topic_priority.h

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#ifndef _TOPIC_PRIORITY_H_
#define _TOPIC_PRIORITY_H_

#include <ros/ros.h>

template <class cmd_type>
class TopicQueuePriority
{
        typename std::map<int,cmd_type> message_map;
        typename std::map<int,cmd_type>::iterator it;
        
        public:
                void push_msg(cmd_type msg)
                {
                        msg->lifetime=ros::Time::now().toSec()+msg->lifetime;
                        
                        it=message_map.find(msg->priority);
                        
                        if(it==message_map.end())
                                message_map[msg->priority]=msg;
                        else
                        {
                                message_map.erase(it);
                                message_map[msg->priority]=msg;
                        }
                }
                
                cmd_type top_msg(void)
                {
                        maintenance();
                        
                        int max_priority=-1;
                        typename std::map<int,cmd_type>::iterator it_max;
                        
                        for(it=message_map.begin();it!=message_map.end();it++)
                                if((*it).second->priority > max_priority)
                                {
                                        max_priority=(*it).second->priority;
                                        it_max=it;
                                }
                        
                        if(message_map.size())
                                return (*it_max).second;
                        
                        cmd_type null_ptr;
                        return null_ptr;
                }
        private:
                void maintenance(void)
                {
                        for(it=message_map.begin();it!=message_map.end();it++)
                                if(ros::Time::now().toSec() > (*it).second->lifetime)
                                        message_map.erase(it);
                }
};

#endif