我在这里写的文字是我之前在 Boost 的另一个线程中打开的后续问题:序列化/反序列化通过 ZeroMQ 拉式套接字传递的自定义 C++ 对象。早期线程中的编译问题已通过使用 textarchive 类型而不是 binaryarchive 解决,但现在我在反序列化时遇到运行时问题。为方便起见,我在这里用一个新的问题陈述重复前面的文本。我对 C++ 领域相对较新,并感谢任何进一步的帮助。
描述:
我有一个名为GenericMessage的 C++ 类,它只包含一个 id 和数据作为其成员(参见下面的代码片段 2 - GenericMessage.hxx)。我的意图是序列化这个类的一个实例,并通过实现推送模式的 ZeroMQ 套接字发送它。
序列化和发送任务已在ZMQHandler 类(参见 sendToBE 函数)中实现,该类位于下面代码片段 3所示的头文件名 ZMQHandler.hxx 中。此类由下面第四个代码片段中所示的TestFE.cxx实例化。
GenericMessage 实例的接收和反序列化在TestBE.cxx中实现, 可在下面的第 5 个代码片段中找到。我的意图是通过 ZMQ 套接字(即拉套接字)接收 GenericMessage 实例,对其进行反序列化,然后将其成员打印到标准输出。
问题陈述:
当我运行接收器(即 TestBE.cxx)时,我在这里验证了我可以通过 ZMQ 套接字将数据从 TestFE.cxx 传输到 TEstBE.cxx。但是,当我尝试反序列化 TestBE.cxx 中第 28 行的输入存档时,我得到了下面第一个代码片段中显示的异常(请参见下面的第 5 个代码片段,第 28 行已被标记)。
在代码片段 5 中的 TestBE.cxx 中实现的这个反序列化过程中是否缺少一些东西?为什么你认为我得到这个例外?可能是我在 ZMQHandler.cxx 中实现的序列化过程中缺少 st(代码片段 3 - 函数 sendToBE)。提前致谢。
代码片段 1 GDB 输出和回溯
$ gdb TestBE
GNU gdb (GDB) 7.5-ubuntu
.....
(gdb) r
Starting program: /TestBE
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/i386-linux-gnu/libthread_db.so.1".
[New Thread 0xb7c12b40 (LWP 16644)]
[New Thread 0xb7411b40 (LWP 16645)]
Connecting to FE...
!!!!!!!!!!!!!!!!!!!!!这里开始!!!!!!!!!!!!!!!!!!!!!!!!!!!
**CHAR [22 serialization::archive 9 0 1 0
0 1 12 Hello there!]
terminate called after throwing an instance of 'std::logic_error'
what(): basic_string::_S_construct null not valid**
!!!!!!!!!!!!!!!!!!!!!!!!这里结束!!!!!!!!!!!!!!!!!!!!!!!!!!!
Program received signal SIGABRT, Aborted.
0xb7fdd424 in __kernel_vsyscall ()
(gdb) bt
#0 0xb7fdd424 in __kernel_vsyscall ()
#1 0xb7c7a1df in raise () from /lib/i386-linux-gnu/libc.so.6
#2 0xb7c7d825 in abort () from /lib/i386-linux-gnu/libc.so.6
#3 0xb7e608ad in __gnu_cxx::__verbose_terminate_handler() () from /usr/lib/i386- linux-gnu/libstdc++.so.6
#4 0xb7e5e4f3 in ?? () from /usr/lib/i386-linux-gnu/libstdc++.so.6
#5 0xb7e5e52f in std::terminate() () from /usr/lib/i386-linux-gnu/libstdc++.so.6
#6 0xb7e5e825 in __cxa_rethrow () from /usr/lib/i386-linux-gnu/libstdc++.so.6
#7 0x0804c1d4 in boost::archive::detail::pointer_iserializer<boost::archive::text_iarchive, GenericMessage<std::string> >::load_object_ptr (this=0x8054444, ar=...,
x=@0x805cb40: 0x805cb50, file_version=0) at /usr/include/boost/archive/detail/iserializer.hpp:327
#8 0xb7f3839d in boost::archive::detail::basic_iarchive::load_pointer(void*&, boost::archive::detail::basic_pointer_iserializer const*, boost::archive::detail::basic_pointer_iserializer const* (*) (boost::serialization::extended_type_info const&)) () from /usr/lib/libboost_serialization.so.1.49.0
#9 0x0804bea9 in boost::archive::detail::load_pointer_type<boost::archive::text_iarchive>::invoke<GenericMes sage<std::string>*> (ar=..., t=@0xbfffef70: 0xbfffeff8)
at /usr/include/boost/archive/detail/iserializer.hpp:524
#10 0x0804be55 in boost::archive::load<boost::archive::text_iarchive, GenericMessage<std::string>*> (ar=..., t=@0xbfffef70: 0xbfffeff8)
at /usr/include/boost/archive/detail/iserializer.hpp:592
#11 0x0804be36 in boost::archive::detail::common_iarchive<boost::archive::text_iarchive>::load_override<Gener icMessage<std::string>*> (this=0xbfffef84, t=@0xbfffef70: 0xbfffeff8)
at /usr/include/boost/archive/detail/common_iarchive.hpp:66
#12 0x0804be14 in boost::archive::basic_text_iarchive<boost::archive::text_iarchive>::load_override<GenericMe ssage<std::string>*> (this=0xbfffef84, t=@0xbfffef70: 0xbfffeff8)
at /usr/include/boost/archive/basic_text_iarchive.hpp:65
#13 0x0804bdf2 in boost::archive::text_iarchive_impl<boost::archive::text_iarchive>::load_override<GenericMes sage<std::string>*> (this=0xbfffef84, t=@0xbfffef70: 0xbfffeff8)
