Re: [Boost-users] [asio] Second connection fails

Subject: Re: [Boost-users] [asio] Second connection fails
From: Florian Lindner (mailinglists_at_[hidden])
Date: 2018-06-21 07:01:55

Am 21.06.2018 um 05:01 schrieb William Jagels:
> Can you re-run your test code with handler tracking enabled and post the output? How to enable:
> https://www.boost.org/doc/libs/1_67_0/doc/html/boost_asio/overview/core/handler_tracking.html

Hey,

I already did, but it shows very little information for non-asnyc operations. Anyways, I managed to fix it yesterday and
it was my own stupid mistake, not related to boost asion.

Thanks a lot for your input!
Florian

> 
> On Tue, Jun 19, 2018, 07:16 Florian Lindner via Boost-users <boost-users_at_[hidden]
> <mailto:boost-users_at_[hidden]>> wrote:
> 
>     Hello,
> 
>     I am using boost.asio to connect a self written host. The function below is called with acceptorRanks = {0, 1}. The
>     first connection went well, but the second one fails (to 1). It is always the second with, e.g. when called with {1, 0},
>     connecting to 0 fails.
> 
>     I took the code out of context, changed some lines for clarity, I hope you can help me!
> 
>     The sockets seems to connect, i.e. there is no error, but the asio::write fails with "Bad file descriptor"
> 
>     Wireshark only shows traffic for the first connections, nothing at all the second (when filtered by port name). The
>     connection is always on localhost.
> 
>     The host to wich I connect always takes on connection per process, that is way I think the problem is with the
>     requester.
> 
>     I would be really thankful for any help what the problem could be.
> 
>     Best Thanks!
>     Florian
> 
> 
>     Same code: https://gist.github.com/floli/d418405ca50d722f1abf8bf5971466e2
> 
>     void requestConnection(std::string      const &nameAcceptor,
>                            std::string      const &nameRequester,
>     Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â std::set<int>Â  Â  const &acceptorRanks,
>                            int                     requesterRank)
> 
>     {
>     Â  boost::asio::ip::tcp::resolver resolver(*_ioService);
> 
>     Â  for (auto const & acceptorRank : acceptorRanks) {
>     Â  Â  try {
>     Â  Â  Â  address = readAddress(nameAcceptor, nameRequester, acceptorRank);
>     Â  Â  Â  DEBUG("Requesting connection to " << address);
> 
>           std::string ipAddress  = address.substr(0, address.find(":"));
>     Â  Â  Â  std::string portNumber = address.substr(ipAddress.length()+1, address.length() - ipAddress.length()-1);
> 
>     Â  Â  Â  _portNumber = static_cast<unsigned short>(std::stoi(portNumber));
> 
>     Â  Â  Â  PtrSocket socket(new Socket(*_ioService)); // shared_ptr to socket
> 
>     Â  Â  Â  using asio::ip::tcp;
> 
>     Â  Â  Â  tcp::resolver::query query(tcp::v4(), ipAddress, portNumber);
> 
>     Â  Â  Â  while (not isConnected()) {
>     Â  Â  Â  Â  tcp::resolver::iterator endpoint_iterator = resolver.resolve(query);
>     Â  Â  Â  Â  boost::system::error_code error = asio::error::host_not_found;
>     Â  Â  Â  Â  boost::asio::connect(*socket, endpoint_iterator, error);
> 
>     Â  Â  Â  Â  _isConnected = not error;
> 
>     Â  Â  Â  Â  if (not isConnected()) {
>     Â  Â  Â  Â  Â  // Wait a little, since after a couple of ten-thousand trials the system
>     Â  Â  Â  Â  Â  // seems to get confused and the requester connects wrongly to itself.
>     Â  Â  Â  Â  Â  boost::asio::deadline_timer timer(*_ioService, boost::posix_time::milliseconds(1));
>     Â  Â  Â  Â  Â  timer.wait();
>     Â  Â  Â  Â  }
>     Â  Â  Â  }
> 
>     Â  Â  Â  DEBUG("Requested connection to " << address << ", rank = " << acceptorRank);
>     Â  Â  Â  _sockets[acceptorRank] = socket;
>     Â  Â  Â  WARN("CHECKPOINT 1 FOR RANK " << acceptorRank);
>     Â  Â  Â  asio::write(*_sockets.at <http://sockets.at>(acceptorRank), asio::buffer(&requesterRank, sizeof(int)));
>     Â  Â  Â  WARN("CHECKPOINT 2 FOR RANK " << acceptorRank); // reached only for acceptorRank=0
>     Â  Â  } catch (std::exception &e) {
>     Â  Â  Â  ERROR("Requesting connection to " << address << " failed: " << e.what());
>     Â  Â  }
>     Â  }
>     Â  // NOTE:
>     Â  // Keep IO service running so that it fires asynchronous handlers from another thread.
>       _work   = PtrWork(new asio::io_service::work(*_ioService));
>     Â  _thread = std::thread([this]() { _ioService->run(); });
>     }
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