支持模板的C++循环队列设计实现与优化

1. 原理

    队列是带先入先出FIFO特性的数据结构。为了充分利用队列，顺序队列常常做成一个逻辑上的循环队列。

  注意：空队时rear等于front，满队时front = (rear+1) mod N,必须空一个位置。

2. 设计

2.1 属性

1. m_size 队列大小
2. m_front, 队头
3. m_rear， 队尾
4. m_data, 数据存存储区

2.2 方法

1. isEmpty()
2. isFull()
3. push()
4. pop()

3. 原始实现

3.1 类实现

#include 
 
using namespace std;
 
template <class T>
class CycleQueue
{
    private:
        unsigned int m_size;
        int m_front;
        int m_rear;
        T*  m_data;
    public:
        CycleQueue(unsigned size)
            :m_size(size),
            m_front(0),
            m_rear(0)
        {
            m_data = new T[size];
        }
 
        ~CycleQueue()
        {
            delete [] m_data;
        }
 
        bool isEmpty()
        {
            return m_front == m_rear;
        }
 
        bool isFull()
        {
            return m_front == (m_rear + 1)%m_size;
        }
 
        void push(T ele) throw(bad_exception)
        {
            if(isFull())
            {
                throw bad_exception();
            }
            m_data[m_rear] = ele;
            m_rear = (m_rear + 1)%m_size;
        }
 
        T pop() throw(bad_exception)
        {
            if(isEmpty())
            {
                throw bad_exception();
            }
            T tmp = m_data[m_front];
            m_front = (m_front + 1)%m_size;
            return tmp;
        }
};

3.2 测试程序

int main()
{
    CycleQueue<int> q(5);
    q.push(1);
    q.push(2);
    q.push(3);
    q.push(4);
    for (int i = 0; i < 4 ; i++)
        cout << q.pop() << endl;
    q.push(5);
    q.push(5);
    q.push(5);
    cout << q.pop() << endl;
    cout << q.pop() << endl;
    cout << q.pop() << endl;
 
    return 0;
}

4. 加锁优化实现

4.1 模板类实现

#include 
 
#include 
 
using namespace std;
 
template <class T>
class CycleQueue
{
    private:
        QMutex	m_mutex;
 
        unsigned int m_size;
        unsigned int m_front;
        unsigned int m_rear;
        T*  m_data;
    public:
        CycleQueue(unsigned size)
            :m_size(size),
            m_front(0),
            m_rear(0)
        {
            m_data = new T[size];
        }
 
        ~CycleQueue()
        {
            delete [] m_data;
        }
 
        bool isEmpty()
        {
            return m_front == m_rear;
        }
 
        bool isFull()
        {
            return m_front == (m_rear + 1)%m_size;
        }
 
        bool push(T element)
        {
            bool bRet = false;
 
            m_mutex.lock();
            if(!isFull())
            {
                m_data[m_rear] = element;
                m_rear = (m_rear + 1) % m_size;
                bRet = true;
            }
            m_mutex.unlock();
 
            return bRet;
        }
 
        bool pop(T& element)
        {
            bool bRet = false;
 
            m_mutex.lock();
            if(!isEmpty())
            {
                element = m_data[m_front];
                m_front = (m_front + 1) % m_size;
                bRet = true;
            }
            m_mutex.unlock();
 
            return bRet;
        }
};

4.2 环形队列测试程序

const int MAXQUEUE = 6;
int main()
{
    int ntmp;
 
    CycleQueue<int> q(MAXQUEUE + 1);
 
    cout << "Queue with max :" << MAXQUEUE << " Space is created!"<< endl;
 
    for (int i = 0; i < 8 ; i++)
    {
        bool bres = q.push(i);
        if(bres)
            cout << "enqueue:" << i << endl;
        else {
            cout << "queue is full!" << endl;
        }
    }
 
    for (int i = 0; i < 4 ; i++)
    {
        bool bres = q.pop(ntmp);
        if(bres)
            cout << "dequeue:" << ntmp << endl;
        else {
            cout << "queue is empty!" << endl;
        }
    }
 
    for (int i = 0; i < 8 ; i++)
    {
        bool bres = q.push(i);
        if(bres)
            cout << "enqueue:" << i << endl;
        else {
            cout << "queue is full!" << endl;
        }
    }
 
    for (int i = 0; i < 10 ; i++)
    {
        bool bres = q.pop(ntmp);
        if(bres)
            cout << "dequeue:" << ntmp << endl;
        else {
            cout << "queue is empty!" << endl;
        }
    }
 
    return 0;
}

4.3 运行结果