C++/CLI 在多个 gcroot 托管对象之间交换对象引用

发布于 2024-09-08 00:41:16 字数 1242 浏览 3 评论 0原文

嗨，不幸的是我在整个垃圾收集方面不太擅长。现在我不确定如果我执行以下操作是否会遇到麻烦：

// unmanaged Class
class CUnmagedClass : public CCmdTarget
{
    auto_gcroot<Dictionary<int, System::String^>^> m_dict;
    auto_gcroot<SomeManagedClass^> m_managedClass;

    // create first manage object in one gcroot
    CUnmagedClass()
    :dict(gcnew Dictionary<LANGID, System::String^>())
    {}

    // do something with the dictionary
    void AddData(int key, String^ value)
    {
         this->m_dict->Add(key, value);
    }

    // Method that could be called multiple times
    void DoOtherThings(Data^ data)
    {
         // create a new object on every method call
         // old object can be garbage collected
         this->m_managedClass = gcnew SomeManagedClass(data);
         // assign a reference to the dictionary from the other gcroot
         this->m_managedClass->DictProp = this->m_dict;

         this->m_managedClass->DoSomething();
    }

}

所以我的问题是，如果我覆盖 this->m_managementClass 和旧 中的值SomeManagedClass 实例被垃圾收集。系统是否也尝试收集 this->m_managementClass->DictProp 中的对象，因为它不再连接到第二个 gcroot，或者垃圾收集器是否足够聪明，知道还存在引用在另一个 gcroot 中？

原文

Hi unfortunately I'm not so good in the whole garbage collection thing. Now I am unsure if I'm going to get into trouble if I'm doing the following:

// unmanaged Class
class CUnmagedClass : public CCmdTarget
{
    auto_gcroot<Dictionary<int, System::String^>^> m_dict;
    auto_gcroot<SomeManagedClass^> m_managedClass;

    // create first manage object in one gcroot
    CUnmagedClass()
    :dict(gcnew Dictionary<LANGID, System::String^>())
    {}

    // do something with the dictionary
    void AddData(int key, String^ value)
    {
         this->m_dict->Add(key, value);
    }

    // Method that could be called multiple times
    void DoOtherThings(Data^ data)
    {
         // create a new object on every method call
         // old object can be garbage collected
         this->m_managedClass = gcnew SomeManagedClass(data);
         // assign a reference to the dictionary from the other gcroot
         this->m_managedClass->DictProp = this->m_dict;

         this->m_managedClass->DoSomething();
    }

}

So my question is, if I overwrite the value in this->m_managedClass and the older SomeManagedClass instance is garbage collected. Does the system try to collect the object in this->m_managedClass->DictProp too because it's not connected to the second gcroot anymore or is the garbage collector clever enough to know that there is a reference left in the other gcroot?

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在你怀里撒娇 2024-09-15 00:41:16

系统也不会尝试收集 this->m_managementClass->DictProp，因为它足够聪明，知道该对象被另一个 gcroot 引用。

gcroot 如此聪明的原因是它包装了 System::Runtime::InteropServices::GCHandle，这是垃圾收集堆中的句柄。 GCHandle 类允许非托管对象存储有效的托管引用。此外，即使垃圾收集器移动了托管对象，GCHandle 引用也会更新以指向其新位置。