take from LCM and ROS, send to LCM

edit

Hi all, I need to interface ROS and LCM.

I thought to do in the following way: I have a class. Let's call it MyClass I have an LCM callback that I use to fill a class variable. Lets call it MyClass::lcm_cb(); I have a ROS callback that I use to do my processing. Let's call it MyClass::ros_cb();

Actually the ROS callback is a synchronized callback that takes from two topics via message_filter.

I need process the data from the ROS message. As soon as I receive the ROS message, I want to get the last available message from LCM, invoking MyClass::lcm_cb(), and use it together with the ROS message. Then I want to publish on LCM again something.

I want that what dictates the frequency is ROS and not LCM. My pseudocode is something like this:

MyClass::MyClass(ros::NodeHandle& nh) : nh_(nh) {
    sync = new message_filters::Synchronizer<MySyncPolicy> (MySyncPolicy(10), first_sub, second_sub);
    sync->registerCallback(boost::bind(&MyClass::ros_cb, this, _1, _2));
    lcm_sub = mylcm.subscribe("LCM_TOPIC", MyClas::lcm_cb, this);
}

MyClass::ros_cb(const sensor_msgs::ImageConstPtr& depth_input,
    const sensor_msgs::PointCloud2ConstPtr& cloud_input) {
    // INVOKE LCM CALLBACK
    mylcm.handle();
    // DO STUFF
    mylcm.publish("LCM_OUTPUT", &out_msg_);
}


void MyClass::lcm_cb(const lcm::ReceiveBuffer *rbuf,
        const string &chan,
        const mav::pose_t *msg) {
     // DO OTHER STUFF
}

MyClass::run() {
    ros::spin();
}

int main(int argc, char **argv) {
    ros::init(argc, argv, "my_node");
    ros::NodeHandle nh;
    MyClass mc(nh);
    mc.run();
}

If I run it, apparently the ROS callback is not called or it gets stuck forever after the first call.

What is wrong?