Exit Waitset without using Signal Handler

[saftabrashid]

Hi,

I am running a simple IPC scenario using Iceoryx. I have a publisher that is publishing messages and a subscriber that receives and prints messages. I am using waitset in my subscriber. I am receiving all the messages from the publisher, however I am not able to exit the subscriber. After the publisher has finished the predefined set of messages, I want the subscriber to exit when, e.g., I press q on the keyboard. I do not want to use a Signal Handler as explained in waitset example codes. Previously, I was using kbhit() to exit my subscriber but now with waitset that does not work. My Subscriber code with waitset is given below

Subscriber with Waitset

//create runtime
//create subscriber
// Defining Waitset
          iox::popo::WaitSet<> waitset;
          // attach subscriber to waitset
          waitset.attachState(subscriber, iox::popo::SubscriberState::HAS_DATA).or_else([](auto)                                                                               {
          std::cerr << "failed to attach subscriber" << std::endl;
          std::exit(EXIT_FAILURE); });

while (running)
          {            
             // We block and wait for samples to arrive.
            auto notificationVector = waitset.wait();
            for (auto &notification : notificationVector)
            {
              if (notification->doesOriginateFrom(&subscriber))
              {
                subscriber.take()
                    //! [sample happy path]
                    .and_then([](auto &sample)
                              {
                                //! [print sample info]
                                std::cout << " got value: " << sample->mypayload << std::endl;
                                //! [print sample info]
                              })
                    //! [sample happy path]
                    .or_else([](auto &result)
                             {
                if (result == iox::popo::ChunkReceiveResult::NO_CHUNK_AVAILABLE)
                {
                    //std::cout << "Error receiving chunk." << std::endl;
                } });
              }
            }
            if (kbhit())
            {
              std::cin >> ch;
              switch (ch)
              {
              case 'q':
              {
                waitset.markForDestruction();
                printf("--> quit\n");
                running = 0;
              }
                default:
                printf("Received unexpected character: %c. Send 'h' to see available command", ch);
              }
            }
          }

Any pointers on how this problem can be solved?

[elBoberido]

@saftabrashid you need either a signal handler or another thread polling kbhit. With just one thread it is not possible to exit the waitset once it blocks in the wait call. Someone needs to tell the waitset to end its operation.

Why are you not able to use a signal handler?