relay_nodelet.cpp

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#include <pluginlib/class_list_macros.h>
#include "jsk_topic_tools/relay_nodelet.h"

namespace jsk_topic_tools
{

  void Relay::onInit()
  {
    advertised_ = false;
    subscribing_ = false;
    pnh_ = getPrivateNodeHandle();
    sub_ = pnh_.subscribe<topic_tools::ShapeShifter>("input", 1,
                                                     &Relay::inputCallback, this, th_);
  }
  
  void Relay::inputCallback(const boost::shared_ptr<topic_tools::ShapeShifter const>& msg)
  {
    boost::mutex::scoped_lock lock(mutex_);
    if (!advertised_) {
      // this block is called only once
      // in order to advertise topic.
      // we need to subscribe at least one message
      // in order to detect message definition.
      ros::SubscriberStatusCallback connect_cb
        = boost::bind( &Relay::connectCb, this);
      ros::SubscriberStatusCallback disconnect_cb
        = boost::bind( &Relay::disconnectCb, this);
      ros::AdvertiseOptions opts("output", 1,
                                 msg->getMD5Sum(),
                                 msg->getDataType(),
                                 msg->getMessageDefinition(),
                                 connect_cb,
                                 disconnect_cb);
      opts.latch = false;
      pub_ = pnh_.advertise(opts);
      advertised_ = true;
      // shutdown subscriber
      sub_.shutdown();
    }
    else if (pub_.getNumSubscribers() > 0) {
      pub_.publish(msg);
    }
  }

  void Relay::connectCb()
  {
    boost::mutex::scoped_lock lock(mutex_);
    NODELET_DEBUG("connectCB");
    if (advertised_) {
      if (pub_.getNumSubscribers() > 0) {
        if (!subscribing_) {
          NODELET_DEBUG("suscribe");
          sub_ = pnh_.subscribe<topic_tools::ShapeShifter>("input", 1,
                                                           &Relay::inputCallback, this, th_);
          subscribing_ = true;
        }
      }
    }
  }

  void Relay::disconnectCb()
  {
    boost::mutex::scoped_lock lock(mutex_);
    NODELET_DEBUG("disconnectCb");
    if (advertised_) {
      if (pub_.getNumSubscribers() == 0) {
        if (subscribing_) {
          NODELET_DEBUG("disconnect");
          sub_.shutdown();
          subscribing_ = false;
        }
      }
    }
  }
  
}

typedef jsk_topic_tools::Relay Relay;
PLUGINLIB_EXPORT_CLASS(Relay, nodelet::Nodelet)