cocos2dx内存管理_app

概述原文地址：http://www.cnblogs.com/yu-chao/p/3697459.html 今天想探索一下cocos2dx的内存管理，我们就先从CCObject开始吧 class CC_DLL CCObject : public CCCopying{public: // object id, CCScriptSupport need public m_uID unsi

原文地址：http://www.cnblogs.com/yu-chao/p/3697459.html

今天想探索一下cocos2dx的内存管理，我们就先从CCObject开始吧

class CC_DLL CCObject : public CCcopying{public:    // object ID,ccScriptSupport need public m_uID    unsigned int        m_uID;     Lua reference ID    int                 m_nLuaID;protected:     count of references    unsigned int        m_uReference;     count of @R_301_6843@release    unsigned int        m_u@R_301_6843@ReleaseCount;public:    CCObject(voID);    virtual ~CCObject(voID);        voID release(voID retain(voID);    CCObject* @R_301_6843@release(voID);    CCObject* copy(bool isSingleReference(voID);    unsigned int retainCount(virtual bool isEqual(const CCObject* pObject);    voID update(float dt) {CC_UNUSED_ParaM(dt);};        frIEnd class CC@R_301_6843@releasePool;        unsigned int get@R_301_6843@ReleaseCount();};

以上是CCObject的定义，可以看出CCObject主要有两个保护成员：m_uReference和m_u@R_301_6843@ReleaseCount，这个两个成员到底有什么用呢？让我们一探究竟，首先我们来看一下CCObject的构造函数：

CCObject::CCObject(voID): m_nLuaID(0),m_uReference(1)  when the object is created,the reference count of it is 1,m_u@R_301_6843@ReleaseCount(0){    static unsigned int uObjectCount = 0;    m_uID = ++uObjectCount;}

从构造函数我么可以看出m_uReference初始化为1，m_uAutoReleaseCount初始化为0，另外CCObject维护了一个静态无符号整型变量：uObjectCount来记录CCObject实例的总数目。然后我们来看一下release()和retain()函数：

void CCObject::release(void){ if (m_uReference == 0) {modify by yangm CCLOG("CCObject::release reference count should greater than 0"); return; } CCAssert(m_uReference > 0,reference count should greater than 0"); --m_uReference; 0) { delete this; }} 由release()函数可以看到每执行一次release()，m_uReference自减一，只有当m_uReference为零时CCObject对象才会被释放；

void CCObject::retain(CCObject::retain reference count should greater than 0,m_uReference=%d",m_uReference); "); ++m_uReference;} retain()函数和release()函数功能正好相反，每调用一次retain()，m_uReference会自增一；接下来我们再来看看autorelease()函数：

CCObject* CCObject::@R_301_6843@release(voID){    CCPoolManager::sharedPoolManager()->addobject(this);    return this;}voID CCPoolManager::addobject(CCObject* pObject){    getCurReleasePool()->addobject(pObject);  获取栈顶得CC@R_301_6843@releasePool实例，并将CCObject加入到CC@R_301_6843@releasePool中}

此处涉及到一个CCPoolManager类，该类内部有一个CC@R_301_6843@releasePool类型的栈，而CCPoolManager又是什么呢？其实CCPoolManager就是一个CCArray一个可增长的数组，我们来看看他得addobject(CCObject* pObject)函数：

voID CC@R_301_6843@releasePool::addobject(CCObject* pObject){ m_pManagedobjectArray->addobject(pObject); 向CCArray中添加CCObject实例 CCAssert(pObject->m_uReference > 1,0); line-height:1.5!important">reference count should be greater than 1"); ++(pObject->m_u@R_301_6843@ReleaseCount); CCObject的m_u@R_301_6843@ReleaseCount自增一 pObject->release(); no ref count,in this case @R_301_6843@release pool added. } 在调试的时候我们会发现CCObject在release()时他的m_uReference为2，也就避免了被释放，其实该对象实例在添加到自动释放池（CC@R_301_6843@releasePool）的时候retain了一下；我们来验证一下，来看看下面的几个函数：

voID CCArray::addobject(CCObject* object){ ccArrayAppendobjectWithResize(data,object);}/** Appends an object. Capacity of arr is increased if needed. */voID ccArrayAppendobjectWithResize(ccArray *arr,CCObject* object){ ccArrayEnsureExtraCapacity(arr,1); ccArrayAppendobject(arr,255); line-height:1.5!important">object);}* Appends an object. Behavior undefined if array doesn't have enough capacity. voID ccArrayAppendobject(ccArray *arr,255); line-height:1.5!important">object){ CCAssert(object != NulL,0); line-height:1.5!important">InvalID parameter!"); object->retain(); 此处果然retain了一下 arr->arr[arr->num] = object; arr->num++;} 接下来我们来看一下cocos2dx如何销毁那些无效的对象实例，以下是整个程序的主循环：

