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Delete a model from within its own modelPlugin

asked 2020-07-10 13:03:52 -0500

rezenders gravatar image

I wrote a ModelPlugin to delete the model to which it is attached after a certain period of time. The problem is that when the model is deleted, gazebo stops working, it just freezes.

Plugin code:

#include <ignition/math/Pose3.hh>
#include <gazebo/common/Plugin.hh>
#include <gazebo/physics/Model.hh>
#include "gazebo_msgs/DeleteModel.h"
#include "ros/ros.h"
#include <thread>
#include <chrono>


namespace gazebo{
  class VictimPlugin : public ModelPlugin{
  private:
    physics::ModelPtr model;

    int drowning_time_ = 0;
    std::thread timer_thread_;

    void timerThreadFunction(){
      std::this_thread::sleep_for(
        std::chrono::milliseconds(this->drowning_time_));

      gazebo_msgs::DeleteModel del_model;
      del_model.request.model_name = this->model->GetName();
      ros::service::call("/gazebo/delete_model", del_model);

   }

  public:
    VictimPlugin() : ModelPlugin(){}
    ~VictimPlugin(){
      timer_thread_.join();
    }

    void Load(physics::ModelPtr _model, sdf::ElementPtr _sdf){
      model = _model;

      if (!_sdf->HasElement("drowningTime")){
        this->drowning_time_ = 5000;
        ROS_DEBUG("Victim plugin missing <drowningTime>, default to 5000ms");
      }else{
        this->drowning_time_ = _sdf->Get<int>("drowningTime");
      }

      this->timer_thread_ =
        std::thread(std::bind(&VictimPlugin::timerThreadFunction, this));
    }
  };
  GZ_REGISTER_MODEL_PLUGIN(VictimPlugin)
}

I am adding the model to the world file like this:

<include>
  <name>victim_randy</name>
  <pose>7 17.5 0.1 -1.57 0 0</pose>
  <uri>model://rescue_randy</uri>
  <plugin name="victim" filename="libvictim.so">
    <drowningTime>5000</drowningTime>
  </plugin>
</include>

I am using gazebo version 9.13.1

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1 Answer

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answered 2020-07-10 14:50:09 -0500

nlamprian gravatar image

updated 2020-07-10 14:51:11 -0500

The problem is that you do not allow the destructor to return. Your thread never joins due to the service call.

You can use directly the gazebo interface to delete the model, which will allow you to do this asynchronously.

#include <gazebo/transport/Node.hh>
transport::NodePtr node = boost::make_shared<transport::Node>();
node->Init();
transport::PublisherPtr request_pub = node->Advertise<msgs::Request>("~/request");
msgs::Request *msg = msgs::CreateRequest("entity_delete", model->GetName());
request_pub->Publish(*msg);
delete msg;
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Comments

That makes sense, it worked. Thank you!

rezenders gravatar imagerezenders ( 2020-07-13 09:01:22 -0500 )edit
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Asked: 2020-07-10 13:03:52 -0500

Seen: 92 times

Last updated: Jul 10 '20