ZeroMQ：如何在Windows上处理Ctrl-C

Question

I wonder how to handle Ctrl-C issued from the windows console.

#include <iostream>
#include <zmq.hpp>
#include <windows.h>

BOOL WINAPI consoleHandler( DWORD dwCtrlType ) {
    // what to do here?
    return TRUE;
}

int main() {
    SetConsoleCtrlHandler( consoleHandler, TRUE );

    zmq::context_t context( 1 );
    zmq::socket_t socket( context, ZMQ_REP );
    socket.bind( "tcp://*:5555" );

    while ( true ) {
        zmq::message_t request;
        try {
            socket.recv( &request );
        }
        catch(zmq::error_t& e) {
            std::cout << "zmq error" << std::endl;
        }
    }
}

This installs a handler function that can act upon a CTRL_C_EVENT coming from the console. Currently, it does nothing. As a result, the revc call does not fail throwing an exception as described here (in "Error handling") .

What I'd like to do is break ing the loop in the exception handler and letting the RAII features of the C++ binding do the required cleanup when exiting main() .

Answer 1

Usually I create a flag or some sort - either a global bool or a kernel Event.

Then you loop waiting on this flag to be reset - so in your case, I would create a simple global bool and then loop on it instead of while (true).

so:

bool g_shutdown = false;

BOOL WINAPI consoleHandler( DWORD dwCtrlType ) {
    g_shutdown = true;
    return TRUE;
}

while (!g_shutdown)
{
// do your zmq work
}

Its simple but effective - though this will not kill your program until the zmq work comes round to the while loop check again. (You can usually do this by shutting down the socket variable)

For a more robust (ie quicker to kill, depending on your situation) use a Event, and WaitforMultipleObject call to wait on both this shutdown event and whatever else your program is waiting on (ie that socket's recv call).