通过new和delete重载实现对象池的应用

MyQueue版本1

#include using namespace std;templateclass MyQueue {private:struct QueueItem {QueueItem(T _data = T(), QueueItem  * _next = nullptr):data(_data),next(_next) {next = nullptr;}T  data;QueueItem  * next;};QueueItem * _front;//指向队头QueueItem * _rear; //指向队尾public://队尾入队操作void push(T & _value) {QueueItem *tep = new QueueItem(_value, nullptr);_rear->next = tep;_rear = tep;}//队头出队操作void pop() {if (empty()) { return; }QueueItem *tep = _front->next;_front->next = tep->next;//如果队中只有一个元素,被删除了,由于这个出队的元素要delete,所以，_rear 就丢失信息了,这个时候要记得把_rear=nullprtif (_front->next == nullptr) { _rear = nullptr; }delete tep;}//队是否为空bool empty() {return _front = _rear;}~MyQueue() {QueueItem *current = _front;while (current != nullptr) {_front = _front->next;delete current;current = _front;}}MyQueue() {QueueItem *tep = new QueueItem;_front = tep;_rear = tep;}T front()  {   return  _front->next; ->data;}};int main() {MyQueue mq;for (int i = 0; i < 10000000; i++) {mq.push(i);mq.pop();}bool isEmpty = mq.empty();cout << isEmpty << endl;system("pause");return 0;}

上面代码有个效率问题,循环 10000000 次,一直在创建 对象，和销毁对象. 如何优化?

MyQueue版本2

#include using namespace std;templateclass MyQueue {private:struct QueueItem {QueueItem(T _data = T(), QueueItem  * _next = nullptr):data(_data),next(_next) {next = nullptr;}//分配内存void * operator new(size_t size) {if (poolItemList == nullptr) {//预先申请内存空间poolItemList = (QueueItem *) new char[sizeof(QueueItem) * POOL_ITEM_SIZE];QueueItem * tp = poolItemList;//把上面申请的内存空间 按照 一个 一个 QueueItem 串到队列中while (tp next = tp + 1;++tp;}tp->next = nullptr;cout << "1:申请缓存池空间" << poolItemList <next;//cout << "申请QueueItem节点空间" << returnPoint <next   = poolItemList;poolItemList = qptr;//cout << "归还空间" << ptr << endl;}}T  data;QueueItem  * next;static  const   int  POOL_ITEM_SIZE = 10000;static  QueueItem    * poolItemList ;};QueueItem * _front;//指向队头QueueItem * _rear; //指向队尾public://构造函数MyQueue() {QueueItem *tep = new QueueItem();_front = tep;_rear  = tep;}~MyQueue() {QueueItem *current = _front;while (current != nullptr) {_front = _front->next;delete current;current = _front;}}//队尾入队操作void push(T & _value) {QueueItem *tep = new QueueItem(_value, nullptr);_rear->next = tep;//原来队尾元素的下一节点设置为当前申请节点_rear = tep;}//队头出队操作void pop() {if (empty()) { return; }QueueItem *first = _front->next;_front->next = first->next;//如果队中只有一个元素,被删除了,由于这个出队的元素要delete,所以，_rear 就丢失信息了,这个时候要记得把_rear=nullprtif (_front->next == nullptr) { _rear = _front; }delete first;}//队是否为空bool empty() {return _front == _rear;}T front()  {   return  _front->next->data;}};templatetypename MyQueue::QueueItem *  MyQueue::QueueItem::poolItemList =nullptr;int main() {MyQueue mq;for (int i = 0; i < 100000; i++) {mq.push(i);mq.pop();}bool isEmpty = mq.empty();cout << isEmpty << endl;system("pause");return 0;}