voID CCdisplaylinkDirector::mainLoop(if (m_bPurgeDirecotorInNextLoop) { m_bPurgeDirecotorInNextLoop = false; purgeDirector(); } else if (! m_bInvalID) { drawScene(); release the objects CCPoolManager::sharedPoolManager()->pop(); }} 由上面函数可知coco2dx在每一帧的帧尾会调用自动释放内存池的管理者—CCPoolManager的pop()函数，我们来看看该函数主要做了哪些工作？

voID CCPoolManager::pop(){ if (! m_pCurReleasePool) { return; } int nCount = m_pReleasePoolStack->count(); m_pCurReleasePool->clear(); if(nCount > 1) { m_pReleasePoolStack->removeObjectAtIndex(nCount-1); if(nCount > 1) { m_pCurReleasePool = m_pReleasePoolStack->objectAtIndex(nCount - 2); return; } m_pCurReleasePool = (CC@R_301_6843@releasePool*)m_pReleasePoolStack->objectAtIndex(nCount - 2); } m_pCurReleasePool = NulL;*/} 主要做的就两点：1、清除当前的自动释放池，2、更新当前自动释放池指针；我们来看看他是如何clear？

voID CC@R_301_6843@releasePool::clear(){ if(m_pManagedobjectArray->count() > 0) { CC@R_301_6843@releasePool* pReleasePool;#ifdef _DEBUG int nIndex = m_pManagedobjectArray->count() - 1;#endif CCObject* pObj = NulL; CCARRAY_FOREACH_REVERSE(m_pManagedobjectArray,pObj) { if(!pObj) break; --(pObj->m_u@R_301_6843@ReleaseCount); if( (int)(pObj->m_u@R_301_6843@ReleaseCount)<0 ){ pObj->m_u@R_301_6843@ReleaseCount = 0; } (*it)->release(); delete (*it);#ifdef _DEBUG nIndex--;#endif } m_pManagedobjectArray->removeAllObjects(); }} 以上函数主要做的工作是：1、将内部的所有元素的自动释放引用m_u@R_301_6843@ReleaseCount减一。2、清除内部的所有元素。看到这里我很诧异：为什么要清除所有的元素呢？难道不是清除那些无效的对象实例吗？紧接着看下面的函数看他如何removeAllObjects。

voID CCArray::removeAllObjects(){ ccArrayRemoveAllObjects(data);}voID ccArrayRemoveAllObjects(ccArray *arr){ while( arr->num > 0 ) { (arr->arr[—arr->num])->release(); 注意此处的—arr->num }} 以上函数其实就是将数组内部的所有元素release一下，并将元素个数减为0。到这里整个对象创建—添加到自动释放池—帧尾的释放的过程就完了，我一开始很是纳闷，假如我有定义了一个类如下：

class A : public CCNode{private: CCSprite* m_pSprite1; CCSprite* m_pSprite2;public: CREATE_FUNC(A); bool init();};bool A::init(){ m_pSprite1 = CCSprite::create(“1.png”); 创建精灵1 m_pSprite2 = CCSprite::create(“2.png”); 创建精灵2 this->addChild(m_pSprite); 只将精灵1添加到父节点} 实际上到下一帧的时候，m_pSprite2所指向的内存已经无效，m_Sprite1仍然有效。上面的过程是如何做到的呢？只有这种情况才能解释：m_pSprite1和m_pSprite2在create的时候加入到了自动释放池被监视，而m_pSprite1再加入到父节点时retain了一下，才不会在帧尾release的时候被释放掉。我们来验证一下CCNode::addChild(…)(参数就不写了):

voID CCNode::addChild(CCNode *child,int zOrder,255); line-height:1.5!important">int tag){ CCAssert( child != NulL,0); line-height:1.5!important">Argument must be non-nil"); CCAssert( child->m_pParent == NulL,0); line-height:1.5!important">child already added. It can't be added again"); if( ! m_pChildren ) { this->childrenAlloc(); } this->insertChild(child,zOrder); child->m_nTag = tag; child->setParent(this); child->setorderOfArrival(s_globalOrderOfArrivaL++); if( m_bRunning ) { child->onEnter(); child->onEnterTransitionDIDFinish(); }} 发现没有retain,继续看insertChild函数：

voID CCNode::insertChild(CCNode* child,255); line-height:1.5!important">int z){ m_bReorderChildDirty = true; ccArrayAppendobjectWithResize(m_pChildren->data,child); child->_setZOrder(z);} 发现也没有retain，继续看ccArrayAppendobjectWithResize函数