前后都可以
		//notify是唤醒wait等待队列上的线程，需要重新抢锁，再判断条件（ctrl点进wait源码查看即可）
		ulock.unlock();
		cvFull.notify_one();

		//睡眠，方便看输出
		//否则想看消费者交替的情况需要调大BufferSize
		//this_thread::sleep_for(chrono::milliseconds(100));
	}
}
void consumer() {
	unique_lock<mutex> ulock(mtxBuffer, defer_lock);
	while (true) {
		ulock.lock();
		if (buffer.empty()) {
			cvFull.wait(ulock, []() {
				return !buffer.empty();
			});
		}
		cout << "消费者" << this_thread::get_id() << "取出" << buffer.front() << "产品" << endl;
		buffer.pop();
		ulock.unlock();
		cvNotFull.notify_one();
	}
}
int main() {
	thread Producer(producer);
	thread Consumer1(consumer);
	thread Consumer2(consumer);
	thread Consumer3(consumer);

	Producer.join();
	Consumer1.join();
	Consumer2.join();
	Consumer3.join();

	return 0;
}