cocos2dx 之内存管理

来源：未知责任编辑：责任编辑发表时间:2014-01-20 07:51　点击:次

cocos2dx 采用引用计数管理自己的内存：

引用计数：

引用计数就是通过给每个对象维护一个引用计数器，记录该对象当前被引用的次数。当对象增加一次引用时，计数器+1.而对象失去一次引用时，计数器-1，当引用计数器为0时。标志着该对象的生命周期结束，自动触发对象的回收释放。为了实现引用计数器，cocos2dx实现了自己的根类ccobject。引擎中所有类都派生自ccobject类。一下ccobject的定义

class CC_DLL Object
{
public:
    /// object id, ScriptSupport need public _ID
    unsigned int        _ID;
    /// Lua reference id
    int                 _luaID;
protected:
    /// count of references
    unsigned int        _reference;
    /// count of autorelease
    unsigned int        _autoReleaseCount;
public:
    /**
     * Constructor
     *
     * The object's reference count is 1 after construction.
     * @js NA
     */
    Object();
    
    /**
     * @js NA
     * @lua NA
     */
    virtual ~Object();
    
    /**
     * Release the ownership immediately.
     *
     * This decrements the object's reference count.
     *
     * If the reference count reaches 0 after the descrement, this object is
     * destructed.
     *
     * @see retain, autorelease
     * @js NA
     */
    inline void release()
    {
        CCASSERT(_reference > 0, "reference count should greater than 0");
        --_reference;

        if (_reference == 0)
            delete this;
    }

    /**
     * Retains the ownership.
     *
     * This increases the object's reference count.
     *
     * @see release, autorelease
     * @js NA
     */
    inline void retain()
    {
        CCASSERT(_reference > 0, "reference count should greater than 0");
        ++_reference;
    }

    /**
     * Release the ownership sometime soon automatically.
     *
     * This descrements the object's reference count at the end of current
     * autorelease pool block.
     *
     * If the reference count reaches 0 after the descrement, this object is
     * destructed.
     *
     * @returns The object itself.
     *
     * @see AutoreleasePool, retain, release
     * @js NA
     * @lua NA
     */
    Object* autorelease();

    /**
     * Returns a boolean value that indicates whether there is only one
     * reference to the object. That is, whether the reference count is 1.
     *
     * @returns Whether the object's reference count is 1.
     * @js NA
     */
    bool isSingleReference() const;

    /**
     * Returns the object's current reference count.
     *
     * @returns The object's reference count.
     * @js NA
     */
    unsigned int retainCount() const;

    /**
     * Returns a boolean value that indicates whether this object and a given
     * object are equal.
     *
     * @param object    The object to be compared to this object.
     *
     * @returns True if this object and @p object are equal, otherwise false.
     * @js NA
     * @lua NA
     */
    virtual bool isEqual(const Object* object);
    /**
     * @js NA
     * @lua NA
     */
    virtual void acceptVisitor(DataVisitor &visitor);
    /**
     * @js NA
     * @lua NA
     */
    virtual void update(float dt) {CC_UNUSED_PARAM(dt);};
    
    friend class AutoreleasePool;
};