c++ - 在 C++ 中创建线程时出错

Question

我正在执行一个发送短信程序，但是当我在线程中创建与服务器的连接时出现错误。

g++ -L/usr/lib/i386-linux-gnu -o main Socket.cpp ServerSocket.cpp modemSMS_w.cpp main.cpp Config.cpp -lpthread -lserial -lxml2 -lmysqlclient
modemSMS_w.cpp: In member function ‘void modem::enviasms()’:
modemSMS_w.cpp:96:77: error: cannot convert ‘void* (modem::*)(void*)’ to ‘void* (*)(void*)’ for argument ‘3’ to ‘int pthread_create(pthread_t*, const pthread_attr_t*, void* (*)(void*), void*)’

程序:

#include "modemSMS_w.hpp"
#define CTRL_C "\x1A"

using namespace LibSerial;
using namespace std;

modem::modem()
{
}

void *modem::func_servidor(void *ptr)
{

ServerSocket server(30001);

        try {
                ServerSocket new_sock;
                while(1)
                {
                        server.accept(new_sock);
                        cout << "Conexao aceita" << endl;
                }
        }
        catch (SocketException& e) {
                cout << "Erro: Criando Servidor" << endl;
        }

}

int modem::setSerial() {
.....
....
...
}

void modem::enviasms(){

  pthread_t thread_servidor;
  pthread_cond_t cv;

  const int PORT_MON = 30000;
  string serialPort = "/dev/ttyS0";

  int argc;
  int ret;
  char **argv;

    cout << "\n------------------------\n  MODEM GPRS \n------------------------" << endl;
    string mensagem ="Conversao";
    mensagem.c_str();

    ret = pthread_cond_init(&cv, NULL);
    bool envia = true;
    envia = true;
    if (ret != 0)
    {
            cout << "Erro na criação do evento. Por favor reeinicie o programa." << endl;
    }

    //ERROR IN THIS LINE
    pthread_create(&thread_servidor, NULL,&modem::func_servidor, (void* ) true );

    Config config;
    SerialStream ssStream;
    setSerial();

....
...
}

抱歉，我对在 C++ 中创建线程几乎一无所知。已经尝试解决这个问题，但没有成功。

Answer 1

您可以向您的类添加一个静态函数并在 pthread_create 函数中使用它:

class modem {
    public:
        //...
        static void* thread_func(void* arg);
        //...
};

void* modem::thread_func(void* arg) {
    return reinterpret_cast<modem*>(arg)->func_servidor();
}

void *modem::func_servidor() {
    // some code
}

void modem::enviasms(){
    //some code scipped
    if(pthread_create(&thread_servidor, NULL, &modem::thread_func, reinterpret_cast<void*>(this)) != 0) {
        //some error handling code
    }
    //...
    if(pthread_join(thread_servidor, NULL) != 0) {
    // handle error
    }
}

但是，恕我直言，使用 boost 或 std 线程要好得多。这种方法不需要静态函数:

auto thr = std::thread{ &modem::func_servidor, this };
//...
thr.join();

但是请注意，当线程存在时，您必须检查 this 指向的对象是否存在。