lightweight_throttle_nodelet.cpp

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#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;

    srv_ = boost::make_shared<dynamic_reconfigure::Server<Config> >(pnh_);
    dynamic_reconfigure::Server<Config>::CallbackType f =
      boost::bind(&LightweightThrottle::configCallback, this, _1, _2);
    srv_->setCallback(f);

    // Subscribe input topic at first in order to decide
    // message type of publisher.
    // nodelet will unsubscribe input topic after it receives the first topic.
    sub_.reset(new ros::Subscriber(
                 pnh_.subscribe<topic_tools::ShapeShifter>("input", 1,
                                                           &LightweightThrottle::inCallback,
                                                           this,
                                                           th_)));
  }

  void LightweightThrottle::configCallback(Config& config, uint32_t level)
  {
    boost::mutex::scoped_lock lock(mutex_);
    update_rate_ = config.update_rate;
  }

  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_ = true;
      }
    }
    else {      // No subscribers, nodelet can unsubscribe input topic
      if (subscribing_) {
        sub_->shutdown();
        subscribing_ = false;
      }
    }
  }
  
  void LightweightThrottle::inCallback(
    const boost::shared_ptr<topic_tools::ShapeShifter const>& msg)
  {
    boost::mutex::scoped_lock lock(mutex_);
    // advertise if not
    if (!advertised_) {
      // This section should be called once
      sub_->shutdown();         // Shutdown before advertising topic
      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);
      advertised_ = true;
      pub_ = pnh_.advertise(opts);
    }

    ros::Time now = ros::Time::now();

    if (latest_stamp_ > now) {
      ROS_WARN("Detected jump back in time. latest_stamp_ is overwritten.");
      latest_stamp_ = now;
    }

    if (update_rate_ > 0.0 && (now - latest_stamp_).toSec() > 1.0 / update_rate_) {
      pub_.publish(msg);
      latest_stamp_ = now;
    }
  }
}

#include <pluginlib/class_list_macros.h>
typedef jsk_topic_tools::LightweightThrottle LightweightThrottle;
PLUGINLIB_EXPORT_CLASS(LightweightThrottle, nodelet::Nodelet)