【C++多线程】生产者消费者模型

文章目录

• • • 一、题目要求
    • 二、解答
    • 三、题目要求
    • 四、解答
    • • （1）行锁
      • （2）表锁

一、题目要求

生产者消费者模型：在多线程下生产0~100个数，生产者线程1生产20个数据后，消费者线程1进行消费输出。

二、解答

使用到的技术：互斥锁、条件变量、多线程、双端队列

#if 1
#include
#include
#include
#include
using namespace std;mutex mtx;
std::condition_variable cv;class Queue
{
public://生产数据: index是生产者编号，val是生产的结果void PushData(int index, int val){unique_lock<mutex> lock(mtx);//size == 20cv.wait(lock, [this]()->bool {return qu.size() != 20; });qu.push_back(val);cv.notify_all();cout << "Producer:" << index << " " << "val:" << val << endl;}//消费数据: index是消费者编号void PopData(int index){unique_lock<mutex> lock(mtx);//!qu空 ->真 , 继续执行cv.wait(lock, [this]()->bool {return !qu.empty(); });int val = qu.front();qu.pop_front();cv.notify_all();cout << "Customer:" << index << " " << "val:" << val << endl;}
private:deque<int> qu;
};
void Producer(Queue& qu, int index)
{for (int i = 0; i < 100; ++i){qu.PushData(index, i);}
}
void Customer(Queue& qu, int index)
{for (int i = 0; i < 100; ++i){qu.PopData(index);}
}int main()
{Queue qu;thread tha(Producer, std::ref(qu), 1);thread thb(Customer, std::ref(qu), 1);//thread thc(Producer, std::ref(qu), 2);//thread thd(Customer, std::ref(qu), 2);tha.join();thb.join();//thc.join();//thd.join();return 0;
}
#endif

三、题目要求

实现一个循环队列，生产者线程生产0~100， 每次最多生产8个，然后消费者线程进行输出使用。

根据锁的粒度分为：

• 行锁：并发性强，锁开销较大
• 表锁：并发性弱，锁开销较小

四、解答

（1）行锁

#if 1
#include
#define MAXSIZE 8
#include
#includeusing namespace std;
template<class T>
class Queue
{
public:Queue() :data(new T[MAXSIZE]), maxsize(MAXSIZE), front(0), rear(0), size(0){}~Queue(){if (nullptr != data){delete data;}maxsize = -1;front = -1;rear = -1;size = -1;}bool Capacity()const { return maxsize; }bool Size()const { return size; }bool Empty()const { return size == 0; }bool Full()const { return size == maxsize; }bool Push_back(T& val){if (Full()) return false;data[rear] = val;rear = (rear + 1) % maxsize;++size;return true;}bool Pop_front(T& val){if (Empty()) return false;val = data[front];front = (front + 1) % maxsize;--size;return true;}private:T* data;int maxsize;int size;int front;int rear;
};
Queue<int> qu;
std::mutex mtx;
std::condition_variable cv;
int number = 0;
void Producer(int index)
{for (int i = number; i < 100; ++i){//行锁unique_lock<mutex> lock(mtx);//当qu不满 为真，继续执行cv.wait(lock, []()->bool {return !qu.Full(); });//qu.Push_back(i);cv.notify_all();cout << "Producer:" << index <<" "<< "val:" << i << endl;std::this_thread::sleep_for(std::chrono::milliseconds(100));}
}
void Customer(int index)
{for (int i = number; i < 100; ++i){//行锁unique_lock<mutex> lock(mtx);//当qu不空 为真，继续执行cv.wait(lock, []()->bool {return !qu.Empty(); });//int val = 0;qu.Pop_front(val);cv.notify_all();cout << "Customer:" << index << " " << "val:" << val << endl;}
}
int main()
{thread tha(Producer, 1);thread thb(Customer, 1);tha.join();thb.join();return 0;
}#endif

（2）表锁

#if 1
#include
#define MAXSIZE 8
#include
#includeusing namespace std;
template<class T>
class Queue
{
public:Queue() :data(new T[MAXSIZE]), maxsize(MAXSIZE), front(0), rear(0), size(0){}~Queue(){if (nullptr != data){delete data;}maxsize = -1;front = -1;rear = -1;size = -1;}bool Capacity()const { return maxsize; }bool Size()const { return size; }bool Empty()const { return size == 0; }bool Full()const { return size == maxsize; }bool Push_back(T& val){if (Full()) return false;data[rear] = val;rear = (rear + 1) % maxsize;++size;return true;}bool Pop_front(T& val){if (Empty()) return false;val = data[front];front = (front + 1) % maxsize;--size;return true;}private:T* data;int maxsize;int size;int front;int rear;
};Queue<int> qu;
std::mutex mtx;
std::condition_variable cv;
int number = 0;
void Producer(int index)
{unique_lock<mutex> lock(mtx);for (int i = number; i < 100; ++i){//当qu不满 为真，继续执行cv.wait(lock, []()->bool {return !qu.Full(); });qu.Push_back(i);cv.notify_all();cout << "Producer:" << index <<" "<< "val:" << i << endl;//std::this_thread::sleep_for(std::chrono::milliseconds(100));}
}
void Customer(int index)
{unique_lock<mutex> lock(mtx);for (int i = number; i < 100; ++i){//当qu不空 为真，继续执行cv.wait(lock, []()->bool {return !qu.Empty(); });int val = 0;qu.Pop_front(val);cv.notify_all();cout << "Customer:" << index << " " << "val:" << val << endl;}
}
int main()
{thread tha(Producer, 1);thread thb(Customer, 1);tha.join();thb.join();return 0;
}

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