lightweight_throttle_nodelet.cpp

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

namespace jsk_topic_tools
{
  void LightweightThrottle::onInit()
  {
    pnh_ = this->getPrivateNodeHandle();
    latest_stamp_ = ros::Time::now();
    advertised_ = false;
    subscribing_ = false;
    pnh_.param("update_rate", update_rate_, 1.0); // default 1.0
    sub_.reset(new ros::Subscriber(
                 pnh_.subscribe<topic_tools::ShapeShifter>("input", 1,
                                                           &LightweightThrottle::inCallback,
                                                           this,
                                                           th_)));
  }

  void LightweightThrottle::connectionCallback(
    const ros::SingleSubscriberPublisher& pub)
  {
    if (pub_.getNumSubscribers() > 0) {
      if (!subscribing_) {
        sub_.reset(new ros::Subscriber(
                     pnh_.subscribe<topic_tools::ShapeShifter>(
                       "input", 1,
                       &LightweightThrottle::inCallback,
                       this,
                       th_)));
        subscribing_ = false;
      }
    }
    else {
      if (subscribing_) {
        sub_->shutdown();
        subscribing_ = true;
      }
    }
  }
  
  void LightweightThrottle::inCallback(
    const boost::shared_ptr<topic_tools::ShapeShifter const>& msg)
  {
    // advertise if not
    if (!advertised_) {
      ros::SubscriberStatusCallback connect_cb
        = boost::bind(&LightweightThrottle::connectionCallback, this, _1);
      ros::AdvertiseOptions opts("output", 1,
                                 msg->getMD5Sum(),
                                 msg->getDataType(),
                                 msg->getMessageDefinition(),
                                 connect_cb,
                                 connect_cb);
      pub_ = pnh_.advertise(opts);
      advertised_ = true;
      sub_->shutdown();
    }
    ros::Time now = ros::Time::now();
    if ((now - latest_stamp_).toSec() > 1 / update_rate_) {
      // publish the message to output topic only if any
      // subscriber is
      if (pub_.getNumSubscribers()) {
        pub_.publish(msg);
      }
      latest_stamp_ = now;
    }
  }
}

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