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我正在准备几周后的面试，我想我会尝试一下，以及我在学校学到的简单的生产者/消费者问题。

好久没做这个了，好奇大家怎么看？我应该添加什么以使其成为更好的示例等。感谢您的反馈！:)

//////////////////////////////////////////////////////////////////////////
boost::mutex bufferMutex;
deque<int> buffer;
const int maxBufferSize = 5;
//////////////////////////////////////////////////////////////////////////

bool AddToBuffer(int i)
{
    if (buffer.size() < maxBufferSize)
    {
        buffer.push_back(i);
        return true;
    }
    else
    {       
        return false;
    }
}

bool GetFromBuffer(int& toReturn)
{
    if (buffer.size() == 0)
    {
        return false;
    }
    else
    {
        toReturn = buffer[buffer.size()-1];
        buffer.pop_back();
        return true;
    }
}

struct Producer 
{
    int ID;
    void operator()()
    {
        while (true)
        {
            boost::mutex::scoped_lock lock(bufferMutex);
            int num = dice();
            bool result = AddToBuffer(num);
            lock.unlock();
            //safe area done
            if (result)
            {
                cout << "Producer " << this->ID << " Added " << num << endl;
            }
            else
            {
                cout << "!!Buffer was Full!!" << endl;
            }
            //Added
            //Now wait
            boost::xtime xt;
            xtime_get( &xt, boost::TIME_UTC);
            xt.nsec += 1000000 + 100000 * (rand() % 1000);
            boost::thread::sleep(xt);
        }
    }
};

struct Consumer 
{
    int ID;
    void operator()()
    {
        while (true)
        {
            int returnedInt = 0;
            boost::mutex::scoped_lock lock(bufferMutex);
            bool result = GetFromBuffer(returnedInt);
            lock.unlock();
            //safe area done
            if (result)
            {
                cout << "\tConsumer " << this->ID << " Took Out " << returnedInt << endl;
            }
            else
            {
                cout << "!!Buffer was Empty!!" << endl;
            }
            //Added
            //Now wait
            boost::xtime xt;
            xtime_get( &xt, boost::TIME_UTC);
            xt.nsec += 1000000 + 100000 * (rand() % 1000);
            boost::thread::sleep(xt);
        }
    }
};



void main()
{
    Producer p, p2;
    Consumer c, c2;

    p.ID = 1;
    p2.ID = 2;

    c.ID = 1;
    c2.ID = 2;

    boost::thread thread1(boost::ref(p));
    boost::thread thread2(boost::ref(c));
    boost::thread thread3(boost::ref(p2));
    boost::thread thread4(boost::ref(c2));

    int x;
    cin >> x;
}
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1 回答 1

3

如果您已经将缓冲区对象包装在 AddToBuffer 和 GetFromBuffer 等调用中，那么将锁定放在包装函数中会更有意义。此外，您正在对 unlock 进行显式调用，这完全违背了 scoped_lock 的目的；scoped_lock 使用资源获取即初始化 (RAII) 来获取和释放锁。更好的用途是将临界区放置在一个块中，以便互斥锁由于锁超出范围而不是由于对解锁函数的显式调用而被释放，因为范围不那么脆弱。例如：

// Code that doesn't need locking
{
    boost::mutex::scoped_lock lck(bufferMutex); // Lock is acquired here
    // Code that needs to be synchronized
} // Lock is automatically released here without explicit call to unlock()
// More code that doesn't need locking
于 2010-05-24T21:41:20.010 回答