bug修复，内存释放问题

碰到了一个内存释放的问题，在进行某个复杂的操作时内存释放后否则会造成崩溃。经过多方面调查发现此时根据就不能释放内存（历史原因），否则会造成不可预知的问题。所以我打算把要删除的指针暂时保存起来，并不立马delete，等到10秒钟还没有操作的时候（稍微空闲）再把保存的指针都销毁掉。

后来顺利的解决了问题，而且改动较小。

代码如下：

class DelayDestory : public QObject {
	Q_OBJECT
public:
	static DelayDestory* instance();
	void deleteItem(TreeItem *item);
	void deleteItem(const QList<TreeItem*> &items);

private slots:
	void onTimer();

private:
	DelayDestory();

private:
	static const int INTERVAL_SECOND = 5;
	static const int TIMEOUT_SECOND = 10;
	QList<TreeItem*> items_;
	class QTimer *timer_;
	QMutex mutex_;
	qint64 lastTime_;
};

DelayDestory* DelayDestory::instance()
{
	static DelayDestory s_inst;
	return &s_inst;
}

void DelayDestory::deleteItem(TreeItem *item)
{
	if (!item) {
		return;
	}

	lastTime_ = QDateTime::currentMSecsSinceEpoch();
	QMutexLocker lock(&mutex_);
	if (!items_.contains(item)) {
		items_.push_back(item);
	}
}

void DelayDestory::deleteItem(const QList<TreeItem*> &items)
{
	if (items.isEmpty()) {
		return;
	}

	lastTime_ = QDateTime::currentMSecsSinceEpoch();
	QMutexLocker lock(&mutex_);
	for (int i = 0; i < items.size(); i++) {
		if (items[i] && !items_.contains(items[i])) {
			items_.push_back(items[i]);
		}
	}
}

DelayDestory::DelayDestory()
	: mutex_(QMutex::Recursive), lastTime_(0)
{
	timer_ = new QTimer(this);
	connect(timer_, SIGNAL(timeout()), this, SLOT(onTimer()));
	timer_->start(INTERVAL_SECOND * 1000);
}

void DelayDestory::onTimer()
{
	qint64 currentTime = QDateTime::currentMSecsSinceEpoch();
	if (currentTime - lastTime_ >= TIMEOUT_SECOND * 1000 && !items_.isEmpty()) {
		QList<TreeItem*> tempList;
		{
			QMutexLocker lock(&mutex_);
			tempList = items_;
			items_.clear();
		}
		qDebug() << "delete tree items, size:" << tempList.size();
		for (int i = 0; i < tempList.size(); i++) {
			delete tempList[i];
		}
	}
}