at /usr/include/boost/archive/text_iarchive.hpp:82
#14 0x0804bcec in boost::archive::detail::interface_iarchive<boost::archive::text_iarchive>::operator>> <GenericMessage<std::string>*> (this=0xbfffef84, t=@0xbfffef70: 0xbfffeff8)
at /usr/include/boost/archive/detail/interface_iarchive.hpp:60
#15 0x0804b2a1 in main () at TestBE.cxx:28
代码片段 2 (GenericMessage.hxx)
#include <iostream>
#include <string>
#include <sstream>
#include <boost/serialization/serialization.hpp>
#include <boost/archive/text_oarchive.hpp>
#include <boost/archive/text_iarchive.hpp>
template <class T>
class GenericMessage {
public:
GenericMessage():
beId(-1),
data(NULL)
{}
GenericMessage(int id, T msg):
beId(id),
data(msg)
{}
~GenericMessage(){}
T getData()
{
return data;
}
std::string toString()
{
std::ostringstream ss;
ss << getBeId();
std::string ret = ss.str();
return ret;
}
void setBeId(int id)
{
beId = id;
}
int getBeId()
{
return beId;
}
private:
friend class boost::serialization::access;
int beId;
T data;
template <class Archive>
void serialize(Archive & ar, const unsigned int version)
{
ar & beId;
ar & data;
}
};
代码片段 3 (ZmqHandler.hxx)
#include "zmq.hpp"
#include "GenericMessage.hxx"
#include <unistd.h>
#include <cassert>
template <class A>
class ZmqHandler {
public:
ZmqHandler():
mContext(1),
mOutbHandlerSocket(mContext, ZMQ_PUSH)
{
mOutbHandlerSocket.bind ("tcp://*:5555");
}
~ZmqHandler() {}
void sendToBE(GenericMessage<A> *theMsg)
{
std::ostringstream archive_stream;
boost::archive::text_oarchive archive(archive_stream);
try
{
archive << theMsg;
} catch (boost::archive::archive_exception& ex) {
std::cout << "Archive Exception during deserializing:" << std::endl;
std::cout << ex.what() << std::endl;
} catch (int e) {
std::cout << "EXCEPTION " << e << std::endl;
}
std::string outbound_data_ = archive_stream.str();
const char * buf = outbound_data_.c_str();
int len = strlen((const char*)buf);
std::cout << "LENGTH [" << len << "]" << std::endl;
zmq::message_t msgToSend(len);
memcpy ((char *) msgToSend.data(), buf, len);
if(memcmp((char *) msgToSend.data(), buf, len) != 0)
{
std::cout << "memcpy error!" << std::endl;
}
mOutbHandlerSocket.send(msgToSend);
std::cout << "SENT request: [" << theMsg->toString() << "]" << std::endl;
}
private:
zmq::context_t mContext;
zmq::socket_t mOutbHandlerSocket;
};
代码片段 4 (TestFE.cxx)
#include "ZmqHandler.hxx"
int main ()
{
ZmqHandler<std::string> zmqHandler;
int counter = 1;
while(1)
{
std::string data = "Hello there!\0";
GenericMessage<std::string> msg(counter, data);
zmqHandler.sendToBE(&msg);
counter++;
sleep(1);
}
return 0;
}
代码片段 5 (TestBE.cxx)
#include "zmq.hpp"
#include "GenericMessage.hxx"
#include <fstream>
int main ()
{
// Prepare our context and socket
zmq::context_t context (1);
zmq::socket_t socket (context, ZMQ_PULL);
std::cout << "Connecting to FE..." << std::endl;
socket.connect ("tcp://localhost:5555");
while(1){
zmq::message_t reply;
socket.recv (&reply);
const char *buf = static_cast<const char*>(reply.data());
std::cout << "CHAR [" << buf << "]" << std::endl;
std::string input_data_(buf);
std::istringstream archive_stream(input_data_);
boost::archive::text_iarchive archive(archive_stream);
GenericMessage<std::string> *theMsg;
try
{
/* !!!!!!!!!! LINE 28 is the following !!!!!!!!!!*/
archive >> theMsg;
} catch (boost::archive::archive_exception& ex) {
std::cout << "Archive Exception during deserializing:" << std::endl;
std::cout << ex.what() << std::endl;
} catch (int e) {
std::cout << "EXCEPTION " << e << std::endl;
}
std::cout << "ID" << theMsg->getBeId() << std::endl;
std::cout << "Data" << theMsg->getData() << std::endl;
}
return 0;
}