publisher_bug_example.cc

/*
 * Copyright (C) 2014 Open Source Robotics Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
*/

#include <atomic>
#include <chrono>
#include <csignal>
#include <iostream>
#include <string>
#include <thread>
#include <ignition/msgs.hh>
#include <ignition/transport.hh>

/// \brief Flag used to break the publisher loop and terminate the program.
static std::atomic<bool> g_terminatePub(false);

//////////////////////////////////////////////////
/// \brief Function callback executed when a SIGINT or SIGTERM signals are
/// captured. This is used to break the infinite loop that publishes messages
/// and exit the program smoothly.
void signal_handler(int _signal)
{
  if (_signal == SIGINT || _signal == SIGTERM)
    g_terminatePub = true;
}

//////////////////////////////////////////////////
int main(int argc, char **argv)
{
  // Install a signal handler for SIGINT and SIGTERM.
  std::signal(SIGINT,  signal_handler);
  std::signal(SIGTERM, signal_handler);

  // Create a transport node and advertise a topic.
  ignition::transport::Node node;
  std::string topic = "/foo";

  auto pub = node.Advertise<ignition::msgs::StringMsg>(topic);
  if (!pub)
  {
    std::cerr << "Error advertising topic [" << topic << "]" << std::endl;
    return -1;
  }

  // Prepare the message.
  ignition::msgs::StringMsg msg;
  unsigned int count{};
  // Publish messages at 1Hz.
  while (!g_terminatePub)
  {
    msg.set_data("HELLO" + std::to_string(count));
    if (!pub.Publish(msg))
      break;

    std::cout << "Publishing " << msg.data() << " on topic [" << topic << "]" << std::endl;
    count++;
    // No loop frequency is set in order to force a big amount of messages being published.
  }

  return 0;
}