c++ - pthread_create 问题

Question

我有这个代码:

void* ConfigurationHandler::sendThreadFunction(void* callbackData)
{
   const EventData* eventData = (const EventData*)(callbackData);

   //Do Something

   return NULL;
}

void ConfigurationHandler::sendCancel()
{
    EventData* eventData = new EventData();
    eventData ->Name = "BLABLA"

    pthread_t threadId = 0;
    int ret = pthread_create(&threadId,
                             NULL,                                                              
                             ConfigurationHandler::sendThreadFunction,
                             (void*) eventData );                                   // args passed to thread function
    if (ret)
    {
        log("Failed to launch thread!\n");
    }
    else
    {
        ret = pthread_detach(threadId);
    }   
}

我收到一个编译器错误:

error: argument of type 'void* (ConfigurationHandler::)(void*)' does not match 'void* (*)(void*)'

Answer 1

解决您的问题的典型方法是通过 void 指针(此数据指针在其接口(interface)中)将 C++ 对象传递给 pthread_create()。传递的线程函数将是全局的(可能是静态函数)，它知道 void 指针实际上是一个 C++ 对象。

就像这个例子:

void ConfigurationHandler::sendThreadFunction(EventData& eventData)
{
   //Do Something
}

// added code to communicate with C interface
struct EvendDataAndObject {
   EventData eventData;
   ConfigurationHandler* handler;
};
void* sendThreadFunctionWrapper(void* callbackData)
{
   EvendDataAndObject* realData = (EvendDataAndObject*)(callbackData);

   //Do Something
   realData->handler->sendThreadFunction(realData->eventData);
   delete realData;
   return NULL;
}

void ConfigurationHandler::sendCancel()
{
    EvendDataAndObject* data = new EvendDataAndObject();
    data->eventData.Name = "BLABLA";
    data->handler = this; // !!!

    pthread_t threadId = 0;
    int ret = pthread_create(&threadId,
                             NULL,                                                              
                             sendThreadFunctionWrapper,
                             data ); 
    if (ret)
    {
        log("Failed to launch thread!\n");
    }
    else
    {
        ret = pthread_detach(threadId);
    }   
}