Boost :: Asio-async_accept处理程序中的async_wait使应用程序崩溃

Question

I am currently trying to create a server application using Boost::Asio that does two simple things:

1. Accept a client's incoming connection
2. Once the client has been accepted, start a boost::asio::deadline_timer which repeats itself

The following code shows my current attempt:

#define BOOST_ASIO_ENABLE_HANDLER_TRACKING

#include <WinSock2.h>
#include <Mswsock.h>
#include <boost/asio/io_service.hpp>
#include <boost/asio/ip/tcp.hpp>
#include <boost/bind.hpp>
#include <boost/date_time/posix_time/posix_time.hpp>

using namespace boost::asio;
using namespace boost::asio::ip;

void timerHandler(const boost::system::error_code& errorCode, deadline_timer* timer) {
    timer->expires_at(timer->expires_at() + boost::posix_time::seconds(1));
    timer->async_wait(boost::bind(timerHandler, _1, timer));
}

void acceptHandler(const boost::system::error_code &errorCode, io_service *ioService) {
    deadline_timer timer(*ioService, boost::posix_time::seconds(1));
    timer.async_wait(boost::bind(timerHandler, _1, &timer));
}

int main(int argc, char** argv) {
    io_service ioService;
    tcp::socket socket(ioService);
    tcp::acceptor acceptor{ ioService, tcp::endpoint{ tcp::v4(), 12345 } };
    acceptor.listen();
    acceptor.async_accept(socket, boost::bind(acceptHandler, _1, &ioService));
    ioService.run();
    return EXIT_SUCCESS;
}

Problem :

The timer somehow does not work as expected in the acceptHandler . Somehow it gets cancelled twice, triggers an error on top of that and eventually crashes the entire application.

Handler Tracking Output :

@asio|1460922050.075890|0*1|socket@000000000015FAD0.async_accept
@asio|1460922051.153952|>1|ec=system:0 
@asio|1460922051.153952|1*2|deadline_timer@000000000015F608.async_wait 
@asio|1460922051.153952|1|deadline_timer@000000000015F608.cancel 
@asio|1460922051.153952|<1| 
@asio|1460922051.153952|>2|ec=system:995 
@asio|1460922051.153952|2|deadline_timer@000000000015F608.cancel

Questions :

1. What causes the acceptHandler to cancel the deadline_timer in line 4 of the Handler Tracking output?

2. What casues the error 995 in line 6 of the Handler Tracking output? Error message is: The I/O operation has been aborted because of either a thread exit or an application request

3. What causes the timerHandler to cancel the deadline_timer in line 7 of the Handler Tracking output?

Answer 1

timer is allocated on the stack in the acceptHandler and is therefore not valid by the time timerHandler is called. You need to allocate the timer dynamically.

Also, you should check for error codes in both handlers. This is especially important when you want to end the program and cancel the timer.