c++ - 从另一个线程修改 vector 中指针的数据是否安全？

事情似乎正在起作用，但是我不确定这是否是解决问题的最佳方法。

基本上我有一个对象，它可以异步检索数据。该对象具有一个指针 vector ，这些指针在主线程上已分配和取消分配。使用boost函数，过程结果回调与该 vector 中的指针之一绑定(bind)。当它触发时，它将在某个任意线程上运行并修改指针的数据。

现在，我有一些关键部分，这些部分将推入 vector 并擦除，以防异步检索对象接收到更多请求，但是我想知道在回调中是否还需要某种保护措施来修改指针数据。

希望这段精简的伪代码可以使事情变得更清楚:

class CAsyncRetriever
{
    // typedefs of boost functions

    class DataObject
    {
         // methods and members
    };

public:
    // Start single asynch retrieve with completion callback
    void Start(SomeArgs)
    {
        SetupRetrieve(SomeArgs);
        LaunchRetrieves();
    }

protected:
    void SetupRetrieve(SomeArgs)
    {
            // ...

        { // scope for data lock
            boost::lock_guard<boost::mutex> lock(m_dataMutex);
            m_inProgress.push_back(SmartPtr<DataObject>(new DataObject)));
            m_callback = boost::bind(&CAsyncRetriever::ProcessResults, this, _1, m_inProgress.back());
        }

            // ...
    }

    void ProcessResults(DataObject* data)
    {
                // CALLED ON ANOTHER THREAD ... IS THIS SAFE?
        data->m_SomeMember.SomeMethod();
                data->m_SomeOtherMember = SomeStuff;
    }

    void Cleanup()
    {
                // ...

        { // scope for data lock
            boost::lock_guard<boost::mutex> lock(m_dataMutex);
            while(!m_inProgress.empty() && m_inProgress.front()->IsComplete())
                m_inProgress.erase(m_inProgress.begin());
        }

                // ...
         }

private:
    std::vector<SmartPtr<DataObject>> m_inProgress;
    boost::mutex m_dataMutex;
        // other members
};

编辑:这是ProccessResults回调的实际代码(为您的利益加上注释)

    void ProcessResults(CRetrieveResults* pRetrieveResults, CRetData* data)
        {
// pRetrieveResults is delayed binding that server passes in when invoking callback in thread pool
// data is raw pointer to ref counted object in vector of main thread (the DataObject* in question)

                // if there was an error set the code on the atomic int in object
            data->m_nErrorCode.Store_Release(pRetrieveResults->GetErrorCode());

                // generic iterator of results bindings for generic sotrage class item
            TPackedDataIterator<GenItem::CBind> dataItr(&pRetrieveResults->m_DataIter);
                // namespace function which will iterate results and initialize generic storage
            GenericStorage::InitializeItems<GenItem>(&data->m_items, dataItr, pRetrieveResults->m_nTotalResultsFound); // this is potentially time consuming depending on the amount of results and amount of columns that were bound in storage class definition (i.e.about 8 seconds for a million equipment items in release)
                // atomic uint32_t that is incremented when kicking off async retrieve
            m_nStarted.Decrement(); // this one is done processing

                // boost function completion callback bound to interface that requested results
            data->m_complete(data->m_items);
        }

最佳答案

不，这不安全。
ProcessResults对通过DataObject传递给它的数据结构进行操作。它表明您在不同线程之间具有共享状态，并且如果两个线程同时在数据结构上运行，则可能会遇到麻烦。